Medicine – Alzheimer’s Disease

Alzheimer’s disease is a progressive neurodegenerative disorder and the most common cause of dementia. It causes gradual deterioration in memory, cognition, language, orientation, judgment, and behaviour, eventually interfering substantially with activities of daily living.

The disease usually develops insidiously over years rather than abruptly, and early impairment of episodic memory is particularly characteristic.

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1. Progressive Memory Loss

The earliest and most typical feature is:

Progressive impairment of recent memory.

Patients may repeatedly:

Forget recent conversations.

Misplace objects.

Ask the same questions.

Miss appointments.

Forget recently learned information.

Older, well-established memories may initially be relatively preserved.

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2. Cognitive Decline

As the disease progresses, cognitive impairment becomes broader.

Patients may develop difficulty with:

Attention.

Planning.

Problem solving.

Judgment.

Executive function.

Recognition of people or objects.

Eventually, cognitive impairment affects independence and daily functioning.

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3. Language Deterioration

Language gradually deteriorates.

Common abnormalities include:

Word-finding difficulty.

Reduced vocabulary.

Difficulty naming objects.

Impaired comprehension in later disease.

Progressively less fluent communication.

This language impairment is often referred to as:

Aphasia.

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4. Disorientation

Patients may become disorientated to:

Time.

Place.

Eventually person.

Early on, they may become confused about dates or unfamiliar environments.

Later, they may become lost even in familiar surroundings.

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5. Personality and Behavioural Change

Behavioural and personality changes can develop as cortical dysfunction progresses.

Possible features include:

Apathy.

Irritability.

Anxiety.

Depression.

Agitation.

Suspiciousness.

Social withdrawal.

Psychotic symptoms such as hallucinations or delusions may occur in later disease.

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6. Pathological Basis

The two classic pathological hallmarks are:

Extracellular beta-amyloid plaques.

and

Intracellular neurofibrillary tangles composed of abnormal tau protein.

These abnormalities are associated with synaptic dysfunction, neuronal loss, and progressive cerebral atrophy.

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7. Beta-Amyloid Plaques

Beta-amyloid is produced from:

Amyloid precursor protein, APP.

Abnormal processing can result in accumulation of amyloid-beta peptides, especially:

Aβ42.

These peptides aggregate and form extracellular plaques.

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8. Neurotoxicity of Amyloid

Beta-amyloid accumulation is associated with:

Synaptic dysfunction.

Neuroinflammation.

Oxidative stress.

Neuronal injury.

The older note describes plaques simply as “neurotoxic,” which captures the concept, although modern understanding recognises a much more complex disease mechanism.

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9. Neurofibrillary Tangles

Neurofibrillary tangles are composed of abnormally phosphorylated:

Tau protein.

Tau normally helps stabilise neuronal microtubules.

When it becomes abnormally phosphorylated, it detaches from microtubules and aggregates inside neurons.

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10. Effect of Tau Abnormality

Abnormal tau causes disruption of:

Axonal transport.

Microtubule stability.

Neuronal function.

Eventually, affected neurons degenerate.

Therefore:

Abnormal tau → neurofibrillary tangles → neuronal dysfunction and death.

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11. Hippocampal Involvement

The hippocampus is particularly affected early in Alzheimer’s disease.

The hippocampus is essential for:

Formation of new memories.

This explains why early impairment of recent memory is such a prominent clinical feature.

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12. Medial Temporal Lobe Atrophy

Because the hippocampus and adjacent medial temporal structures are affected, imaging may demonstrate:

Hippocampal atrophy.

and

Medial temporal lobe atrophy.

As disease progresses, more widespread cortical atrophy develops.

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13. Cholinergic Neuron Loss

Alzheimer’s disease is associated with degeneration of cholinergic neurons, particularly those projecting from the:

Basal forebrain.

There is reduced activity of:

Choline acetyltransferase.

This leads to reduced synthesis and availability of:

Acetylcholine.

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14. Importance of Acetylcholine

Acetylcholine is important for:

Memory.

Attention.

Learning.

Loss of cholinergic activity contributes to cognitive impairment.

This provides the basis for the use of:

Cholinesterase inhibitors.

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15. Risk Factors

Important risk factors include:

Increasing age.

Family history.

Genetic susceptibility.

Down syndrome.

Vascular risk factors.

Previous significant head injury.

Age is the strongest overall risk factor.

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16. APOE

The APOE ε4 allele increases the risk of developing late-onset Alzheimer’s disease.

However:

APOE ε4 is a risk factor, not a deterministic diagnostic mutation.

Many people carrying APOE ε4 never develop Alzheimer’s disease, and many patients with Alzheimer’s disease do not carry it.

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17. Familial Early-Onset Alzheimer’s Disease

Rare familial forms of early-onset Alzheimer’s disease can result from mutations in genes such as:

APP.

PSEN1.

PSEN2.

These mutations can produce autosomal dominant inheritance.

They account for only a small proportion of total Alzheimer’s disease cases.

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18. Down Syndrome

People with Down syndrome have an increased risk of Alzheimer-type pathology.

This is partly because the APP gene is located on chromosome 21.

An extra copy of chromosome 21 can increase amyloid precursor protein production.

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19. Clinical Course

Alzheimer’s disease typically progresses gradually through:

Mild cognitive impairment or early dementia.

Then:

Moderate dementia.

Then:

Severe dementia.

Progression usually occurs over years.

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20. Early Stage

Early features commonly include:

Recent memory loss.

Word-finding difficulty.

Difficulty with complex tasks.

Reduced organisation.

Disorientation to time.

Patients may still retain considerable independence.

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21. Moderate Stage

With progression, patients may develop:

Increasing memory impairment.

Difficulty recognising people.

Impaired activities of daily living.

Behavioural symptoms.

Wandering.

Sleep disturbance.

Urinary problems in later stages.

Supervision becomes increasingly necessary.

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22. Severe Stage

Advanced Alzheimer’s disease can lead to:

Profound cognitive impairment.

Severe language loss.

Loss of mobility.

Dysphagia.

Incontinence.

Dependence for all daily activities.

Complications such as aspiration, infections, malnutrition, and immobility become increasingly important.

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23. Diagnosis

Diagnosis is based on:

Clinical history.

Collateral history from family or carers.

Cognitive assessment.

Neurological examination.

Laboratory investigation for reversible causes.

Brain imaging.

Biomarker testing may be used in selected cases.

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24. Cognitive Assessment

Cognitive testing may assess:

Memory.

Attention.

Language.

Executive function.

Visuospatial ability.

Examples include:

MMSE.

MoCA.

However, no single score establishes the diagnosis by itself.

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25. Excluding Reversible Causes

Investigations may be performed to exclude other causes of cognitive impairment.

Examples include:

Thyroid dysfunction.

Vitamin B12 deficiency.

Electrolyte abnormalities.

Medication effects.

Depression.

Normal pressure hydrocephalus.

Subdural haematoma.

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26. Brain Imaging

CT or MRI may demonstrate:

Generalised cerebral atrophy.

Medial temporal lobe atrophy.

Hippocampal volume loss.

Imaging also helps exclude structural causes such as tumour, stroke, or subdural collections.

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27. Biomarkers

Modern diagnostic assessment may include biomarkers of Alzheimer pathology.

These can include measures of:

Amyloid-beta.

Phosphorylated tau.

in CSF or through approved blood-based or imaging approaches in appropriate specialist settings.

These biomarkers can support diagnosis, especially when the clinical picture is uncertain.

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28. Treatment Goals

Traditional symptomatic treatments do not reverse established neuronal loss.

Their goals are to:

Temporarily improve or stabilise cognition.

Improve daily function.

Reduce some behavioural symptoms.

The overall benefit is usually modest.

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29. Cholinesterase Inhibitors

Cholinesterase inhibitors reduce the breakdown of:

Acetylcholine.

This increases acetylcholine availability at synapses.

Therefore:

Acetylcholinesterase inhibition → ↑ acetylcholine → improved cholinergic transmission.

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30. Donepezil

Donepezil is a commonly used acetylcholinesterase inhibitor.

It may produce modest improvement or stabilisation in:

Cognition.

Daily functioning.

Behavioural symptoms.

The effect varies between individuals.

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31. Rivastigmine

Rivastigmine also enhances cholinergic transmission.

It inhibits:

Acetylcholinesterase.

and

Butyrylcholinesterase.

It is used in Alzheimer’s disease and is also particularly associated with treatment of dementia in Parkinson disease.

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32. Galantamine

An additional cholinesterase inhibitor is:

Galantamine.

It is also used for mild-to-moderate Alzheimer’s disease in appropriate patients.

This is an important modern addition to the older list.

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33. Adverse Effects of Cholinesterase Inhibitors

Common adverse effects include:

Nausea.

Vomiting.

Diarrhoea.

Loss of appetite.

Weight loss.

Bradycardia.

Syncope.

Because of their cholinergic effects, caution is needed in patients with conduction disease or significant bradycardia.

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34. Memantine

Memantine acts as an antagonist at:

NMDA glutamate receptors.

It is used particularly in:

Moderate-to-severe Alzheimer’s disease.

It may also be combined with a cholinesterase inhibitor in selected patients.

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35. Mechanism of Memantine

The older note states that memantine “improves function of hippocampal neurons.”

A more accurate mechanism is:

Memantine reduces pathological excessive glutamatergic NMDA receptor activity while preserving much normal neurotransmission.

This may reduce excitotoxic neuronal stress and provide modest symptomatic benefit.

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36. NMDA Receptors

NMDA receptors are glutamate receptors involved in:

Learning.

Memory.

Synaptic plasticity.

Excessive activation can contribute to:

Excitotoxicity.

Memantine partially limits this excessive stimulation.

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37. Disease-Modifying Therapy

Modern Alzheimer treatment also includes anti-amyloid monoclonal antibodies for selected patients with early symptomatic disease and confirmed amyloid pathology.

These therapies aim to reduce amyloid burden rather than simply improve neurotransmitter function.

They are not suitable for every patient and require specialist assessment because benefits are modest and important adverse effects, including amyloid-related imaging abnormalities (ARIA), can occur.

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38. Non-Drug Management

Management should also include:

Regular physical activity.

Optimisation of hearing and vision.

Management of vascular risk factors.

Medication review.

Cognitive and social stimulation.

Support for carers.

Home safety assessment.

Advance care planning when appropriate.

These measures are important throughout the disease course.

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39. Alzheimer’s Disease – Note Form

Main presentation: progressive memory loss + cognitive decline.

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Other features: language deterioration + disorientation + behavioural/personality change.

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Early structure affected: hippocampus and medial temporal lobe.

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Plaques: extracellular beta-amyloid.

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Tangles: intracellular abnormal tau.

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Neurotransmitter change: loss of cholinergic neurons → reduced acetylcholine.

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Choline acetyltransferase: reduced activity.

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Course: gradual progressive decline over years.

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40. Treatment – Note Form

Cholinesterase inhibitors:

Donepezil.

Rivastigmine.

Galantamine.

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Mechanism:

Reduce acetylcholine breakdown.

Increase synaptic acetylcholine.

Produce modest symptomatic benefit.

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NMDA antagonist:

Memantine.

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Mechanism:

Reduces excessive NMDA-mediated glutamatergic activity.

Used particularly in moderate-to-severe disease.

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41. Pathology – Note Form

Beta-amyloid plaques → extracellular.

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Tau neurofibrillary tangles → intracellular.

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Hippocampal degeneration → early episodic memory loss.

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Basal forebrain cholinergic neuron loss → reduced acetylcholine.

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42. Alzheimer’s Disease versus Normal Pressure Hydrocephalus

Alzheimer’s disease:

Memory impairment often prominent early.

Gradual progression.

Hippocampal/medial temporal atrophy.

Gait disturbance usually not the dominant early feature.

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Normal pressure hydrocephalus:

Magnetic gait often appears early.

Cognitive slowing follows.

Urinary urgency/incontinence is characteristic.

Imaging shows disproportionate ventriculomegaly.

This distinction is useful because NPH may improve with CSF shunting.

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Key Clinical Pattern

Think of Alzheimer’s disease as:

PROGRESSIVE RECENT MEMORY LOSS → LANGUAGE AND ORIENTATION PROBLEMS → GLOBAL COGNITIVE AND FUNCTIONAL DECLINE.

The classic pathology is:

BETA-AMYLOID PLAQUES + TAU TANGLES + HIPPOCAMPAL ATROPHY + CHOLINERGIC NEURON LOSS.

The classic symptomatic treatments are:

DONEPEZIL / RIVASTIGMINE / GALANTAMINE → inhibit cholinesterase → ↑ acetylcholine.

and

MEMANTINE → NMDA receptor antagonist → reduces pathological glutamate-mediated excitation.

The key treatment principle is that these drugs may modestly improve or stabilise symptoms, but they do not fully restore lost neurons or reverse established dementia.

Medicine – Normal Pressure Hydrocephalus

Normal pressure hydrocephalus (NPH) is a form of communicating hydrocephalus in which the cerebral ventricles enlarge because cerebrospinal fluid is not absorbed normally. Despite the name, CSF pressure measured at a single lumbar puncture may be normal because the pressure can fluctuate over time.

The classic clinical triad is:

Gait disturbance + cognitive impairment + urinary dysfunction.

A common memory aid is:

“Wet, wobbly and wacky.”

1. Basic Mechanism

Normal pressure hydrocephalus usually results from impaired CSF absorption, particularly at the arachnoid granulations.

This causes gradual accumulation of CSF within the ventricular system.

Therefore:

Reduced CSF absorption → ventricular enlargement → stretching/compression of periventricular white matter → gait, cognitive and bladder dysfunction.

2. CSF Pressure

The term normal pressure hydrocephalus can be misleading.

CSF pressure is not necessarily continuously normal.

Instead, patients may experience:

Intermittent rises in intracranial pressure.

A lumbar puncture performed at one moment may therefore show a pressure within the normal range.

3. Communicating Hydrocephalus

NPH is usually a form of:

Communicating hydrocephalus.

This means that CSF can still flow through the ventricular system, but its absorption into the venous circulation is impaired.

There is no fixed obstruction within the ventricles themselves.

4. Role of Meningeal Scarring

Previous inflammation or bleeding around the meninges can interfere with CSF absorption.

This may occur after:

Meningitis.

Subarachnoid haemorrhage.

Head injury.

These conditions can produce scarring of the arachnoid pathways and reduce CSF resorption.

5. Idiopathic NPH

Many patients have no clear preceding cause.

This is called:

Idiopathic normal pressure hydrocephalus.

It is particularly seen in older adults.

6. Secondary NPH

When there is an identifiable cause, it is called:

Secondary NPH.

Important causes include:

Subarachnoid haemorrhage.

Meningitis.

Head trauma.

Previous neurosurgery in some cases.

7. Classic Clinical Triad

The classic triad consists of:

Gait disturbance.

Cognitive impairment.

Urinary dysfunction.

Gait disturbance is usually the earliest and most prominent feature.

8. Gait Disturbance

The gait abnormality is classically described as:

Magnetic gait.

The patient’s feet appear to be:

“Glued to the floor.”

There may be difficulty initiating walking, with short shuffling steps and a broad-based unsteady gait.

9. Magnetic Gait

Patients may have particular difficulty:

Starting to walk.

Turning.

Lifting the feet from the floor.

Maintaining balance.

The legs may appear weak or slow despite relatively preserved strength on formal testing.

10. Gait versus Parkinson Disease

The gait of NPH can resemble parkinsonism, but there are useful differences.

NPH tends to produce:

Broad-based gait.

Short steps.

Difficulty initiating gait.

Feet appearing stuck to the floor.

Parkinson disease more typically includes:

Bradykinesia.

Rigidity.

Reduced arm swing.

Rest tremor in some patients.

However, overlap can occur.

11. Cognitive Impairment

The older term dementia is often used in the classic triad, but early NPH more typically produces a subcortical/frontal cognitive syndrome.

Features can include:

Mental slowing.

Poor attention.

Reduced concentration.

Executive dysfunction.

Apathy.

Memory difficulty.

12. Frontal Lobe Dysfunction

The cognitive and bladder features are partly related to dysfunction of frontal-subcortical pathways running near the enlarged ventricles.

This explains why NPH can produce:

Executive dysfunction.

Reduced initiative.

Urinary urgency or incontinence.

13. Urinary Dysfunction

Bladder symptoms often begin with:

Urinary urgency.

and

Increased frequency.

Later, patients may develop:

Urinary incontinence.

Therefore, urinary incontinence is usually a later feature rather than necessarily the first bladder symptom.

14. Sequence of Symptoms

A useful clinical pattern is:

Gait disturbance first.

Then:

Cognitive decline.

Then:

Urinary dysfunction.

This sequence is not absolute, but gait abnormality is often the earliest and most treatment-responsive feature.

15. Causes of NPH

Important causes include:

Meningitis.

Head injury.

Subarachnoid haemorrhage.

These may impair CSF absorption through arachnoid scarring.

16. Meningitis

Previous meningitis can cause inflammation and scarring of the meninges.

This can impair CSF absorption and result in communicating hydrocephalus.

Therefore:

Meningitis → meningeal scarring → impaired CSF absorption → hydrocephalus.

17. Subarachnoid Haemorrhage

Subarachnoid haemorrhage is an important acquired cause.

Blood within the subarachnoid space may interfere with arachnoid granulation function.

This can result in:

Reduced CSF resorption.

and

Communicating hydrocephalus.

18. Head Injury

Significant head injury can also disturb CSF absorption.

Post-traumatic inflammation, haemorrhage, or scarring may eventually contribute to hydrocephalus.

19. Brain Imaging

Brain imaging usually demonstrates:

Ventriculomegaly.

This means enlargement of the ventricles.

The ventricular enlargement is typically greater than would be expected from ordinary age-related cerebral volume loss.

20. Ventricular Dilatation

The ventricles, particularly the lateral ventricles, become enlarged.

Therefore:

Dilated ventricles are a central radiological feature of NPH.

This reflects hydrocephalus rather than simple loss of brain tissue alone.

21. Cortical Atrophy – Important Clarification

The original note lists:

Cortical atrophy.

However, cortical atrophy is not the defining radiological feature of NPH.

In fact, an important diagnostic issue is distinguishing:

Ventricular enlargement due to hydrocephalus

from

Ventricular enlargement due to cerebral atrophy.

The latter is called:

Hydrocephalus ex vacuo.

22. Hydrocephalus Ex Vacuo

In cerebral atrophy, brain tissue volume decreases and the ventricles enlarge passively.

This is not true NPH.

Therefore:

NPH → ventricles enlarged disproportionately to cortical atrophy.

Hydrocephalus ex vacuo → ventricles enlarged because the brain itself has atrophied.

This distinction is important.

23. CT and MRI Findings

CT or MRI may demonstrate:

Enlarged lateral ventricles.

Enlargement of the third ventricle.

Disproportionate ventriculomegaly.

Periventricular signal change from transependymal CSF flow in some patients.

MRI can also help assess the pattern of sulci and other features supporting NPH.

24. DESH Pattern

A useful modern imaging pattern is:

Disproportionately enlarged subarachnoid-space hydrocephalus, or DESH.

This can include:

Ventriculomegaly.

Relatively tight high-convexity sulci.

Relatively enlarged Sylvian fissures.

This pattern can support the diagnosis of NPH.

25. Evans Index

Ventricular enlargement may be quantified using the:

Evans index.

This compares the width of the frontal horns of the lateral ventricles with the internal diameter of the skull.

An elevated value supports ventriculomegaly, although imaging diagnosis should not rely on this measurement alone.

26. Diagnosis

Diagnosis combines:

Typical clinical features.

Compatible brain imaging.

Assessment of response to CSF removal.

The clinical picture and imaging should be interpreted together.

27. Lumbar Puncture

A diagnostic lumbar puncture may be performed.

The opening pressure is often:

Normal or only mildly elevated.

More importantly, removal of a relatively large volume of CSF may temporarily improve symptoms.

28. Large-Volume Tap Test

The CSF tap test involves removing CSF by lumbar puncture and then reassessing the patient’s function.

Particular attention is paid to:

Walking speed.

Step length.

Balance.

Gait initiation.

Improvement after CSF removal supports the possibility that shunting may be beneficial.

29. External Lumbar Drainage

In selected cases, temporary:

External lumbar drainage

may be used when the diagnosis remains uncertain.

A more sustained improvement in gait or cognition after drainage can support shunt responsiveness.

30. Treatment

The principal treatment for symptomatic NPH in appropriately selected patients is:

CSF shunt surgery.

The commonest procedure is:

Ventriculoperitoneal shunting.

31. Ventriculoperitoneal Shunt

A ventriculoperitoneal shunt drains CSF from the:

Cerebral ventricles

to the:

Peritoneal cavity.

This lowers ventricular CSF volume and may improve neurological function.

32. Response to Treatment

The symptom most likely to improve after successful shunting is:

Gait disturbance.

Urinary symptoms may also improve.

Cognitive impairment can improve, but response is more variable, particularly if longstanding or if another neurodegenerative disorder is present.

33. Shunt Complications

Potential complications include:

Infection.

Shunt blockage.

Over-drainage.

Subdural haematoma or hygroma.

Mechanical failure.

Therefore, careful patient selection is important.

34. Important Differential Diagnoses

Conditions that can resemble NPH include:

Parkinson disease.

Vascular parkinsonism.

Alzheimer disease.

Lewy body dementia.

Cervical myelopathy.

Peripheral neuropathy.

Medication effects.

Hydrocephalus ex vacuo from cerebral atrophy.

35. NPH versus Alzheimer Disease

NPH often presents with:

Gait disturbance early.

Frontal-subcortical cognitive slowing.

Urinary symptoms.

Alzheimer disease more characteristically begins with:

Progressive episodic memory impairment.

A prominent early magnetic gait should therefore raise suspicion for NPH rather than uncomplicated Alzheimer disease.

36. Normal Pressure Hydrocephalus – Note Form

Type: communicating hydrocephalus.

Mechanism: impaired CSF absorption.

Pressure: may fluctuate; a single lumbar puncture may show normal pressure.

Classic triad: gait disturbance + cognitive impairment + urinary dysfunction.

Gait: magnetic gait, “feet glued to the floor.”

Cognition: frontal/subcortical slowing and executive dysfunction.

Bladder: urgency/frequency followed by possible incontinence.

Causes: idiopathic, meningitis, subarachnoid haemorrhage, head injury.

Imaging: ventriculomegaly disproportionate to cerebral atrophy.

Diagnostic support: improvement following CSF removal.

Treatment: ventriculoperitoneal shunt in suitable patients.

37. Important Correction to the Original Radiology Note

The original sequence:

Cortical atrophy + dilated ventricles + hydrocephalus

can be misleading.

A better way to remember the radiology is:

NPH → enlarged ventricles out of proportion to cortical atrophy.

If ventricular enlargement is simply due to severe cortical atrophy, consider:

Hydrocephalus ex vacuo rather than NPH.

Key Clinical Pattern

Think:

NORMAL PRESSURE HYDROCEPHALUS = GAIT + COGNITION + BLADDER.

The classic sequence is:

MAGNETIC GAIT → COGNITIVE SLOWING → URINARY URGENCY/INCONTINENCE.

The underlying mechanism is:

Impaired CSF absorption → communicating hydrocephalus → ventriculomegaly.

On imaging:

Dilated ventricles disproportionate to cortical atrophy.

And treatment is:

Ventriculoperitoneal shunting in appropriately selected patients.

Medicine – Creutzfeldt–Jakob Disease

Creutzfeldt–Jakob disease (CJD) is a rare, rapidly progressive and fatal prion disease of the central nervous system. It is characterised by rapidly worsening cognitive decline, myoclonus, ataxia and other neurological abnormalities.

Prion diseases are unusual because the infectious agent is not a virus, bacterium or fungus. Instead, disease results from abnormal folding of a naturally occurring prion protein.

1. Prion Disease

CJD belongs to the group of disorders known as:

Transmissible spongiform encephalopathies.

These are neurodegenerative diseases caused by accumulation of abnormal prion protein within the CNS.

The abnormal protein induces normally folded prion proteins to adopt the abnormal configuration.

Therefore:

Abnormal prion protein → conversion of normal prion protein → progressive accumulation → neuronal injury and death.

2. Prion Protein

The normal cellular prion protein is often referred to as:

PrPᶜ.

The abnormal disease-associated form is commonly referred to as:

PrPˢᶜ.

The abnormal form is resistant to normal protein degradation and tends to accumulate within nervous tissue.

3. Effect on the Brain

Accumulation of abnormal prion protein produces progressive neurodegeneration.

Characteristic pathological changes include:

Neuronal loss.

Gliosis.

Spongiform change.

The term spongiform refers to the microscopic appearance of numerous tiny vacuoles within brain tissue, giving it a sponge-like appearance.

4. Main Forms of CJD

CJD can occur in several forms.

The major categories are:

Sporadic CJD.

Familial or genetic CJD.

Acquired CJD.

Variant CJD is usually considered a distinct acquired prion disease.

5. Sporadic CJD

Sporadic CJD is the most common form.

It occurs without a clear family history or known exposure.

The exact trigger for spontaneous abnormal prion folding is unknown.

It typically presents in later adulthood with rapidly progressive neurological deterioration.

6. Familial CJD

Familial CJD results from pathogenic variants in the:

PRNP gene.

Inheritance is usually:

Autosomal dominant.

Therefore, an affected individual may have a significant family history of prion disease or rapidly progressive neurological illness.

7. Genetic Prion Diseases

Familial CJD is one of several inherited prion disorders.

Other important genetic prion diseases include:

Fatal familial insomnia.

Gerstmann–Sträussler–Scheinker syndrome.

These are also associated with mutations in the PRNP gene.

8. Acquired Prion Disease

Prion disease can rarely be acquired from exposure to abnormal prion protein.

Important examples include:

Kuru.

Iatrogenic CJD.

Variant CJD.

These differ from sporadic and familial forms because transmission has occurred from an external source.

9. Kuru

Kuru was historically seen among the Fore people of Papua New Guinea.

It was transmitted through ritualistic consumption of human nervous tissue during mortuary practices.

The disease became an important demonstration that prion diseases could be transmissible.

Kuru is now extremely rare.

10. Iatrogenic CJD

Iatrogenic CJD has occurred through medical exposure to contaminated biological material.

Historical examples include:

Cadaveric human growth hormone.

Dura mater grafts.

Contaminated neurosurgical instruments.

Because prions are unusually resistant to standard sterilisation methods, special infection-control procedures are required when prion contamination is suspected.

11. Variant CJD

Variant CJD is linked to exposure to the agent causing:

Bovine spongiform encephalopathy – BSE.

BSE is commonly known as:

Mad cow disease.

Variant CJD differs clinically from typical sporadic CJD.

12. Clinical Features

The major clinical features of CJD include:

Rapidly progressive dementia.

Myoclonus.

Ataxia.

Behavioural or psychiatric disturbance.

Sleep abnormalities.

Visual or cerebellar abnormalities.

Pyramidal or extrapyramidal signs.

The disease usually progresses rapidly over months.

13. Rapidly Progressive Dementia

One of the most important features is:

Rapid cognitive decline.

Patients may develop:

Memory impairment.

Poor concentration.

Disorientation.

Language difficulty.

Executive dysfunction.

Unlike most common dementias, which progress over years, CJD often progresses over a much shorter period.

Therefore:

Rapid dementia over weeks to months → consider CJD among the differential diagnoses.

14. Myoclonus

Myoclonus is a classic feature.

It consists of:

Brief, sudden, shock-like involuntary muscle jerks.

These movements may be spontaneous or triggered by:

Sound.

Touch.

Movement.

Myoclonus is particularly characteristic when it develops in a patient with rapidly progressive dementia.

15. Ataxia

Cerebellar involvement can produce:

Gait ataxia.

Limb incoordination.

Dysarthria.

Unsteadiness.

Ataxia may appear early or develop during disease progression.

16. Visual Disturbance

Some patients develop visual abnormalities.

These may include:

Blurred vision.

Visual-field abnormalities.

Visual hallucinations.

Cortical visual impairment.

Prominent visual and cerebellar features may occur in some subtypes of sporadic CJD.

17. Pyramidal and Extrapyramidal Features

As the disease progresses, patients may develop:

Rigidity.

Bradykinesia.

Tremor.

Spasticity.

Hyperreflexia.

Extensor plantar responses.

This reflects widespread CNS involvement.

18. Sleep Abnormalities

Sleep disturbances can occur in prion disease.

These may include:

Insomnia.

Disrupted sleep–wake cycles.

Reduced sleep quality.

Severe progressive insomnia is particularly characteristic of fatal familial insomnia, although sleep abnormalities can also occur in CJD.

19. Behavioural Disturbance

Behavioural and psychiatric symptoms may occur in CJD.

These can include:

Anxiety.

Depression.

Irritability.

Withdrawal.

Personality change.

They are particularly important in variant CJD.

20. Variant CJD Presentation

Variant CJD tends to affect younger patients than classic sporadic CJD.

Early manifestations often include prominent psychiatric symptoms such as:

Depression.

Anxiety.

Behavioural change.

Social withdrawal.

Painful sensory symptoms.

Neurological deterioration, ataxia and dementia then develop.

Therefore:

Early psychiatric symptoms are particularly characteristic of variant CJD.

21. Investigation

Diagnosis is based on the clinical picture together with:

MRI brain.

EEG.

CSF biomarkers.

Definitive confirmation requires demonstration of prion pathology, but in practice diagnosis is usually made using validated clinical and laboratory criteria.

22. MRI Brain

MRI is one of the most useful investigations.

Typical sporadic CJD may show restricted diffusion involving:

Cerebral cortex.

Caudate nucleus.

Putamen.

This cortical signal abnormality is often called:

Cortical ribboning.

23. Cortical Ribboning

Cortical ribboning refers to high signal along the cerebral cortex, particularly on:

Diffusion-weighted imaging.

and

FLAIR sequences.

This finding is strongly supportive of CJD when combined with the appropriate rapidly progressive clinical syndrome.

24. Variant CJD MRI

Variant CJD is associated with a characteristic MRI abnormality involving the:

Pulvinar of the thalamus.

This is known as the:

Pulvinar sign.

Historically it has also been called the hockey-stick sign when dorsomedial thalamic involvement accompanies the pulvinar abnormality.

25. EEG

EEG in sporadic CJD may demonstrate:

Periodic sharp-wave complexes.

These are classically repeated at roughly regular intervals.

However, they are not present in every patient and may appear later in the illness.

26. CSF Biomarkers

CSF may be tested for markers of rapid neuronal injury.

Historically important tests include:

14-3-3 protein.

Total tau.

These support the diagnosis but are not completely specific, because they may also be elevated in other causes of rapid brain injury.

27. RT-QuIC

A more specific modern investigation is:

RT-QuIC – real-time quaking-induced conversion.

This test detects abnormal prion-seeding activity in samples such as CSF.

A positive RT-QuIC result strongly supports a diagnosis of prion disease.

28. Differential Diagnosis

Because CJD causes rapidly progressive dementia, important alternative diagnoses must be excluded.

These include:

Autoimmune encephalitis.

HSV encephalitis.

Other CNS infections.

Metabolic encephalopathy.

Toxic disorders.

Malignancy.

Vasculitis.

Rapidly progressive neurodegenerative disease.

Some of these conditions are treatable, making early exclusion important.

29. Treatment

There is currently no established curative treatment for CJD.

Management is mainly:

Supportive.

Treatment focuses on:

Control of myoclonus.

Management of behavioural symptoms.

Nutrition and hydration.

Mobility and pressure-area care.

Palliative and family support.

30. Management of Myoclonus

Myoclonus may be treated symptomatically.

Drugs that may be used include:

Clonazepam.

Valproate.

Other antiseizure medications may be considered depending on the clinical situation.

31. Prognosis

CJD is relentlessly progressive and usually fatal.

In sporadic CJD, progression is typically rapid, often occurring over:

Months rather than years.

This rapid course is one of its most distinguishing features compared with more common dementias.

32. Sporadic CJD – Note Form

Most common form.

No known exposure.

No necessary family history.

Rapidly progressive dementia.

Myoclonus.

Ataxia.

MRI cortical ribboning / basal ganglia abnormalities.

EEG may show periodic sharp-wave complexes.

RT-QuIC supports diagnosis.

33. Familial CJD – Note Form

Cause: PRNP gene mutation.

Inheritance: autosomal dominant.

Mechanism: genetically determined abnormal prion protein folding.

May have: positive family history.

34. Acquired Prion Disease – Note Form

Important acquired forms include:

Kuru.

Iatrogenic CJD.

Variant CJD.

These involve transmission of abnormal prion protein from an external source.

35. Variant CJD – Note Form

Association: bovine spongiform encephalopathy.

Patients: typically younger than those with sporadic CJD.

Early features: psychiatric and behavioural symptoms.

Later features: ataxia + cognitive decline + neurological deterioration.

MRI: pulvinar sign.

36. Classic Clinical Pattern

The characteristic combination is:

Rapidly progressive dementia.

Myoclonus.

Ataxia.

These may be accompanied by:

Behavioural disturbance.

Visual abnormalities.

Pyramidal/extrapyramidal signs.

Sleep disturbance.

37. Important Investigation Pattern

For examination purposes:

MRI → cortical ribboning ± caudate/putamen involvement.

EEG → periodic sharp-wave complexes.

CSF → RT-QuIC positive ± elevated 14-3-3/tau.

Key Clinical Pattern

Think of CJD when you see:

RAPIDLY PROGRESSIVE DEMENTIA + MYOCLONUS + ATAXIA.

Then remember:

Prion accumulation → spongiform neurodegeneration.

Sporadic = most common.

Familial = autosomal dominant PRNP mutation.

Acquired = kuru / iatrogenic / variant CJD.

Variant CJD = younger patient + early behavioural/psychiatric disturbance + BSE association.

And the classic investigations are:

MRI cortical ribboning + EEG periodic sharp waves + CSF RT-QuIC.

Medicine – Causes of Meningitis

Meningitis is inflammation of the meninges, the membranes surrounding the brain and spinal cord. The most important causes are infectious, particularly bacterial, viral, fungal, and tuberculous infections.

The likely organism depends strongly on age, immune status, exposure, clinical setting, and CSF pattern.

1. Acute Bacterial Meningitis

Acute bacterial meningitis is a medical emergency because infection can progress rapidly and cause:

Cerebral oedema.

Raised intracranial pressure.

Sepsis.

Neurological damage.

Death.

The most likely organisms vary with age.

2. Acute Bacterial Meningitis in Adults

The two classic major causes in adults are:

Neisseria meningitidis – meningococcus.

and

Streptococcus pneumoniae – pneumococcus.

These remain among the most important organisms to recognise.

3. Meningococcal Meningitis

Neisseria meningitidis can cause meningitis and meningococcal septicaemia.

Typical features may include:

Fever.

Headache.

Neck stiffness.

Photophobia.

Altered consciousness.

A non-blanching petechial or purpuric rash suggests meningococcal infection, particularly when associated with sepsis.

4. Pneumococcal Meningitis

Streptococcus pneumoniae is an important cause of bacterial meningitis, especially in adults.

Risk may be increased by:

Older age.

Asplenia.

Immunocompromise.

CSF leak.

Cochlear implants.

Recent otitis media or sinus disease.

Pneumococcal meningitis can be severe and is associated with substantial neurological morbidity.

5. Acute Bacterial Meningitis in Neonates

The causative organisms in neonates differ from those in adults.

Important organisms include:

Group B Streptococcus.

Escherichia coli.

Listeria monocytogenes.

The original note lists group B streptococci and E. coli, but Listeria is also a classic neonatal pathogen.

6. Group B Streptococcus

Streptococcus agalactiae, or group B Streptococcus, is an important cause of neonatal sepsis and meningitis.

Transmission may occur around the time of birth from maternal genital tract colonisation.

7. Escherichia coli

E. coli is another major neonatal cause.

Certain strains, particularly those with the K1 capsule, have a strong association with neonatal meningitis.

8. Listeria monocytogenes

Listeria monocytogenes is an important cause of meningitis in:

Neonates.

Older adults.

Pregnant patients.

Immunocompromised patients.

It is therefore not simply a rare organism.

This is an important update to the older classification in your note.

9. CSF Pattern in Typical Acute Bacterial Meningitis

The classic CSF findings are:

Neutrophilic or polymorphonuclear pleocytosis.

High protein.

Low glucose.

Raised opening pressure.

Therefore:

Bacterial meningitis → neutrophils ↑↑ + protein ↑↑ + glucose ↓.

10. Bacterial Meningitis with Lymphocytic CSF

Although bacterial meningitis usually produces neutrophils, some bacterial infections may produce a lymphocytic or mixed CSF pattern, especially in subacute or partially treated disease.

Important examples include:

Listeria monocytogenes.

Leptospira species.

Treponema pallidum causing neurosyphilis.

Borrelia burgdorferi causing Lyme neuroborreliosis.

11. Listeria and CSF

Listeria meningitis may show:

Neutrophils.

Lymphocytes.

or a

Mixed cellular response.

Therefore, CSF cell type alone cannot reliably exclude Listeria.

12. Leptospirosis

Leptospira infection can cause an aseptic meningitis picture.

The CSF often shows:

Lymphocytic pleocytosis.

This may occur along with systemic features such as:

Fever.

Myalgia.

Conjunctival suffusion.

Renal dysfunction.

Hepatic dysfunction.

depending on disease severity.

13. Syphilis

Treponema pallidum can involve the CNS at different stages of infection.

Neurosyphilis may produce:

Lymphocytic pleocytosis.

Raised protein.

Usually normal or mildly reduced glucose.

The presentation may be meningitic, vascular, cognitive, sensory, or mixed.

14. Lyme Disease

Borrelia burgdorferi can cause neuroborreliosis.

Neurological manifestations may include:

Lymphocytic meningitis.

Facial nerve palsy.

Radiculopathy.

Therefore, lymphocytic CSF does not always indicate a viral infection.

15. Causes with Predominantly Polymorphs in CSF

A neutrophilic or polymorphonuclear CSF response is classically associated with acute bacterial meningitis.

Important organisms in this category include:

Staphylococcus aureus.

Pseudomonas species.

and many other pyogenic bacteria.

However, some infections traditionally regarded as lymphocytic can be neutrophilic early.

16. Tuberculous Meningitis and Polymorphs

Mycobacterium tuberculosis classically causes a:

Lymphocytic CSF picture.

However, early TB meningitis can initially show neutrophils before evolving toward lymphocytic predominance.

Therefore, TB should not be excluded solely because an early CSF sample is neutrophilic.

17. Staphylococcus aureus

Staphylococcus aureus meningitis is relatively uncommon compared with pneumococcal or meningococcal disease.

It is more likely in situations such as:

Neurosurgery.

Head trauma.

Bacteraemia.

Endocarditis.

Spinal procedures.

Indwelling CNS devices.

The CSF is typically neutrophilic.

18. Pseudomonas

Pseudomonas aeruginosa is an uncommon community cause but is important in:

Hospital-acquired meningitis.

Neurosurgical patients.

Patients with ventricular drains or shunts.

Severe immunocompromise.

It generally produces a neutrophilic CSF response.

19. Chronic Bacterial Meningitis

The classic chronic bacterial cause in your notes is:

Mycobacterium tuberculosis.

Tuberculous meningitis usually has a more gradual onset than acute pyogenic bacterial meningitis.

20. Tuberculous Meningitis

TB meningitis commonly presents over days to weeks with:

Headache.

Fever.

Lethargy.

Confusion.

Cranial nerve palsies.

Altered consciousness.

Complications include:

Hydrocephalus.

Basal meningeal inflammation.

Cerebral infarction due to vasculitis.

21. CSF in Tuberculous Meningitis

The classic CSF findings are:

Lymphocytic pleocytosis.

Markedly raised protein.

Low glucose.

Raised opening pressure.

Early disease may occasionally show more neutrophils.

Therefore:

TB meningitis → lymphocytes ↑ + protein ↑↑ + glucose ↓.

22. Chronic Fungal Meningitis

The classic chronic fungal cause is:

Cryptococcus.

Cryptococcal meningitis is particularly associated with:

Advanced HIV infection.

Other forms of significant immunosuppression.

but it can also occur in apparently immunocompetent patients.

23. Cryptococcal Meningitis

Cryptococcal meningitis often develops subacutely.

Typical features include:

Headache.

Fever.

Altered mental status.

Raised intracranial pressure.

Meningism may sometimes be relatively mild.

24. CSF in Cryptococcal Meningitis

Typical findings may include:

Lymphocytic or mononuclear pleocytosis.

Raised protein.

Low glucose.

Markedly raised opening pressure.

In profoundly immunocompromised patients, the CSF white cell count may be surprisingly low despite severe infection.

25. Acute Viral Meningitis

Viral meningitis is usually less severe than acute bacterial meningitis.

The CSF classically shows:

Lymphocytic pleocytosis.

Mildly raised protein.

Normal glucose.

Therefore:

Viral meningitis → lymphocytes ↑ + protein mildly ↑ + glucose normal.

26. Enteroviruses

Enteroviruses are among the most common causes of viral meningitis.

Important examples include:

Coxsackieviruses.

Echoviruses.

Other non-polio enteroviruses.

The older note states “especially polio,” but modern practice more often implicates non-polio enteroviruses.

27. Poliovirus

Poliovirus is an enterovirus and can cause meningitis.

However, widespread vaccination has made poliomyelitis far less common in many regions.

Therefore, for examination purposes:

Enteroviruses are important viral causes, but non-polio enteroviruses are usually more common than poliovirus.

28. Mumps

Mumps virus can cause aseptic meningitis and encephalitis.

It was historically a more important cause before widespread vaccination.

Possible associated features include:

Parotitis.

Orchitis.

Pancreatitis.

However, neurological disease can occasionally occur without obvious parotid swelling.

29. Herpes Simplex Virus

HSV can cause viral meningitis.

HSV-2 is particularly associated with:

Aseptic meningitis.

In contrast:

HSV-1 is classically associated with encephalitis, especially temporal-lobe encephalitis.

This distinction is useful for exams.

30. Varicella-Zoster Virus

An additional important viral cause is:

Varicella-zoster virus.

VZV may cause:

Meningitis.

Encephalitis.

Myelitis.

Cerebral vasculopathy.

Neurological infection may sometimes occur without a typical shingles rash.

31. HIV and Viral Meningitis

Acute HIV infection can occasionally present with an aseptic meningitis syndrome.

In advanced HIV infection, however, the differential diagnosis expands considerably because opportunistic infections such as:

Cryptococcus.

Tuberculosis.

and other CNS infections become important.

32. Other Non-Infectious Causes

Not all meningitis is infectious.

Aseptic meningitis can occasionally occur with:

Drugs.

Malignancy.

Autoimmune or inflammatory disease.

Examples of drug-associated aseptic meningitis include some:

NSAIDs.

Antibiotics.

IV immunoglobulin.

These are less common but useful to remember when microbiological tests are negative.

33. Adult Causes – Note Form

Common acute bacterial:

Neisseria meningitidis.

Streptococcus pneumoniae.

Important additional organism:

Listeria monocytogenes, especially older or immunocompromised patients.

34. Neonatal Causes – Note Form

Group B Streptococcus.

Escherichia coli.

Listeria monocytogenes.

These are the classic organisms to remember.

35. Lymphocytic CSF Causes – Note Form

Lymphocytic CSF is not synonymous with viral infection.

Important causes include:

Viral meningitis.

Tuberculous meningitis.

Cryptococcal meningitis.

Listeria – sometimes mixed/lymphocytic.

Lyme disease.

Syphilis.

Leptospirosis.

36. Neutrophilic CSF Causes – Note Form

Important causes include:

Acute pyogenic bacterial meningitis.

Meningococcus.

Pneumococcus.

Staphylococcus aureus.

Pseudomonas.

Listeria – sometimes.

Early TB – occasionally.

Therefore, the differential cannot be based on cell type alone.

37. Chronic Meningitis – Note Form

Think particularly of:

Tuberculosis.

Cryptococcus and other fungal infections.

Syphilis.

Lyme disease.

Malignancy.

Inflammatory disorders.

38. CSF Pattern Summary

Acute bacterial meningitis:

Neutrophils ↑↑.

Protein ↑↑.

Glucose ↓.

Opening pressure often ↑.

Viral meningitis:

Lymphocytes ↑.

Protein mildly ↑.

Glucose usually normal.

Opening pressure normal or mildly ↑.

Tuberculous meningitis:

Lymphocytes ↑.

Protein markedly ↑.

Glucose ↓↓.

Opening pressure often ↑.

Cryptococcal meningitis:

Lymphocytes/mononuclear cells ↑.

Protein ↑.

Glucose ↓.

Opening pressure often markedly ↑.

Key Clinical Pattern

For rapid recall:

ADULT ACUTE BACTERIAL → MENINGOCOCCUS + PNEUMOCOCCUS.

NEONATE → GROUP B STREP + E. COLI + LISTERIA.

CHRONIC BACTERIAL → TB.

CHRONIC FUNGAL → CRYPTOCOCCUS.

ACUTE VIRAL → ENTEROVIRUSES ± MUMPS/HSV/VZV.

And remember the CSF pattern:

Bacterial = neutrophils + high protein + low glucose.

Viral = lymphocytes + mild protein rise + normal glucose.

TB/fungal = lymphocytes + high protein + low glucose.

Medicine – Encephalitis

Encephalitis is inflammation of the brain parenchyma, most commonly caused by viral infection. Because the brain tissue itself is affected, patients characteristically develop evidence of cerebral dysfunction, such as confusion, altered consciousness, seizures, behavioural changes, or focal neurological deficits.

This differs from meningitis, in which inflammation primarily involves the meninges surrounding the brain and spinal cord.

⸻

1. Encephalitis versus Meningitis

The major distinction is the anatomical site of inflammation.

Encephalitis → brain parenchyma.

Meningitis → meninges.

Because encephalitis affects functioning brain tissue, abnormalities of mental state and neurological function are particularly prominent.

⸻

2. Clinical Presentation

The typical presentation of encephalitis includes:

Headache.

Fever.

Confusion.

Altered level of consciousness.

Seizures.

Focal neurological abnormalities.

The presence of encephalopathy or altered mental status is especially important in distinguishing encephalitis from uncomplicated meningitis.

⸻

3. Headache

Headache is common and may occur because of:

Inflammation of intracranial structures.

Cerebral oedema.

Associated meningeal irritation.

Patients may therefore have overlapping features of both encephalitis and meningitis.

When both the meninges and brain parenchyma are involved, the term:

Meningoencephalitis

may be used.

⸻

4. Fever

Fever is common in infectious encephalitis and reflects the underlying inflammatory or infectious process.

Therefore, the combination:

Fever + altered mental state

should raise suspicion for a CNS infection, particularly when accompanied by seizures or focal neurological signs.

⸻

5. Confusion

Confusion is one of the characteristic features of encephalitis.

Patients may become:

Disorientated.

Agitated.

Behaviourally abnormal.

Unable to concentrate.

Unable to form new memories.

Behavioural or personality abnormalities may be particularly prominent when the temporal or frontal lobes are involved.

⸻

6. Altered Level of Consciousness

More severe encephalitis can cause progressive impairment of consciousness.

The patient may progress from:

Confusion → drowsiness → stupor → coma.

This may result from widespread cerebral inflammation, cerebral oedema, seizures, or raised intracranial pressure.

⸻

7. Seizures

Seizures are an important feature of encephalitis because inflamed cerebral tissue becomes electrically unstable.

Patients may develop:

Focal seizures.

Focal to bilateral tonic-clonic seizures.

Generalised convulsive seizures.

Status epilepticus.

Non-convulsive seizures should also be considered in a patient with persistent unexplained impaired consciousness.

⸻

8. Focal Neurology

Encephalitis can produce focal neurological abnormalities depending on the cerebral regions affected.

Examples include:

Hemiparesis.

Dysphasia.

Cranial nerve abnormalities.

Visual-field defects.

Focal sensory abnormalities.

Focal seizures.

Focal neurological abnormalities are particularly important because they indicate involvement of the brain parenchyma rather than isolated meningeal inflammation.

⸻

9. Viral Encephalitis

Viruses are among the most important infectious causes of encephalitis.

Important viral causes include:

Herpes simplex virus.

Enteroviruses.

Arboviruses.

Varicella-zoster virus.

HIV-associated infections or neurological disease.

Other viruses can also cause encephalitis depending on geography, age, immune status, vaccination history, and exposure.

⸻

10. Herpes Simplex Virus

HSV-1 is a particularly important cause of sporadic encephalitis in adults.

HSV encephalitis is clinically important because it is:

Potentially fatal.

but also

Specifically treatable with intravenous aciclovir.

Treatment should therefore begin promptly when HSV encephalitis is suspected.

⸻

11. HSV and the Temporal Lobes

HSV encephalitis characteristically affects the:

Medial and inferior temporal lobes.

It may also involve the:

Insular cortex.

and sometimes the:

Frontal lobes.

This produces the classic association between HSV encephalitis and temporal-lobe abnormalities.

⸻

12. Clinical Features of HSV Encephalitis

Patients may develop:

Fever.

Headache.

Confusion.

Personality or behavioural change.

Memory impairment.

Seizures.

Focal neurological deficits.

The combination of fever + altered behaviour/confusion + seizures + temporal-lobe abnormalities is highly suggestive.

⸻

13. Enteroviruses

Enteroviruses can cause CNS infection.

Examples include:

Coxsackieviruses.

Echoviruses.

Other enteroviruses.

They are particularly well known as causes of viral meningitis, although encephalitis and meningoencephalitis can also occur.

⸻

14. Arboviruses

Arboviruses are viruses transmitted by arthropods such as:

Mosquitoes.

or

Ticks.

The specific viruses encountered depend strongly on geographical location and travel history.

⸻

15. Japanese Encephalitis

Japanese encephalitis virus is an important mosquito-borne flavivirus causing encephalitis, particularly in parts of Asia and the Western Pacific.

It can cause severe neurological disease with:

Fever.

Altered consciousness.

Seizures.

Movement abnormalities.

Focal neurological deficits.

Vaccination is available for people at appropriate exposure risk.

⸻

16. Varicella-Zoster Virus

Varicella-zoster virus (VZV) can cause encephalitis, particularly in older or immunocompromised patients, although it can occur in other groups.

VZV can also produce:

Meningitis.

Myelitis.

Cerebellitis.

Cerebral vasculopathy and stroke.

Importantly, neurological VZV disease does not always require a prominent shingles rash.

⸻

17. HIV

HIV can affect the CNS through several mechanisms.

Neurological disease may result from:

Direct effects of HIV.

or, particularly with advanced immunosuppression:

Opportunistic CNS infections.

Therefore, an immunocompromised patient with encephalopathy requires consideration of a broader differential diagnosis.

⸻

18. Other Important Viral Causes

Other viruses capable of producing encephalitis include:

West Nile virus.

Tick-borne encephalitis virus.

Measles virus.

Mumps virus.

Influenza-associated neurological disease.

EBV and CMV in selected patients, particularly immunocompromised individuals.

The likely cause depends heavily on epidemiological and clinical context.

⸻

19. History

The history should assess:

Time course of illness.

Fever and systemic symptoms.

Seizures.

Behavioural or personality change.

Travel history.

Mosquito or tick exposure.

Animal exposure.

Immunosuppression.

Vaccination history.

Recent infections.

Medication or toxin exposure.

These clues may substantially narrow the differential diagnosis.

⸻

20. CSF Findings

Lumbar puncture is usually an important investigation when safe.

Typical viral encephalitis CSF findings include:

Lymphocytic pleocytosis.

Mild to moderately elevated protein.

Usually normal glucose.

However, the exact pattern varies according to the pathogen and timing of the lumbar puncture.

⸻

21. HSV PCR

When HSV encephalitis is suspected, CSF should be tested for:

HSV PCR.

PCR detects HSV DNA and is the key specific diagnostic test.

Other viral PCR or antibody tests may be performed depending on the suspected pathogen.

⸻

22. MRI Brain

MRI brain is generally the preferred imaging modality for encephalitis because it is more sensitive than CT for many forms of cerebral inflammation.

The distribution of abnormalities can sometimes provide important diagnostic clues.

For example:

Temporal/insular involvement → strongly suggests HSV in the appropriate clinical context.

⸻

23. EEG

EEG may demonstrate:

Diffuse cerebral slowing.

Focal abnormalities.

Epileptiform discharges.

It is particularly useful when seizures or non-convulsive status epilepticus are suspected.

In HSV encephalitis, temporal-lobe EEG abnormalities may occur.

⸻

24. Treatment

Management depends on the underlying cause.

However, because HSV encephalitis is both dangerous and treatable, suspected encephalitis commonly requires urgent consideration of:

Intravenous aciclovir.

If HSV encephalitis is clinically suspected, treatment should not be delayed while waiting for PCR confirmation.

⸻

25. Seizure Management

Associated seizures require appropriate antiseizure treatment.

A prolonged convulsive seizure is initially treated according to status epilepticus protocols, generally beginning with a:

Benzodiazepine.

Further antiseizure medication may be required if seizures continue.

⸻

26. Supportive Treatment

Severe encephalitis may require:

Airway and respiratory support.

Fluid and electrolyte management.

Treatment of seizures.

Management of cerebral oedema and raised intracranial pressure.

Critical-care monitoring.

Nutritional support.

Early recognition of neurological deterioration is essential.

⸻

27. Encephalitis – Note Form

Definition: inflammation of the brain parenchyma, commonly infectious and often viral.

⸻

Main features: headache + fever + confusion + altered consciousness + seizures ± focal neurology.

⸻

HSV: particularly important treatable cause; HSV-1 predominates in typical adult sporadic HSV encephalitis.

⸻

Enteroviruses: including coxsackieviruses; meningitis is particularly common, but encephalitis can occur.

⸻

Arboviruses: mosquito- or tick-borne viruses causing encephalitis.

⸻

Japanese encephalitis: important mosquito-borne cause, especially in endemic parts of Asia and the Western Pacific.

⸻

VZV: can cause encephalitis, meningitis, vasculopathy and other neurological disease.

⸻

HIV: CNS disease may occur directly or through opportunistic infections in immunosuppression.

⸻

28. Encephalitis versus Meningitis – Note Form

Encephalitis:

Brain parenchyma affected.

Confusion/behavioural change prominent.

Altered consciousness common.

Seizures common.

Focal neurological deficits may occur.

MRI brain may be abnormal.

⸻

Meningitis:

Meninges affected.

Headache prominent.

Neck stiffness/meningism prominent.

Photophobia common.

Mental status may initially remain relatively preserved in uncomplicated disease.

Seizures and focal neurological deficits are less characteristic than in encephalitis.

⸻

Key Clinical Pattern

Think:

ENCEPHALITIS = BRAIN DYSFUNCTION.

The classic clinical pattern is:

FEVER + HEADACHE + ALTERED MENTAL STATE ± SEIZURES ± FOCAL NEUROLOGY.

For the major treatable viral cause:

HSV-1 → temporal-lobe encephalitis → behavioural/memory changes + seizures → CSF HSV PCR → IV aciclovir.

The most important distinction is:

Meningitis → predominantly meningeal irritation.

Encephalitis → cerebral dysfunction with confusion, altered consciousness, seizures or focal neurological abnormalities.

Medicine – Herpes Simplex Encephalitis

Herpes simplex encephalitis (HSE) is an acute, potentially fatal viral infection of the brain caused most commonly by herpes simplex virus type 1 (HSV-1) in adults. It characteristically produces a necrotising encephalitis involving the temporal lobes, particularly the medial and inferior temporal regions.

It is one of the most important treatable causes of sporadic viral encephalitis. Because neurological damage can progress rapidly, intravenous aciclovir should be started immediately when HSV encephalitis is suspected, without waiting for definitive PCR confirmation.

1. Cause

In adults and older children, herpes simplex encephalitis is most commonly caused by:

HSV-1.

HSV-2 is less commonly responsible for encephalitis in adults but is particularly important in neonatal HSV infection and can also cause meningitis.

2. Temporal Lobe Predilection

HSV encephalitis has a characteristic tendency to involve the:

Temporal lobes.

The pathology particularly affects the:

Medial temporal lobes.

Inferior temporal lobes.

Insular cortex.

The frontal lobes may also become involved.

The original description of anterior temporal lobe pathology therefore captures an important feature, although involvement is often broader than the anterior temporal region alone.

3. Pathology

HSV produces a severe:

Necrotising haemorrhagic encephalitis.

There is inflammation, neuronal destruction, cerebral oedema, and often small areas of haemorrhage.

This explains why red blood cells may sometimes be found in the CSF.

4. Cerebral Oedema

Significant cerebral oedema can develop.

Severe cerebral swelling may increase intracranial pressure and contribute to:

Reduced consciousness.

Seizures.

Neurological deterioration.

Brain herniation in extreme cases.

Therefore, severe cases require close neurological and critical-care monitoring.

5. Clinical Presentation

HSV encephalitis typically presents as an acute febrile encephalopathy.

Important features include:

Fever.

Headache.

Confusion.

Altered behaviour or personality.

Reduced consciousness.

Seizures.

Focal neurological deficits.

The combination of fever + altered mental state + seizures or focal neurological signs should raise suspicion for encephalitis.

6. Behavioural and Psychiatric Changes

Because the temporal and limbic regions are commonly involved, patients may develop striking behavioural abnormalities.

These can include:

Personality change.

Agitation.

Confusion.

Memory disturbance.

Hallucinations or unusual behaviour.

Occasionally, the initial presentation can resemble a primary psychiatric disorder.

7. Memory Disturbance

Temporal-lobe and limbic-system involvement can produce significant:

Short-term memory impairment.

Patients who survive severe disease may be left with persistent memory problems because the medial temporal structures are important for memory formation.

8. Seizures

Seizures are common in HSV encephalitis.

They may be:

Focal seizures.

Focal to bilateral tonic-clonic seizures.

or

Generalised convulsive seizures.

Temporal-lobe involvement makes focal seizures particularly understandable.

9. Focal Neurological Features

Patients may develop focal abnormalities such as:

Dysphasia.

Hemiparesis.

Focal seizures.

Visual-field abnormalities.

The exact deficit depends on the distribution and severity of cerebral involvement.

10. CSF Examination

Lumbar puncture is an important investigation when it can be performed safely.

The characteristic CSF pattern is:

Lymphocytic pleocytosis.

Mild to moderately raised protein.

Usually normal glucose.

This is broadly the pattern expected in viral encephalitis.

11. CSF Lymphocytosis

The CSF white cell count is usually elevated with predominantly:

Lymphocytes.

Early in the illness, however, neutrophils can occasionally predominate before the typical lymphocytic pattern develops.

Therefore, an early neutrophilic CSF does not completely exclude viral encephalitis.

12. CSF Protein

CSF protein is generally:

Mildly to moderately elevated.

This reflects inflammation and disruption of the blood–brain barrier.

Very marked protein elevation should encourage consideration of additional or alternative diagnoses.

13. CSF Glucose

CSF glucose is usually:

Normal.

This helps distinguish typical viral encephalitis from conditions such as:

Bacterial meningitis.

Tuberculous meningitis.

Fungal meningitis.

where CSF glucose is commonly reduced.

14. Red Blood Cells in CSF

HSV causes haemorrhagic necrosis, particularly in the temporal lobes.

Therefore, CSF may sometimes contain:

Red blood cells.

However, this finding is neither sufficiently sensitive nor specific to diagnose HSV encephalitis.

A traumatic lumbar puncture can also introduce red cells into CSF.

15. HSV PCR

The most important specific CSF investigation is:

HSV polymerase chain reaction (PCR).

HSV PCR detects viral DNA in the CSF and is the key diagnostic test for HSV encephalitis.

16. Early Negative HSV PCR

An important clinical point is that PCR can occasionally be negative very early in the disease.

Therefore, if clinical suspicion remains high despite an early negative result:

Aciclovir should generally be continued and repeat CSF HSV PCR may be required.

A single early negative PCR should not automatically override a strongly suggestive clinical picture.

17. MRI Brain

MRI is the preferred brain imaging investigation for suspected HSV encephalitis.

Typical abnormalities involve:

Medial temporal lobes.

Inferior temporal lobes.

Insular cortex.

Sometimes the frontal lobes are also involved.

18. MRI Appearance

MRI may demonstrate:

T2/FLAIR hyperintensity.

Cerebral oedema.

Restricted diffusion.

Haemorrhagic changes in some patients.

Temporal-lobe abnormalities can be unilateral initially but frequently become bilateral or asymmetric.

19. CT Brain

CT is less sensitive than MRI early in HSV encephalitis.

It may initially be normal.

Later it may demonstrate:

Temporal-lobe oedema.

Low-density changes.

Mass effect.

Haemorrhage.

CT may nevertheless be useful urgently when MRI is unavailable or when evaluating for another intracranial process.

20. EEG

EEG commonly demonstrates abnormalities over the:

Temporal regions.

Possible findings include:

Focal slowing.

Epileptiform discharges.

Historically, periodic lateralised epileptiform discharges have been associated with HSV encephalitis, although they are not specific to the disease.

21. EEG and Non-Convulsive Seizures

EEG is particularly valuable when a patient remains confused or unconscious and non-convulsive status epilepticus is suspected.

Therefore, EEG can provide both:

Supportive evidence of temporal-lobe dysfunction

and

Detection of ongoing electrical seizure activity.

22. Treatment Is an Emergency

Suspected HSV encephalitis is a neurological emergency.

The key treatment is:

Intravenous aciclovir.

Treatment should be started as soon as the diagnosis is suspected.

23. Do Not Wait for PCR

A crucial management principle is:

Do not wait for the HSV PCR result before starting intravenous aciclovir.

Waiting for laboratory confirmation can allow further irreversible brain injury.

Therefore:

Suspected HSV encephalitis → take appropriate investigations + start IV aciclovir immediately.

24. Aciclovir Mechanism

Aciclovir is converted within infected cells to an active nucleotide analogue.

It inhibits viral:

DNA polymerase.

This suppresses HSV DNA replication and limits further viral proliferation.

25. Renal Considerations with Aciclovir

Intravenous aciclovir can cause renal toxicity, particularly through crystal-associated kidney injury.

Therefore, management includes attention to:

Adequate hydration.

Renal function monitoring.

Dose adjustment in renal impairment.

26. Treatment of Seizures

Seizures should be treated appropriately.

The original note lists:

Phenytoin.

Phenytoin can be used in seizure management, but it is no longer appropriate to regard it as the universal antiseizure drug specifically required for HSV encephalitis.

Modern treatment may use drugs such as:

Levetiracetam.

Fosphenytoin/phenytoin.

or other antiseizure medications depending on the clinical situation.

27. Acute Convulsive Seizures

If a prolonged convulsive seizure occurs, initial emergency treatment generally involves a:

Benzodiazepine.

If seizures continue, a longer-acting antiseizure medication is given according to the status epilepticus protocol.

Therefore:

Aciclovir treats the infection.

Antiseizure medication treats associated seizures.

28. Supportive Management

Severe HSV encephalitis may require:

Airway protection.

Mechanical ventilation.

Management of raised intracranial pressure.

Fluid and electrolyte management.

Treatment of seizures.

Nutritional support.

Critical-care monitoring.

29. Prognosis

Untreated HSV encephalitis carries a very high risk of severe neurological damage and death.

Early aciclovir treatment substantially improves outcome.

However, survivors may still develop persistent neurological problems such as:

Memory impairment.

Cognitive impairment.

Personality or behavioural changes.

Epilepsy.

Focal neurological deficits.

30. Herpes Simplex Encephalitis – Note Form

Main virus in adults: HSV-1.

Characteristic site: temporal lobes, especially medial/inferior temporal regions, with possible insular and frontal involvement.

Pathology: necrotising haemorrhagic encephalitis + cerebral oedema.

Clinical presentation: fever + headache + confusion/behavioural change + seizures ± focal neurological deficits.

CSF cells: lymphocytic pleocytosis.

CSF protein: mildly/moderately increased.

CSF glucose: usually normal.

CSF red cells: may occur because of haemorrhagic necrosis.

Specific investigation: CSF HSV PCR.

MRI: temporal-lobe/insular abnormalities.

EEG: focal temporal abnormalities ± epileptiform discharges.

Treatment: immediate intravenous aciclovir.

Seizures: treat with appropriate antiseizure therapy; phenytoin/fosphenytoin is one possible option rather than a mandatory specific treatment.

31. HSV Encephalitis versus Typical Viral Meningitis

HSV encephalitis:

Altered mental state prominent.

Behaviour/personality change.

Seizures common.

Focal neurological deficits may occur.

Temporal-lobe MRI abnormalities.

HSV PCR positive.

Viral meningitis:

Headache and meningism more prominent.

Consciousness usually relatively preserved.

Focal cerebral abnormalities are less characteristic.

Therefore, brain dysfunction is the key feature distinguishing encephalitis from uncomplicated meningitis.

Key Clinical Pattern

Think of herpes simplex encephalitis as:

FEVER + CONFUSION/BEHAVIOURAL CHANGE + SEIZURES + TEMPORAL-LOBE ABNORMALITY.

The classic investigation pattern is:

CSF lymphocytes ↑ + protein mildly ↑ + glucose usually normal + HSV PCR positive.

Imaging:

MRI → medial/inferior temporal-lobe ± insular lesions.

And the most important management rule is:

SUSPECT HSV ENCEPHALITIS → START IV ACICLOVIR IMMEDIATELY.

Do not wait for PCR confirmation before treating.

Medicine – Epilepsy

Epilepsy is a neurological disorder characterised by an enduring tendency to develop recurrent unprovoked seizures. A seizure results from a sudden episode of abnormal, excessive and synchronous electrical activity within neuronal networks of the brain.

The older classification divides seizures into partial seizures and generalised seizures. Modern terminology uses focal seizures instead of partial seizures and describes them according to whether awareness is preserved or impaired.

1. Basic Mechanism of Epilepsy

Normal brain function depends on a balance between excitatory and inhibitory neuronal activity.

The major excitatory neurotransmitter is:

Glutamate.

The major inhibitory neurotransmitter is:

GABA – gamma-aminobutyric acid.

When excitation becomes excessive or inhibition becomes inadequate, groups of neurons may begin firing abnormally and synchronously.

Therefore:

↑ Excitation or ↓ inhibition → paroxysmal neuronal discharge → seizure.

2. Epilepsy versus a Provoked Seizure

Not every seizure means that a patient has epilepsy.

A seizure may occur because of an acute reversible disturbance such as:

Hypoglycaemia.

Hyponatraemia.

Alcohol withdrawal.

Acute CNS infection.

Acute brain injury.

These are acute symptomatic or provoked seizures.

Epilepsy implies an ongoing predisposition to develop unprovoked seizures.

3. Focal Seizures

The older term partial seizure has been replaced by:

Focal seizure.

A focal seizure begins within neuronal networks in one cerebral hemisphere.

Its manifestations depend on the area of cerebral cortex involved.

Focal seizures can be divided according to awareness into:

Focal aware seizures.

and

Focal impaired-awareness seizures.

They may subsequently spread to both hemispheres and become a focal to bilateral tonic-clonic seizure.

4. Focal Aware Seizures

The older term:

Simple partial seizure

is now called:

Focal aware seizure.

The defining feature is:

Awareness remains preserved throughout the seizure.

The patient knows what is happening and can usually remember the event afterwards.

5. Duration of Focal Aware Seizures

These seizures are usually brief.

They may last:

A few seconds to a few minutes.

The exact clinical manifestations depend on the cerebral region from which the seizure originates.

6. Motor Focal Seizures

If abnormal electrical activity begins in the motor cortex, the patient may develop:

Jerking of one hand.

Jerking of one side of the face.

Movement of one limb.

Tonic posturing.

The patient may remain fully aware during these movements.

7. Sensory Focal Seizures

If sensory regions are involved, the patient may experience:

Tingling.

Numbness.

Visual phenomena.

Abnormal smells.

Abnormal tastes.

These symptoms may occur without loss of awareness.

8. EEG in Focal Seizures

EEG may demonstrate:

Localised or focal epileptiform discharges corresponding to the affected area of the brain.

However:

A normal routine EEG does not exclude epilepsy.

Epileptiform activity may be intermittent and may not occur during the recording.

9. Focal Impaired-Awareness Seizures

The older term:

Complex partial seizure

is now called:

Focal impaired-awareness seizure.

The defining feature is:

Impaired awareness during the seizure.

The patient may appear awake but cannot respond normally to the environment.

10. Duration

A typical focal impaired-awareness seizure lasts approximately:

60–90 seconds, although the duration can vary.

After the seizure, the patient commonly develops a period of:

Post-ictal confusion.

11. Post-Ictal Confusion

After the seizure has stopped, the patient may be:

Confused.

Disorientated.

Drowsy.

Unable to remember the event.

This post-ictal period is particularly useful when distinguishing focal impaired-awareness seizures from typical absence seizures.

12. Aura

A focal impaired-awareness seizure may be preceded by an:

Aura.

An aura is actually a focal aware seizure occurring before further seizure spread.

The symptoms can provide useful information about where the seizure originates.

13. Typical Aura Symptoms

Classic aura symptoms include:

Déjà vu.

A strong or unusual smell.

An unusual taste.

A rising sensation in the abdomen or epigastrium.

Sudden fear or an unusual emotional sensation.

These are particularly associated with temporal lobe seizures.

14. Temporal Lobe Epilepsy

Temporal lobe seizures commonly produce:

Déjà vu.

Olfactory hallucinations.

Rising epigastric sensations.

Fear.

The seizure may then progress to impaired awareness.

15. Automatisms

Focal impaired-awareness seizures may produce automatisms.

These are repetitive, apparently purposeful movements performed without normal awareness.

Examples include:

Lip smacking.

Chewing movements.

Repeated swallowing.

Picking at clothes.

Hand rubbing.

The patient usually has little or no memory of these behaviours.

16. Focal to Bilateral Tonic-Clonic Seizures

The older term:

Secondarily generalised seizure

is now called:

Focal to bilateral tonic-clonic seizure.

The seizure begins focally in one hemisphere and subsequently spreads to involve both hemispheres.

17. Typical Progression

A possible sequence is:

Aura → focal impaired-awareness seizure → bilateral tonic-clonic seizure.

However, not every patient goes through all of these stages.

Some seizures may progress very rapidly from focal onset to bilateral tonic-clonic activity.

18. Importance of an Aura

If a patient experiences a clear aura before a tonic-clonic seizure, it suggests that the seizure may have:

Focal onset.

Therefore:

Aura before tonic-clonic activity → think focal to bilateral tonic-clonic seizure.

This contrasts with a true generalised-onset tonic-clonic seizure, where a focal aura is absent.

19. Generalised Seizures

Generalised seizures involve neuronal networks in both cerebral hemispheres from the onset.

Important types include:

Absence seizures.

Generalised tonic-clonic seizures.

Myoclonic seizures.

Tonic seizures.

Clonic seizures.

Atonic seizures.

20. Absence Seizures

Absence seizures cause very brief episodes of impaired awareness.

The patient may suddenly:

Stop talking.

Stop an activity.

Stare blankly.

Become temporarily unresponsive.

After several seconds, normal activity resumes.

21. Duration of Absence Seizures

Typical absence seizures are very short.

They usually last:

Less than about 20 seconds.

Because they are so brief, a child may experience many episodes during a single day.

22. No Aura in Absence Seizures

Typical absence seizures begin abruptly.

There is usually:

No aura.

The patient does not experience the warning symptoms typical of some focal seizures.

23. No Post-Ictal Confusion

After a typical absence seizure:

There is no significant post-ictal confusion.

The patient immediately returns to their previous activity.

Therefore:

Brief staring + immediate recovery → think absence seizure.

24. Age of Onset

Typical absence epilepsy generally begins during:

Childhood.

or

Adolescence.

Some syndromes remit with age, while others may persist into adulthood or coexist with other generalised seizure types.

25. EEG in Absence Seizures

The classic EEG finding is:

Generalised 3-Hz spike-and-wave activity.

This is one of the most important examination associations for absence epilepsy.

26. Hyperventilation and Absence Seizures

Hyperventilation can provoke a typical absence seizure.

For this reason, controlled hyperventilation may be performed during EEG testing when absence epilepsy is suspected.

27. Generalised Tonic-Clonic Seizures

The older term:

Grand mal seizure

is now called:

Generalised tonic-clonic seizure.

The seizure begins with loss of consciousness and a tonic phase, followed by a clonic phase.

28. Tonic Phase

During the tonic phase there is:

Sudden loss of consciousness.

Generalised muscle stiffening.

Tonic extension of the limbs.

The tonic phase usually lasts several seconds.

The patient may fall abruptly and sustain an injury.

29. Clonic Phase

The tonic phase is followed by:

Rhythmic bilateral jerking of the limbs.

This represents the clonic phase.

The jerking gradually becomes slower and eventually stops.

30. Other Features During a Tonic-Clonic Seizure

Associated features may include:

Cyanosis.

Excessive salivation.

Tongue biting.

Urinary incontinence.

Transient abnormal breathing.

Lateral tongue biting is particularly supportive of a generalised convulsive seizure.

31. Post-Ictal Phase

After the seizure, the patient usually develops a significant post-ictal period.

Features include:

Prolonged confusion.

Drowsiness.

Headache.

Muscle aches.

Fatigue.

The patient may subsequently sleep for some time.

32. No Aura in Primary Generalised Tonic-Clonic Seizures

A truly generalised-onset tonic-clonic seizure generally has:

No focal aura.

If a clear aura such as déjà vu, an abnormal smell, or a rising epigastric sensation occurs first, consider:

Focal onset with subsequent bilateral spread.

33. Focal Aware Seizure – Note Form

Old name: simple partial seizure.

Onset: one cerebral hemisphere.

Awareness: preserved.

Duration: seconds to a few minutes.

Symptoms: depend on cortical area involved.

EEG: may demonstrate a focal discharge.

34. Focal Impaired-Awareness Seizure – Note Form

Old name: complex partial seizure.

Awareness: impaired.

Duration: commonly around 60–90 seconds.

Aura: may precede the impairment of awareness.

Typical aura: déjà vu, unusual smell or rising abdominal sensation.

Automatisms: lip smacking, chewing, picking movements.

Afterward: brief post-ictal confusion.

35. Focal to Bilateral Tonic-Clonic Seizure – Note Form

Old name: secondarily generalised seizure.

Starts: focally.

May begin with: aura.

May progress through: focal impaired awareness.

Then: spreads to both hemispheres.

Result: bilateral tonic-clonic seizure.

36. Absence Seizure – Note Form

Onset: generalised.

Main feature: brief impairment of awareness/staring.

Duration: usually less than 20 seconds.

Aura: absent.

Post-ictal confusion: absent.

Typical onset: childhood or adolescence.

EEG: generalised 3-Hz spike-and-wave.

37. Generalised Tonic-Clonic Seizure – Note Form

Old name: grand mal seizure.

Onset: generalised from the beginning.

Awareness: lost.

Tonic phase: generalised stiffening and extension.

Clonic phase: rhythmic jerking.

Aura: absent in a true generalised-onset seizure.

Afterward: prolonged post-ictal confusion and drowsiness.

38. Focal Impaired Awareness versus Absence Seizure

Focal impaired-awareness seizure:

Usually lasts around 1–2 minutes.

Aura may occur.

Automatisms are common.

Post-ictal confusion is common.

Often associated with temporal lobe epilepsy.

Absence seizure:

Usually lasts only seconds.

No aura.

Abrupt staring and impaired awareness.

Immediate recovery.

No significant post-ictal confusion.

Classic 3-Hz spike-and-wave EEG.

39. Modern Terminology

For current terminology, remember:

Simple partial → Focal aware seizure.

Complex partial → Focal impaired-awareness seizure.

Secondarily generalised → Focal to bilateral tonic-clonic seizure.

Grand mal → Generalised tonic-clonic seizure.

Key Clinical Pattern

The easiest way to classify a seizure is to ask:

WHERE DID IT START, AND WAS AWARENESS PRESERVED?

One hemisphere + awareness preserved → Focal aware seizure.

One hemisphere + awareness impaired → Focal impaired-awareness seizure.

Focal onset followed by bilateral convulsion → Focal to bilateral tonic-clonic seizure.

Both hemispheres from onset → Generalised seizure.

For rapid examination recall:

ABSENCE = brief staring + <20 seconds + no aura + no post-ictal confusion + 3-Hz spike-and-wave.

FOCAL IMPAIRED AWARENESS = aura ± automatisms + 60–90 seconds + post-ictal confusion.

GENERALISED TONIC-CLONIC = tonic stiffening → clonic jerking → prolonged post-ictal confusion.

Medicine – Mechanisms of Action of Antiseizure Drugs

Antiseizure drugs work by reducing excessive neuronal excitability and preventing abnormal repetitive firing in the brain. They do this mainly by blocking excitatory ion channels, enhancing inhibitory neurotransmission through GABA, or reducing excitatory neurotransmission through glutamate.

1. Sodium Channel Blockade

Voltage-gated Na⁺ channels are essential for generation and propagation of action potentials.

During seizures, neurons fire repeatedly at high frequency.

Blocking sodium channels stabilises the neuronal membrane and keeps the channels in an inactive state for longer.

Therefore:

Na⁺ channel blockade → reduced repetitive neuronal firing → reduced seizure activity.

2. Drugs Acting on Sodium Channels

Important examples include:

Phenytoin.

Carbamazepine.

Lamotrigine.

Valproate also has some sodium-channel effects as part of its broader mechanism.

3. Calcium Channel Blockade

Calcium channels are involved in neuronal excitability and neurotransmitter release.

A particularly important type in epilepsy is the:

T-type calcium channel in the thalamus.

These channels contribute to the rhythmic thalamocortical activity responsible for absence seizures.

4. Thalamic T-Type Calcium Channels

Inhibition of thalamic T-type Ca²⁺ channels reduces abnormal oscillatory activity.

Therefore:

T-type Ca²⁺ channel inhibition → reduced thalamocortical rhythmic firing → reduced absence seizures.

The classic drug is:

Ethosuximide.

5. GABA

Gamma-aminobutyric acid, GABA, is the major inhibitory neurotransmitter in the central nervous system.

Its overall function is to reduce neuronal excitability.

Therefore:

↑ GABA activity → ↑ inhibition → ↓ seizures.

Several antiseizure drugs work by increasing GABA-mediated inhibition.

6. GABA-A Receptors

The GABA-A receptor is a ligand-gated chloride channel.

When GABA activates this receptor, chloride conductance increases, making the neuron less excitable.

This produces neuronal inhibition.

7. Benzodiazepines

Benzodiazepines enhance the action of GABA at GABA-A receptors.

They are more accurately described as positive allosteric modulators rather than direct receptor agonists.

They increase the:

Frequency of chloride-channel opening.

This rapidly suppresses neuronal activity.

8. Barbiturates

Barbiturates also enhance GABA-A receptor activity.

They characteristically increase the:

Duration of chloride-channel opening.

An important antiseizure example is:

Phenobarbital.

A useful memory aid is:

Benzodiazepines = frequency.

Barbiturates = duration.

9. GABA Synthesis

GABA is produced from:

Glutamate.

The enzyme responsible is:

Glutamic acid decarboxylase, GAD.

Therefore:

Glutamate → GAD → GABA.

Increasing GABA synthesis increases inhibitory neurotransmission.

10. Important Clarification About GAD

The original note states that activation of glutamic acid decarboxylase increases GABA.

Conceptually this is correct.

However, most antiseizure drugs do not work primarily by directly stimulating GAD.

Rather, they increase GABA through several different mechanisms.

11. GABA Breakdown

GABA is metabolised by:

GABA transaminase.

If this enzyme is inhibited, less GABA is broken down.

Therefore:

GABA transaminase inhibition → ↑ GABA concentration → ↑ neuronal inhibition.

12. Vigabatrin

The classic drug acting through this mechanism is:

Vigabatrin.

It irreversibly inhibits GABA transaminase.

Therefore:

Vigabatrin → reduced GABA breakdown → increased GABA.

13. GABA Reuptake

Another way to increase GABA is to prevent its reuptake from the synaptic cleft.

The classic drug is:

Tiagabine.

It inhibits GABA transporters.

Therefore:

Reduced GABA reuptake → more GABA remains in the synapse → increased inhibition.

14. Valproate and GABA

Valproate increases GABA activity through several mechanisms.

It also affects sodium channels and other neuronal processes.

Therefore, valproate is considered a broad-spectrum antiseizure drug with multiple mechanisms.

15. Glutamate

Glutamate is the major excitatory neurotransmitter in the central nervous system.

It promotes neuronal depolarisation and firing.

Excessive glutamate activity can contribute to seizure generation and spread.

16. Reducing Glutamate Activity

Reducing glutamate transmission decreases neuronal excitation.

Therefore:

↓ glutamate activity → ↓ neuroexcitability → ↓ seizures.

This can be achieved by either:

Reducing glutamate release.

or

Blocking glutamate receptors.

17. Lamotrigine and Glutamate

Lamotrigine reduces glutamate release partly through sodium-channel blockade.

Therefore:

Lamotrigine → Na⁺ channel blockade + reduced glutamate release → reduced excitation.

18. AMPA Receptor Blockade

Glutamate acts on several receptor types, including the:

AMPA receptor.

Blocking AMPA receptors reduces excitatory neurotransmission.

A classic example is:

Perampanel.

Therefore:

Perampanel → AMPA receptor antagonism → reduced glutamate-mediated excitation.

19. Overall Balance of Excitation and Inhibition

Seizures can be thought of as resulting from excessive excitation relative to inhibition.

Antiseizure drugs restore balance by:

Reducing excitatory firing.

and/or

Increasing inhibitory activity.

The four main mechanisms in your original notes fit into this framework.

20. Sodium Channel Mechanism – Note Form

Target: voltage-gated Na⁺ channels.

Effect: stabilises neuronal membranes.

Result: prevents repetitive high-frequency firing.

Examples: phenytoin, carbamazepine, lamotrigine.

21. Calcium Channel Mechanism – Note Form

Target: thalamic T-type Ca²⁺ channels.

Effect: suppresses thalamocortical oscillations.

Main seizure type: absence seizures.

Classic drug: ethosuximide.

22. GABA Mechanism – Note Form

GABA: major inhibitory neurotransmitter.

↑ GABA → ↓ neuronal excitability.

Benzodiazepines: enhance GABA-A receptor activity and increase frequency of chloride-channel opening.

Barbiturates: enhance GABA-A receptor activity and increase duration of chloride-channel opening.

Vigabatrin: inhibits GABA transaminase.

Tiagabine: inhibits GABA reuptake.

23. GABA Synthesis – Note Form

Precursor: glutamate.

Enzyme: glutamic acid decarboxylase.

Reaction:

Glutamate → GABA.

Increasing GABA synthesis increases inhibitory neurotransmission.

24. GABA Breakdown – Note Form

Enzyme: GABA transaminase.

If inhibited: GABA accumulates.

Result: increased neuronal inhibition.

Drug example: vigabatrin.

25. Glutamate Mechanism – Note Form

Glutamate: major excitatory neurotransmitter.

Inhibition: reduces neuronal excitation.

Lamotrigine: reduces glutamate release.

Perampanel: blocks AMPA glutamate receptors.

Key Clinical Pattern

The easiest framework is:

Na⁺ channels → stop repetitive firing.

Ca²⁺ channels → suppress thalamic absence-seizure rhythms.

GABA → increase inhibition.

Glutamate → reduce excitation.

And the classic drug associations are:

Phenytoin / Carbamazepine / Lamotrigine → Na⁺ blockade.

Ethosuximide → T-type Ca²⁺ blockade.

Benzodiazepines / Barbiturates → enhance GABA-A.

Vigabatrin → inhibits GABA transaminase.

Lamotrigine / Perampanel → reduce glutamate-mediated excitation.

Medicine – Antiseizure Drugs

Antiseizure medications, traditionally called antiepileptic drugs, reduce the frequency or terminate seizures by modifying neuronal excitability and neurotransmission. Different drugs act through different mechanisms, including blockade of voltage-gated sodium or calcium channels and enhancement of inhibitory GABAergic transmission.

Drug choice depends on the seizure type or epilepsy syndrome, patient characteristics, comorbidities, pregnancy potential, adverse-effect profile, and drug interactions. Some recommendations in the supplied table reflect older prescribing practice, so the notes below preserve the core material while updating important points.

1. Sodium Valproate

Sodium valproate is a broad-spectrum antiseizure medication effective against several seizure types.

Its mechanism is complex rather than truly “uncertain.” It increases inhibitory GABA activity and also affects voltage-gated sodium channels and other ion-channel mechanisms.

2. Indications for Valproate

Valproate is effective against:

Generalised tonic-clonic seizures.

Absence seizures.

Myoclonic seizures.

Focal seizures in some circumstances.

Because of its broad-spectrum activity, it has historically been described as effective for “all forms of epilepsy.”

However, calling it the universal drug of choice for tonic-clonic seizures is outdated. Selection now depends strongly on epilepsy type and individual patient factors.

3. Valproate and Generalised Epilepsy

Valproate can be particularly effective in generalised epilepsies, including those with myoclonic seizures.

However, its effectiveness must be balanced against its important adverse effects and reproductive risks.

Its use is especially restricted in people who could become pregnant because fetal exposure carries substantial risks.

4. Adverse Effects of Valproate

Important adverse effects include:

Tremor.

Weight gain.

Sedation.

Gastrointestinal disturbance.

Thrombocytopenia.

Hepatotoxicity.

Pancreatitis.

Hair loss can also occur.

5. Valproate and Pregnancy

Valproate has particularly important teratogenic and neurodevelopmental risks.

Fetal exposure increases the risk of:

Neural tube defects.

Other major congenital malformations.

Developmental impairment.

Adverse cognitive outcomes.

Autism spectrum disorder and other neurodevelopmental difficulties.

Therefore, valproate requires particularly careful reproductive counselling and is subject to major prescribing restrictions in many settings.

6. Phenytoin

Phenytoin primarily acts by blocking voltage-gated sodium channels.

It stabilises neuronal membranes and reduces repetitive high-frequency neuronal firing.

7. Uses of Phenytoin

Phenytoin has traditionally been used for:

Focal seizures.

Focal-to-bilateral tonic-clonic seizures.

Generalised tonic-clonic seizures in selected settings.

It also has an important role in the treatment of status epilepticus, although other agents are now frequently preferred depending on local protocols.

8. Phenytoin in Status Epilepticus

In established convulsive status epilepticus, a benzodiazepine is generally given first to terminate the seizure rapidly.

A longer-acting intravenous antiseizure medication is then used if required.

Modern protocols may use:

Levetiracetam.

Fosphenytoin/phenytoin.

Valproate.

Therefore, phenytoin remains relevant but is not the only option.

9. Adverse Effects of Phenytoin

Characteristic adverse effects include:

Gingival hyperplasia.

Hirsutism.

Coarsening of facial features.

Ataxia.

Nystagmus.

Drowsiness.

Diplopia.

Peripheral neuropathy with chronic exposure.

Hepatotoxicity.

10. Cerebellar Features of Phenytoin Toxicity

Excessive phenytoin concentrations can cause neurological toxicity.

Features include:

Nystagmus.

Ataxia.

Dysarthria.

Diplopia.

Drowsiness.

These neurological findings are useful clues to phenytoin toxicity.

11. Phenytoin and Vitamin Metabolism

Long-term phenytoin treatment can interfere with vitamin metabolism.

Important associations include:

Folate deficiency.

Vitamin D deficiency and impaired bone health.

It can also interact with vitamin K metabolism, which is particularly relevant in certain clinical contexts.

12. Phenytoin Pharmacology

Phenytoin has complex pharmacokinetics.

At higher concentrations, its metabolism can become saturated, meaning that:

A small dose increase can produce a disproportionately large rise in serum concentration.

This is why drug-level monitoring can be useful in selected patients.

13. Carbamazepine

Carbamazepine acts primarily by blocking voltage-gated sodium channels.

It reduces repetitive neuronal firing and is particularly useful in focal epilepsy.

14. Uses of Carbamazepine

Important indications include:

Focal seizures.

Focal-to-bilateral tonic-clonic seizures.

It has historically also been described for tonic-clonic seizures more generally, but seizure classification matters because carbamazepine can worsen certain generalised seizure types.

15. Carbamazepine Can Worsen Some Seizures

Carbamazepine is not appropriate for every epilepsy syndrome.

It may aggravate:

Absence seizures.

and

Myoclonic seizures.

Therefore, accurate classification of the patient’s epilepsy is important before prescribing it.

16. Other Uses of Carbamazepine

Outside epilepsy, carbamazepine is particularly well known for treating:

Trigeminal neuralgia.

It is also used in selected psychiatric conditions.

17. Adverse Effects of Carbamazepine

Important adverse effects include:

Dizziness.

Diplopia.

Ataxia.

Drowsiness.

Hepatotoxicity.

Hyponatraemia due to SIADH.

Rash.

Blood dyscrasias.

18. Carbamazepine and Blood Dyscrasias

Rare but potentially serious haematological complications include:

Leukopenia.

Agranulocytosis.

Aplastic anaemia.

Therefore, unexplained fever, infection, bruising, or bleeding requires appropriate assessment.

19. Carbamazepine and Severe Skin Reactions

Carbamazepine can cause severe cutaneous adverse reactions, including:

Stevens–Johnson syndrome.

Toxic epidermal necrolysis.

Genetic susceptibility is particularly relevant in certain ancestry groups, and HLA-B*1502 testing is important in appropriate populations before treatment.

20. Carbamazepine as an Enzyme Inducer

Carbamazepine induces hepatic enzymes.

This creates numerous drug interactions.

One important consequence is:

Reduced effectiveness of some hormonal contraceptives.

This is particularly relevant when counselling patients with epilepsy about pregnancy prevention.

21. Lamotrigine

Lamotrigine is a broad-spectrum antiseizure medication.

It primarily blocks voltage-gated sodium channels and reduces the release of excitatory neurotransmitters such as glutamate.

22. Uses of Lamotrigine

Lamotrigine can be used as monotherapy or adjunctive therapy for several seizure types, including:

Focal seizures.

Focal-to-bilateral tonic-clonic seizures.

Generalised tonic-clonic seizures.

It is also used in some generalised epilepsy syndromes.

23. Lamotrigine and Myoclonic Seizures

The original table lists lamotrigine for some myoclonic seizures.

This is possible, but an important nuance is that lamotrigine may occasionally worsen myoclonus in some patients.

Therefore, treatment should be tailored to the epilepsy syndrome.

24. Adverse Effects of Lamotrigine

Important adverse effects include:

Rash.

Headache.

Dizziness.

Diplopia.

Ataxia.

Tremor.

Nausea.

The most important serious adverse effect is a severe skin reaction.

25. Stevens–Johnson Syndrome

Lamotrigine can rarely cause:

Stevens–Johnson syndrome or toxic epidermal necrolysis.

Risk is increased by:

Starting at too high a dose.

Increasing the dose too rapidly.

Concurrent valproate therapy.

Therefore, lamotrigine must usually be started at a low dose and titrated gradually.

26. Lamotrigine and Pregnancy

Lamotrigine is commonly used when an antiseizure medication is required during pregnancy because available pregnancy data are comparatively reassuring relative to higher-risk drugs such as valproate.

However, pregnancy can increase lamotrigine clearance considerably.

Therefore:

Lamotrigine concentrations can fall during pregnancy → breakthrough seizures may occur.

Monitoring and dose adjustment may be necessary.

27. Gabapentin

Gabapentin was originally developed as a GABA analogue, but the table’s description that it simply “enhances GABA” is an oversimplification.

Its major clinically relevant action is binding to the:

α2δ subunit of voltage-gated calcium channels.

This reduces release of excitatory neurotransmitters.

28. Uses of Gabapentin

Gabapentin may be used as adjunctive therapy for:

Focal seizures.

However, it is now particularly familiar clinically for treating:

Neuropathic pain.

Examples include selected cases of painful peripheral neuropathy and other neuropathic pain syndromes.

29. Adverse Effects of Gabapentin

Important adverse effects include:

Drowsiness.

Dizziness.

Ataxia.

Peripheral oedema.

Weight gain.

Rash can occur but is not usually the defining adverse effect.

30. Ethosuximide

Ethosuximide is particularly associated with treatment of:

Absence seizures.

Its mechanism involves inhibition of T-type calcium channels in thalamic neurons.

These thalamocortical circuits are important in the generation of typical absence seizures.

31. Ethosuximide – High-Yield Association

The classic examination association is:

ABSENCE SEIZURES → ETHOSUXIMIDE.

It is particularly appropriate when a patient has pure absence epilepsy without other seizure types requiring a broader-spectrum medication.

32. Adverse Effects of Ethosuximide

Common adverse effects include gastrointestinal symptoms such as:

Nausea.

Vomiting.

Abdominal discomfort.

Other possible effects include:

Fatigue.

Headache.

Dizziness.

Rarely, significant blood dyscrasias can occur.

33. Benzodiazepines

Benzodiazepines enhance inhibitory neurotransmission through the:

GABA-A receptor.

More precisely, they are positive allosteric modulators rather than direct GABA agonists.

They increase the frequency of chloride-channel opening in the presence of GABA, increasing neuronal inhibition.

34. Benzodiazepines and Acute Seizures

Benzodiazepines are particularly important for:

Rapid termination of ongoing seizures.

and

Initial treatment of convulsive status epilepticus.

Examples include:

Lorazepam.

Diazepam.

Midazolam.

The exact choice depends on the clinical setting and route available.

35. Adverse Effects of Benzodiazepines

Important adverse effects include:

Sedation.

Drowsiness.

Dizziness.

Impaired coordination.

Respiratory depression.

Respiratory depression is especially important with high doses or when combined with other CNS depressants.

36. Status Epilepticus – Drug Sequence

A useful simplified approach is:

Ongoing convulsive seizure → benzodiazepine first.

If seizures continue:

Give a longer-acting intravenous antiseizure medication, according to the clinical protocol.

Options may include:

Levetiracetam.

Fosphenytoin/phenytoin.

Valproate.

Persistent refractory status requires escalation to critical-care management.

37. Important Modern Addition – Levetiracetam

Although it is absent from the older table, levetiracetam is now an important and commonly used antiseizure medication.

It binds to the synaptic vesicle protein:

SV2A.

This modifies neurotransmitter release and reduces seizure activity.

38. Uses of Levetiracetam

Levetiracetam is a broad-spectrum medication used for:

Focal seizures.

Generalised tonic-clonic seizures.

Myoclonic seizures in appropriate syndromes.

It is also widely used intravenously in acute neurological settings.

39. Adverse Effects of Levetiracetam

Important adverse effects include:

Somnolence.

Dizziness.

Fatigue.

Particularly important are behavioural or psychiatric effects such as:

Irritability.

Agitation.

Mood change.

These can occasionally limit treatment.

40. Antiseizure Drugs – Valproate Note Form

Mechanism: multiple actions, including increased GABA activity and effects on ion channels.

Uses: broad-spectrum; generalised tonic-clonic, absence and myoclonic seizures.

Important adverse effects: tremor, weight gain, sedation, hepatotoxicity and pancreatitis.

Major warning: significant teratogenic and neurodevelopmental fetal risk.

41. Phenytoin Note Form

Mechanism: voltage-gated sodium-channel blockade.

Uses: focal and tonic-clonic seizures; intravenous phenytoin/fosphenytoin can be used in status epilepticus after initial benzodiazepine treatment.

Classic adverse effects: gingival hyperplasia + hirsutism + coarse facial features.

Toxicity: nystagmus + ataxia + diplopia + drowsiness.

Long-term effects: folate/vitamin D abnormalities and peripheral neuropathy.

42. Carbamazepine Note Form

Mechanism: voltage-gated sodium-channel blockade.

Main epilepsy use: focal seizures and focal-to-bilateral tonic-clonic seizures.

Other classic use: trigeminal neuralgia.

Adverse effects: dizziness, diplopia, ataxia, hyponatraemia, hepatotoxicity, rash and blood dyscrasias.

Important warning: can worsen absence and myoclonic seizures.

Drug interaction: hepatic enzyme inducer.

43. Lamotrigine Note Form

Mechanism: sodium-channel blockade + reduced glutamate release.

Uses: broad-spectrum treatment, including focal and generalised tonic-clonic seizures.

Adverse effects: headache, dizziness, ataxia, tremor and rash.

Major warning: Stevens–Johnson syndrome/toxic epidermal necrolysis.

Prevention: start low and increase slowly.

Pregnancy: comparatively favourable option when clinically appropriate, but concentrations may fall during pregnancy.

44. Gabapentin Note Form

Mechanism: binds α2δ subunit of voltage-gated calcium channels.

Uses: adjunctive treatment of focal epilepsy and treatment of neuropathic pain.

Adverse effects: drowsiness, dizziness, ataxia, oedema and weight gain.

45. Ethosuximide Note Form

Mechanism: blocks thalamic T-type calcium channels.

Main indication: absence seizures.

Adverse effects: gastrointestinal disturbance, fatigue and headache; rare blood dyscrasias.

Memory association: Ethosuximide = absence epilepsy.

46. Benzodiazepines Note Form

Mechanism: enhance GABA-A receptor-mediated inhibition.

Main indication: acute termination of seizures/status epilepticus.

Examples: lorazepam, diazepam and midazolam.

Adverse effects: sedation, dizziness, impaired coordination and respiratory depression.

47. Levetiracetam Note Form

Mechanism: binds SV2A synaptic vesicle protein.

Uses: focal, generalised tonic-clonic and selected myoclonic seizures; also commonly used in acute seizure management.

Adverse effects: somnolence, fatigue, dizziness, irritability and behavioural/mood changes.

48. High-Yield Drug Associations

Absence seizure → Ethosuximide.

Acute ongoing seizure/status epilepticus → Benzodiazepine first.

Focal seizures → Lamotrigine, levetiracetam or carbamazepine are important options depending on the patient.

Myoclonic/generalised epilepsy → broad-spectrum therapy; valproate is highly effective but reproductive risks are crucial.

Neuropathic pain + antiseizure drug → Gabapentin.

Gingival hyperplasia + hirsutism + ataxia → Phenytoin.

Hyponatraemia + diplopia + blood dyscrasia → Carbamazepine.

Serious rash/Stevens–Johnson syndrome → Lamotrigine or carbamazepine are important associations.

Weight gain + tremor + hepatotoxicity + pancreatitis → Valproate.

Irritability/behavioural change → Levetiracetam.

Key Clinical Pattern

For rapid recall:

VALPROATE → broad-spectrum + weight gain/tremor + major pregnancy risk.

PHENYTOIN → Na⁺ blockade + gingival hyperplasia + hirsutism + ataxia.

CARBAMAZEPINE → Na⁺ blockade + focal seizures + hyponatraemia + blood dyscrasias.

LAMOTRIGINE → Na⁺ blockade/glutamate reduction + rash/SJS.

GABAPENTIN → α2δ calcium-channel subunit + neuropathic pain + sedation.

ETHOSUXIMIDE → T-type Ca²⁺ blockade + absence seizures.

BENZODIAZEPINES → enhance GABA-A + terminate acute seizures + respiratory depression.

LEVETIRACETAM → SV2A + broad-spectrum + behavioural adverse effects.

Medicine – Pregnancy and Epilepsy

Pregnancy in a woman with epilepsy requires careful planning because both uncontrolled seizures and antiseizure medications can affect maternal and fetal health. The central principle is to maintain good seizure control while using the lowest-risk effective antiseizure medication at the lowest effective dose, preferably as monotherapy when possible.

Older teaching often describes all antiepileptic drugs as having similar teratogenic effects. This is no longer accurate. Fetal risk differs substantially between individual antiseizure medications, with valproate carrying particularly important risks.

1. Epilepsy and Contraception

Some antiseizure medications induce hepatic enzymes and can increase the metabolism of hormonal contraceptives.

Important enzyme-inducing antiseizure medications include:

Carbamazepine.

Phenytoin.

Phenobarbital.

Primidone.

These drugs can reduce the effectiveness of some hormonal contraceptive methods.

2. Oral Contraceptive Pill and Enzyme-Inducing Drugs

The original teaching that the oral contraceptive pill may be less effective with enzyme-inducing antiseizure medications is correct.

Enzyme induction accelerates metabolism of contraceptive hormones and can reduce their circulating concentrations.

Therefore:

Carbamazepine or phenytoin + certain hormonal contraceptives → increased risk of contraceptive failure.

Contraceptive choice should be reviewed with the patient’s antiseizure medication.

3. Lamotrigine and the Combined Oral Contraceptive

There is another important interaction involving lamotrigine.

Estrogen-containing combined hormonal contraceptives can reduce lamotrigine concentrations, potentially worsening seizure control.

Therefore, the interaction can work in the opposite direction:

Some antiseizure drugs reduce contraceptive effectiveness.

Estrogen-containing contraception can reduce lamotrigine levels.

4. Antiseizure Medication Is Not Automatically Contraindicated in Pregnancy

Epilepsy treatment should not simply be stopped because a woman becomes pregnant.

Abrupt withdrawal may cause:

Breakthrough seizures.

Status epilepticus.

Maternal injury.

Fetal hypoxia.

Therefore, medication changes should be planned with specialist guidance.

5. Importance of Pre-Pregnancy Planning

Whenever possible, pregnancy should be planned in advance.

Preconception assessment allows clinicians to:

Review whether medication is still required.

Choose the safest effective drug.

Optimise the dose.

Consider monotherapy where possible.

Start folic acid supplementation.

Discuss maternal and fetal risks.

This is safer than making major medication changes after conception.

6. Risks of Uncontrolled Epilepsy

Uncontrolled seizures during pregnancy can endanger both mother and fetus.

Generalised tonic-clonic seizures are particularly concerning because they may cause:

Maternal trauma.

Falls.

Hypoxia.

Aspiration.

Status epilepticus.

Fetal hypoxia or distress.

Therefore, maintaining seizure control remains a major priority.

7. Do Not Stop Medication Abruptly

A pregnant patient taking antiseizure medication should not abruptly stop treatment without medical advice.

Sudden discontinuation can precipitate severe seizures.

The aim is not to eliminate medication at all costs but to achieve:

Maximum seizure control with minimum fetal drug exposure.

8. Fetal Malformation Risk

Pregnancy in women with epilepsy requires discussion of congenital malformation risk.

However, the original statement that fetal malformations are 25% higher even in untreated epilepsy should be interpreted cautiously.

Modern evidence suggests that much of the increased congenital-malformation risk is related to specific antiseizure medications, dose, and polytherapy, rather than epilepsy itself producing a large uniform increase in risk.

9. Not All Antiseizure Medications Have the Same Teratogenic Risk

The older statement that all antiepileptic drugs cause approximately three times the normal teratogenic risk is too broad.

Different drugs have very different pregnancy safety profiles.

Some have relatively low observed major congenital malformation rates, whereas others—particularly valproate—carry substantially greater risks.

10. Valproate

Sodium valproate is particularly important in pregnancy because of its high fetal risk.

Exposure is associated with increased risk of major congenital malformations, including:

Neural tube defects.

Cardiac abnormalities.

Craniofacial abnormalities.

Limb abnormalities.

It is also associated with adverse neurodevelopmental outcomes.

11. Neurodevelopmental Effects of Valproate

Prenatal valproate exposure has been associated with increased risk of:

Developmental delay.

Lower cognitive performance.

Autism spectrum disorder.

Other neurodevelopmental difficulties.

For this reason, valproate is subject to particularly strict pregnancy-prevention and prescribing restrictions in many healthcare systems.

12. Lamotrigine

Lamotrigine is commonly considered one of the more pregnancy-compatible antiseizure medications when clinically appropriate.

However, pregnancy can substantially increase its clearance.

This means lamotrigine concentrations may fall during pregnancy, potentially leading to breakthrough seizures.

Therefore, dose and/or serum concentration monitoring may be required.

13. Levetiracetam

Levetiracetam is another commonly used option with comparatively reassuring pregnancy safety data.

As with any antiseizure medication, the choice depends on:

Seizure type.

Epilepsy syndrome.

Previous treatment response.

Individual pregnancy risks.

14. Carbamazepine

Carbamazepine has long been used during pregnancy.

It carries some teratogenic risk, including an association with neural tube defects, but its overall fetal risk is generally lower than that associated with valproate.

It is also an enzyme inducer, which is relevant when contraception is being used before pregnancy.

15. Phenytoin

Phenytoin exposure during pregnancy is associated with congenital abnormalities and the historically described fetal hydantoin syndrome.

Features can include:

Craniofacial abnormalities.

Growth restriction.

Limb or nail abnormalities.

Therefore, medication choice should be individualised rather than assuming all antiseizure drugs have equal risk.

16. Monotherapy versus Polytherapy

Where seizure control permits, monotherapy is generally preferred over multiple antiseizure medications.

The principle is:

One appropriate drug at the lowest effective dose.

However, seizure control should not be sacrificed simply to achieve monotherapy.

17. Folic Acid

Women taking antiseizure medication who may become pregnant should receive folic acid supplementation according to local preconception guidance.

Folic acid is particularly important because neural tube development occurs very early in pregnancy, often before a woman knows she is pregnant.

It should ideally be started before conception.

18. Why Folic Acid Is Important

Folate is required for normal neural tube development.

Adequate folate supplementation reduces the risk of neural tube defects in the general population and is routinely recommended around conception.

Women taking antiseizure medication may be advised to take a higher-dose preparation depending on the drug and national guideline.

Therefore, the exact dose should follow current local guidance rather than assuming one dose applies universally.

19. Monitoring During Pregnancy

Pregnancy can alter the pharmacokinetics of antiseizure medications.

Drug concentrations may fall because of changes in:

Plasma volume.

Protein binding.

Renal clearance.

Hepatic metabolism.

This is especially clinically important for drugs such as lamotrigine and levetiracetam.

20. Seizure Control During Pregnancy

Many women remain stable during pregnancy, but seizure frequency can increase in some patients.

Possible contributing factors include:

Falling medication concentrations.

Vomiting.

Poor adherence.

Sleep deprivation.

Stress.

Regular neurological and obstetric follow-up is therefore important.

21. Labour and Delivery

Most women with epilepsy can have a vaginal delivery.

Epilepsy alone is not an indication for caesarean section.

Regular antiseizure medication should generally be continued during labour, and factors that can precipitate seizures—particularly sleep deprivation and missed medication—should be minimised.

22. Breastfeeding

The original statement that there is no general contraindication to breastfeeding while taking antiseizure medication is broadly correct.

For many commonly used antiseizure medications, breastfeeding is possible and often encouraged after individual assessment.

However, drug transfer into breast milk varies.

23. Monitoring the Breastfed Infant

Depending on the medication, the infant may need observation for:

Excessive sedation.

Poor feeding.

Poor weight gain.

Reduced alertness.

Therefore, breastfeeding decisions should consider the particular drug rather than applying an absolute rule to every antiseizure medication.

24. Risk of Epilepsy in the Child

Children of parents with epilepsy have a somewhat increased risk of developing epilepsy compared with the general population.

The original figure of approximately 3% is a useful rough teaching estimate for some situations, but there is no single risk applicable to every patient.

The actual risk depends strongly on:

The parent’s epilepsy syndrome.

Whether there is a known genetic cause.

Family history.

Whether one or both parents are affected.

Some genetically determined epilepsy syndromes carry substantially higher recurrence risks.

25. Pregnancy and Epilepsy – Note Form

Main principle: maintain maternal seizure control while minimising fetal medication risk.

Do not abruptly stop antiseizure medication during pregnancy.

Enzyme-inducing drugs: carbamazepine, phenytoin, phenobarbital and primidone can reduce the effectiveness of some hormonal contraceptives.

Lamotrigine: estrogen-containing contraceptives can lower lamotrigine concentrations.

Preconception: review medication before pregnancy whenever possible.

Preferred strategy when appropriate: effective monotherapy at the lowest effective dose.

Highest-concern drug: valproate because of major congenital and neurodevelopmental risks.

Lower-risk commonly used options when appropriate: lamotrigine and levetiracetam have comparatively reassuring pregnancy data.

Folic acid: start before conception according to local guidance.

Pregnancy monitoring: drug concentrations may change, particularly with lamotrigine and levetiracetam.

Uncontrolled seizures: can cause maternal trauma, hypoxia and fetal compromise.

Delivery: vaginal delivery is usually possible.

Breastfeeding: generally possible with many antiseizure medications, with drug-specific assessment.

Child’s epilepsy risk: increased above background, but the traditional ~3% figure is only an approximate estimate and varies with epilepsy type and genetics.

26. Important Corrections to the Older Teaching

“All antiepileptic drugs have three times the teratogenic risk” → Not accurate.

Teratogenic risk differs considerably between drugs.

“Epilepsy without medication increases malformations by 25%” → Too simplistic.

Epilepsy itself does not appear to produce the same degree of congenital-malformation risk as high-risk antiseizure medication exposure.

“Folic acid decreases all malformations” → Too broad.

Folic acid is particularly important for neural tube development and should be used preconceptionally, but it does not eliminate the teratogenic effects of high-risk antiseizure medications.

“Child’s epilepsy risk is exactly 3%” → Approximation only.

Risk depends strongly on the underlying epilepsy syndrome and genetic background.

Key Clinical Pattern

Think of pregnancy and epilepsy as a balance between:

SEIZURE CONTROL ↔ FETAL MEDICATION RISK.

The practical principles are:

Plan pregnancy + review antiseizure medication + avoid abrupt withdrawal + use the safest effective regimen + give folic acid + monitor throughout pregnancy.

The most important drug association to remember is:

VALPROATE → particularly high risk of congenital malformations and adverse neurodevelopmental outcomes.

And for contraception:

ENZYME-INDUCING ANTISEIZURE DRUGS → some hormonal contraceptives become less effective.