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.

Medicine – Wernicke Encephalopathy

Wernicke encephalopathy is an acute neurological syndrome caused by thiamine (vitamin B1) deficiency. It is a medical emergency because untreated thiamine deficiency can lead to permanent neurological damage, coma, or death.

It is classically associated with chronic alcohol misuse, but it can occur in any condition causing severe nutritional deficiency or impaired thiamine absorption.

1. Cause

The underlying problem is acute thiamine deficiency.

Thiamine is essential for carbohydrate metabolism and normal neuronal energy production.

Deficiency particularly affects metabolically active regions of the brain, including:

Mammillary bodies.

Medial thalamus.

Periaqueductal region.

Cerebellar structures.

2. Association with Chronic Alcohol Misuse

The most familiar clinical association is:

Chronic alcohol misuse.

Alcohol increases the risk through several mechanisms:

Poor nutritional intake.

Reduced gastrointestinal absorption of thiamine.

Reduced hepatic storage.

Impaired utilisation of thiamine.

Therefore, a malnourished patient with chronic alcohol misuse and acute neurological symptoms should be considered at high risk.

3. Other Causes

Wernicke encephalopathy is not limited to alcohol-related disease.

Other causes include:

Severe malnutrition.

Prolonged vomiting.

Hyperemesis gravidarum.

Bariatric surgery.

Malabsorption.

Prolonged fasting or starvation.

Cancer-associated malnutrition.

Long-term inadequate nutritional intake.

4. Classic Clinical Triad

The traditional triad consists of:

Confusion.

Ataxia.

Ocular abnormalities.

The ocular abnormalities may include:

Nystagmus.

Ophthalmoplegia.

However, many patients do not present with the complete triad.

Therefore, absence of one or more of these findings does not exclude the diagnosis.

5. Global Confusional State

A global confusional state is one of the most important features.

Patients may appear:

Disoriented.

Inattentive.

Drowsy.

Apathetic.

Unable to concentrate.

In severe cases, consciousness may deteriorate further.

6. Ataxia

Ataxia is another classic feature.

It most commonly affects:

Gait.

Patients may have a broad-based, unsteady gait and difficulty standing or walking.

The ataxia may result from involvement of:

Cerebellar pathways.

and

Peripheral sensory pathways.

7. Nystagmus

Nystagmus is a common ocular sign.

It may be:

Horizontal.

Gaze-evoked.

or associated with other eye movement abnormalities.

Nystagmus can sometimes be one of the earliest neurological signs.

8. Ophthalmoplegia

Wernicke encephalopathy may cause weakness of extraocular movements.

Possible abnormalities include:

Lateral rectus weakness.

Gaze palsies.

Conjugate eye movement abnormalities.

Complete ophthalmoplegia is less common than partial eye movement disturbance.

9. Peripheral Neuropathy

Peripheral neuropathy can accompany thiamine deficiency.

Patients may develop:

Distal numbness.

Paraesthesiae.

Distal weakness.

Reduced reflexes.

This neuropathy is sometimes referred to as dry beriberi when prominent.

10. Why the Diagnosis Is Often Missed

The classic triad is useful for exams, but in real clinical practice many patients have only part of it.

A patient may present predominantly with:

Confusion.

or

Ataxia.

or

Eye movement abnormalities.

Because delay in treatment is dangerous, the threshold for giving thiamine should be low when the clinical context suggests deficiency.

11. Clinical Diagnosis

Wernicke encephalopathy is primarily a clinical diagnosis.

Treatment should not be delayed while waiting for laboratory confirmation.

Blood thiamine measurements are not always rapidly available and may not reliably exclude the diagnosis.

12. MRI Findings

MRI may support the diagnosis, although a normal MRI does not exclude it.

Typical abnormalities may involve:

Mammillary bodies.

Medial thalami.

Periaqueductal grey matter.

Regions around the third ventricle.

Imaging is mainly supportive rather than essential for immediate treatment.

13. Treatment

The main treatment is:

Parenteral thiamine.

Intravenous thiamine is generally preferred in suspected Wernicke encephalopathy because oral absorption may be unreliable and rapid treatment is required.

Treatment should be started promptly.

14. Thiamine and Glucose

A classic clinical teaching point is:

Give thiamine before or together with glucose whenever possible in a severely thiamine-deficient patient.

A carbohydrate load increases the requirement for thiamine and may worsen neurological injury in a deficient patient.

However:

Urgent treatment of severe hypoglycaemia should never be dangerously delayed.

15. Magnesium

Magnesium should also be checked and corrected if deficient.

Magnesium is required for normal thiamine-dependent enzyme function.

Therefore, severe magnesium deficiency can reduce the effectiveness of thiamine replacement.

16. General Supportive Treatment

Management may also require:

Correction of dehydration.

Correction of electrolyte abnormalities.

Nutritional rehabilitation.

Management of alcohol withdrawal.

Prevention and treatment of associated infections or complications.

17. Response to Treatment

Some manifestations improve quickly after thiamine.

Ocular abnormalities may improve within:

Hours to days.

Confusion often improves more gradually.

Ataxia may take longer and may not completely resolve if neuronal damage is already established.

18. Progression to Korsakoff Syndrome

Untreated or inadequately treated Wernicke encephalopathy can progress to:

Korsakoff syndrome.

Korsakoff syndrome is a chronic memory disorder characterised mainly by:

Anterograde amnesia.

Severe impairment of new learning.

Confabulation.

Poor insight.

19. About the “80% Develop Korsakoff Syndrome” Figure

The traditional teaching figure that around 80% develop Korsakoff syndrome comes largely from older descriptions of inadequately treated cases.

It should not be interpreted as an inevitable outcome in a patient who is recognised and treated promptly.

The key clinical message is:

Delayed or insufficient thiamine treatment greatly increases the risk of persistent amnestic impairment.

20. Wernicke–Korsakoff Syndrome

Wernicke encephalopathy and Korsakoff syndrome represent different parts of the same spectrum of severe thiamine deficiency.

A useful distinction is:

Wernicke encephalopathy = acute neurological emergency.

Korsakoff syndrome = chronic amnestic disorder.

21. Wernicke Encephalopathy – Note Form

Cause: acute severe vitamin B1 deficiency.

Classic association: chronic alcohol misuse.

Other causes: malnutrition, prolonged vomiting, bariatric surgery and malabsorption.

Classic triad: confusion + ataxia + ocular abnormalities.

Ocular signs: nystagmus and ophthalmoplegia/gaze palsy.

Peripheral nervous system: neuropathy may coexist.

Diagnosis: primarily clinical.

Treatment: immediate parenteral thiamine.

Do not delay treatment: laboratory confirmation is not required before giving thiamine when strongly suspected.

Glucose: give thiamine before or alongside carbohydrate when possible, but do not delay emergency glucose for severe hypoglycaemia.

Important electrolyte: correct magnesium deficiency.

Major chronic complication: Korsakoff syndrome.

22. Wernicke versus Korsakoff

Wernicke encephalopathy:

Acute.

Confusion.

Ataxia.

Nystagmus/ophthalmoplegia.

Emergency treatment with thiamine.

Korsakoff syndrome:

Chronic.

Severe memory impairment.

Anterograde amnesia.

Confabulation.

Poor insight.

Often follows inadequately treated Wernicke encephalopathy.

Key Clinical Pattern

Think of Wernicke encephalopathy as:

THIAMINE DEFICIENCY + CONFUSION + ATAXIA + EYE SIGNS.

The classic examination pattern is:

Confusion + gait ataxia + nystagmus/ophthalmoplegia.

And the key management point is:

Treat immediately with parenteral thiamine—do not wait for confirmation.

The major long-term consequence is:

Korsakoff syndrome with persistent severe memory impairment.

Medicine – Korsakoff Syndrome

Korsakoff syndrome is a chronic amnestic disorder caused by thiamine (vitamin B1) deficiency, most commonly in the setting of chronic alcohol misuse. It often develops after Wernicke encephalopathy, especially when thiamine deficiency is prolonged or inadequately treated.

It is characterized mainly by severe impairment of new memory formation, with relatively preserved alertness and other cognitive functions in the early stages.

1. Relationship to Wernicke Encephalopathy

Korsakoff syndrome commonly follows Wernicke encephalopathy.

Wernicke encephalopathy is the acute neurological syndrome caused by thiamine deficiency and classically presents with:

Confusion.

Ocular abnormalities.

Gait ataxia.

If the thiamine deficiency persists, the acute encephalopathy may evolve into the more chronic memory disorder known as Korsakoff syndrome.

2. Wernicke–Korsakoff Syndrome

Because the two conditions are closely related, they are often grouped together under the term:

Wernicke–Korsakoff syndrome.

Wernicke encephalopathy represents the more acute stage, while Korsakoff syndrome represents the more chronic amnestic stage.

3. Underlying Cause

The underlying abnormality is severe thiamine deficiency.

Although chronic alcohol misuse is the classic association, thiamine deficiency may also occur with:

Severe malnutrition.

Prolonged vomiting.

Hyperemesis gravidarum.

Bariatric or gastric surgery.

Malabsorption.

Prolonged starvation.

Therefore, Korsakoff syndrome is not exclusive to alcohol-related disease.

4. Why Alcohol Misuse Causes Thiamine Deficiency

Chronic alcohol misuse can contribute through several mechanisms.

These include:

Poor nutritional intake.

Reduced intestinal thiamine absorption.

Impaired hepatic storage.

Reduced conversion to active thiamine metabolites.

The combination places patients at high risk of Wernicke encephalopathy and later Korsakoff syndrome.

5. Main Clinical Feature

The central feature is a severe disorder of memory.

Patients may appear awake and able to converse normally, yet they have profound difficulty retaining new information.

This contrast can make the disorder less obvious unless memory is specifically tested.

6. Poor Short-Term Memory

The original note describes poor short-term memory.

More precisely, the major deficit is an inability to form and retain new long-term memories.

For example, a patient may:

Forget a conversation that occurred minutes earlier.

Repeatedly ask the same question.

Forget that they have already eaten.

Fail to remember people they have just met.

7. Anterograde Amnesia

The hallmark memory deficit is:

Anterograde amnesia.

This means the patient has difficulty forming new memories after the onset of the disorder.

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

8. Retrograde Amnesia

Some patients also have retrograde amnesia.

This means loss of memories from the period before the illness.

Remote childhood memories may be better preserved than more recent pre-illness memories.

Therefore, Korsakoff syndrome may involve both:

Severe anterograde amnesia.

and

Variable retrograde amnesia.

9. Confabulation

Confabulation is a classic feature.

The patient may unintentionally produce inaccurate or invented explanations to fill gaps in memory.

For example, when asked what happened earlier in the day, the patient may give a plausible but incorrect account.

10. Confabulation Is Not Deliberate Lying

An important point is that confabulation is usually not intentional deception.

The patient is not consciously trying to mislead the examiner.

Instead, the brain automatically fills in missing memory with an invented or distorted account.

Therefore:

Confabulation = false memories produced without deliberate intent to deceive.

11. Lack of Insight

Patients may have limited awareness of their memory impairment.

This produces:

Poor insight.

They may underestimate the severity of their deficits or deny having significant memory problems.

This can complicate assessment and management.

12. Other Cognitive Functions

Compared with many dementias, other cognitive domains may initially be relatively preserved.

A patient may still have:

Normal conversational language.

Reasonable general knowledge.

Preserved social interaction.

Relatively intact immediate attention.

Yet the ability to learn and retain new information is profoundly impaired.

13. Immediate Memory versus New Learning

It is useful to distinguish immediate memory from anterograde memory.

A patient may repeat a short sequence of numbers immediately after hearing them, showing reasonable attention and working memory.

However, after several minutes, the patient may be unable to recall the same information.

This demonstrates the failure of new memory consolidation.

14. Brain Structures Involved

Thiamine deficiency particularly damages structures involved in memory circuits.

Important areas include:

Mammillary bodies.

Medial thalamus.

Other diencephalic memory pathways.

These abnormalities help explain the severe impairment of memory formation.

15. Association with Wernicke Features

Some patients with Korsakoff syndrome may have a history of earlier features of Wernicke encephalopathy, such as:

Confusion.

Ataxia.

Nystagmus.

Ophthalmoplegia.

However, the full classic triad is not always present.

Therefore, Wernicke encephalopathy can easily be missed.

16. Wernicke Encephalopathy – Classic Triad

The traditional triad is:

Confusion.

Ataxia.

Ophthalmoplegia or other ocular abnormalities.

Ocular findings may include:

Nystagmus.

Lateral rectus weakness.

Gaze palsies.

However, not all patients show all three signs.

17. Diagnosis

Korsakoff syndrome is primarily a clinical diagnosis based on the characteristic memory disorder and history suggesting thiamine deficiency.

Assessment may include:

Detailed history.

Cognitive examination.

Nutritional assessment.

Alcohol-use history.

Blood tests to identify associated deficiencies or metabolic disease.

Brain imaging may be used to exclude alternative causes.

18. Treatment

The most important treatment is:

Thiamine replacement.

If Wernicke encephalopathy is suspected, treatment should be given promptly because delay can cause irreversible neurological damage.

Thiamine is commonly given parenterally initially in high-risk or symptomatic patients.

19. Thiamine Before Glucose

A classic clinical teaching point is that in a patient at risk of severe thiamine deficiency:

Thiamine should be given before or together with glucose-containing treatment whenever possible.

Glucose metabolism increases thiamine demand and may worsen acute thiamine deficiency.

However, urgently required treatment for severe hypoglycaemia should not be dangerously delayed.

20. Nutritional Management

Patients also require correction of:

General malnutrition.

Electrolyte abnormalities.

Magnesium deficiency.

Magnesium is particularly relevant because it is required for normal thiamine-dependent enzymatic function.

21. Alcohol Management

If chronic alcohol misuse is responsible, treatment should also address:

Alcohol withdrawal where necessary.

Long-term alcohol abstinence.

Nutritional rehabilitation.

Psychological and addiction support.

These measures help prevent recurrence and further neurological injury.

22. Prognosis

The prognosis is variable.

Some patients improve significantly with thiamine and abstinence, particularly when treatment begins early.

However, established Korsakoff syndrome can be persistent or only partially reversible.

Residual problems may include:

Severe memory impairment.

Poor new learning.

Confabulation.

Reduced independence.

23. Korsakoff Syndrome – Note Form

Cause: chronic thiamine deficiency.

Classic association: chronic alcohol misuse.

Relationship: often follows Wernicke encephalopathy.

Main problem: chronic severe memory disorder.

Hallmark: anterograde amnesia.

Other memory deficit: variable retrograde amnesia.

Confabulation: invented or distorted memories used unconsciously to fill memory gaps.

Insight: often impaired.

Consciousness: usually relatively clear compared with acute Wernicke encephalopathy.

Treatment: urgent thiamine replacement and correction of nutritional deficiency.

24. Wernicke versus Korsakoff

Wernicke encephalopathy:

Acute.

Confusion.

Ataxia.

Ocular abnormalities.

Medical emergency.

Potentially reversible if treated promptly.

Korsakoff syndrome:

Chronic.

Severe memory impairment.

Anterograde amnesia.

Confabulation.

Poor insight.

May be only partially reversible.

25. Useful Clinical Pattern

Alcohol misuse + confusion + ataxia + eye signs → think Wernicke encephalopathy.

History of Wernicke/thiamine deficiency + severe inability to form new memories + confabulation → think Korsakoff syndrome.

Key Clinical Pattern

Think of Korsakoff syndrome as:

THIAMINE DEFICIENCY → CHRONIC MEMORY DISORDER.

The high-yield features are:

Anterograde amnesia + poor recent memory + confabulation + lack of insight.

And remember the relationship:

Wernicke = acute encephalopathy.

Korsakoff = chronic amnestic syndrome.

Medicine – Carpal Tunnel Syndrome

Carpal tunnel syndrome is a compression neuropathy of the median nerve at the wrist, where the nerve passes beneath the flexor retinaculum through the carpal tunnel.

It is the most common entrapment neuropathy and typically causes pain, numbness, and paraesthesiae in the median nerve distribution, often worse at night.

⸻

1. Basic Mechanism

The carpal tunnel is a narrow space at the wrist containing:

The median nerve.

Flexor tendons.

The roof of the tunnel is formed by the flexor retinaculum, also called the transverse carpal ligament.

Compression of the median nerve within this tunnel produces the characteristic symptoms.

⸻

2. Median Nerve Involvement

Carpal tunnel syndrome is therefore a median nerve palsy or entrapment neuropathy at the wrist.

Because the lesion is distal, forearm muscles supplied by the median nerve are spared.

The main deficits involve:

Median-innervated sensation in the hand.

and

Median-innervated intrinsic muscles of the thenar region.

⸻

3. Pain and Paraesthesiae

The most common symptoms are:

Pain.

Tingling.

Pins and needles.

Numbness.

Symptoms commonly affect the hand but may radiate proximally into the forearm.

⸻

4. Worse at Night

Symptoms are classically:

Worse at night.

Patients may wake from sleep because of tingling or pain.

They may report that shaking or moving the hand temporarily relieves the symptoms.

This is a common and useful clinical clue.

⸻

5. Sensory Distribution

Paraesthesiae typically involve the:

Thumb.

Index finger.

Middle finger.

Radial half of the ring finger.

This corresponds to the:

Lateral three and a half fingers.

⸻

6. Important Sensory Sparing

An important localisation clue is that sensation over the thenar eminence is usually spared.

This is because the palmar cutaneous branch of the median nerve arises proximal to the carpal tunnel and passes superficial to the flexor retinaculum.

Therefore:

Carpal tunnel syndrome → numb lateral 3½ digits, but thenar skin sensation is usually preserved.

⸻

7. Motor Weakness

More advanced carpal tunnel syndrome may cause weakness of the median-innervated intrinsic hand muscles.

The classic muscles are remembered using:

LOAF.

⸻

8. LOAF Muscles

L = Lateral two lumbricals.

O = Opponens pollicis.

A = Abductor pollicis brevis.

F = Flexor pollicis brevis, particularly its superficial head.

These are the main median-innervated intrinsic hand muscles.

⸻

9. Lateral Two Lumbricals

The first and second lumbricals are supplied by the median nerve.

They help:

Flex the metacarpophalangeal joints.

and

Extend the interphalangeal joints.

Weakness may contribute to impaired fine finger movement.

⸻

10. Opponens Pollicis

Opponens pollicis is essential for thumb opposition.

Weakness may cause difficulty:

Touching the thumb to the little finger.

Picking up small objects.

Buttoning clothes.

Using keys or coins.

Thumb opposition is therefore an important bedside test.

⸻

11. Abductor Pollicis Brevis

Abductor pollicis brevis is commonly tested in suspected carpal tunnel syndrome.

The patient is asked to lift the thumb perpendicular to the palm against resistance.

Weakness suggests median nerve dysfunction at the wrist.

⸻

12. Flexor Pollicis Brevis

The superficial head of flexor pollicis brevis is typically supplied by the median nerve.

Weakness may contribute to impaired thumb movement.

The deep head can receive ulnar nerve innervation, so the muscle has variable dual innervation.

⸻

13. Thenar Wasting

Severe or longstanding median nerve compression may cause:

Thenar muscle wasting.

This is seen as flattening of the thenar eminence.

It suggests significant chronic motor involvement.

⸻

14. Functional Consequences

Patients may have difficulty with:

Fine finger movements.

Thumb opposition.

Pinching objects.

Holding small objects.

Buttoning clothes.

They may also report dropping objects because of sensory loss and weakness.

⸻

15. Pregnancy

Pregnancy is a recognised association with carpal tunnel syndrome.

Fluid retention may increase pressure within the carpal tunnel.

Symptoms often appear during later pregnancy and may improve after delivery.

⸻

16. Hypothyroidism

Hypothyroidism is associated with carpal tunnel syndrome.

Tissue swelling and mucopolysaccharide deposition may contribute to median nerve compression.

⸻

17. Acromegaly

In acromegaly, enlargement of soft tissues and connective tissues around the wrist may narrow the carpal tunnel.

Therefore, bilateral carpal tunnel syndrome can occasionally be a clue to underlying acromegaly.

⸻

18. Amyloidosis

Amyloid deposition can contribute to median nerve compression within the carpal tunnel.

Bilateral carpal tunnel syndrome may sometimes precede other manifestations of systemic or transthyretin amyloidosis.

⸻

19. Rheumatoid Arthritis

Rheumatoid arthritis may produce inflammation and swelling of flexor tendon sheaths within the carpal tunnel.

This increases pressure on the median nerve.

Carpal tunnel syndrome is therefore a recognised complication of inflammatory arthritis.

⸻

20. Obesity

Obesity is associated with increased risk of carpal tunnel syndrome.

The mechanism is likely multifactorial and may include increased tissue pressure within the carpal tunnel.

⸻

21. PHARO Association Mnemonic

The traditional mnemonic is:

P – Pregnancy

H – Hypothyroidism

A – Acromegaly

R – Rheumatoid arthritis

O – Obesity

The original note also includes amyloidosis, which is an important association even though it does not fit neatly into PHARO.

A practical expanded memory pattern is:

Pregnancy + Hypothyroidism + Acromegaly + Amyloidosis + RA + Obesity.

⸻

22. Other Associations

Other recognised associations include:

Diabetes mellitus.

Chronic kidney disease.

Previous wrist fracture or trauma.

Repetitive wrist activity.

Tenosynovitis.

However, many cases occur without a clearly identifiable underlying disorder.

⸻

23. Tinel Sign

Tinel sign is tested by tapping over the median nerve at the carpal tunnel.

A positive test reproduces:

Tingling or electric sensations in the median nerve distribution.

This may support the diagnosis.

⸻

24. Phalen Sign

Phalen test is performed by holding the wrists in maximal flexion, usually with the backs of the hands pressed together.

A positive test reproduces:

Numbness or tingling in the lateral three and a half fingers.

Symptoms often appear within about a minute.

⸻

25. Limitations of Tinel and Phalen Tests

Tinel and Phalen signs can support the diagnosis, but neither is completely sensitive or specific.

Therefore:

A negative test does not exclude carpal tunnel syndrome.

The overall clinical pattern remains important.

⸻

26. Nerve Conduction Studies

Nerve conduction studies are useful when:

The diagnosis is uncertain.

Symptoms are severe.

There is motor weakness or thenar wasting.

Surgery is being considered.

Typical findings include slowed median nerve conduction across the wrist.

⸻

27. Electromyography

EMG may be added when severe nerve damage is suspected.

It can show evidence of denervation in median-innervated thenar muscles.

It is particularly useful in advanced cases or when another neuropathy needs to be excluded.

⸻

28. Wrist Splinting

Initial treatment often includes a neutral-position wrist splint.

This is especially useful at night.

Keeping the wrist neutral reduces pressure within the carpal tunnel and may improve nocturnal symptoms.

⸻

29. Activity Modification

Patients may also benefit from reducing activities that involve:

Repeated wrist flexion.

Repeated wrist extension.

Prolonged pressure over the wrist.

Ergonomic modification can be useful when occupational factors contribute.

⸻

30. Corticosteroid Injection

A local corticosteroid injection into the carpal tunnel can provide symptom relief.

The injection is placed into the carpal tunnel region, taking care to avoid direct injury to the median nerve.

It is more accurate to say carpal tunnel steroid injection rather than steroid injection “to the flexor retinaculum.”

⸻

31. Surgical Decompression

Surgical treatment involves division of the:

Flexor retinaculum / transverse carpal ligament.

This releases pressure on the median nerve.

The procedure is known as:

Carpal tunnel release.

⸻

32. Indications for Surgery

Surgery is more strongly considered when there is:

Persistent symptoms despite conservative treatment.

Severe nerve conduction abnormalities.

Thenar weakness or wasting.

Persistent sensory loss.

Progressive neurological deficit.

⸻

33. Carpal Tunnel Syndrome – Note Form

Nerve: median nerve.

⸻

Site: wrist, beneath the flexor retinaculum.

⸻

Sensory symptoms: pain, numbness and paraesthesiae.

⸻

Timing: often worse at night.

⸻

Sensory distribution: lateral three and a half fingers.

⸻

Thenar skin: usually spared because palmar cutaneous branch does not pass through the tunnel.

⸻

Motor weakness: LOAF muscles.

⸻

L: lateral two lumbricals.

⸻

O: opponens pollicis.

⸻

A: abductor pollicis brevis.

⸻

F: flexor pollicis brevis.

⸻

Advanced feature: thenar wasting.

⸻

Associations: pregnancy, hypothyroidism, acromegaly, amyloidosis, rheumatoid arthritis and obesity.

⸻

Tinel sign: tapping over median nerve produces tingling.

⸻

Phalen sign: wrist flexion reproduces paraesthesiae.

⸻

Investigation: nerve conduction studies when indicated.

⸻

Initial treatment: neutral wrist splint.

⸻

Further treatment: local corticosteroid injection.

⸻

Definitive treatment in persistent/severe disease: surgical carpal tunnel decompression.

⸻

34. Median Nerve Lesion at the Wrist

Carpal tunnel syndrome should be distinguished from a more proximal median nerve lesion.

In carpal tunnel syndrome:

Forearm median-innervated muscles are spared.

Thenar muscles may be weak.

Lateral 3½ digits develop sensory symptoms.

Thenar eminence sensation is usually preserved.

This helps localise the lesion specifically to the carpal tunnel.

⸻

Key Clinical Pattern

Think of carpal tunnel syndrome as:

MEDIAN NERVE COMPRESSION AT WRIST → NOCTURNAL PAIN/PARAESTHESIA + LATERAL 3½ FINGERS + LOAF WEAKNESS.

Remember:

LOAF = Lateral 2 lumbricals + Opponens pollicis + Abductor pollicis brevis + Flexor pollicis brevis.

And the useful localisation clue is:

Lateral 3½ fingers numb, but thenar eminence sensation usually spared.

Medicine – Ulnar Nerve Palsy

Ulnar nerve palsy causes weakness and wasting of muscles supplied by the ulnar nerve, together with sensory loss over the medial part of the hand. The exact pattern depends on whether the lesion occurs at the elbow or more distally at the wrist.

A key clinical feature is clawing of the ring and little fingers, especially in distal lesions.

1. Main Functions of the Ulnar Nerve

The ulnar nerve supplies many of the intrinsic muscles of the hand.

Important motor functions include:

Finger abduction.

Finger adduction.

Hypothenar movements.

Flexion at the metacarpophalangeal joints of the ring and little fingers through the medial two lumbricals.

Thumb adduction through adductor pollicis.

It also supplies some forearm muscles, especially:

Flexor carpi ulnaris.

Medial half of flexor digitorum profundus.

2. Lesion at the Elbow

A lesion at the elbow affects both the forearm and hand branches of the ulnar nerve.

This can produce:

Weakness of ulnar-innervated forearm muscles.

Weakness and wasting of intrinsic hand muscles.

Sensory loss over the medial one and a half fingers.

The classic site is around the medial epicondyle and cubital tunnel.

3. Forearm Wasting

The original note describes wasting of the medial side of the forearm.

This may occur because proximal ulnar nerve lesions weaken:

Flexor carpi ulnaris.

and

The ulnar half of flexor digitorum profundus.

However, the most striking wasting is often in the hand rather than the forearm.

4. Hypothenar Wasting

The hypothenar eminence contains muscles controlling the little finger.

Ulnar nerve palsy may cause wasting and weakness of:

Abductor digiti minimi.

Flexor digiti minimi.

Opponens digiti minimi.

This produces flattening of the hypothenar eminence.

5. Interosseous Muscle Weakness

All the interossei are supplied by the ulnar nerve.

Therefore, ulnar palsy causes weakness of:

Finger abduction.

Finger adduction.

A useful mnemonic is:

DAB = Dorsal interossei ABduct.

PAD = Palmar interossei ADduct.

6. Testing Finger Abduction

The patient is asked to spread the fingers apart against resistance.

Weakness suggests dysfunction of the:

Dorsal interossei.

This is a classic test of ulnar nerve function.

7. Testing Finger Adduction

The patient is asked to bring the fingers together against resistance.

Weakness reflects impairment of the:

Palmar interossei.

A simple bedside test is to ask the patient to hold a piece of paper between adjacent fingers.

8. Medial Two Lumbricals

The third and fourth lumbricals, corresponding mainly to the ring and little fingers, are supplied by the ulnar nerve.

These muscles normally:

Flex the metacarpophalangeal joints.

and

Extend the interphalangeal joints.

Therefore, ulnar palsy causes impaired coordinated finger movement.

The original note says “weak finger flexion,” but more precisely the lumbricals help flex the MCP joints while extending the IP joints.

9. Claw Hand Deformity

The classic deformity is an ulnar claw.

This especially affects the:

Ring finger.

Little finger.

The deformity consists of:

Hyperextension at the MCP joints.

with

Flexion at the interphalangeal joints.

This results from loss of the medial lumbricals and interossei.

10. Why the Fingers Claw

Normally, the lumbricals and interossei flex the MCP joints and extend the IP joints.

When these muscles are paralysed:

Extensor digitorum hyperextends the MCP joints.

while

Long finger flexors flex the IP joints.

The result is:

Clawing.

11. Ulnar Paradox

An important clinical principle is the ulnar paradox.

A distal lesion at the wrist may produce more obvious clawing than a proximal lesion at the elbow.

Why?

In a proximal lesion, the ulnar half of flexor digitorum profundus is also weakened, reducing flexion at the distal interphalangeal joints of the ring and little fingers.

Therefore:

More proximal lesion → more weakness, but sometimes less obvious clawing.

This is called the ulnar paradox.

12. Sensory Loss

The ulnar nerve supplies sensation to approximately the:

Little finger.

and

Ulnar half of the ring finger.

This corresponds to the medial one and a half fingers.

Sensory loss may affect both the palmar and dorsal surfaces depending on the level of the lesion.

13. Sensory Distribution at the Elbow

A lesion at or above the elbow usually affects both:

Palmar ulnar sensation.

and

Dorsal ulnar sensation.

This is because the dorsal cutaneous branch arises in the distal forearm, proximal to the wrist.

14. Causes of Ulnar Nerve Lesions at the Elbow

Common causes include:

Compression around the cubital tunnel.

Fracture or dislocation around the elbow.

Prolonged leaning on the elbows.

Degenerative changes such as osteoarthritis.

Mononeuritis multiplex.

15. Fracture or Dislocation at the Elbow

The ulnar nerve passes behind the medial epicondyle and is therefore vulnerable to trauma.

Fracture or dislocation around the elbow may cause:

Motor weakness.

Hand wasting.

Clawing.

Sensory loss.

16. Occupational Compression

Repeated or prolonged pressure on the elbow can compress the ulnar nerve within the cubital tunnel.

Examples include:

Leaning on elbows for long periods.

Frequent elbow flexion.

Certain occupational postures.

Patients may initially complain of tingling in the ring and little fingers.

17. Osteoarthritis

Degenerative changes around the elbow may narrow the cubital tunnel or produce local compression.

This can lead to chronic ulnar neuropathy.

Symptoms may progress slowly.

18. Mononeuritis Multiplex

Ulnar nerve palsy may occur as part of mononeuritis multiplex, where several individual peripheral nerves are affected asymmetrically.

This pattern is particularly associated with:

Vasculitis.

Diabetes.

Systemic inflammatory disease.

19. Wrist Lesions

A lesion at the wrist affects the ulnar nerve after the forearm branches have already been given off.

Therefore, ulnar-innervated forearm muscles are spared.

The main deficits involve the intrinsic hand muscles.

20. Motor Findings in Wrist Lesions

A wrist-level ulnar lesion may cause weakness of:

Hypothenar muscles.

Interossei.

Medial two lumbricals.

Adductor pollicis.

This produces:

Finger abduction and adduction weakness.

Clawing of ring and little fingers.

Weak thumb adduction.

21. Dorsal Sensation Is Spared in Wrist Lesions

This is an important localisation clue.

The dorsal cutaneous branch of the ulnar nerve usually leaves the main nerve in the distal forearm before the nerve reaches the wrist.

Therefore, a lesion at the wrist may spare:

Sensation over the dorsum of the ulnar side of the hand.

This matches the original note.

22. Palmar Sensory Loss at the Wrist

Although dorsal sensation may be spared, a wrist lesion can still cause sensory loss over the:

Palmar little finger.

Palmar ulnar half of the ring finger.

The exact pattern depends on whether the superficial sensory branch is involved.

23. Guyon Canal Syndrome

A common site for distal ulnar nerve compression is Guyon canal at the wrist.

Compression here may occur with:

Cycling or prolonged handlebar pressure.

Ganglion cysts.

Trauma.

Occupational repetitive pressure.

The motor and sensory pattern depends on which branch is compressed.

24. Froment Sign

Froment sign tests ulnar nerve function through adductor pollicis.

The patient holds a piece of paper between the thumb and index finger.

If adductor pollicis is weak, the patient compensates by flexing the thumb interphalangeal joint using flexor pollicis longus, which is supplied by the median nerve.

Therefore:

Positive Froment sign → ulnar nerve weakness.

25. Wartenberg Sign

Another possible finding is Wartenberg sign.

The little finger remains abducted because of weakness of the palmar interossei and imbalance of muscle forces.

This may be seen in ulnar neuropathy.

26. Examination

Important tests include:

Finger abduction.

Finger adduction.

Thumb adduction.

Hypothenar strength.

Sensation over the little finger and ulnar half of the ring finger.

Inspection for interosseous wasting and clawing.

27. Interosseous Wasting

Ulnar neuropathy can produce visible wasting between the metacarpals.

This may be especially noticeable in the:

First dorsal interosseous space.

The hand may appear hollowed between the metacarpal bones.

28. Investigations

Diagnosis is often clinical, but further tests may include:

Nerve conduction studies.

Electromyography.

X-ray of the elbow if trauma or arthritis is suspected.

Ultrasound or MRI in selected compressive lesions.

These can help identify the lesion level and severity.

29. Treatment

Treatment depends on the cause.

Management may include:

Avoiding prolonged elbow pressure.

Reducing excessive elbow flexion.

Splinting.

Physiotherapy and occupational therapy.

Treating underlying inflammatory or metabolic disease.

Surgical decompression or transposition in selected severe or persistent cases.

30. Ulnar Nerve Palsy – Lesion at the Elbow

Forearm muscles: may be weak.

Hand muscles: interossei, hypothenar muscles, medial two lumbricals and adductor pollicis affected.

Clawing: ring and little fingers.

Finger abduction: weak.

Finger adduction: weak.

Thumb adduction: weak.

Sensation: medial one and a half fingers, palmar and dorsal surfaces may be affected.

Causes: elbow fracture/dislocation, cubital tunnel compression, leaning on elbows, osteoarthritis, mononeuritis multiplex.

31. Ulnar Nerve Palsy – Lesion at the Wrist

Forearm muscles: spared.

Intrinsic hand muscles: weak.

Clawing: often more obvious than in a proximal lesion.

Finger abduction/adduction: weak.

Thumb adduction: weak.

Dorsal hand sensation: usually spared.

Palmar ulnar sensation: may be impaired.

Typical site: Guyon canal.

32. Elbow versus Wrist Localisation

Elbow lesion:

Forearm + hand weakness.

Dorsal and palmar sensory loss may occur.

Clawing may be less pronounced because flexor digitorum profundus is also weak.

Wrist lesion:

Intrinsic hand weakness only.

Dorsal sensation usually spared.

Clawing may be more pronounced.

This is the basis of the ulnar paradox.

Key Clinical Pattern

Think of ulnar nerve palsy as:

CLAWING OF RING + LITTLE FINGERS + INTEROSSEOUS WASTING + WEAK FINGER ABDUCTION/ADDUCTION + SENSORY LOSS OF MEDIAL 1½ FINGERS.

For localisation:

Elbow lesion → forearm + hand weakness + dorsal sensory loss may occur.

Wrist lesion → intrinsic hand weakness + dorsal sensation spared.

And remember:

DAB = dorsal interossei abduct.

PAD = palmar interossei adduct.

Positive Froment sign = weak adductor pollicis from ulnar nerve palsy.

Medicine – Radial Nerve Palsy

Radial nerve palsy causes weakness of muscles supplied by the radial nerve, especially the extensor muscles of the wrist and fingers. The most characteristic clinical sign is wrist drop.

The exact pattern depends on the level of the lesion, because the radial nerve gives off branches at different points along the arm and forearm.

1. Main Function of the Radial Nerve

The radial nerve mainly supplies the extensor compartments of the upper limb.

Its motor functions include extension at the:

Elbow.

Wrist.

Metacarpophalangeal joints.

It also contributes to forearm supination through the supinator muscle.

2. Wrist Drop

The classic sign of radial nerve palsy is:

Wrist drop.

This occurs because the wrist extensors are weak or paralysed, while the flexor muscles remain relatively unopposed.

As a result, the hand falls into flexion at the wrist.

3. Finger Extension Weakness

Patients may also have difficulty extending the fingers at the metacarpophalangeal joints.

This can interfere with:

Opening the hand.

Releasing objects.

Positioning the fingers for grip.

Grip strength may also appear reduced because effective gripping requires the wrist to be stabilised in extension.

4. Sensory Loss

The radial nerve supplies sensation to part of the posterior arm and forearm and the dorsolateral hand.

A commonly tested area is the skin over the:

First dorsal web space between the thumb and index finger.

This area is particularly useful for testing the superficial radial nerve.

5. Correction of “First Dorsal Interosseus”

The original note says sensory loss occurs over the first dorsal interosseus.

More precisely, sensory testing is performed over the:

First dorsal web space.

The first dorsal interosseous muscle itself is supplied by the ulnar nerve, not the radial nerve.

Therefore:

Radial sensory testing → first dorsal web space.

6. No Intrinsic Hand Muscles Supplied

The original note correctly emphasizes that the radial nerve supplies no intrinsic muscles of the hand.

Intrinsic hand muscles are mainly supplied by:

Ulnar nerve.

and

Median nerve.

The radial nerve acts mainly through extrinsic extensor muscles located in the forearm.

7. Why Hand Function Is Still Affected

Even though the radial nerve does not supply intrinsic hand muscles, radial palsy can significantly impair hand function.

This is because wrist and finger extension are essential for normal:

Grip strength.

Release of objects.

Fine positioning of the hand.

Therefore, radial nerve palsy can produce major functional disability despite sparing the intrinsic hand muscles.

8. Humeral Shaft Fracture

A classic cause of radial nerve palsy is:

Fracture of the shaft of the humerus.

The radial nerve travels in the radial groove along the posterior aspect of the humerus.

It is therefore vulnerable to injury in mid-shaft fractures.

9. Features of a Radial Groove Lesion

A lesion at the radial groove commonly causes:

Wrist drop.

Finger extension weakness.

Sensory loss over the dorsolateral hand, especially the first dorsal web space.

Triceps function is often relatively preserved because most branches to the triceps arise proximal to the radial groove.

10. Saturday Night Palsy

Saturday night palsy is a compression neuropathy of the radial nerve.

It classically occurs after prolonged pressure on the upper arm, often when a person falls asleep with the arm compressed over a chair or firm surface.

The name historically reflects association with intoxication and prolonged unconscious positioning.

11. Mechanism of Saturday Night Palsy

Compression usually affects the radial nerve around the:

Radial groove of the humerus.

This produces:

Wrist drop.

Finger extension weakness.

Variable sensory loss.

The lesion is often neuropraxic and may recover over time if axonal injury is limited.

12. Mononeuritis Multiplex

Mononeuritis multiplex can also affect the radial nerve.

This refers to an asymmetric disorder involving multiple individual peripheral nerves, often due to:

Vasculitis.

Diabetes.

Inflammatory disease.

If the radial nerve is affected, wrist drop may occur.

13. Higher Radial Nerve Lesions

A very proximal radial nerve lesion, such as in the axilla, can affect more functions.

Possible findings include:

Weak elbow extension due to triceps involvement.

Wrist drop.

Finger extension weakness.

More extensive sensory loss.

This may occur with prolonged axillary compression, such as improper crutch use.

14. Posterior Interosseous Nerve Palsy

The posterior interosseous nerve is a deep motor branch of the radial nerve.

A lesion here causes mainly:

Finger extension weakness.

Thumb extension weakness.

Importantly:

There is no sensory loss, because the posterior interosseous nerve is motor.

Wrist extension may be preserved, although it may be weak and radially deviated.

15. Superficial Radial Nerve Lesion

The superficial radial nerve is predominantly sensory.

A lesion may cause:

Numbness or paraesthesia over the dorsolateral hand.

There is:

No motor weakness.

This helps distinguish it from a more proximal radial nerve palsy.

16. Examination

Important aspects of examination include testing:

Wrist extension.

Finger extension.

Thumb extension.

Elbow extension if a proximal lesion is suspected.

Sensation over the first dorsal web space.

The pattern helps localise the lesion.

17. Wrist Extension

The patient is asked to extend the wrist against resistance.

Weakness suggests radial nerve dysfunction.

In a major lesion, the wrist cannot be actively extended and falls into flexion.

18. Finger Extension

The patient is asked to extend the fingers at the metacarpophalangeal joints.

Weakness is typical of radial nerve or posterior interosseous nerve dysfunction.

This should be distinguished from interphalangeal extension, which also involves intrinsic hand muscles supplied by median and ulnar nerves.

19. Sensory Examination

The most useful autonomous sensory zone for the radial nerve is:

The first dorsal web space.

Reduced sensation here supports involvement of the superficial sensory fibres of the radial nerve.

20. Investigations

Many cases can be diagnosed clinically.

Further tests may include:

X-ray if fracture is suspected.

Nerve conduction studies.

Electromyography.

These are particularly useful when the lesion is severe, persistent, or when localisation is uncertain.

21. Treatment

Treatment depends on the cause.

Management may include:

Treating the underlying fracture or compression.

Avoiding further pressure.

Wrist splinting.

Physiotherapy and occupational therapy.

Monitoring recovery.

Surgical exploration may be required in selected traumatic or persistent lesions.

22. Radial Nerve Palsy – Note Form

Main motor deficit: weakness of wrist and finger extensors.

Classic sign: wrist drop.

Sensory loss: first dorsal web space.

Intrinsic hand muscles: not supplied by radial nerve.

Common cause: humeral shaft fracture.

Compression cause: Saturday night palsy.

Systemic cause: mononeuritis multiplex.

Proximal lesion: may also weaken triceps.

Posterior interosseous lesion: motor weakness without sensory loss.

Key Clinical Pattern

Think of radial nerve palsy as:

WRIST DROP + FINGER EXTENSION WEAKNESS + FIRST DORSAL WEB SPACE SENSORY LOSS.

Important causes are:

Humeral shaft fracture + prolonged radial-groove compression (Saturday night palsy) + mononeuritis multiplex.

And remember the anatomical distinction:

Radial nerve supplies forearm extensors, but NO intrinsic hand muscles.

Toxicology – Iron Poisoning

Source

Iron poisoning most commonly occurs from ingestion of iron-containing medications or supplements, such as ferrous sulfate or ferrous gluconate. Young children are particularly vulnerable because tablets may resemble candy.

Typical Presentation

A child with significant iron ingestion may develop:

• Repeated vomiting
• Abdominal pain
• Diarrhea
• GI bleeding
• Lethargy
• Metabolic acidosis

Severe poisoning can progress to shock, liver injury, coma, and death.

Clinical Features

Severity depends mainly on the amount of elemental iron absorbed.

Milder toxicity commonly causes:

• Nausea
• Vomiting
• Abdominal pain
• Diarrhea

More severe toxicity may cause:

• Hematemesis or GI bleeding
• Dehydration and hypovolemia
• Hypotension and shock
• Metabolic acidosis
• Altered mental status
• Hepatic failure
• Coma

Marked acidosis and very high serum iron concentrations suggest more serious poisoning.

Stages of Toxicity

1. GI Phase – first several hours
2. Vomiting, diarrhea, abdominal pain, and possible GI bleeding.
3. Latent Phase – roughly 6–24 hours
4. GI symptoms may temporarily improve even though systemic toxicity continues. Tachycardia, lethargy, and metabolic acidosis may persist.
5. Shock Phase – about 12–24 hours
6. Hypotension, vasodilation, impaired cardiac output, and circulatory collapse may develop.
7. Hepatic Phase – approximately 2–3 days
8. Severe poisoning can produce acute hepatotoxicity and liver failure.
9. Late GI Scarring – weeks later
10. Healing gastrointestinal injury can produce strictures and, in some cases, gastric outlet obstruction.

Mechanism of Action

Normally, iron is carried in the blood bound to transferrin. In overdose, transferrin becomes saturated and excess free iron circulates.

Free iron:

• Directly damages the gastrointestinal mucosa
• Disrupts mitochondrial energy production
• Generates oxidative injury
• Damages blood vessels and solid organs

This contributes to acidosis, shock, and hepatic injury.

Management

Treatment is primarily supportive and may include:

• Airway and cardiovascular stabilization
• IV fluids for dehydration or shock
• Monitoring of serum iron, electrolytes, acid-base status, glucose, and liver function
• Abdominal imaging in selected cases because some iron tablets are radiopaque
• Whole bowel irrigation when substantial tablets remain in the GI tract and toxicology guidance supports it

Activated charcoal is ineffective because it does not meaningfully bind iron.

Deferoxamine is the specific iron chelator and may be used for patients with severe clinical toxicity or other findings suggesting substantial systemic iron poisoning.

Key Points

• Think of the classic progression: GI symptoms → temporary improvement → shock → liver injury → possible late GI stricture.
• A symptom-free interval does not guarantee recovery.
• Activated charcoal does not work for iron.
• Deferoxamine binds circulating free iron in severe poisoning.
• Some iron tablets may be visible on plain abdominal radiographs.

Toxicology – Cadmium Poisoning

Source

Cadmium exposure is usually occupational and may occur during:

• Welding
• Soldering
• Electroplating
• Mining and smelting of zinc, copper, or lead

Other possible sources include nickel–cadmium batteries, ceramic pigments and glazes, and some metal-containing consumer products.

Typical Presentation

A worker exposed to cadmium fumes may initially develop a flu-like illness several hours later, with fever, chills, muscle aches, and dry cough. Despite an initially mild examination, severe lung injury can develop later.

Clinical Features

Inhaled cadmium is particularly dangerous because it can cause delayed pulmonary toxicity.

Acute inhalation may lead to:

• Fever and chills
• Myalgia
• Dry cough
• Shortness of breath
• Chemical pneumonitis
• Pulmonary edema
• Acute respiratory distress syndrome (ARDS)
• Respiratory failure

The early flu-like syndrome is sometimes called the “cadmium blues.”

Acute ingestion may cause severe gastrointestinal irritation and injury.

Chronic Toxicity

Long-term exposure may cause:

• Renal tubular dysfunction
• Bone disease, including osteomalacia
• Neurologic abnormalities
• Increased cancer risk

Mechanism of Action

Cadmium is a toxic metal that binds to cellular proteins and interferes with normal enzyme and cellular functions. It also promotes oxidative injury.

The protein metallothionein can bind cadmium and reduce its immediate toxicity, but cadmium–metallothionein complexes can accumulate in the kidneys and contribute to chronic renal injury.

Management

Treatment is primarily supportive:

• Immediate removal from exposure
• Respiratory support as needed
• Monitoring for delayed pulmonary edema and ARDS
• Renal and electrolyte monitoring

There is no well-established chelation therapy for cadmium poisoning, and some chelators may worsen toxicity. Management should involve a medical toxicologist or poison center.

Key Points

• Inhalation of cadmium fumes can cause delayed, severe lung injury.
• Early symptoms may resemble metal fume fever but can progress to respiratory failure.
• Chronic exposure primarily damages the kidneys and bones.
• BAL (dimercaprol) is generally avoided because it may increase renal toxicity.
• Significant suspected exposure warrants careful observation because pulmonary deterioration may be delayed.

Here’s the paraphrased study-note version:

135. Toxicology – Metal Fume Fever

Source

Metal fume fever is an acute illness caused by inhalation of metal oxide fumes, classically zinc oxide. It is most often seen in welders, smelters, and others who work with heated metals.

Typical Presentation

A worker develops a flu-like illness several hours after welding or similar metal exposure. Symptoms may recur after time away from work, such as after a weekend, and then become less severe with repeated daily exposure.

This pattern is sometimes called “Monday fever.”

Mechanism of Action

The exact mechanism is not fully understood. It appears to involve an inflammatory response in the lungs rather than a true allergic reaction.

Repeated exposure can produce temporary tolerance, but this tolerance may fade after a period away from work.

Clinical Features

Symptoms usually begin within a few hours of exposure and may include:

• Fever
• Chills
• Malaise
• Headache
• Muscle aches
• Nausea
• Cough
• Shortness of breath
• Chest discomfort

Chest X-rays are often normal.

Management

Treatment is mainly supportive:

• Remove the patient from further exposure
• Rest and hydration
• Symptomatic treatment for fever and discomfort
• Evaluate for other causes if symptoms are severe, prolonged, or atypical

Most cases resolve spontaneously within a short period.

Key Points

• Classically associated with zinc oxide fumes from welding.
• Symptoms resemble an acute viral illness.
• Onset is usually several hours after exposure.
• Temporary tolerance can develop with repeated exposure and disappear after time away.
• Prevention depends on proper ventilation and occupational respiratory protection.

Toxicology – Extrapyramidal Side Effects (EPS)

Definition

Extrapyramidal side effects are drug-induced movement disorders caused mainly by dopamine-blocking medications. They can occur at normal therapeutic doses.

Common Causes

EPS can occur with many antipsychotic drugs, but they are more common with first-generation (typical) antipsychotics, especially:

• Butyrophenones
• Phenothiazines

They may also occur with other dopamine-blocking drugs.

Mechanism of Action

EPS result from dopamine D₂ receptor blockade in the basal ganglia, especially within the nigrostriatal pathway.

Reduced dopamine activity disrupts normal motor control and produces several characteristic movement disorders.

Clinical Features

The type of EPS often depends on how long the patient has been taking the medication.

• Acute dystonia: Usually occurs early. Causes sustained involuntary muscle contractions, abnormal posturing, neck or facial spasms, and sometimes tongue or jaw involvement.
• Akathisia: A feeling of intense inner restlessness with an inability to remain still.
• Drug-induced parkinsonism: May develop after weeks to months and can cause bradykinesia, shuffling gait, tremor, and cogwheel rigidity.
• Tardive dyskinesia: Usually appears after prolonged treatment and causes repetitive involuntary movements, especially of the mouth, lips, tongue, and face. It may persist even after the drug is stopped.

Management

Treatment depends on the specific movement disorder.

Common approaches include:

• Reducing or stopping the offending medication when appropriate
• Diphenhydramine or benztropine for acute dystonia and some parkinsonian symptoms
• Benzodiazepines in selected cases
• Beta-blockers such as propranolol for akathisia

Tardive dyskinesia requires a different long-term management approach and may be treated with medications that reduce abnormal dopamine signaling, such as VMAT2 inhibitors.

Key Points

• EPS are caused by dopamine blockade in the basal ganglia.
• Acute dystonia and akathisia tend to occur early.
• Parkinsonism usually develops later.
• Tardive dyskinesia is associated with long-term exposure and may be irreversible.
• EPS and neuroleptic malignant syndrome can both occur during therapeutic antipsychotic use, but NMS is distinguished by fever, autonomic instability, altered mental status, and severe rigidity.