Medicine – Parkinsonism

Parkinsonism is a clinical syndrome characterised mainly by bradykinesia together with rigidity and/or resting tremor, usually caused by impaired dopaminergic function within the nigrostriatal pathway of the basal ganglia.

The commonest cause is idiopathic Parkinson disease, but several drugs, toxins, neurodegenerative disorders, and structural neurological conditions can produce a similar syndrome.

1. Dopamine Deficiency

In Parkinson disease, there is progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta.

These neurons normally project to the striatum, particularly the caudate nucleus and putamen.

Loss of these neurons causes:

Reduced dopamine in the nigrostriatal pathway → impaired basal ganglia motor control → bradykinesia, rigidity and tremor.

So the important site is not simply “dopamine deficiency in the substantia nigra,” but rather loss of substantia nigra neurons causing reduced dopamine delivery to the striatum.

2. Lewy Bodies

A classic pathological feature of idiopathic Parkinson disease is the presence of Lewy bodies within affected neurons.

Lewy bodies are intracellular inclusions composed largely of abnormal aggregates of alpha-synuclein.

They are particularly associated with degeneration in the substantia nigra but can also be found in other regions of the nervous system.

3. Core Motor Features

The classic motor syndrome consists of:

Bradykinesia.

Rigidity.

Resting tremor.

Postural instability may occur later in the disease.

Modern diagnostic approaches generally require bradykinesia as a central feature of parkinsonism.

4. Resting Tremor

The typical Parkinson tremor occurs mainly at rest.

It often begins asymmetrically in one hand and may resemble the repetitive movement of rolling a small object between the thumb and fingers.

This is the classic pill-rolling tremor.

5. Characteristics of Parkinson Tremor

Typical features include:

Resting tremor.

Usually asymmetric at onset.

Frequency commonly around 4–6 Hz.

Reduced during voluntary movement.

Disappears during sleep.

The older figure of 3–5 Hz is close, but 4–6 Hz is a commonly used modern description.

Stress or emotional tension may make the tremor more obvious.

6. Bradykinesia

Bradykinesia means slowness of movement and is one of the most important features of Parkinsonism.

Patients may have difficulty initiating movement and may progressively reduce the speed and amplitude of repetitive movements.

Examples include:

Slow walking.

Difficulty turning in bed.

Reduced spontaneous movement.

Slow dressing and eating.

Difficulty starting to walk.

7. Hypokinesia and Akinesia

Bradykinesia is often accompanied by:

Hypokinesia – reduced amplitude of movement.

Akinesia – difficulty initiating movement or episodes of temporary inability to move.

These features contribute to freezing and gait difficulty in more advanced disease.

8. Rigidity

Rigidity is increased resistance to passive movement of a limb.

Unlike spasticity, Parkinsonian rigidity is not strongly dependent on the speed of movement.

Two classic patterns are described.

9. Lead-Pipe Rigidity

Lead-pipe rigidity produces smooth, sustained resistance throughout the range of passive movement.

The examiner feels continuous stiffness when moving the patient’s limb.

10. Cogwheel Rigidity

Cogwheel rigidity produces a ratchet-like or jerky resistance during passive movement.

It is thought to result from rigidity combined with an underlying tremor.

This is particularly characteristic of Parkinsonism.

11. Expressionless Face

Patients may develop reduced spontaneous facial movement, producing a relatively expressionless or mask-like face.

This is called hypomimia.

Blinking may also become less frequent.

12. Speech Changes

Speech may become:

Quiet.

Monotonous.

Rapid or indistinct.

Reduced voice volume is called hypophonia.

Patients may also have difficulty articulating clearly as the disease progresses.

13. Festinant and Shuffling Gait

Parkinsonian gait is typically short-stepped and shuffling.

Patients may walk with:

Reduced arm swing.

Stooped posture.

Short steps.

Difficulty initiating gait.

Difficulty turning.

14. Festination

Festination refers to progressively faster, shorter steps as the patient appears to chase the body’s centre of gravity.

The patient may lean forward and seem unable to stop easily.

Therefore, festination is related to but not exactly identical to a simple shuffling gait.

15. Freezing of Gait

Patients may experience freezing, particularly when:

Starting to walk.

Turning.

Passing through narrow doorways.

Approaching obstacles.

The feet may appear temporarily “stuck to the floor.”

16. Reduced Arm Swing

Loss of normal arm swing during walking is an early and useful clue.

It may be more marked on one side, reflecting the typical asymmetrical onset of Parkinson disease.

17. Micrographia

Micrographia means progressively small handwriting.

As the patient continues writing, the letters may become smaller and more cramped.

It reflects bradykinesia and reduced amplitude of repetitive movement.

18. Dysphagia

Difficulty swallowing may develop because of impaired coordination and bradykinesia of the bulbar muscles.

Dysphagia can lead to:

Choking.

Weight loss.

Aspiration.

Aspiration pneumonia.

It becomes particularly important in more advanced disease.

19. Postural Instability

Postural reflexes may become impaired later in Parkinson disease.

This can cause:

Poor balance.

Falls.

Difficulty recovering after being pushed.

Early severe postural instability should raise suspicion for an atypical Parkinsonian disorder rather than uncomplicated idiopathic Parkinson disease.

20. Autonomic Dysfunction

Autonomic symptoms are common.

These can include:

Postural hypotension.

Constipation.

Urinary dysfunction.

Sexual dysfunction.

Excessive sweating.

Orthostatic hypotension may result from the disease itself or be worsened by dopaminergic medication.

21. Depression

Depression is common in Parkinson disease and may occur before or after motor symptoms begin.

The old figure of about 30% is a reasonable historical approximation, but prevalence varies depending on definitions and patient population.

Depression should be regarded as an important non-motor manifestation, not merely a psychological reaction to disability.

22. Other Non-Motor Features

Parkinson disease is a multisystem disorder.

Other important non-motor symptoms include:

Anosmia or hyposmia.

REM sleep behaviour disorder.

Constipation.

Fatigue.

Anxiety.

Cognitive impairment.

Hallucinations.

Sleep disturbance.

Some of these can precede the motor syndrome by years.

23. Idiopathic Parkinson Disease

Idiopathic Parkinson disease is the commonest cause of Parkinsonism.

It typically begins asymmetrically and progresses gradually.

A good clinical response to levodopa supports the diagnosis.

24. Drug-Induced Parkinsonism

A common secondary cause is drug-induced Parkinsonism, particularly from medications that block dopamine receptors.

Important examples include some:

Antipsychotic drugs.

Antiemetic dopamine antagonists.

Examples include metoclopramide and prochlorperazine.

Drug-induced Parkinsonism is often more symmetrical than idiopathic Parkinson disease.

25. Dementia Pugilistica

The older term dementia pugilistica refers to neurological damage associated with repeated head trauma, historically described in boxers.

The broader modern concept is chronic traumatic encephalopathy (CTE).

Repeated head injury can produce cognitive, behavioural, and motor abnormalities, including Parkinsonian features in some patients.

26. Post-Encephalitic Parkinsonism

Parkinsonism can occur after encephalitic illness.

Historically, this was particularly associated with encephalitis lethargica, although this is now rare.

Damage to basal ganglia structures can lead to persistent Parkinsonian symptoms.

27. Normal-Pressure Hydrocephalus

Normal-pressure hydrocephalus (NPH) can produce a gait disorder that may resemble Parkinsonism.

The classic triad is:

Gait disturbance.

Cognitive impairment.

Urinary incontinence.

The gait is often broad-based, short-stepped, and described as “magnetic.”

Prominent resting tremor is less typical than in idiopathic Parkinson disease.

28. Toxin-Induced Parkinsonism

Several toxins can damage dopaminergic pathways and produce Parkinsonism.

Important examples include:

MPTP.

Carbon monoxide.

Manganese.

Some other toxic exposures may also contribute depending on dose and duration.

29. MPTP

MPTP is a neurotoxin that selectively damages dopaminergic neurons in the substantia nigra.

It produces a syndrome that can closely resemble idiopathic Parkinson disease.

Its discovery played an important role in understanding Parkinson disease pathophysiology.

30. Carbon Monoxide

Severe carbon monoxide poisoning can damage the basal ganglia, particularly the globus pallidus.

Delayed neurological complications may include:

Parkinsonism.

Cognitive impairment.

Movement disorders.

31. Manganese

Chronic manganese exposure can cause a Parkinsonian syndrome.

However, the pattern may differ somewhat from idiopathic Parkinson disease, with more prominent gait and postural abnormalities and less classic resting tremor.

32. Narcotics

The original note lists “narcotics” as a cause.

This is too broad.

Most opioids do not directly cause classical chronic Parkinsonism.

The historically important association is with MPTP contamination in illicit drug exposure, which can produce profound Parkinsonism.

Therefore, it is better to remember MPTP specifically rather than “narcotics” in general.

33. Wilson Disease

Wilson disease is an important cause of Parkinsonian symptoms in younger patients.

It results from abnormal copper metabolism due to mutations in ATP7B.

Neurological features may include:

Tremor.

Rigidity.

Dystonia.

Dysarthria.

Parkinsonism.

The presence of Kayser–Fleischer rings and liver disease can provide important clues.

34. Other Atypical Parkinsonian Disorders

Not every patient with Parkinsonism has idiopathic Parkinson disease.

Important atypical neurodegenerative causes include:

Multiple system atrophy.

Progressive supranuclear palsy.

Corticobasal syndrome.

Dementia with Lewy bodies.

These conditions often respond less well to levodopa and may have additional early neurological features.

35. Multiple System Atrophy

Multiple system atrophy (MSA) combines Parkinsonism with prominent autonomic dysfunction and sometimes cerebellar or pyramidal signs.

Early severe postural hypotension, urinary dysfunction, and poor levodopa response may suggest MSA.

36. Progressive Supranuclear Palsy

Progressive supranuclear palsy (PSP) can cause:

Parkinsonism.

Early falls.

Axial rigidity.

Vertical gaze palsy.

The levodopa response is usually limited.

37. Dementia with Lewy Bodies

Dementia with Lewy bodies may cause Parkinsonism together with:

Early cognitive impairment.

Fluctuating cognition.

Visual hallucinations.

REM sleep behaviour disorder.

When dementia occurs before or within about a year of Parkinsonism, dementia with Lewy bodies is generally considered rather than Parkinson disease dementia.

38. Diagnosis

Parkinson disease is primarily a clinical diagnosis.

There is no single routine blood test that confirms it.

Diagnosis is based on the pattern of bradykinesia, rigidity, tremor, asymmetry, progression, response to levodopa, and absence of features strongly suggesting another disorder.

39. Imaging

Routine brain imaging is not always required to diagnose typical Parkinson disease.

MRI may be useful when the presentation is atypical or when another structural cause needs to be excluded.

Specialised dopamine-transporter imaging can sometimes help distinguish degenerative Parkinsonism from disorders such as essential tremor, but it does not by itself distinguish all Parkinsonian syndromes.

40. Drug Treatment

Drug treatment aims to improve motor symptoms by increasing dopaminergic activity or reducing relative cholinergic activity within the basal ganglia.

The major drug groups include:

Levodopa combined with carbidopa or benserazide.

Dopamine agonists.

MAO-B inhibitors.

COMT inhibitors.

Anticholinergic drugs in selected patients.

41. Levodopa

Levodopa remains the most effective symptomatic treatment for Parkinson motor symptoms.

It is usually combined with carbidopa or benserazide, which reduce peripheral conversion of levodopa into dopamine.

Levodopa is particularly effective for:

Bradykinesia.

Rigidity.

It also frequently improves tremor.

42. Dopamine Agonists

Dopamine agonists include:

Pramipexole.

Ropinirole.

Rotigotine.

Apomorphine in selected advanced disease.

They directly stimulate dopamine receptors and may be used alone or in combination with levodopa.

43. MAO-B Inhibitors

Examples include:

Selegiline.

Rasagiline.

Safinamide.

They inhibit dopamine breakdown and can provide symptomatic benefit or reduce “off” time when used with levodopa.

44. COMT Inhibitors

Examples include:

Entacapone.

Opicapone.

They prolong the effect of levodopa and are particularly useful for end-of-dose wearing-off.

45. Anticholinergic Drugs

Examples include:

Procyclidine.

Benztropine.

They mainly reduce tremor and are sometimes particularly useful in drug-induced Parkinsonism.

Because they can cause confusion, urinary retention, constipation, and blurred vision, they are generally used cautiously, especially in older patients.

46. Non-Drug Management

Management should not rely only on medication.

Important supportive measures include:

Physiotherapy.

Occupational therapy.

Speech and language therapy.

Swallowing assessment.

Exercise programmes.

Falls prevention.

Management of depression, sleep problems, constipation, and autonomic symptoms.

47. Advanced Treatment

Selected patients with advanced Parkinson disease and motor fluctuations despite optimal medication may be considered for treatments such as:

Deep brain stimulation.

Continuous apomorphine infusion.

Continuous levodopa-based infusion therapies.

These require specialist assessment.

48. Parkinsonism – Note Form

Pathology in Parkinson disease: degeneration of dopaminergic neurons in substantia nigra pars compacta.

Result: reduced dopamine in the striatum.

Pathological hallmark: Lewy bodies containing alpha-synuclein.

Core feature: bradykinesia.

Resting tremor: pill-rolling, usually asymmetric, around 4–6 Hz, reduced with movement and absent during sleep.

Rigidity: lead-pipe or cogwheel.

Face: hypomimia or mask-like expression.

Gait: short, shuffling steps with reduced arm swing; festination and freezing may occur.

Writing: micrographia.

Swallowing: dysphagia may occur.

Autonomic symptoms: postural hypotension, constipation and urinary dysfunction.

Psychiatric feature: depression is common.

Idiopathic cause: Parkinson disease.

Drug-induced: dopamine receptor antagonists, especially antipsychotics and some antiemetics.

Trauma: chronic repetitive head injury may cause Parkinsonian features.

NPH: gait disturbance + cognitive decline + urinary incontinence.

Toxins: MPTP, carbon monoxide and manganese.

Young patient: consider Wilson disease.

Treatment: levodopa, dopamine agonists, MAO-B inhibitors, COMT inhibitors and selected anticholinergics.

Key Clinical Pattern

Remember Parkinsonism as:

Bradykinesia + resting tremor + rigidity.

The classic patient has:

Asymmetric pill-rolling resting tremor.

Cogwheel rigidity.

Slow movements.

Reduced facial expression.

Micrographia.

Shuffling gait with reduced arm swing.

The underlying mechanism in idiopathic Parkinson disease is:

Substantia nigra degeneration → ↓ striatal dopamine → impaired basal ganglia motor control.

And the major secondary causes to remember are:

Dopamine-blocking drugs + NPH + toxins + Wilson disease + atypical neurodegenerative disorders.