- Combination of tremor, rigidity, akinesia and postural hypotension
Prevalence
- Increases with age
- 1:200 over 70 years of age
- Less prevalent in smokers
Aetiology
- Idiopathic
- Drug induced, e.g. phenothiazines
- MPTP (methylphenyltetrapyridine, impurity in illegally synthesised opiates)
- Encephalitis lethargica
Pathology
- Cell degeneration in substantia nigra
- Loss of dopamine in the extrapyramidal nuclei
Clinical
- Tremor - 4-7 Hz resting tremor (pill-rolling)
- Micrographia
- Rigidity - increased tone throughout the range of movement
- Cogwheel rigidity (stuttering rigid tone combined with tremor)
- Bradykinesia - poverty of movement
- Falls
- Mask-like facies
- Reduced blinking
- Stooping, shuffling gait (festinant)
- Poor arm swinging
- Monotonous speech, slurring dysarthria
- Normal power
- Brisk reflexes
- Downgoing plantars
- Cognitive function initially preserved; late dementia sometimes occurs
Investigations
- No diagnostic test; diagnosis made on clinical grounds
Management
- Levodopa plus dopa decarboxylase inhibitor (e.g. Sinemet or Madopar; start gradually increasing the dose until adequate response or limiting side-effects)
- Dopaminergic agonists, e.g. bromocriptine
- Selegiline - monoamine oxidase B inhibitor
- Neurosurgery (occasionally for intractable tremor)
- Physiotherapy
- Physical aids
Side-effects of levodopa
- Short-term
- Nausea and vomiting
- Confusion
- Visual hallucinations
- Chorea
- Long-term
- End-of-dose dyskinesia
- On-off syndrome
- Chorea
- Dystonic movements
Prognosis
- Variable
- Usually worsens over 10-15 years with death from bronchopneumonia
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