Summary of Common Conditions Seen in OSCEs

Bold type denotes the specific and important points that help to distinguish the cause.

Hints and Tips for the Exam

Keep an open mind, and don’t forget that there are several non-neurological causes of a tremor (e.g. thyroid disease, anxiety and caffeine).

Figure 38.1 Flowchart for diagnosing the cause of a tremor

If the cause turns out to be neurological (e.g. Parkinson’s disease), remember to ask about the psychological features (depression) and whether the patient has support at home. These patients have an increased risk of falls so addressing this issue in the history and also in your discussion of management will be important. Mentioning a multidisciplinary review (e.g. a physiotherapist and occupational therapist) will grab those few marks for considering a holistic approach that are earmarked for better candidates.

Parkinson-Plus Syndromes

To grab those extra few marks for a merit or distinction, you should consider knowing the salient features of the most common Parkinson-plus syndromes as well as lithium toxicity:

• Progressive supranuclear palsy: a Parkinson’s-plus syndrome in which patients exhibit asymmetrical Parkinsonism with early falls (often backwards) and a vertical supranuclear gaze palsy. The latter is the result of a failure to initiate vertical gaze above the level of the brainstem nuclei. To confirm a pure supranuclear palsy, vertical gaze can be elicited by assessing for the presence of vestibular ocular reflexes by turning the patient’s head down, with resultant upward eye deviation (the upward eye deviation is possible despite the vertical gaze palsy because the reflex does not require the supranuclear pathways).
  
• Multiple system atrophy: early autonomic dysfunction (e.g. postural hypotension), cerebellar signs (DANISH – dysdiadochokinesis, ataxia, nystagmus, intention tremor, scanning dysarthria, heel–shin test positive).
  
• Corticobasal syndrome: a very rare atypical parkinsonian syndrome. It is classically unilateral with rapid motor and cognitive decline. Patients develop apraxia and alien hand phenomenon.
  
• Lewy body dementia: early dementia is associ­ated with visual hallucinations and fluctuating cognition.
  
• Vascular Parkinsonism (multi-infarct dementia): in this condition, there is a step-by-step decline. Cardiovascular risk factors (hypertension, diabetes, hypercholesterolaemia) are apparent.
  
• Lithium toxicity: depends on blood level:
  
  
  
  • >1.5 mmol/L – mild tremor
    
  • >2.0 mmol/L – coarse tremor, arrhythmias, fitting, renal failure (may require haemodialysis)

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