Neurology
Neurology questions reward localisation and time-awareness. The commonest exam scenarios are acute stroke, first seizure and status epilepticus, acute weakness (stroke versus Guillain-Barre versus myasthenia), sudden headache, and delirium versus dementia.
Acute stroke
- Non-contrast CT first to exclude haemorrhage, with CT angiography to look for large vessel occlusion.
- Intravenous thrombolysis is licensed up to 4.5 hours from onset when there is no haemorrhage, blood pressure is below 185/110 mmHg, and there is no contraindication. Mechanical thrombectomy is offered up to 6 hours for proximal anterior circulation occlusion, and later in selected patients with salvageable tissue.
- Do not lower blood pressure aggressively unless it exceeds 220/120, or above 185/110 when thrombolysis is planned. Admit to a stroke unit, screen swallowing, and start secondary prevention after imaging.
Seizures and weakness
- Status epilepticus: benzodiazepine first (intravenous lorazepam or intramuscular midazolam), then a second-line agent such as levetiracetam, valproate, or phenytoin; refractory cases need anaesthesia with intensive care.
- Guillain-Barre syndrome: ascending symmetrical weakness, areflexia, albuminocytological dissociation in cerebrospinal fluid, and respiratory monitoring with vital capacity. Treat with intravenous immunoglobulin or plasma exchange; steroids do not help.
- Myasthenia gravis: fatigable weakness, ptosis and diplopia, decrement on repetitive nerve stimulation, anti-acetylcholine receptor antibodies; crisis needs respiratory support and immunomodulation, avoiding aminoglycosides and quinolones.
Headache and cognition
- Thunderclap headache: CT within six hours is highly sensitive for subarachnoid haemorrhage; if negative and suspicion persists, lumbar puncture for xanthochromia after 12 hours.
- Delirium is acute, fluctuating, and inattentive; dementia is chronic and progressive. Always look for the delirium trigger rather than sedating.
Worked example
A 70-year-old has sudden right hemiplegia and aphasia with onset 90 minutes ago, glucose 6 mmol/L, blood pressure 170/95, and CT showing no haemorrhage. Proceed to thrombolysis after checking contraindications, activate thrombectomy pathways if a large vessel occlusion is seen on angiography, keep pressure below 185/110, and admit to the stroke unit.
Traps
Giving thrombolysis without excluding haemorrhage; treating a normal CT as excluding subarachnoid haemorrhage at 24 hours; giving steroids in Guillain-Barre syndrome; and sedating a delirious patient without searching for the cause.