Case

A 31-year-old man, previously well and in full-time employment was admitted as an emergency following a convulsive seizure, with a 5-day history of headache, altered behaviour and drowsiness. He had an established history of episodic migraine with aura, and his symptoms this time had begun with what he regarded as a ‘typical’ migraine: opaque, spectral lines in the visual periphery, progressing to a hemicranial headache, with associated photophobia, nausea and motion sensitivity, sufficient for him to take time off work. Two days into his illness, his general practitioner prescribed naproxen 250 mg three times a day. Over the next 3 days his headache persisted and his wife reported alteration in his behaviour. He was intermittently drowsy, distractible and confused. Five days into his illness he had a generalised seizure from sleep, precipitating his hospital admission.

On examination in the emergency department, he was afebrile; his Glasgow Coma Scale score was 10/15 (E3 V2 M5), which improved to 13/15 (E4 V4 M5) over the ensuing hours. A CT scan of head was normal. He had an elevated serum creatinine (145 µmol/L (60–110)) and urea, a serum C reactive protein of 45 mg/L (<10). His full blood count was normal. The following morning he was assessed by the neurology registrar: there was no relevant travel history, no exposure to alcohol, drugs of abuse or any other over-the-counter treatments, and no family history of neurological disease. On examination, he had a partial left homonymous hemianopia, dysfluent speech and possibly an expressive dysphasia. There was no meningism or pyramidal signs.

Our first thought might reasonably be that the initial diagnosis of migraine was clearly wrong! The combination of headache progressing to encephalopathy and seizures makes an acute …