A 56-year-old man attended the emergency department with his wife, who reported that his speech had become slurred (he denied this) and that he may be having a stroke. The patient described only occasional swallowing difficulty. He had a 10-year history of progressive hearing loss requiring bilateral hearing aids. When aged 11 years, he had undergone resection and radiotherapy for a posterior fossa astrocytoma. He smoked cigarettes and took a statin for hyperlipidaemia.

On examination, he had dysarthria and bilateral ptosis. CT scan of head showed no acute changes. He was admitted for 3 days under the stroke team, and his symptoms improved. An MR scan of brain 5 days later showed the previous posterior fossa surgery with cerebellar atrophy, chronic small vessel disease but no acute infarction. He was referred to neurology.

In neurology outpatients, we obtained a 10-year history of worsening ptosis and vertical diplopia. In the preceding 12 months, there had been occasional slurred speech, swallowing difficulty, loss of balance and an abnormal sensation over the right upper lip. His symptoms would worsen towards the end of the day. His wife had noticed that his slurred speech had notably worsened on the evening he attended the emergency department. There was no limb weakness or sphincter problem. His hearing had progressively deteriorated over 10 years, for which he had attended an ENT clinic. Two MR scans of brain, 5 years apart had identified evidence of previous surgery, left cerebellar hemisphere atrophy, and enlargement of the fourth ventricle and cisterna magna.

On examination, he had bilateral hearing aids and a scar from a previous posterior fossa craniotomy. There was bilateral ptosis without fatigability. His eye movements were full but with vertical separation of images on right horizontal gaze. His speech was nasal in character. There was a spastic catch in the right arm, but …