A man with weak limbs.

A 58 year old man presented with one week of progressive right sided weakness and headache. He drank approximately 7 units of alcohol a week and had stopped smoking cigarettes 20 years ago (10 pack year history). He had no recent head injuries and took no medications or recreational drugs. He had no fever, weight loss, or night sweats and was fully alert. He had no signs of meningism or papilloedema and was afebrile with normal observations. Power in his right upper and lower limbs was of Medical Research Council grade 4/51 and he had …