Main manuscript

A 70-year-old right-handed man was admitted to the general medical department after his first ever generalised seizure. His past history included resection of a bowel carcinoid tumour in 2003 and Alzheimer's disease, diagnosed in 2011 because of isolated short term memory problems. He was independent in activities of daily living and otherwise well. His medications were rivastigmine, citalopram, aspirin, loperamide and omeprazole. He did not smoke and drank little alcohol.

On examination, he was febrile (38°C) but with no other signs of infection. He was fully conscious but reportedly ‘confused’. He had a right-sided pyramidal weakness but no other signs. Routine blood tests and a CT scan of head were normal. Lumbar puncture (LP) showed clear cerebrospinal fluid (CSF) with a red cell count of 4/µl, white cell count of 2/µl (≤5), protein 0.33 g/l (0.15–0.45) and normal CSF glucose 4.0 mmol/l, with plasma glucose 5.6 mmol/l. He was treated with aciclovir and ceftriaxone. Ceftriaxone was stopped when blood cultures/CSF showed no growth, and aciclovir stopped after 4 days when PCR of CSF for herpes simplex virus (HSV) was negative. A urine sample was positive for group B streptococcus, and he received a 7-day course of co-amoxiclav. On discharge, he was described as ‘confused’ but the right-sided weakness and fever had resolved.