A 43-year-old man presented in April 2004 with a six-week history of a runny nose and a “cold”, and for three weeks he had also been feeling generally unwell with mild vertigo, tinnitus and unsteadiness; the latter symptoms had worsened over a week but had not progressed for two weeks. On examination his blood pressure was 120/70, he was afebrile, and there was no meningism. He was orientated, and told his own story. Fundoscopy was normal. There was fine gaze-evoked bilateral horizontal nystagmus and obvious ataxia of his upper and lower limbs and gait. General medical examination, including the testicles and skin, was normal.

THE FIRST TESTS

He was extensively investigated and the following tests were normal or negative: full blood count, urea and electrolytes, liver function (alkaline phosphatase 52 IU/l (30–115), aspartate transaminase 31 IU/l (5–45)), thyroid function, ANCA, anti-dsDNA antibodies, C-reactive protein, vitamin B12 and folate, calcium, chest x ray, 12-lead ECG, MRI head. The cerebrospinal fluid (CSF) contained 24 red blood cells and 16 white blood cells/cm³. CSF cytology showed a moderate number of reactive lymphocytes, the significance of which was difficult to interpret in the presence of red blood cells. The CSF protein was 0.55 g/l and the glucose 3.7 mmol/l. Oligoclonal bands were present, unmatched in serum. No changes in viral antibody titres in blood were detected and syphilis serology was negative. CSF PCR for herpes simplex virus type 1 and 2, and herpes zoster was negative. Serum alphafeto protein was 11 kU/l (3–8) and serum human chorionic gonadotrophin <1 IU/l (<5). During 13 days in hospital he did not obviously change.

On review in June 2004 he needed help to walk and had noticed deafness in his right ear. He was admitted for further investigation. Clinical examination suggested bilateral sensorineural deafness, the limb and gait …