A 35-year-old, right-handed man of Asian origin presented to the local ophthalmology service in June 2001 with headaches and decreasing visual acuity in the left eye, which progressed over one week to near-blindness. He had a left afferent pupillary defect and swollen left optic disc when seen in the ophthalmology clinic, with restricted elevation of the left eye. There was marked enlargement and peripheral gadolinium enhancement of the left optic nerve on MRI, but there were no brain lesions (fig 1).

In November 2002 he underwent endoscopic biopsy of the left optic nerve, and this showed a patchy perivascular infiltrate of small mature-appearing B and T lymphocytes. Staining for glial fibrillary astrocytic protein (GFAP) was negative, favouring an inflammatory cause rather an intrinsic neoplasm. His visual symptoms were stable although he had no perception of light in the left eye.

A follow-up MRI scan a year later showed expansion of the left optic nerve extending to the chiasm, with enhancement of both optic nerves. A further optic nerve biopsy showed one focal dense inflammatory infiltrate with a surrounding giant cell response, and mural thickening of two blood vessels. There was scant GFAP positivity, and the appearances were felt to be in keeping with a granulomatous process. Chest x ray, serum autoantibodies and angiotensin-converting enzyme (ACE) levels were all normal.

FROM THE OPHTHALMOLOGISTS TO THE NEUROLOGISTS

He was eventually referred for neurological assessment in October 2004, complaining of a six-month history of numbness and paraesthesiae in his feet, which had progressed proximally to his waist. His exercise tolerance was much reduced, and he also complained of erectile dysfunction, urinary hesitancy and severe constipation with faecal incontinence. In addition, he had developed oscillopsia and deafness. On examination he was obese and …