[Ischemic optic neuropathy despite pulse methylprednisolone therapy in a giant cell arteritis patient with perineural optic nerve enhancement].

A 76-year-old woman with a 1-month history of headache, jaw claudication, scalp tenderness, and blurred vision was admitted to our hospital. Erythrocyte sedimentation rate was highly elevated. Brain MRI showed marked perineural optic nerve enhancement and superficial temporal artery enhancement bilaterally. Neuro-ophthalmic examination detected left dominant decline in critical fusion frequency whereas visual acuity, visual fields, and ophthalmoscopy were normal. Intravenous pulse methylprednisolone was administered for 3 days to treat suspected giant cell arteritis (GCA); however, visual acuity in the left eye declined and horizontal hemianopia developed. Ophthalmoscopy revealed pallid optic disc edema on the left. Histopathologic examination of a right temporal artery biopsy specimen showed intimal thickening, mild mural inflammation consisting predominantly of lymphocytes with occasional giant cells, and focal disruption of the internal elastic lamina, consistent with GCA. Perineural optic nerve enhancement on contrast-enhanced MRI may be a valuable clue for diagnosing ischemic optic neuropathy and may indicate the need for urgent treatment.