[Unilateral optic neuritis and Miller Fisher syndrome]

Miller Fisher syndrome is an autoimmune neuropathy characterized by the clinical triad of ataxia, areflexia and external ophthalmoplegia. Ophthalmologic involvement in this syndrome is most often represented by motility disorders. The diagnosis is confirmed by the presence of anti-GQ1b antibodies.

We report the case of a 65-year-old patient referred by his treating physician to the emergency department for ataxia, dizziness and decreased visual acuity in the left eye. In addition, the patient presented with clinical signs of subacute appendicitis for 2 weeks. After treatment with intravenous immunoglobulin, the patient complained of further decreased visual acuity and oculomotor disorders. On ophthalmological follow-up, he quickly recovered his initial visual acuity and more gradually his ocular motility.

Unilateral optical neuropathy does not preclude the diagnosis of Miller Fisher syndrome. On the contrary, in the case of any rapidly progressive ophthalmologic involvement associated with peripheral neurological signs of ataxia, the diagnosis of Miller Fisher syndrome must be considered.

Miller Fisher is a rare syndrome for which the diagnosis must be made quickly, so that the patient may benefit from urgent intravenous immunoglobulin therapy. In most cases, ophthalmologic recovery precedes peripheral neurologic recovery by 6 months to 1 year.