Optic neuritis in a patient with Miller-Fisher syndrome.

Miller-Fisher syndrome (MFS) is considered a variant of Guillain-Barrd syndrome (GBS). The syndrome is characterized by acute onset of gait ataxia, ophthalmoplegia, and areflexia. Conventionally, MFS has been considered exclusively a disease of the peripheral nervous system. However there are occasional reports of central nervous system involvement. Here, a 62 year-old woman who presented with classical features of MFS and progressive bilateral dyschromatopsia and reported visual impairment. Normal MRI of the brain and CSF albumino-cytologic dissociation were observed. CSF oligoclonal IgG pattern indicated a passive transfer of oligoclonal IgG from a systemic inflammatory response. Nerve conduction studies showed slow motor conduction velocity in her extremities. The optic fundi were normal. Visual evoked potentials (VEPs) revealed bilateral optic neuropathy. Marked spontaneous improvement of her syndrome was documented within six weeks. Optic neuritis may be a central nervous system feature that should be recognized as part of the MFS.