Electrophysiologic study of 10 cases of Miller Fisher syndrome

The association of ophthalmoplegia, ataxia and areflexia was described by Miller Fisher in 1956. It is postulated as a variant of the Guillain Barré syndrome. We report 10 Miller Fisher syndrome patients admitted in an intensive care unit between June 1990 and February 1999 who were selected according to clinical criteria of Ropper and Wijdicks. All patients had motor and sensory nerve conduction studies and electromyography, nine had visual and brainstem auditory evoked potentials and two had short latency somatosensory evoked potentials. Peripheral neuropathy was found in all patients. All had sensory nerve changes and some were severe. Motor nerve conduction abnormalities were observed in 7 only cases with moderate increase of F latency in 3 cases and compound muscle action potential reduction in 3 other cases. In the last case, motor conduction abnormalities was more severe, characterized by conduction velocity slowing in both distal and proximal sites and by temporal dispersion of action potentials. All brainstem auditory evoked studies were normal. In 4 patients, MRI studies were normal. These data support that brainstem is preserved in MFS. Only one patient had visual evoked potential abnormalities. Optic neuropathy is debated in Miller Fisher and in Guillain Barré syndrome. As a conclusion, in MFS peripheral neuropathy is always present with severe sensitive changes and moderate motor changes (This is different as compared to Guillain Barré syndrome according to electrophysiological data). We did not find involvement of brainstem in our patients with Miller Fisher syndrome.