Walsh & Hoyt: Diagnosis

MFS should be considered in any patient who develops the rapidly progressive triad of ophthalmoparesis (with or without pupillary and eyelid involvement), ataxia, and areflexia, and also in patients who develop only a part of the syndrome such as an isolated unilateral or bilateral ophthalmoparesis, ophthalmoparesis and ataxia, ophthalmoplegia and areflexia, or ataxia and areflexia. Diagnoses to exclude in such cases are Wernickes encephalopathy, vascular brainstem disease, botulism, multiple sclerosis, myasthenia gravis, brainstem neoplasm, and a variety of bacterial or viral brainstem encephalitides. EMG and lumbar puncture help confirm the diagnosis, particularly when neuroimaging studies show no evidence of overt CNS involvement.