Facial onset sensory and motor neuronopathy (FOSMN) syndrome responding to immunotherapies

Abstract

We report the first non-Caucasian case of facial onset sensory and motor neuronopathy (FOSMN) syndrome partially responding to various immunotherapies. A 55-year-old man had first felt paresthesia on his right cheek at age 45. This gradually extended to the scalp. Paresthesia of bilateral fingers and dysphagia appeared 6 years later. On admission, facial sensory impairment and bulbar palsy were found. There were no sensory or motor deficits evident in any limb, except for decreased deep tendon reflex and vibratory sensation. Videofluorography (VF) revealed decreased pharyngeal clearance. The sensory nerve action potential (SNAP) amplitudes of median and ulnar nerves were decreased. Intravenous immunoglobulin therapy and plasma exchange ameliorated his dysesthesia and dysphagia after several weeks, and resulted in improvements in VF and SNAP abnormalities. These observations suggest that FOSMN syndrome maybe, in part, immune-mediated.