Clinical features of FOSMN syndrome in Korea: A comparative analysis with bulbar-onset amyotrophic lateral sclerosis.

Facial onset sensory and motor neuronopathy (FOSMN) syndrome is a rare neurodegenerative disorder initially characterized by facial sensory deficits, which later progress to motor deficits in a rostral-caudal distribution. This study investigated the prevalence, clinical features, and prognosis of FOSMN syndrome and compared these aspects with those of bulbar-onset amyotrophic lateral sclerosis (ALS) within a single institutional cohort of motor neuron diseases. We identified four patients with FOSMN syndrome who had been misclassified as having bulbar-onset ALS, representing approximately 2 % of such ALS cases.