RESUMEN
Objective:To investigate the clinical and electrophysiological characteristics of facial onset sensory motor neuronopathy (FOSMN) syndrome.Methods:Ten patients diagnosed with FOSMN syndrome in Peking Union Medical College Hospital from January 2012 to December 2022 were included. The clinical and electrophysiological characteristics of patients were analyzed and summarized, and the genetic testing was also performed in these patients.Results:The age of onset was (56.6±6.5) years, and the longest survival duration of disease was 10 years. All patients had numbness around the face and mouth as the first symptom and abnormal blink reflex. A total of 52 sensory nerve conduction nerves were detected, among which 2 median nerves and 2 μlnar nerves showed decreased amplitude of sensory nerve action potential. Needle electromyography showed neurogenic lesions, with both progressive and chronic denervation. Whole exome sequencing identified the heterozygous variant c.272A>C in the exon 4 of the SOD1 gene resulting in the amino acid change p.Asp90Ala in 1 patient. In all patients, the disease progressed relentlessly and eventually led to involvement of respiratory muscle. Conclusion:FOSMN syndrome is characterized by abnormal blink reflex and sometimes abnormal sensory nerve conduction may be shown on electrophysiologic testing.