Facial onset sensory and motor neuronopathy (FOSMN) is a recently defined slowly progressive motor neuron disorder. It is characterized by facial onset sensory abnormalities which may spread to the scalp, neck, upper trunk and extremities, followed by lower motor neuron deficits. Bulbar symptoms, such as dysarthria and dysphagia, muscle weakness, cramps and fasciculations, can present later in the course of the disease.

Typically, FOSMN patients experience slowly evolving numbness of the face followed by neck and arm weakness. Reduced or absent of corneal reflexes and blink reflex is the main pathognomonic features of FOSMN.

Only 38 cases of FOSMN have been reported in the Pubmed database in 2016 since it was first reported in 2006.

Cited from PubMed