Facial onset sensory and motor neuronopathy

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. We search the PubMed database for articles published in English from 2006 to 2016 using the term of "Facial onset sensory and motor neuronopathy". Reference lists of the identified articles were selected and reviewed. Only 38 cases of FOSMN have been reported in the Pubmed database since it was first reported in 2006. Typically, FOSMN present with 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. In this review, we summarize the epidemiology, clinical presentation, auxiliary examination, and treatment of all the reported cases of FOSMN. Moreover, we discuss the pathogenesis of this rare disorder. In addition, we propose diagnostic criteria for FOSMN.