Facial onset sensorimotor neuronopathy syndrome: a case series

J Clin Neuromuscul Dis. 2012 Sep;14(1):7-10. doi: 10.1097/CND.0b013e31825f82b3.


Objective: Facial onset sensorimotor neuronopathy (FOSMN) is a recently described neurological syndrome characterized by slow onset of facial sensory abnormalities and subsequent development of motor deficits. Except for 1 patient, FOSMN has so far been identified only in men.

Methods: We describe a case series of 3 women with FOSMN. We report their clinical, laboratory, and neurophysiological findings.

Results: The age of onset ranged from 39 to 72 years (mean, 60 years) with presentation 4-7 years after symptom onset. The first symptom was slowly progressive facial numbness, which was followed years later by dysphagia and impaired corneal reflexes. Dysarthria occurred in 2 patients, and mild arm weakness was noted in 2. Muscle stretch reflexes were increased in 1 patient, and in another case, arm sensation was reduced. Laboratory studies were unremarkable, and magnetic resonance imaging of the brain in 3 patients and of the cervical spine in 2 patients was normal. Nerve conduction studies showed reduced leg compound muscle action potential amplitudes in 1 patient and asymmetrically reduced arm sensory nerve action potentials in another case. In 2 patients, electromyography showed widespread active denervation in arm muscles in conjunction with the involvement of leg muscles in 1 case and the tongue in the other patient. We identified chronic neurogenic motor unit action potentials in the genioglossus muscle of all 3 cases while facial EMG performed in case 3 showed similar findings. Blink reflexes were abnormal in all patients. We treated 1 patient with high-dose intravenous methylprednisolone followed by intravenous immunoglobulin without any improvement, and she required percutaneous endoscopic gastrostomy (PEG) tube placement.

Conclusions: This is the first case series describing 3 women with the FOSMN syndrome. We expand phenotype of FOSMN to include upper motor neuron signs and normal arm sensory nerve action potentials.

Publication types

  • Case Reports

MeSH terms

  • Aged
  • Blinking / physiology
  • Creatine Kinase / metabolism
  • Facial Nerve Diseases / complications*
  • Facial Nerve Diseases / pathology
  • Female
  • Gait Disorders, Neurologic / diagnosis
  • Gait Disorders, Neurologic / etiology*
  • Humans
  • Magnetic Resonance Imaging
  • Middle Aged
  • Motor Neurons / pathology
  • Muscle, Skeletal / physiopathology
  • Neural Conduction / physiology*
  • Tongue / physiopathology


  • Creatine Kinase