What is the role of Möbius syndrome in the etiology of congenital facial paralysis?

Updated: Jan 07, 2019
  • Author: Alan D Bruns, MD, FACS; Chief Editor: Arlen D Meyers, MD, MBA  more...
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A broad spectrum of clinical and pathological findings characterize this syndrome. The patient usually presents with bilateral paralysis of the facial nerve with unilateral or bilateral palsy of the abducens nerve (cranial nerve VI). This syndrome may also affect other cranial nerves, with XII being the next most common. It often involves abnormalities of the extremities, including absence of the pectoralis major muscle in Poland syndrome. [11, 12, 13]

A few families with Möbius syndrome have been described, but most cases are sporadic. Associations have also been made with fetal exposure to misoprostol, cocaine, ergotamine. [14, 15, 16] Malformations of the limbs and other cranial nerves are often identified with this syndrome. Several theories regarding the pathogenesis of Möbius syndrome are as follows:

  • Aplasia or hypoplasia of cranial nerve nuclei

  • Nuclear destruction

  • Peripheral nerve abnormality

  • Primary myopathy

  • Disruption sequence in vascular territory of subclavian artery

Autopsy studies have supported all of the causes listed above. A neurophysiologic study of patients with sporadic Mobius syndrome demonstrated 2 distinct groups characterized by 1) increased facial distal motor latencies (DML) and poor recruitment of small neuropathic motor unit action potentials (MAUP) and 2) normal facial DMLs and neuropathic MAUPs. The functional impairment of facial movements appears to be caused by a nuclear or peripheral site of lesion without brainstem interneuronal involvement. [17]

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