Mobius syndrome is a congenital cranial dysinnervation disorder that presents with a combination of facial nerve (CN7) and abducens nerve (CN6) palsy.
Due to the said cranial nerve palsies, affected individuals typically present with difficulty feeding (due to poor sucking), lack of facial expression, esotropia, and limited abduction. It may coexist with a horizontal gaze palsy when the interneurons associated with the abducens nucleus are involved. In about 30% of cases, globe retraction on adduction and failure to abduct are present, making Duane syndrome a likely differential.
Associated craniofacial anomalies include crocodile tears (due to lid lag), micrognathia, dental anomalies tongue anomalies, and facial and oral clefts. Associated limb anomalies include Poland sequence (underdeveloped pectoral muscles), syndactyly, club foot, or even amputation defects. Epilepsy, mental retardation and autism may be present.
Most cases of Mobius syndrome are sporadic and there is a great variability of findings suggesting that it is a heterogenous group of neuromuscular disorders. Family studies suggest different patterns of inheritance in families including recessive , dominant, and x linked inheritance. Male and females are equally affected. To date, four gene loci (MBS1, MBS2, MBS3, MBS4) have been identified in individuals with Mobius sequence.
External factors influencing intrauterine development (poor nutrition & medications) could modify the clinical manifestations. Prenatal exposure to abortifacient such as misoprostol, has been implicated as a risk factor.
The treatment for Mobius syndrome is tailored to the need of the patient. Initial feeding problems may be addressed by modifying the type of feeding bottle. The use of eye lubricants might help the dryness associated with the lid lag from the CN7 palsy.
Refractive errors, amblyopia, and eye misalignment need the appropriate management. Patients with large esotropia and tight medial rectus muscles and poor abduction would benefit from maximal medial rectus recessions. Some cases might need vertical muscle transpositions.
The lack of facial expression may pose a difficulty with interpersonal relations and communication. Plastic surgeries that improve facial movement exist. Dental anomalies require orthodontist consultation.