Moebius syndrome is a rare, nonprogressive neurological disorder (prevalence is estimated to be 0.002% of births) characterized by unilateral or bilateral facial paralysis and defective extraocular eye movements secondary to congenital paresis of the facial (VII) and abducens (VI) cranial nerves. These classic features of the syndrome are often accompanied by hypoglossal (XII), trigeminal (V), glossopharyngeal (IX) and vagal (X) nerve palsies. Affected infants typically present with congenital esotropia and immobile, expressionless facies. Depending on the pattern of cranial nerve involvement, there may be a wide range of clinical expression. Feeding difficulties due to poor coordination of sucking and swallowing may be present with IXth and Xth cranial nerve involvement. This may be associated with dysphagia and retention of oral secretions leading to recurrent bouts of aspiration pneumonia. Inadequate function of the soft palate can also result in dysarthria. Moebius syndrome may also occur in association with various craniofacial (mandibular hypoplasia, microstomia, temporomandibular joint dysfunction, cleft palate, external ear deformities), limb (club foot) and musculoskeletal malformations as well as multiple ophthalmic abnormalities (incomplete eye closure, inability to blink). Other associated manifestations include seizure disorders, congenital heart diseases, hypotonia, hypogonadotropic hypogonadism, hydrosyringomyelia and some degree of mental retardation.
The cause of Moebius syndrome is unknown, but rhomboencephalic maldevelopment and brainstem ischemia during the first trimester are two possible etiological hypotheses in children with normal karyotype. The list of potential associated teratogenic events has included hyperthermia, trauma, thrombus formation, embolism, hemorrhage, as well as in utero exposure to various medications including misoprostol. Most cases are sporadic, but some familial cases are also known. The inheritance patterns of Moebius sequence are heterogeneous and can be autosomal recessive, autosomal dominant or even X-linked. Some candidate regions and candidate genes (3q21-q22 and 13q12.2-q13) have been described but no causative gene has yet been confirmed.
The syndrome has most frequently been confused with hereditary congenital facial paresis which is restricted to involvement of the facial nerve and no other abnormalities.
Poland-Mobius syndrome is a rare congenital disorder that includes combination features of Poland and Mobius syndromes. Poland syndrome consists of absence of pectoralis major muscle, syndactyly, brachydactyly and hypoplasia of the hands.