Mobius syndrome is a rare birth defect caused by the absence or underdevelopment of the 6th and 7th cranial nerves, which control eye movements and facial expression. The first symptom, present at birth, is an inability to suck. Other symptoms can include: feeding, swallowing, and choking problems; excessive drooling; crossed eyes; lack of facial expression; inability to smile; eye sensitivity; motor delays; high or cleft palate; hearing problems; and speech difficulties. Small or absent brain stem nuclei that control the cranial nerves, as well as decreased numbers of muscle fibers, have been reported. Deformities of the tongue, jaw, and limbs, such as clubfoot and missing or webbed fingers, may also occur. As children get older, lack of facial expression and inability to smile become the dominant visible symptoms. The prognosis for otherwise normal development is excellent in most cases.

There is no specific course of treatment for Mobius syndrome. Treatment is supportive and in accordance with symptoms. Infants may require feeding tubes or special bottles to maintain sufficient nutrition. Surgery may correct crossed eyes and improve limb and jaw deformities. Physical and speech therapy often improves motor skills and coordination, and leads to better control of speaking and eating abilities. Plastic reconstructive surgery may be beneficial in some individuals. Nerve and muscle transfers to the corners of the mouth have been performed to provide limited ability to smile.

There is no cure for Mobius syndrome. In spite of the impairments that characterize the disorder, proper care and treatment give many individuals a normal life expectancy.

Prepared by the National Institutes of Health