Moebius Syndrome

What is Moebius syndrome?

Moebius syndrome (or, Mobius syndrome) is a rare neurological disorder affecting muscles involved in facial expression and eye movement. It is a congenital condition, meaning that it is present at birth, and is usually bilateral (or, occurring on both sides of the face). It results from the failure of development of cranial nerves VI and VII in the brainstem. Children with Moebius syndrome have a characteristic mask-like facial appearance with no ability to communicate emotions through facial movements. The eyes are unable to rotate in an outward direction. The exact occurrence of Moebius syndrome is unknown, but is estimated at 1 in 50,000 to 500,000 infants.

Why does Moebius syndrome occur?

It is still largely unknown why Moebius syndrome occurs. As with many craniofacial disorders, Moebius syndrome is possibly the result of a combination of environmental and genetic factors. Several chromosomal relationships are associated, including abnormalities in chromosomes 3, 10, and 13. Maternal use of certain medications and recreational drugs have also been implicated. The result of these effects during pregnancy is the failure of development of cranial nerves VI and VII. New studies are being conducted to elucidate the potential genetic relationship.

 

What are some associated problems with Moebius syndrome?

In Moebius syndrome, facial and eye movement differences are present in virtually all patients. Rarely, the condition will affect only one side of the face (or, unilateral). Additionally, if other cranial nerves are involved, then there can be issues with chewing, tongue coordination, speech, hearing, or balance. Hand and foot deformities can also occur. Moebius syndrome can include other malformations including club feet, missing fingers and/or pectoralis muscle (similar to Poland syndrome), and hearing loss. Other cranial nerves may also be involved on rare occasions. The majority of patients have normal intelligence, although psychological issues are common due to difficulties integrating with family and friends. The lack of facial expression is often the source of stress. Problems with eye closure can rarely result in drying of eyes and corneal scarring. Failure of mouth closure can result in drooling and dental problems.

 

Can Moebius syndrome be inherited?

Although various genetic markers seem to be associated with Moebius syndrome, the vast majority of cases occur in people with no history of the disorder in their families. There is no clear pattern of inheritance.

 

How is Moebius syndrome treated?

Children with Moebius syndrome may have a number of issues requiring intervention based on the severity of the condition and the presence of associated malformations. A multidisciplinary team of specialists is critical in managing issues related to speech, hearing, feeding, orthopedics, and psychosocial development. For correction of craniofacial issues, surgery is currently the only option. Correction of eye movements will need to be addressed by an ophthalmologist.

Facial paralysis in Moebius syndrome is typically complete and bilateral. In other words, facial nerves on both sides of the face are absent; therefore, use of cranial nerve VII is not possible in restoring movement as in one-sided facial paralysis. However, cranial nerve V is usually present. This nerve is usually responsible for activation of biting muscles. Based on this concept, one of two methods for lower facial reanimation (or, smile reanimation) is possible: free gracilis muscle transfer or temporalis muscle transfer. These techniques are discussed at great length in the Facial Paralysis section.

Incomplete eye closure causing symptomatic drying or excessive tear production may need to be corrected surgically. Various options exist for achieving this. Please refer to the Facial Paralysis section for further details.

Club foot deformities will need to be corrected by an orthopedic surgeon. Hand deformities are most often characterized by an underdeveloped hand (or, symbrachydactyly). In this condition, a combination of webbing of fingers and missing fingers occurs. The severity of symbrachydactyly can be quite variable. Please refer to the section on Symbrachydactyly for further details regarding improvement of hand function. Chest wall deformities can be corrected towards the end of skeletal development at approximately 16 years of age. Girls with lack of breast development will proceed with breast reconstruction at that time.

 

What is the recovery from surgery for Moebius syndrome?

Recovery from surgical correction of Moebius syndrome depends on the deformity being corrected. Some procedures, such as facial reanimation, will require a brief hospitalization, while others such as correction of hand malformations can be done on an outpatient basis. Also, the duration of each surgery is also highly variable from 2 hours to 8 hours.

Patients requiring hospitalization may return to their usual physical activity between 2 and 4 weeks following surgery. Activity restrictions will need to be tailored to the procedure performed and is directly proportional to the intricacy of the intervention. Facial therapy is started usually at 3 weeks postoperatively for facial reanimation using the temporalis muscle or at 3 months when using the gracilis free muscle transfer.

Correction of hand problems usually requires a 2- to 3-week period of casting to ensure proper take of skin grafts (if used) and optimal healing of bone and soft tissues. Following removal of the cast, patients are allowed to shower once again and resume use of the hand. A nighttime splint is worn for 3 to 4 months following surgery.

 

What are the risks and complications of surgeries for Moebius syndrome?

All procedures for correcting deformities related to Moebius syndrome will carry a different set of risks and potential complications. Thankfully, all procedures are relatively safe when appropriate preoperative evaluation is performed. Airway complications are the most serious issue encountered. Anesthesia pre-evaluation is necessary to stratify risk and to make provisions at the time of surgery for successful intubation and postoperative management.

Bleeding, infection, and anesthetic complications are risks of any surgical procedure. In addition, poor scarring or wound problems can occur rarely. More frequently, achieving perfect symmetry is an impossibility. Improvements can be substantial, but reversing the deformity to a normal state cannot be realized in the majority of patients. Revisional surgery may be required to improve scars, contour, symmetry, or facial movement.