Moebius Syndrome

What is Moebius syndrome?

Moebius syndrome is a rare neurological disorder that is characterized by weakness or paralysis of multiple cranial nerves, most often, the abducens and facial nerves, which are the 6^th and 7^th nerves, respectively. In addition to these, the 3^rd, 4^th, 5^th, 9^th, 10^th, and 12^th nerves may also be affected, causing skeletal involvement.

What causes Moebius syndrome?

The exact cause of Moebius syndrome is not known, but it appears to occur sporatically, for no apparent reason. However, some cases of this disorder occur in families, which suggests that there may be a genetic component to its onset with an autosomal dominant inheritance pattern. Another hypothesis is that Moebius syndrome is the result of diminished or interrupted blood flow to the developing fetus during pregnancy, which could result from an environmental, mechanical, or genetic cause.

What are the symptoms of Moebius syndrome?

Moebius syndrome is a congenital disorder, so it is present at birth. However, the signs and symptoms of it vary greatly, depending on which cranial nerves are affected. If the facial nerves are involved, the patient is unable to smile, frown, pucker his/her lips, raise the eyebrows, or close the eyelids. This is often described as a “mask-like” face. If the abducens nerves are affected, the eye cannot turn outward past the midline. In addition, other signs and symptoms of Moebius syndrome include underdevelopment of the pectoral muscles and defects of the limbs, drooling excessively from a short, malformed tongue, cleft palate, and delays in certain developmental milestones, such as crawling and walking. Alongside these characteristic signs and symptoms, many individuals affected with Moebius syndrome may have the following complications:

• Respiratory problems
• Speech and swallowing difficulties
• Visual impairments
• Sensory integration dysfunction
• Sleep disorders
• Weak upper body strength
• Autism spectrum disorders

How is Moebius syndrome diagnosed?

Moebius syndrome is diagnosed after a thorough patient and family history and clinical examination and an observation of the characteristic signs and symptoms of the disorder. While there are no particular tests to confirm this diagnosis, some specialized tests may be used to rule out other causes of facial palsy.

What are the available treatments for Moebius syndrome?

Fortunately, Moebius syndrome is not progressive, so it does not worsen over time. With that being said, the disorder is debilitating, so corrective procedures for facial paralysis involve transfer or muscle and/or graft nerves from another area of the face or the body. These corrective procedures can include any of the following:

• Temporalis tendon transfer, to transfer the chewing muscles to the corners of the mouth
• Cross-Facial Nerve Graft, to take a sensory nerve from the calf
• The Smile Operation, to transfer a muscle from the thigh to the face

In addition to these, physical, speech, and occupational therapy may also be beneficial for patients, and splints, braces, and prostheses may be necessary for those affected by congenital limb abnormalities.

Where can I find more information on Moebius syndrome?

• National Organization for Rare Disorders (NORD)
• Moebius Syndrome Foundation
• U.S. National Library of Medicine