Moebius syndrome is usually first suspected in newborn infants who are unable to suck. They may also have crossed eyes and drool excessively. Other signs may be present, such as abnormalities of the limbs, palate, and tongue. As the infant grows, smiling does not develop.
Signs of Moebius Syndrome
There is no specific test for Moebius syndrome. Diagnosis is made on the basis of symptoms and clinical findings, primarily the lack of facial expression and the inability to close the mouth. Others include facial nerve paralysis, malformations of the limbs, and clinical features related to the loss of function of specific nerves. These may include:
- ocular nerve palsies
- swallowing and speech difficulties
- malformations of structures around the mouth
- abnormalities of the musculoskeletal system
Typically facial nerve palsy is bilateral and incomplete, and affects either the upper or lower part of the face. The face has a masklike expression. Ocular palsies such as ptosis are present in about 80 percent of patients.
Chronic or recurrent conjunctivitis is a common finding, since incomplete blinking provides little protection to the cornea and conjunctiva. Skin abnormalities are sometimes also found with Moebius syndrome. These include webbing of the axilla, lack of subcutaneous tissue, and cafe-au-lait pigmentation. Involvement of masticatory muscles is rare in Moebius syndrome.
About 75% of patients with Moebius syndrome have abducens nerve palsies. Most of those are bilateral and complete. Internal strabismus may be present, as well as partial or complete ophthalmoplegia. Affected children and adults may show lateral gaze paralysis.
25% of patients with Moebius syndrome have hypoglossal nerve involvement, which can lead to atrophy of the tongue.
Deformities of the limbs can include amputation or clubbing of the hand. One hand may be smaller than the other. Syndactyly or brachydactyly may be observed. In addition to webbing of the fingers, the radius, ulna, metacarpal, or phalanx bones may be absent or small. Clubfoot is present in about one third of patients.
About 15 percent of Moebius syndrome patients have missing muscle groups of the body, such as the pectoralis or trapezius. The latissimus dorsi, external abdominals, serratus anterior, and intercostal muscles may be hypoplastic or aplastic.
MRI and CT scans may show calcification of some parts of the nuclei of cranial nerve VI and calcification of basal ganglia. However, these scans are not conclusive.
Moebius syndrome may be misdiagnosed in children who actually have a muscular dystrophy or infantile myotonic dystrophy.
There is no cure for Moebius syndrome, but some of the symptoms can be treated. Feeding difficulties are typical during infancy, as a result of which they may require supplementation with bottle feeding or tube feeding. Irritation of the eyes and cornea is treated with topical medications. Surgery is available for crossed eyes and abnormalities of the cornea. Physical and speech therapy may be helpful for helping a child with Moebius syndrome catch up with the developmental milestones and correct musculo-skeletal abnormalities.
Psychotherapy and counseling is very important for people with Moebius syndrome due to their difficulties with social interaction as a result of the lack of facial expression and frequent deformities.
Corrective surgery may require grafting muscles or nerves from other parts of the body to the face. In a procedure known as the smile surgery, a muscle from the thigh is grafted onto the face to restore the ability to smile. Another operation helps the patient to close their eyes.
Reviewed by Liji Thomas, MD