Moebius syndrome is a rare disorder affecting the muscles used in facial expression and eye movement. It is also known as congenital facial diplegia, congenital ophthalmoplegia, and facial paresis. The syndrome is present from birth, and affected infants may have feeding difficulties. People with Moebius syndrome lack all facial expressions such as smiling, frowning, or raising eyebrows in surprise.
Other signs of the disease include a small chin and mouth or an abnormally shaped tongue. The palate may be cleft or unusually high and arched. Speech problems and dental abnormalities are also common.
In addition to lacking facial expression, eye movement is affected. People with Moebius syndrome lack control of the muscles that move the eyes from side to side, and must move their heads to read or track objects. Eyes may look in different directions and the eyelids may not close completely in sleep or when blinking. That can lead to dryness or irritation of the eyes.
People with Moebius syndrome may also have bone abnormalities, weak muscle tone, and loss of hearing. Development of motor skills is typically delayed.
Origin of Moebius Syndrome
Moebius syndrome does not have a clear pattern of inheritance, and most people with the disorder have no positive family history. The syndrome is believed to be caused by a combination of environmental and genetic factors. There may be some association with genetic alterations on chromosomes 3, 10, and 13. Medications and recreational drugs used in pregnancy have been implicated as risk factors for the disease.
The symptoms of Moebius syndrome are mainly caused by deficits in development of cranial nerves VI and VII. Other cranial nerves may also be affected.
Types of Moebius Syndrome
There are four categories of Moebius syndrome:
- Group I: Cranial nerve nuclei are small or absent
- Group II: Peripheral cranial neurons have degenerated.
- Group III: Loss or degeneration of neurons, areas of microscopic damage in the brain, and hardened tissue in the brainstem nuclei
- Group IV: Muscular symptoms without lesions in the cranial nerve.
Outlook for Patients
There is no cure for Moebius syndrome, but supportive treatments for some of the symptoms are available. These include surgical options to correct some of the facial expression deficits, nutritional support, orthodontic devices, speech therapy, and counseling.
Surgery may be an option for correcting drooping eyelids and restoring the ability to smile. The smile surgery is carried out by grafting muscle from another part of the body into the face to restore the ability to smile. It has not yet been found possible to restore other facial expressions.
Lack of ability to blink properly can cause dry eyes and irritation of the eyes. A procedure called tarsorrhaphy can offer relief by partially closing the eyelids. Crossed eyes can also be addressed using a number of available treatments like eye patches and surgery.
Social and psychological effects of Moebius syndrome can be deep and long lasting. Therapy can help a child with Moebius syndrome build self-esteem, learn coping skills, and advocate for himself with others who may misunderstand the lack of expression.
Reviewed by Liji Thomas, MD.