An Overview of Moebius Syndrome

A rare neurological condition affecting nerves controlling facial expressions

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Moebius syndrome (also called Möbius syndrome) is a rare neurological condition that can affect several cranial nerves, particularly those that control the muscles of the face. In most cases, the sixth and seventh cranial nerves are missing from birth (congenitally absent). The absence of these nerves leads to the characteristic facial paralysis of Moebius syndrome.

Symptoms

The symptoms of Moebius syndrome depend on which nerves are affected. Whatever symptoms a person has will be apparent from birth. In most cases, the sixth and seventh cranial nerves are missing, though other cranial nerves may also be affected.

Common Symptoms

The most common features of Moebius syndrome include:

  • Facial paralysis (palsy)
  • Lack of facial expressions; children with Moebius syndrome cannot smile or frown (face is often referred to as being "mask-like")
  • Infants with Moebius syndrome can't move their eyes to track an object. Instead, they will need to fully turn their head to follow an object.
  • Eyelids that don't completely close, even during sleep
  • Dry and irritated eyes
  • A small chin and mouth; many people with Moebius syndrome cannot close their mouth all the way
  • Dental problems related to the small jaw, misaligned teeth, or the effect of having the mouth be constantly open (increased risk of cavities)
  • Drooling, feeding problems, poor sucking in infancy
  • Cleft palate
  • Tipping the head back when swallowing
  • Webbing of the hands or feet (syndactyly)
  • Crossed eyes (strabismus)
  • Short tongue
  • Weak muscle tone (hypotonia)
  • Abnormal curvature of the spine (scoliosis)
  • Respiratory disorders
  • Sleep problems
  • Upper body weakness which can lead to delays in motor function
  • Ear abnormalities that may lead to frequent or persistent ear infections (otitis media)
  • Hearing loss (if certain cranial nerves are affected)
  • Skeletal abnormalities of the hands, feet, and limbs (club feet)
  • Other disorders related to speech, swallowing, and vision
  • Underdeveloped chest wall muscles (which may also include breast tissue)

Other Symptoms

In some cases, the underdeveloped muscles of the chest are associated with another condition called Poland syndrome (or Poland anomaly). People with Poland syndrome are missing part of one of the big muscles of the chest (pectoralis major). This abnormal development can give the chest a concave appearance and usually causes upper body weakness and, sometimes, ribcage abnormalities. These missing muscles generally only affect appearance, and people with the condition don't experience any health issues directly related to the condition. However, people who also have Moebius syndrome may have other symptoms that do affect movement.

Some studies report up to 20 percent to 30 percent of children with Moebius syndrome have also been diagnosed with autism spectrum disorder, though this association may be overstated. Since people with Moebius syndrome are physically unable to demonstrate facial expressions and may struggle to look people in the eye, these features may be construed as autistic behavior even though they are due to physical limitations.

Some children with Moebius syndrome may have motor, speech, or other delays. Most people with the condition do not have intellectual impairments, though assumptions may be made due to their physical struggle to speak and unique facial characteristics.

Causes

The exact cause of Moebius syndrome is not known. Researchers suspect that, like many other rare conditions, it is most likely caused by many different factors (multifactorial). Environmental exposures and genetics have been implicated in some studies, but more research is needed.

Rarely, Moebius syndrome has occurred in families (less than 2 percent of cases), suggesting there may be a genetic component in some cases. The majority of Moebius syndrome cases develop randomly (sporadic) in people with no family history of the disorder.

Moebius syndrome is extremely rare. While the exact number of cases worldwide is unknown, it's estimated to occur in every two to 20 people per million. Males and females are equally affected.

Diagnosis

There is no specific test to diagnose Moebius syndrome. Since the condition is present at birth, it can usually be diagnosed during a thorough newborn exam. While the specific manifestations depend on the cranial nerves that are underdeveloped or missing, there are three diagnostic criteria to make a diagnosis of Moebius syndrome:

Diagnostic Criteria

  • Paralysis or weakness of at least one side of the face (usually both)
  • Sideways movement of the eyes is paralyzed
  • Vertical movement of the eyes is intact

Medical professionals may perform more specialized testing (such as neurological or ophthalmologic exams) to rule out other conditions that can cause facial paralysis and other symptoms of Moebius syndrome.

It's very important that the correct diagnosis be made soon after birth. Children with Moebius syndrome typically need to work with a team of medical specialists, but the earlier intervention and care teams are assembled, the better the long-term outcomes for patients.

While Moebius syndrome is not progressive, the nature of the symptoms can present challenges for each patient individually depending on the specific nerves affected, the severity of the condition, and the availability of prompt diagnosis, treatment, and supportive resources.

Treatment

Each person with Moebius syndrome will have different needs. While there's no definitive treatment or cure for the condition, a team of specialists can help coordinate care for people with Moebius syndrome.

Since the diagnosis can usually be made at birth or soon after, early interventions, such as physical, occupational, and speech therapy can be made early. A thorough eye exam and the ongoing support of an ophthalmologist can help address vision problems. If hearing is impaired, an audiologist may be consulted.

Other specialists that may be involved in care include:

  • Pediatricians and pediatric surgeons
  • War, nose and throat specialists
  • Respiratory specialists
  • Neurologists
  • Maxillofacial surgeons
  • Plastic surgeons
  • Psychiatrists
  • Orthopedists

Surgery

If symptoms are severe, surgery may be needed. In some cases, grafting of nerves from other parts of the body to replace the missing cranial nerves may be possible.

Other surgical procedures that may be necessary include:

  • Surgery on the eye or eyelid to improve vision and correct strabismus
  • Oral surgery to address dental issues
  • Orthopedic procedures (or nonsurgical interventions such as splinting) to improve mobility
  • Braces or surgery to correct scoliosis

Smile Operation

One fairly recent surgical innovation is known as the "smile operation." The procedure involves taking a nerve from the thigh and grafting it to the face, specifically to the muscles that help a person chew (masseter). The operation has improved facial mobility and speech for some patients with Moebius syndrome—including successfully restoring the ability to make certain facial expressions, such as smiling.

For patients who are diagnosed with Poland syndrome, cosmetic surgery procedures to correct structural abnormalities of the chest wall, including breast tissue, is also possible in many cases.

Living With Moebius Syndrome

Although the condition is not believed to be genetic, if Moebius syndrome does occur in a single family, genetic counseling may be helpful.

While children with Moebius syndrome often "catch up" with any developmental or motor delays they experience and have normal intellectual functioning, they may still have a difficult time socially with peers or at school due to the uniqueness of their condition. Supportive counseling and educational resources may be helpful for families.

If children do struggle academically, for example, due to physical limitations like poor vision, special education programs, tutoring, or homeschooling can be considered.

Since Moebius syndrome is very rare, some parents may choose to send a letter or brief explainer to a child's teacher before they start school. The Moebius Syndrome Foundation has a template that families can use to start this conversation with caregivers, educators, and health care professionals who may be unfamiliar with the condition.

A Word From Verywell

Moebius syndrome is usually diagnosed at birth and prompt diagnosis and treatment are important to ensuring a person with the condition gets the support they need. While some children with Moebius syndrome may have motor or speech delays, these are usually a result of physical symptoms associated with the mouth or muscles of the limbs.

Most people with Moebius syndrome don't have any intellectual delays, though some research has indicated children with Moebius syndrome may be more likely to have autism spectrum disorders. While there is no definitive treatment or cure, there are a variety of treatment options including occupational and physical therapy and specialized surgery.

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Article Sources
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  • What is Moebius syndrome? Moebius Syndrome Foundation. Published 2017.

  • Moebius Syndrome. NORD (National Organization for Rare Disorders). Published 2016.

  • Moebius syndrome. Genetics Home Reference. NIH. U.S. National Library of Medicine. Published 2016. Reviewed October 16, 2018.