What is Moebius Syndrome?
Moebius 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 and other symptoms of Moebius syndrome.
Moebius Syndrome was named after Dr. Paul Julius Moebius who first reported the condition in 1888.
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.
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
- Short tongue
- Weak muscle tone (hypotonia)
- Abnormal curvature of the spine
- 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
- 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)
- In some cases, the underdeveloped muscles of the chest are associated with another condition called Poland syndrome. People with Poland syndrome are missing part of one of the large 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. Often individuals with Poland syndrome will also have abnormalities of the hand on the same side and, rarely, internal organs will be affected. People who also have Moebius syndrome may have other symptoms that do affect movement.
- Some studies report up to 20 to 30% of children with Moebius syndrome have also been diagnosed with an autism spectrum disorder, though this association may be overstated.1 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.
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. More research is needed.
Rarely, Moebius syndrome has occurred in families (less than 2% of cases), suggesting there may be a genetic component in some cases. Most Moebius syndrome cases develop randomly (sporadically) in people with no family history of the disorder.
Moebius syndrome is extremely rare. While the exact number of cases worldwide is unknown, it is estimated to occur in every two to 20 people per million. Males and females are equally affected.
At this time there are no clinically approved diagnostic tests for Moebius Syndrome. If you suspect someone you know has Moebius Syndrome we urge you to have them examined by a medical professional to make that determination. You can get started by using our Children’s Medical Resource List to find a physician in your area.
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