Moebius Syndrome: What Does It Consist Of?

Moebius syndrome is a rare disease clinically characterized by the absence of a smile. This is not due to the absence of happiness but to the facial paralysis that characterizes this syndrome.

Moebius syndrome is an uncommon and rare condition,  although its incidence appears to be increasing. The latest neurology and ophthalmology congresses around the world report an increase in the number of cases identified.

We can say that  the main feature of Moebius syndrome is the lack of ability to smile ; even though those affected experience happy situations and would like to sketch a smile, they cannot.

But that’s not all. People with this rare disease cannot perform many of the classic and typical facial gestures. Even their ability to move their eyes from side to side is affected, for example.

This happens because they have not developed, in part or completely, two pairs of cranial nerves : pair number six and pair number seven. These nerves are in charge of the facial muscles and part of the muscles. muscles that perform certain eye movements.

As we will see a little later,  each pair of cranial nerves has specific functions. The sixth nerve is the one that regulates the laterality of the eye and the seventh nerve is called the “facial nerve” because it is in charge of facial expressions.

We know that Moebius syndrome usually appears in isolation. In other words,  it is not usual for a family to have more than one confirmed case. It is calculated that one in 120,000 people is born with this problem.

What are the cranial nerves?

Let us first see what are the pairs of cranial nerves and their functions,  to then understand for Moebius syndrome presents such symptoms. The cranial nerves are:

• Optics:  it is the nerve of vision.
• Trigeminal: it is involved in chewing.
• Facial:  the other nerve affected in the pathology.
• Olfactory:  it provides information to perceive odors.
• Hypoglossus:  it innervates the muscles of the tongue and neck.
• Auditory:  it conducts the information we hear to the brain.
• Glossopharyngeal:  it transmits part of the taste picked up by the tongue.
• Pathetic:  it also innervates the muscles of eye movement.
• External ocular motor:  one of the nerves affected in Moebius syndrome.
• Wave:  it extends outside the skull to reach the thorax and abdomen.
• Accessory:  it also extends outside the skull to the muscles of the neck and back.
• Oculomotor:  it is the third cranial pair and it innervates part of the muscles of eye movement.

Etiology of Moebius syndrome

It should be noted that even if it is known under the name of “syndrome”, in reality, it is not. Moebius is, in genetics, what is known as “sequence”. In the sequences, there are a lot of malformations at the same time, created by a single anomaly.

In the case of Moebius,  the anomaly is the lack of development or the complete absence of nerve nuclei in cranial nerves number six and seven.  Imaging examinations performed on patients and necropsies performed coincide with this same diagnosis.

The etiology is not always genetic. We have been able to identify cases in which the problem with the skull pairs is due to drugs. Misoprostol is the drug most associated with the problem.

This medicine is usually used as an abortifacient substance and, if it is unsuccessful,  the subsequent pregnancy may develop Moebius syndrome.

Symptoms of Moebius syndrome

Newborns with Moebius syndrome  do not only have a lack of facial expression: they also have difficulty breathing. They drool excessively and have poor muscle tone, which can affect walking.

If, to this, we add the possibility that the patients suffer from deformities in the feet,  the trip then experiences real risks of delay. Other symptoms that have been associated are:

• Arched palace.
• Absence of eyelids.
• Hypersensitivity to the sun and strong lights.
• Hearing problems due to the accumulation of fluids in the inner and middle ear.

Experimental treatments

There is no cure for Moebius syndrome. Once it has settled in, it is not completely reversible. Facial rehabilitation sessions have not shown efficacy.

There is an experimental surgical treatment that originated in Canada. It consists of an intervention where a muscle graft is carried out in the facial area to allow the expression of a smile.

It is estimated that this operation has a greater chance of success if it is performed when the patient is about 5 years old. Although this practice is promising, it is true that it is not available worldwide and that the costs of access are not universal either.

One of the struggles waged by relatives of patients with Moebius syndrome is to avoid discrimination. They therefore try to raise awareness among the population, by emphasizing the fact that patients have feelings,  even if they cannot express them.

Treatments are still being tested in the medical world. Surgical projections are promising. In the meantime, it is fundamental to respect these patients  and to understand that their inclusion in social life depends on greater knowledge of their disease.