Moebius Syndrome

What Is Moebius Syndrome?

Moebius syndrome was first described by Von Graefe in 1880 and Moebius in 1888. And hence this congenital syndrome is named after the German neurologist Moebius. Though it is a rare condition, this syndrome causes weakness or paralysis of multiple cranial nerves in affected people and is not usually progressive.

What Is the Cause of Moebius Syndrome?

The exact cause of this syndrome remains elusive. However, the presence of a robust genetic component or the use of certain drugs during pregnancy may be potentially capable of causing this condition. The occurrence is also generally sporadic or very randomized. These conditions are also known in medical literature as congenital facial diplegia syndrome or congenital oculofacial paralysis. This presents only at birth and is hence congenital. The cranial nerves affected are the sixth (abducent nerve) or the seventh cranial nerve (facial nerve).

What Are the Classic Symptoms of Moebius Syndrome?

Though the abnormalities in affected individuals vary greatly, the classic symptoms or diagnostic criterion for confirming the presence of this syndrome is by the validation of the below signs:

• Facial paralysis or weakness affecting one or both sides of the face. In the case of facial nerve paralysis, there may be an inability even to smile, frown, raise the eyebrows, or even close the eyelid.

• There may be paralysis of the eyes' lateral movement resulting in an inability to move laterally. Vertical eye movements are not affected in this syndrome. Hence the lateral eye movement paralysis can be a confirmative sign.

• Underdeveloped pectoral muscles.

• Defective limbs.

• Widespread involvement of other cranial nerve abnormalities; for example, the 5th, 8th, 9th, 10th, 11th, and 12th cranial nerves can also have the possibility to be affected.

What Is the Pathogenesis of Moebius Syndrome?

Though the causes of this condition may be elusive or multifactorial, it is still poorly understood as per traditional medical research.

1. Medications: In a few cases, the use of drugs like Thalidomide and Misoprostol during pregnancy have been known to cause Moebius syndrome in the newborn infant.

2. Illicit Drug Usage: Similarly, the use of detrimental drugs or substance abuse, commonly cocaine, has also been implicated in the pathogenesis of the condition.

3.Maternal Trauma: The major hypothesis that is commonly accepted regarding the prenatal pathogenesis of Moebius syndrome is the vascular disruption or impaired or interrupted blood flow. This maternal trauma during pregnancy can create a temporary blood loss within the brain leading to events stimulating the underdevelopment of the sixth or seventh nerve that mainly plays a role in the control of lateral eye movements and facial expressions.

Maternal trauma is considered a primary hypothetical reason for ischemias and hypoxia (reduced oxygen levels) in the developing fetus, causing the affected cranial nerves to be incompletely developed or detrimentally impacted.

4. Congenital Causes: In a few rare cases of this syndrome, a robust genetic component has also been deemed likely to trigger such a condition in the developing fetus due to disturbances in reciprocal translation in the chromosomes. In cases of autosomal dominant inheritance of this syndrome, both sixth and seventh cranial nerve abnormalities have been detected congenitally without any other cranial nerves being affected or limbic abnormalities.

What Are the Psychosocial Implications of the Defects in Moebius Syndrome?

Though the individuals affected by Moebius syndrome may be completely normal, they may face psychosocial and physiological complications.

Physiological Complications:

• Skeletal malformations are common in nearly half of the affected individuals, including:

  • Clubbed feet.

  • Webbed fingers.

  • Upper or lower limb extremities.

  • Undeveloped hand structure.

• Also, scoliosis or abnormal spine curvature and underdevelopment of the chest or pectoral muscles can occur in over 15 % of affected cases.

• Though minor intellectual disabilities and autism are also possible in the individuals concerned, the relationship between autism and this syndrome remains elusive without any direct linkage.

• Additional abnormalities like external ear abnormalities or ear infections occur when the eighth cranial nerve is affected in these patients, leading to hearing loss.

Psychosocial Complications:

Because of the individual's inability to smile or change their facial expressions, the syndrome is not only associated with psychological and social implications, but the observers of society can also misinterpret these individuals to be unfriendly or may not perceive their true nature which can lead to these individuals developing clinical anxiety and depression, especially in the adolescent ages. With this perceived psychosocial view and stress about how they are perceived, the individual can also tend to be apprehensive and prefer to be socially dissociated.

What Are the Oral Manifestations and Management of Moebius Syndrome?

1. This syndrome's dental and oral manifestations that can be found at birth are:

   1. A malformed jaw or short jaw (micrognathia).

   2. Cleft lip or cleft palate.

2. In addition, the tongue can also tend to be frequently malformed. This malformation can further lead to difficulty swallowing, opening, or closing the mouth because of the fasciculating tongue and low muscle tone.

3. The eruption timing is also significantly affected in these individuals, while there is also a possibility of incomplete enamel formation (enamel hypoplasia). This is because of the incomplete or partially mineralized tooth structure, which, in turn, paves the road for problems like dental decay and erosion.

4. Also, because of the deficient jaw, the alignment of the teeth tends to over-erupt. In addition, the bite forces are entirely altered because of incomplete formation of the maxillary segment and retruded or underdeveloped mandible (like open bite and anterior deep bite).

Thus, facial and skeletal malformations that can have a consequential impact on the infant upon the primary and permanent dentition, alignment, and risk of increased decay make dental management very elaborate and clinically challenging in these individuals. However, interceptive orthodontics during the eruption of permanent teeth, timely dental checkups, and restorative treatments can help these individuals retain proper form and masticatory function.

How Is Moebius Syndrome Managed?

Though there is no single or curative treatment for this lifelong syndrome's multiple signs and symptoms, treatment is multidisciplinary and made after a thorough clinical evaluation of the patient.

1. Besides physical, occupational, and speech therapy, mental counseling can help promote socialization and improve motor and coordination skills.

2. In addition, these individuals need strong psychological support from their families and peers.

3. Frequent lubrication with eye drops to prevent harm to the corneal layer of the eye due to impaired blinking, reconstructive facial smile surgery by muscle transfer, and orthodontic treatment or surgery to correct dentofacial abnormalities are the primary treatment strategies by the maxillofacial or plastic surgeon, physician, neurologist, and an ENT specialist.

Conclusion:

To conclude, even though the individuals suffering from Moebius syndrome are as intelligent as any average individual, the impairment of the sixth or seventh cranial nerves causing this syndrome is indeed a life-debilitating condition. Hence this needs crucial physical and psychological support and multidisciplinary management.