Mobius syndrome
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| ICD-10 | Q87.0 |
|---|---|
| ICD-9 | {{{1}}} |
Mobius syndrome (also spelled Moebius) is an extremely rare neurological disorder.
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[edit] Clinical features
Mobius syndrome is caused by abnormal development of the cranial nerves. This rare disorder has a number of causes. Most often affected are the cranial nerves VI and VII. Occasionally the cranial nerves V and VIII are affected.
If the cranial nerve VI is affected, the patient suffers from reduction of lateral gaze. If cranial nerve VII is affected, the patient suffers from bilateral facial palsy — mask-like expressionless face with mouth constantly held open. If cranial VIII is affected the patient suffers from hearing loss.
Although its rarity often leads to late diagnosis, infants with this disorder can be identified at birth: by a "mask-like" expression detectable during crying or laughing due to paresis (palsy) of the sixth and seventh cranial nerves. Other characteristics include:
- abnormalities in the lower appendages, limbs — their fingers may be webbed, shorter than usual or they may have more than 5 fingers on their foot
- impaired listening ability
- inability to follow objects with the eye—instead the child turns his or her head to follow
- crossed legs while in fetus (esotropia)
- limitation of heart movement
- exposure keratopathy or corneal erosion
- Hearing loss due to fluid in the ear or nerve loss
Later on, the child may develop speech difficulties, crossed eyes, abnormally small eyes, and fluid building up in the lungs, causing bronchopneumonia. Moebius syndrome has also been linked to increased occurrence of the symptoms of autism[1]. Some children with Mobius syndrome are mistakenly labelled as mentally retarded, due to their expressionless faces, strabismus, and frequent drooling.
[edit] Treatment
Treatment for Moebius syndrome differs according to whether one is an individual with the syndrome or one who is trying to 'fix' that individual (i.e., doctor or other professional, loved ones - including parents and siblings). Most importantly for the person with Moebius syndrome is the need to feel 'worthy' rather than 'defective'. This need can be recognized via learning about and accepting the challenges as perceived by the individual with the condition. Children with Moebius may grow up to feel alone and 'defective' - especially when the greatest effort is made to 'fix' rather than 'accept'. Finding others with Moebius - and learning about the contributions they have made in their lives - can go a long way towards enabling that person with Moebius to feel a part of a group of people that positively impacts the world around them.
Families and professionals affected by individuals with Moebius syndrome need to understand the deletorious impact a "medical model" of disability can have on an individual with a difference. These people - whether they have Moebius syndrome or any other condition - need to embrace a sense of self-worth while recognizing they also have a 'dis'ability. Families and professionals must learn how to see a disability from the viewpoint of one that has it, rather than primarily their own point of view (one which most likely wishes the disability never occurred). Thus, while using appropriate "treatments" in addressing various medical aspects of a condition, acknowledge and respect the reality that people WITH this 'condition' do view having the condition from a vastly different point of view. This is called the "social model" of disability - the mentally healthy and life-affirming viewpoint that enables rather than degrades.
There is no single course of medical treatment for Mobius syndrome. Treatment is supportive and in accordance with symptoms. Infants may require feeding tubes or special bottles, such as the Haberman Feeder, to maintain sufficient nutrition. Surgery may correct crossed eyes, protect the cornea (via frequent lubrication or tarsorraphy), and improve limb and jaw deformities. Physical and speech therapy often improves motor skills and coordination, and leads to better control of speaking and eating abilities. Plastic reconstructive surgery may be beneficial in some individuals. Nerve and muscle transfers to the corners of the mouth have been performed to provide limited ability to smile. Most significantly, however, treatment must address the psycho-social implications of having a facial disfigurement/disability so that, ultimately, the individual with Moebius percieves himself/herself as indeed a normal and worthy member of society.
[edit] Pathological picture
The causes of Mobius syndrome are poorly understood. Many cases have no obvious cause. Others may be genetic.
Some cases are associated with reciprocal translocation between chromosomes or maternal illness. Some maternal trauma may result in impaired or interrupted blood flow (Ischemia) or lack of oxygen (Hypoxia) to a developing fetus. The use of drugs and a traumatic pregnancy may also be linked to the development of Mobius syndrome. The use of the drugs Misoprostol or Thalidomide by women during pregnancy has been linked to the development of Mobius syndrome in some cases.
Some researchers have suggested that the underlying problem of this disorder could be congenital hypoplasia or agenesis of the cranial nerve nuclei. Certain symptoms associated with Mobius syndrome may be caused by incomplete development of facial nerves, other cranial nerves, and other parts of the central nervous system.
In the majority of cases of Mobius syndrome in which autosomal dominant inheritance is suspected, sixth and seventh cranial nerve paralysis (palsy) occurs without associated limb abnormalities.
[edit] Oral/dental concerns
[edit] Neonatal Period
When a child is born with Moebius Syndrome, there may be difficulty in closing the mouth or swallowing. The tongue may be hypotonic (low muscle tone) or faciculate (quiver). The tongue may be larger or smaller than average. There may be low tone of the muscles of the soft palate, pharynges, and the masticatory system. The palate may be arched excessively (a high palate) since the tongue does not form a suction that would normally shape the palate down further. The palate may have a groove (this may be partially due to intubation early on if it is for an extended period of time) or may be incompletely formed (cleft palate). The opening to the mouth may be small. Feeding problems may become a critical issue early on if adequate nutrition is difficult. If the infant can close and suck but needs assistance, the Mead-Johnson Soft Bottle can help. If the infant's can suck just minimally, the Haberman Bottle can be used to express milk for the baby. If the infant tends to aspirate, a gastrostomy feeding tube may be required. Often this is in combination with the tracheostomy breathing tube if the infant cannot control salivary secretions.
[edit] Primary Dentition
The primary (baby) teeth generally have started coming in by the first birthday and all 20 teeth may be in by the second birthday. The eruption timing varies a lot. There may be an incomplete formation of the enamel on the teeth called enamel hypoplasia that makes the teeth more vulnerable to caries (cavities). There may be missing teeth. The lower jaws become more noticeably deficient (micrognathia or retrognathia) if the infant is not closing down properly. The front teeth may not touch when the child closes down because the back teeth have overerrupted. This condition is called an anterior open bite and has facial/skeletal implications. The saliva may be thick or the infant may have a dry mouth. As soon as the first tooth comes in the parent can start to gently brush the teeth each day. Minimal toothpaste is needed or just a wet toothbrush is acceptable if the child tends to aspirate. As more teeth come in, it becomes important to start flossing between teeth. Babies should not be "put to bed" with a bottle of milk or juice as the residual nutrients in the mouth allow bacteria to proliferate and cause a condition called Bottle Caries. The first appointment with a dentist should come by age one and a half or two. This should probably be with a pediatric dentist, though there may be a need for a dental team to be involved as the child grows. The team may include the general dentist, orthodontist, and oral and maxillo-facial surgeon. Examinations and professional cleaning should be performed at least every six months. Fluoride treatments can be applied in the office or it may be prescribed as a gel to be applied at home. In addition, fluoride tablets or drops may be prescribed if the patient lives in an area that does not have an optimal amount in the water supply to help prevent dental caries. Sealants can be applied to the deep grooves of the back teeth as another prevention method that is very affective.
[edit] Transitional Dentition
Between age 5 and 7 most children start losing their primary teeth. Occasionally some primary teeth are slow to exfoliate (fall out) and the dentist will have to remove that tooth. There are other reasons that a dentist may want to remove a primary tooth early to prevent orthodontic problems. Likewise, premature loss of primary teeth may create orthodontic problems later on. Removable or fixed spacers may be needed to prevent the shifting of teeth when a tooth is lost prematurely. Interceptive orthodontic treatment may be initiated at this stage of development to help with crowding or to help relate the upper and lower jaws. Consistent with a high palate is a narrow arch shape of the upper teeth as they line up in the mouth. This may cause the upper front teeth to flare out and become more prone to fracture if accidentally hit. Interceptive orthodontics has an important role in this situation. Appliances that expand the upper arch tend to bring the front teeth back into a more normal position. Some appliances can even help allow the front teeth to close to normal in an open bite situation. The mouth and lips may tend to get dry with the Moebius patient. Lack of a good oral seal (lips together) allows the gingiva (gums) to get dry and may get inflamed and irritated. Oral products such as Oral Balance, Xerolube, or Salvert Spray may be helpful.
[edit] Permanent Dentition
After the last primary tooth is lost, usually around age twelve, final orthodontic treatment can be initiated. A patient that has not been able to close or swallow well, probably will have an open bite, deficient lower jaw growth, a narrow archform with crowded teeth and upper anterior flaring of teeth. Orthognathic (jaw) surgery may be indicated. This should be completed in most situations before smile surgery where the Gracilis Muscle is grafted to the face. Good home care of the mouth and teeth includes brushing with fluoride toothpaste and flossing (they make floss holders that are easier to grip). In addition, water irrigation devises can be very helpful. Regular check-ups at the dental office are also important to help maintain a healthy mouth for a lifetime
