Moebius syndrome

موضوع: Moebius syndrome الإثنين يناير 03, 2011 11:49 am

Moebius syndrome
Definition
Moebius syndrome is a
condition in which the facial nerve is underdeveloped, causing
paralysis or weakness of the muscles of the face. Other nerves to the
facial structures may also be underdeveloped
Demographics
Moebius
syndrome is extremely rare and does not seem to affect any particular
ethnic group more than others. The families in which genes on
chromosomes 3 and 10 were mapped were Dutch
Causes and symptoms
Most
cases of Moebius syndrome are isolated and do not appear to be genetic,
but occurrence in multiple individuals within some families indicates
that there are multiple genetic forms. The underlying problem is a
defect in or absence of the sixth and seventh cranial nerves. The
seventh or facial nerve normally controls facial expression. The
abducens or sixth cranial nerve controls blinking and back-and-forth
eye movement and is the second most commonly affected cranial nerve in
Moebius syndrome. Additional cranial nerves affected in some patients
control other eye movements and other functions such as hearing,
balance, speech, and feeding
The first sign of Moebius syndrome in
newborns is an inability to suck, sometimes accompanied by excessive
drooling and crossed eyes. Also seen at birth in some patients are
abnormalities of the limbs, tongue, and jaw. Children also often have
low muscle tone, particularly in the upper body. The lack of facial
expression and inability to smile become apparent as children get older
When cranial nerve palsy is associated with limb reduction abnormalities and the absence of the pectoralis muscles, the condi
tion
is known as Poland-Moebius or Möebius-Poland syndrome. Common
limb abnormalities are missing or ***bed fingers and clubfoot
The
prevalence of mental retardation in Moebius syndrome is uncertain. It
has been estimated in the past to be between 10% and 50%, but these
numbers are thought to be overestimates resulting from the lack of
facial expression and drooling seen in people with Moebius syndrome. In
one study of familial cases of Moebius syndrome, 3% were reported to be
mentally retarded
Diagnosis
Diagnosis of Moebius syndrome is made
on the basis of clinical symptoms, especially the lack of facial
expression. Because the exact genes involved in Moebius syndrome have
not yet been identified, molecular genetic testing is not available
Treatment team
Neurologists,
neurosurgeons, and plastic surgeons may play a role in the treatment of
a child with Moebius syndrome. Physical and speech therapists may help
improve control over coordination, speech, and eating

Treatment

The
ability to smile has been restored in some cases of Moebius syndrome by
surgery which transfers nerve and muscle from the thigh to the face.
Other surgeries can be used to treat eye, limb, and jaw problems. In
children with feeding problems, special bottles or feeding tubes are
used
Prognosis
Moebius syndrome does not appear to affect life span, and individuals who are treated for their symptoms can lead normal lives