Möbius syndrome is a congenital condition characterized by strabismus, lagophthalmos, neurodevelopmental abnormalities, autism and sometimes limb and pectoral abnormalities. Not much is known about the disease, but its speculated that it results from abnormal vascularization of the brain stem during early intrauterine life and several mutagens have been incriminated.
Möbius syndrome (otherwise spelled Moebius syndrome)is a rare congenital disorder that was named after the Leipzig-born German scholar Paul Julius Möbius, who excelled in Theology, Philosophy and Neurology. It's characterized by congenital, non-progressive uni- or bilateral paralysis of the facial musculature and full preservation of the vertical eye movements. The symptoms can be asymetrical and may vary in severity.
The disease is characterized by neurological deficits and palsies of several cranial nerves of the brain stem with different severity at a time. The main nerves affected are the sixth (CN VI) and the seventh (CN VII) which results in abnormal gazing and mask like facies. The affected babies are usually referred to as unable to smile and suck.This can cause bonding problems to the mother and such parents should be referred to behavioural specialists.
Other nerves associated with the disease are the fifth nerve (CN V), the eighth (CN VIII), the ten (CN X) and the twelfth ( CN XII). Frequently limb abnormalities are also present in which case the disorder is known as Poland-Moebius.
Because of the neurological anomalies, low blinking rate and eye dryness has been observed. But usually corneas are intact.
The etiology is poorly understood, but it is speculated that temporary vascular abnormalities during early intrauterine life is related to the pathogenesis. Drugs like cocaine abuse during pregnancy and the early abortion agent misoprostol (popular in latin America) have been linked to increased incidence of the disease, by means of their vaso-active effects. Finally the known teratogen thalidomide was also found responsible in the past.
There has been no frequent gene has been incriminated but a variety of autosomal dominant and X-linked genes have been detected.
Since it's a genetic disorder, not much can be done about prevention, but early screening of all neonates is required.
Extensive history should be investigated including abuse of cocaine,ergotamine, use of misoprostol and in the past thalidomide.
Signs & Symptoms
Paralysis of the ocular sphincter is common and ends up in lagophthalmos, cornea however is intact since usually vertical movements are preserved, preventing it from exposure. Strabismus is a common feature and its usually esotropic.
Other manifestations of the disease include deafness, thoracic muscle weakness, tongue atrophy, limb abnormalities.
In the past mental retardation and autism was considered a part of the syndrome but after studies conducted in Holland showed that the intelligence of Mobius patients didn't vary from that of the general Dutch population. Because of the doll-facies they have trouble in expressing their emotions and percieving other people's emotions as well.
Since the tongue is atrophic, the palate isn't shaped normally that may result in difficult swallowing.
Poland anomaly is characterised by dextrocardia and absense of the pectoralis major. Jaw and teeth as well as digital anomalies can be present.
The clinical characteristics as well as the pathological and electromyographical evidence show that there is an extended supranuclear malfunction of the brain stem with additional subnuclear characteristics.
According to the National Institute of Neurological Disorders and Stroke there are four categories of Moebius syndrome.
Group I, characterized by small or absent brain stem nuclei that control the cranial nerves;
Group II, characterized by loss and degeneration of neurons in the facial peripheral nerve;
Group III, characterized by loss and degeneration of neurons and other brain cells, microscopic areas of damage, and hardened tissue in the brainstem nuclei, and,
Group IV, characterized by muscular symptoms in spite of a lack of lesions in the cranial nerve.
Behavioural management can be used, such as suction aids, or evaluation from specialized orthopedics surgeons, dentists and ophthalmologists but there is no definitive treatment.
When present eye dryness and low blinking rate should be managed by early temporary tarsoraphy untill the baby can look after it self and drainage block (such as punctal plugs) should also be considered.
Many ophthalmic surgeons refrain from surgical treatment, but medial rectus muscle recession has been advocated, as well as vertical rectus muscle transposition in a later operation. Because of inconsistent results however surgical options should be explored conservatively.
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