Möbius Syndrome
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Möbius syndrome is a congenital condition characterized by strabismus, lagophthalmos, mental retardation, autism and sometimes limb and pectoral abnormalities. Not many 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.
Disease Entity
Möbius syndrome (otherwise spelled Moebius syndrome)is a rare congenital disorder that was named after the Leipzig-born German scholar Paul Julius Möbius, who exelled in Theology, Philosophy and Neurology. Its characterised by billateral paralysis of the facial musculature and weakness of the vertical eye movements. The symptoms can be assymetrical and may vary in severity.
Disease
The disease is characterised 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.
Other nerves associated with the disease are the fifth nerve (CN V), the eightth (CN VIII), the ten (CN X) and the twelvth ( CN XII). Frequently limb abnormalities are also present in which case the disorder is known as Poland-Moebius.
Etiology
The etiology is poorly understood, but it is speculated that temporary vascular abnormalities during early intrauterine life is related to the pathogenesis. Drugs like coccaine abuse during pregnancy and the early abortion agent misoprostol 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.
Primary prevention
Since its a genetic disorder, not much can be done about prevention, but early screening of all neonates is required.
History
Extensive history should be investigated including abuse of coccaine, use of misoprostol and in the past thalidomide.
Signs & Symptoms
Paralysis of the occular 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, and mental retardation and autism.
Since the tongue is atrophic, the palate isn't shaped normally that may result in difficult swallowing.
Clinical diagnosis
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.
Staging
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.
Management
Behavioural management can be used, such as suction aids, or evaluation from specialized orthopedics surgeons, dentists and ophthalmologists but there is no definitive treatment.
Surgery
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.
Additional Resources
[1] NINDS Moebius syndrome information page
References
1) Alexandros Damanakis, Stabismoi 2nd edition, Litsas medical editions, Athens-Greece.
2) American Academy of Ophthalmology. Pediatric Ophthalmology and Strabismus BCSC, Leo, 2011-2012.
3) Jack J. Kanski- Brad Bowling, Clinical Ophthalmology- A systematic approach, Seventh Edition, Elsevier, 2011.
4) Briegel W (August 2006). "Neuropsychiatric findings of Möbius sequence — a review". Clin. Genet. 70 (2): 91–7. doi:10.1111/j.1399-0004.2006.00649.x. PMID 16879188
5) Pastuszak AP, Schuller L, Speck-Martins CF, Coelho KE, Cordello SM, Vargas F et al. (1998). "Use of Misoprostol during pregnancy and Möbius' syndrome in infants". N Engl J Med 338 (26): 1881–5. doi:10.1056/NEJM199806253382604. PMID 9637807.
6) Puvabanditsin S, Garrow E, Augustin G, Titapiwatanakul R, Kuniyoshi KM (April 2005). "Poland-Möbius syndrome and cocaine abuse: a relook at vascular etiology". Pediatr. Neurol. 32 (4): 285–7. doi:10.1016/j.pediatrneurol.2004.11.011. PMID 15797189.
7) Miller MT, Ventura L, Strömland K. (2009 Aug;85).Thalidomide and misoprostol: Ophthalmologic manifestations and associations both expected and unexpected. doi: 10.1002/bdra.20609. Review.Birth Defects Res A Clin Mol Teratol. PMID: 19639653
8)[2] NINDS Moebius syndrome information page(NIH), June 23, 2011
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