Original Editor - Wendy Walker
Moebius, or Möbius, syndrome is defined as congenital facial palsy combined with abnormal ocular abduction, caused by abnormal development of the 6th and 7th cranial nerves. It is a rare congenital condition that was first described by German neurologist Paul Julius Möbius in 1888.
The most common description of the face of an individual with Moebius syndrome is "mask-like" as there is no activity of the muscles of facial expression, hence no smile or frown.
Moebius syndrome occurs due to the loss of function of motor cranial nerves. Most cases are diagnosed during infancy. The disease is not progressive.
Clinically Relevant Anatomy
Cranial nerve six, AKA the abducens nerve, innervates the ipsilateral lateral rectus muscle which abducts the ipsilateral eye.
The sixth nerve nucleus is located in the pons, just ventral to the floor of the fourth ventricle. Bilateral palsy of the abducens nerve (as seen in Moebius Syndrome) results in lack of eye movement in the horizontal plane, ie. inability to move the eyes laterally. This can be observed by testing lateral tracking of eye movement (keeping the head still) and also when the individual reads text, it is apparent that they have to move their head laterally.
Mechanism of Injury / Pathological Process
The etiology of Moebius syndrome is not known, but it appears to be multifactorial. There has been evidence of a genetic component related to various loci on chromosomes 3, 10, and 13.
The close relationship embryologically between the motor nuclei of the sixth and seventh cranial nerves explains the pathology of this rare condition.
Equal risk between boys and girls. Thought to be increased risk if one of parents has Moebius Syndrome.
Cranial Nerve VII Involvement
Bilateral facial immobility/paralysis is the most noticeable symptom, and is frequently noticed very soon after birth, with the parents reporting incomplete eyelid closure during sleep and difficulty sucking (due to lack of lip seal).
However, ooccasionally the facial paralysis is not noticed for a few weeks or months, until the baby's inability to smile or the lack of facial movement with crying arouses the parents' concern. In extremely rare cases the facial paralysis is unilateral.
As the child grows, speech problems emerge due to inability to seal the lips for thee labial consonants. Speech problems are reported in 76-90% of patients with Möbius syndrome.
Cranial Nerve VI Involvement
Abducens nerve palsies are reported in approximately 75% of patients and are some of the most characteristic features of the syndrome.
Cranial Nerve XII Involvement
The hypoglossal nerve is the third most commonly affected cranial nerve (CN) and is involved in approximately 25% of reported cases. Involvement of the hypoglossal nerves often leads to atrophy of the tongue. Patients may be unable to protrude their tongue beyond their lips because of this weakness. This involvement may result in paralysis and hypoplasia of the tongue, or fasciculations may be seen as a result of hypoglossal denervation. The ocular muscles are always involved when the tongue is affected.
Brachial malformation is common and can involve the following:
Talipes Equinovarus AKA Clubfoot, frequently bilateral, occurs in almost one third of patients
Reports include hand malformations or congenital amputation of hand
In some cases, the affected hand is smaller than the other hand
Syndactyly is not uncommon, and brachydactyly is frequently reported
Other abnormalities in the upper extremities include finger webbing and an absence or hypoplasia of the radius, ulna, metacarpal, or phalanx
A congenital condition called the Poland sequence, characterized by ipsilateral hand malformations and by partial or complete absence of the pectoralis muscles and breast,occurs with Möbius syndrome in approximately 15% of patients.
The patient’s intelligence is usually normal, but mild mental retardation is thought to occur in approximately 10-15% of patients.
No diagnostic laboratory studies yield findings specific to Moebius syndrome.
The diagnosis is usually made using the most commonly accepted definition: the typical phenotypic appearance is an immobile facial appearance with various gaze palsies.
Electromyography can be used to help determine whether a patient’s symptoms stem from birth trama and are therefore NOT associated with Moebius syndrome.
CT scanning or MRI of the brain may demonstrate bilateral calcifications in the regions of the CN VI nuclei, but this is not true for all cases of Moebius syndrome.
Management / Interventions
No definitive treatment is available, with medical care being supportive and symptomatic.
In ealy infancy special bottles or even feeding tube may be required due to lack of lip seal.
Treatment for corneal ulcerations or abrasions may be required. These occur secondary to keratitis and conjunctivitis, which result from incomplete eyelid closure.
Surgery may be considered in order to try and provide the ability to smile; however, the results are limited and movement can be restored along only 1 vector.
Most frequently, the reconstructive surgery involves free-tissue transfers with bilateral gracilis muscles anastomosed to the masseter nerves on both sides in order to achieve a small smile.
Abducens (CN VI) nerve palsy
Congenital facial (CNVII) nerve palsy
Congenital muscular dystrophy
http://www.moebiussyndrome.com/ USA organisation
http://www.moebiusresearchtrust.org/projects-1/ Scottish organisation
http://www.facialpalsy.org.uk/about-facial-palsy/causes-diagnoses/developmental/moebius-syndrome/275 A useful, concise summary of Moebius syndrome on a general UK facial palsy website
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Recent Related Research (from Pubmed)
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- ↑ Mobius PJ. Uber angeboren doppelseitige abducens-facialis-lahmung. Munchen Medizinische Wochenschrift. 1888;35:91-4.
- ↑ Uzumcu A, Karaman B, Toksoy G, Uyguner ZO, Candan S, Eris H. Molecular genetic screening of MBS1 locus on chromosome 13 for microdeletions and exclusion of FGF9, GSH1 and CDX2 as causative genes in patients with Moebius syndrome. Eur J Med Genet. Sep-Oct 2009;52(5):315-20
- ↑ May M, Schaitkin BM. Facial Nerve Disorders in Newborns and Children. In: The Facial Nerve. 2nd ed. New York, NY: Thieme New York; 2000:339-65
- ↑ Kumar D. Moebius syndrome. J Med Genet. Feb 1990;27(2):122-6
- ↑ Briegel W. Neuropsychiatric findings of Mobius sequence -- a review. Clin Genet. Aug 2006;70(2):91-7
- ↑ Kumar D. Moebius syndrome. J Med Genet. Feb 1990;27(2):122-6
- ↑ Sugarman GI, Stark HH. Mobius syndrome with Poland's anomaly. J Med Genet. 1973;10(2):192-6
- ↑ Gillberg C, Steffenburg S. Autistic behaviour in Moebius syndrome. Acta Paediatr Scand. Mar 1989;78(2):314-6.
- ↑ Johansson M, Wentz E, Fernell E, Strömland K, Miller MT, Gillberg C. Autistic spectrum disorders in Möbius sequence: a comprehensive study of 25 individuals. Dev Med Child Neurol. May 2001;43(5):338-45
- ↑ Verzijl HT, van Es N, Berger HJ, Padberg GW, van Spaendonck KP. Cognitive evaluation in adult patients with Möbius syndrome. J Neurol. Feb 2005;252(2):202-7
- ↑ Dooley JM, Stewart WA, Hayden JD, Therrien A. Brainstem calcification in Möbius syndrome. Pediatr Neurol. Jan 2004;30(1):39-41
- ↑ Marre D, Hontanilla B. Brain plasticity in Möbius syndrome after unilateral muscle transfer. Ann Plast Surg. 2011