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At a glance

It is a rare developmental disorder characterized by facial paralysis (mask-like face) present at birth. Facial nerve development is absent, and the sixth (abducens) and seventh (facialis) cranial nerves are most often affected. Other features include numerous abnormalities of the orofacial region and malformations of limbs. Mental retardation occurs in approximately 10% of cases.

Synonyms

Congenital Oculofacial Paralysis; Congenital Facial Diplegia, Moebius Sequence.

History

The first full description of this disorder was provided by Henri M. Thomas, an American neurologist, in 1898. However, the association of congenital facial and abducens palsy was first described in 1868 by Friedrich Wilhelm Ernst Albrecht Von Graefe (1828-1870), a Prussian pioneer of German Ophthalmology, and later by Paul Julius Moebius (1853-1907) in 1888. Moebius was a German neurologist after whom the syndrome was later named.

Incidence

The exact incidence remains unknown. It affects males and females equally. Most cases of Moebius Syndrome occur randomly for no apparent reason (sporadic cases).

Genetic inheritance

Usually sporadic. Cases of autosomal dominant inheritance described (1898). Gene map locus is 13q12.2-q13. Recurrence risk is low at less than 1 in 50. Clinically they can often be differentiated by lack of limb involvement. A Moebius Syndrome type II has been described in a large Dutch family with strong autosomal dominant transmission. Gene map locus is 3q21-q22. It is associated with multiple vascular abnormalities and poor prognosis.

Pathophysiology

Etiology is unknown. Four possible pathologic causes have been suggested: (a) hypoplasia to absence of central brain nuclei; (b) destructive degeneration of the central brain nuclei (this is the most common form; it is likely caused by a transient brain stem hypoxic event occurring at a critical time in utero and affecting the structures supplied by the developing subclavian artery); (c) peripheral nerve involvement; and (d) a myopathy. Moebius Syndrome is thus considered as a nonspecific sign.

Diagnosis

Based on clinical findings. Usually manifests soon after birth with sixth and seventh nerve palsies, which are either partial or complete and may be bilateral. Patients present with mask-like facies, incomplete closure of the eyelids during sleep, drooling of saliva, and difficulty sucking. Aspiration is common. On examination, multiple other abnormalities are usually detected. Important to differentiate from neuromuscular disorders occurring in early childhood.

Clinical aspects

Multiple cranial nerves may be involved (nerves V, VI, VII, IX, X, and XII can all be affected) and lead to orofacial malformations, abnormalities of tongue coordination, swallowing (bulbar muscle weakness), and drooling. Speech abnormalities are common. There is an increased risk for corneal abrasions. Usually the affected individuals are mentally normal. However, there is a 10% incidence of mild mental retardation. Occasionally, peripheral neuropathy and pectoral muscle deficiency are ...

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