BASICS

DESCRIPTION

• Unilateral or bilateral facial weakness with impairment of ocular abduction

– Other cranial nerves may be involved

– Limb anomalies may be present

EPIDEMIOLOGY

Incidence

0.0002–0.002% of live births (1)

Prevalence

• Estimated 2,000 living cases worldwide (2)

• Estimated 800 living in the US (2)

RISK FACTORS

• Family history of Moebius or possibly other overlapping congenital cranial dysinnervation disorders (CCDD)

• Multiple teratogens have been suggested (1)

– Gestational hyperthermia

– Electric shock

– Chorionic villus sampling

– Abuse of benzodiazepines

– Alcohol

– Cocaine

– Thalidomide

– Misoprostol

Genetics

• Autosomal dominant, autosomal recessive and X-linked recessive have been reported.

• Variable expression and penetrance

– MBS1 (13q12.2–q13) involved in two unrelated families (1)

– MBS2 (3q21–q22) and MBS3 (10q21.3–q22.1) await confirmation (1)

– Multiple chromosomal aberrations known to have Moebius as a feature

GENERAL PREVENTION

• Avoidance of in utero exposure to known teratogens.

• Genetic counseling

PATHOPHYSIOLOGY

• Not completely understood but felt to be secondary to rhombencephalic maldevelopment involving predominantly motor nuclei and axons traversing long tracts (3)

– Complex disruption of development thought to occur between 21–34 days of embryogenesis (4)

ETIOLOGY

• Genetic/inherited

– Exposure to teratogens

COMMONLY ASSOCIATED CONDITIONS

• Crenulations on sides of tongue/hypoplasia (75%): Involvement of cranial nerve XII

• Craniofacial malformations: Epicanthal folds, flat nasal bridge, micrognathia, high arched palate, external ear defects, teeth defects, and hypertelorism (90%)

• Malformations of extremities (85%)

• Feeding problems (86%)

• Duane syndrome (34%)

• Poland syndrome (11%)

– Rare associations: Congenital heart defects, dextrocardia, arthrogryposis multiplex, urinary tract anomalies, anosmia, and hypogonadotropic hypogonadism (3)

DIAGNOSIS

HISTORY

• Family history

• Known exposure to teratogen in utero

• Other known associated anomalies

PHYSICAL EXAM

• Complete ocular examination

– Evaluate ocular motility and alignment (usually orthophoric in primary position)

– Evaluate weakness of orbicularis oculi (involvement of cranial VII)

– Evaluation of ocular surface

– Assessment of visual function

– Evaluate external structures for craniofacial findings

– Complete systemic evaluation for associated anomalies

DIAGNOSTIC TESTS & INTERPRETATION

Lab

Initial lab tests

• None required

• Consider karyotype/microarray if no teratogen is identified. Gene testing not yet available specifically for Moebius, although testing of other genes known to be causative of CCDD may have a role.

Follow-up & special considerations

Consider evaluation for mitochondrial disorder including Kearn Sayres with chronic progressive ophthalmoplegia (acquired), if history of congenital involvement unclear.

Imaging

• No imaging is necessary

– MRI of head may be performed to evaluate cranial nerves and nuclei

DIFFERENTIAL DIAGNOSIS

• Isolated cranial nerve 6 palsy

• Esotropia with pseudo-abduction deficit (especially with congenital/infantile esotropia)

• Other oromandibular limb hypogenesis syndromes: Hypoglossia-hypodactylia syndrome, Hanhart syndrome, glossopalatine ankylosis syndrome

• Chronic progressive external ophthalmoplegia and other mitochondrial disorders

• Thyroid eye disease

• Intranuclear ophthalmoplegia

TREATMENT

MEDICATION

• Ocular lubricants as needed for ocular surface drying

• Artificial tear ointment at bedtime or taping lids close may be helpful in cases of lagophthalmos

ADDITIONAL TREATMENT

General Measures

Amblyopia therapy as needed

Issues for Referral

• These patients have multiple system involvement and often need multidisciplinary approach

– Nutritionists, occupational therapist for feeding issues

– Orthopedist, physical and occupational therapist for limb anomalies

– Speech pathologist for language delay

– ENT for tracheostomy if unable to manage their secretion

– Dentist for teeth anomalies

– Neuropsychologist is often helpful

– Genetic counseling

Additional Therapies

Bandage contact lenses may be useful in the treatment of extreme corneal involvement from exposure.

COMPLEMENTARY & ALTERNATIVE THERAPIES

None proven

SURGERY/OTHER PROCEDURES

• Surgery for esotropia may be performed as needed

– Temporary tarsorrhaphy for extreme exposure may be beneficial

ONGOING CARE

FOLLOW-UP RECOMMENDATIONS

• Frequent follow-up required if ocular surface drying is present.

• As needed for amblyopia monitoring and treatment

Patient Monitoring

• Visual function and school performance

• Overall health and development of child

• Attention to concerns about self image

DIET

Adjust as needed in view of possible swallowing issues.

PATIENT EDUCATION

• Genetic counseling

• Family support network: Moebius Syndrome Foundation (www.moebiussyndrome.com)

PROGNOSIS

• Moebius is a nonprogressive congenital condition

– With good supportive care, normal life expectancy

COMPLICATIONS

• Corneal ulceration and/or perforation

• Amblyopia

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