Moebius Syndrome

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.

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Congenital Oculofacial Paralysis; Congenital Facial Diplegia, Moebius Sequence.

First described by Henri M. Thomas, an American neurologist, in 1898.

Rare. Affects males and females equally. Most cases of Moebius syndrome occur randomly for no apparent reason (sporadic cases).

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.

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 brainstem 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.

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.

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. High 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. Abnormalities of ventilation (central hypoventilation and idiopathic tachypnea) presumably result from brainstem abnormalities. Craniofacial features include micrognathia, microstomia, mandibular hypoplasia, tongue tethering, premaxillary overgrowth, and cleft lip and palate. Strabismus is common. Congenital cardiac anomalies include ventricular septal defect (VSD) and patent ductus arteriosus (PDA). Skeletal features are talipes equinovarus (in up to 50%), arthrogryposis, and terminal limb defects. Cervical spine anomalies have been described.

Full assessment of the airway is particularly important in these children because of a high incidence of difficult direct laryngoscopy and failed tracheal intubation. The availability of a laryngeal mask airway is highly recommended in case of failure to ventilate or intubate. In this case, the use of a fiberoptic scope could be used through the laryngeal mask to facilitate tracheal intubation. Review of previous anesthetic records is important. Evaluation of respiratory function for acute and chronic pulmonary complications by clinical examination and chest radiographs. Involvement of bulbar muscles increases the risk of aspiration. Assessment and documentation of existing neurologic defects, associated cardiac lesions (echocardiography may be required), or cervical spine abnormalities.

An anesthetic plan must be made considering whether or not tracheal intubation is necessary. Use of an antisialagogue is recommended for induction and recovery secondary to copious secretions. A number of cases with secretions causing airway obstruction and severe hypoxia and bradycardia postoperatively have been reported. Peripheral deformities may result in difficult intravenous access. Induction is most commonly accomplished by inhalational technique in a spontaneously breathing patient. Prepare for difficult or failed tracheal intubation by having additional equipment available. In a series of 41 attempted intubations by experienced anesthetists, 28 (68%) were unsuccessful. Face-mask anesthesia has been used successfully many times without complications and is the anesthetic technique of choice when appropriate. Attempts at intubation have been aided by use of intubating stylets, gum elastic bougies, a variety of laryngoscopes, and fiberoptic devices. Laryngeal mask airways have been used successfully (although correct placement was reported to be difficult in some cases) when intubation failed. Corneal protection with lubrication and tape is required. Careful positioning and padding. Close postoperative observation is mandatory for patients with a history of apneas and central hypoventilation.

Avoid neuromuscular blockers until the airway has been secured. Caution with opioids may be appropriate if there is evidence of central hypoventilation and apneas. Depending on the planned procedure, subacute bacterial endocarditis prophylaxis may be necessary in patients with congenital cardiac lesions.

Poland-Moebius Syndrome: Characterized by the association of the abnormalities observed with the Moebius syndrome and the Poland syndrome. The clinical features of the Poland syndrome are agenesis or hypoplasia of the pectoralis major and pectoralis minor and symbrachydactyly. Additional findings may include underdevelopment or absence of one nipple and patchy axillary hair growth. In females, the presence of unilateral hypoplastic breast development or complete amastia.