Brown-Vialetto-Van Laere Syndrome

Genetic disorder characterized by bilateral sensorineural deafness and variable but progressive cranial and spinal motor nerve involvement.

Pontobulbar Palsy with Deafness; Progressive Bulbar Palsy with Perceptive Deafness; Progressive Bulbar Palsy with Sensorineural Deafness.

Unknown, but more than 30 cases have been reported in the literature with an unconfirmed number of affected siblings and relatives.

Originally thought to be autosomal recessive transmitted, but later suggested to be genetically heterogeneous with autosomal recessive and dominant transmission or the result of a mutant gene carried on the X-chromosome. Both familial and sporadic cases have been reported.

Muscle biopsy sections demonstrate atrophic fibers scattered equally between type I and II fibers. Histologically, silver staining shows loss of axons in intravascular nerve bundles. Sural nerve biopsy shows a depletion of nerve fibers and fibrosis in the perineurium. Electron microscopy reveals nonspecific changes characteristic of denervated muscle fibers. Cranial nerves and nuclei show a marked loss of both myelin and axons with gliosis. Electrophysiologic testing of affected muscle groups shows widespread and symmetrical denervation at the level of the lower motor neuron suggesting a pathologic process affecting the motor neuron or proximal part of the motor nerve roots. An upper motor neuron component was also detected in certain muscle groups.

Characteristic clinical findings, clinical course, electrophysiologic testing, muscle and nerve biopsy, and histopathologic analysis.

The onset is usually in childhood, and the course tends to be irregularly progressive. The presenting symptom is usually a perceptive hearing loss caused by bilateral sensorineural deafness of slow or rapid onset. This is followed by signs of lower cranial nerve motor palsies. Intercurrent illness or physiologic stress, including surgery or pregnancy, may precipitate or exacerbate the condition. The severity of the condition varies from mild to severe, resulting in death. Neurologic involvement includes bulbar palsy, loss of cranial and spinal motor nerve function, wasting and fasciculation of the tongue, widespread muscle wasting with weakness and hypotonia most obviously in neck and lower limb girdle. Coordination and sensation remain intact. Respiratory complications include nocturnal hypoventilation because of marked diaphragmatic weakness (forced vital capacity [FVC] is severely reduced) and obstructive sleep apnea. Bulbar nerve involvement causes laryngeal and pharyngeal dyscoordination, nasal speech, and dysphagia with failure to protect the laryngeal inlet resulting in aspiration episodes. Scoliosis and cervical subluxation have been reported.

Full neurologic assessment (degree of bulbar involvement), chest radiography, respiratory function tests (in advanced cases, the FVC is often reduced to <1 liter), arterial blood gas analysis (hypercapnia). Consider postoperative need for mechanical ventilation. Cervical spine radiograph may be indicated if any signs or a suspicion for cervical subluxation exists.

Bulbar nerve palsy may predispose to aspiration in the perioperative period. There is a high risk of diminished respiratory reserve and respiratory complications such as aspiration, pneumonia, nocturnal hypoventilation, and hypercarbia. Bilateral deafness may make communication during the perioperative period difficult. Regional anesthesia may be appropriate (maintained consciousness, limited respiratory depression, reduced risk of aspiration). A rapid sequence induction technique is recommended, however keep in mind that cervical subluxation requires special attention during airway management and positioning. In-line stabilization and/or fiberoptic tracheal intubation limits cervical movements. Consider placement of a nasogastric tube, gastrostomy tube, or a longterm intravenous line for parenteral nutrition.

Be careful with sedative premedication and opioid analgesic agents. There is a high risk of respiratory depression and loss of protective reflexes. Titration of nondepolarizing muscle relaxants to clinical effect using a peripheral nerve stimulator is recommended. Ensure the nerve stimulator is used in a nonaffected nerve-muscle unit. Although no specific reports of anesthetic management of these cases have been published, avoidance of suxamethonium probably is wise. Consider acid aspiration prophylaxis in the presence of significant bulbar palsy.

Progressive Bulbar Palsy of Childhood (Fazio-Londe disease): an inherited condition characterized by progressive paralysis of muscles innervated by cranial nerves. Significant atrophy of muscles innervated by cranial nerves and the corticobubar tracts occurs.