Plott Syndrome

Congenital X-linked laryngeal abductor paralysis associated with psychomotor retardation.

Familial Vocal Cord Dysfunction; Laryngeal Abductor Paralysis.

First described by D. Plott, an American neurologist, in 1964. A congenital laryngeal abductor anomaly was seen in three brothers.

Very rare condition. Ten patients have been diagnosed up to 2000.

X-linked recessive disorder. Familial genetic disorder; clinical expression in male children only.

Abnormal development of nerve nuclei is thought to be involved in the pathophysiology of this disease; medullar nucleus ambiguus abnormalities can explain laryngeal dysfunction by total dysfunction of the posterior cricoarytenoid that provides a midline adducted position of the vocal cords at rest and a complete adduction when crying. Ninth, tenth, and twelve cranial nerve nuclei can also be involved.

This syndrome belongs to a larger group of congenital laryngeal abductor paralysis but is often associated with mental, growth, speech, and motor retardation.

Inspiratory stridor, laryngomalacia, respiratory distress, and swallowing difficulty can occur as a consequence of laryngeal abnormalities; neonatal death has been suspected. It is also possible to observe hypotonia, blank facies, and, more rarely, blindness, nystagmus, optical nerve atrophia, and hearing deficiency.

Evaluate mental and motor retardation. Evaluate severity of the laryngeal abnormalities through patient history (frequency of dysphonia, stridor, or asphyxia). Evaluate pulmonary consequences by chest radiograph, arterial blood gas analysis, and 24-hour SaO2 record. Evaluate swallowing difficulty by barium swallow.

No difficult tracheal intubations have been reported in this syndrome. Postoperative stridor can be observed and pulmonary inhalation has to be considered for food reintroducing. Postoperative SpO2 monitoring is recommended.

Drugs used to premedicate must avoid respiratory depression. When muscle relaxants are used, monitoring is imperative. Locoregional anesthesia rather than opioids is preferred for postoperative pain relief so as to avoid hypoxemic risk.

Barbieri Syndrome (Laryngeal Abductor Paralysis with Cerebellar Ataxia and Motor Neuropathy Syndrome): Characterized by late-onset and slowly progressive cerebellar ataxia and severe dysphonia because of laryngeal abductor paralysis. Other clinical features include urinary incontinence, dysphagia, diffuse limb fasciculations with mild distal muscular wasting. It is most likely transmitted as an autosomal recessive trait.

Erythromelalgia: Characterized by neonatal stridor, vocal cord paralysis, laryngeal abductor paralysis, mental retardation, infantile swallowing difficulty, and microcephaly. It is also considered a familial vocal cord dysfunction with mental retardation. It is most likely inherited as an autosomal dominant trait with variable expression but may also be X-linked.