Watson Syndrome

At a glance

A rare disease combining moderate to severe pulmonary valvular stenosis with “café-au-lait” spots, macrocephaly, decreased intelligence, neurofibromas, and short stature. Other features include macrocephaly and Lisch nodules. Neurofibromas are usually present in 30% of affected individuals. In most cases, it is a condition that overlaps those of neurofibromatosis and Noonan Syndrome.

Synonyms

Neurofibromatosis-Noonan Syndrome; Neurofibromatosis with Noonan Phenotype; Pulmonic Stenosis Café-au-Lait Spots Syndrome; Café-au-Lait Spots Pulmonic Stenosis Syndrome.

History

This medical condition was first described and reported in the literature by G. H. Watson in 1967.

Incidence

The incidence remains unknown. Twenty years ago, Watson studied three families with this medical condition.

Genetic inheritance

It is an autosomal dominant inherited disorder (possibly allelic with Neurofibromatosis Type 1 [NF1]).

Pathophysiology

Possibly caused by a mutation in the NF1 gene located on 17q11.2.

Diagnosis

Characterized by pulmonary valvular stenosis, café-au-lait spots, low-normal intelligence, and short stature.

Clinical aspects

Patients have short stature. Clinical features involve head and neck (macrocephaly, short neck, hypertelorism, broad forehead, down-slanted fissures, ptosis, puffy eyelids, triangular face, deeply grooved or flat philtrum, excess nuchal skin, large ears, epicanthic folds), musculoskeletal system (limited knee and ankle movement, pectus excavatum, scoliosis kyphosis), central nervous system (CNS) (hypotonia, seizures, mental retardation), and heart (ectasia of coronary arteries, pulmonary valve). Other features can include retroperitoneal or visceral neurofibromata, ectopic testes, hypospadias, and inguinal hernia.

Precautions before anesthesia

Evaluate cardiac function, especially for the severity of the pulmonic valve stenosis (clinical, ECG, echocardiography), neurological function (clinical, CT, EEG), and for potential difficulty during direct laryngoscopy and tracheal intubation because of the possible existence of neurofibromata in the airway (clinical, radiographs, fiberoptic if necessary) must be obtained.

Anesthetic considerations

The anesthetic management will be dictated by the severity of the pulmonic valve stenosis. The presence of macrocephaly, neurofibromas, and short stature may lead to difficult airway management. It is recommended to prepare for unexpected difficult tracheal intubation, especially when neurofibromas are present. The neurological involvement and intellectual condition may cause management issues at the time of induction and postoperatively. Care in positioning patient in view of limited knee and ankle movement. The use of regional anesthesia will be limited by the existence of neurofibromata.

Pharmacological implications

Muscle relaxants should be used only after airway is secured and lung ventilation is confirmed. Controversies exist about muscle relaxant (both nondepolarizing and depolarizing) action duration in patients affected with neurofibromatosis. Monitoring of the neuromuscular function is necessary. Consider interaction between anesthetic drugs and antiepileptic treatment.