Rare genetic disorder present at birth. Characterized
by distinctive facial appearance, broad or webbed neck, low hairline in the
back of the head, and short stature. Micrognathia, kyphosis and/or
scoliosis, and cardiac defects (pulmonary valvular stenosis) are present.
Other features include coagulation disorders, platelet deficiencies, mild
mental retardation, and cryptorchidism in the first year of life.
Rare genetic disorder. Noonan syndrome is phenotypically
similar to Turner syndrome; however, the karyotype in Noonan syndrome is
Autosomal dominant with variable phenotypic
expression. Genes have been identified on loci 12q22-qter and 12q24.
Sporadic cases arise as a result of sporadic mutations.
Unknown. An abnormality of tissue migration in
utero is suggested, and the presence of cystic hygromas and lymphedema is
cited as evidence supporting this hypothesis.
Clinical features of Turner syndrome associated with
pulmonary valve dysplasia and a normal karyotype.
Neonate: Marked edema with excess nuchal skin; Infancy:
Hypotonia, poor feeding.
Features of the Noonan phenotype are webbed neck with low posterior
hairline, pterygium colli, flattened midface, cystic hygroma, pectus
carinatum or excavatum, short stature (50%), high-arched palate, ptosis,
hypertelorism, down-slanting palpebral fissures, dental malocclusion,
micrognathia, strabismus, cryptorchidism, mental retardation (25%),
kyphoscoliosis, and several skeletal abnormalities (spina bifida occulta,
hemivertebra, narrow spinal canal, cubitus valgus). Approximately 50% of
patients have a cardiac problem. The most common cardiac anomalies are
pulmonary stenosis, hypertrophic cardiomyopathy, atrial septal defect,
tetralogy of Fallot, atrioventricular canal anomaly, and coarctation of the
aorta. Stature is short. Lymphedema may occur. Coagulopathy is frequent and
most commonly caused by factor XI deficiency, although thrombocytopenia and
deficiencies of factors XII and VIII are well described.
Careful history to evaluate cardiac
and respiratory function. Careful airway assessment for potentially
difficult laryngoscopy and tracheal intubation. Electroencephalogram, and echocardiography to assess cardiac
function/anatomy must be obtained. Cervical spine radiography to exclude atlantoaxial
instability and any other anomaly is highly recommended. Lumbosacral spine radiograph if a
neuraxial block is foreseen must be done to exclude vertebral anomalies. Consider chest
radiograph and pulmonary function tests in presence of severe
kyphoscoliosis. Laboratory investigation for coagulopathy is mandatory if
regional techniques are under consideration. Continue perioperative
medications, especially if taking beta-blocker for hypertrophic obstructive
Short or webbed neck, micrognathia, and
dental malocclusion may make direct laryngoscopy and tracheal intubation
difficult. Anesthetic management according to cardiac malformation. Regional
techniques have been used but require careful assessment of cardiac
function, coagulation, and vertebral anatomy.
Isoflurane may cause undesirable
tachycardia. Esmolol may be useful in the presence of hypertrophic
Watson Syndrome: Rare disease combining pulmonary valvular
stenosis with café-au-lait spots, dull intelligence, and short stature.
Other features include macrocephaly and iris Lisch nodules in most cases, a
condition that overlaps those of neurofibromatosis and the Noonan syndrome.