Sotos Syndrome

At a glance

Characterized by excessively rapid growth during the first year of life, acromegalic craniocerebral features (macrocephaly, prominent forehead) and a nonprogressive cerebral disorder with mental retardation. Other clinical features include high-arched palate and prognathism with premature eruption of teeth, hypotonia, hyper- or hypothyroidism, and delayed motor and cognitive development.

Synonym

Cerebral Gigantism Syndrome.

History

First described by Juan Fernandez Sotos, American pediatrician in 1964.

Incidence

Rare. Estimated 1/10,000 to 1/50,000 with about 500 cases reported. Affects males and females equally.

Genetic inheritance

Sporadic or autosomal dominant.

Pathophysiology

Caused by a mutation in the NSD1 gene on 5q35. This gene encodes a histone methyltransferase involved in chromatin regulation. Possibly prenatal abnormality or yet unidentified growth-stimulating factor. Gene deletions may have greater intellectual disability.

Diagnosis

Clinical based on facial gestalt, growth pattern, bone age, and developmental delay. Typical abnormalities of the brain on the MRI scan, including absence of the corpus callosum. The most common abnormalities of the cerebral ventricle are prominence of the trigone (90%), occipital horns (75%), and ventriculomegaly (60%).

Clinical aspects

Prenatal onset of excessive growth. Birth weight and length usually greater than 90th percentile. Large hands and feet at birth. Neonatal problems with feeding and respiration. Rapid early growth, arm span greater than height, and advanced osseous maturation. Normal levels of growth hormone. Scoliosis. Macrocephaly, prominent forehead, strabismus, hypertelorism, high-arched palate, alveolar ridge exostoses, early teeth, and prominent jaw. Variable developmental and mental retardation, neonatal hypotonia, and seizures. Significant behavioral problems. Abnormal glucose tolerance test; hyper- and hypothyroidism. Normal growth hormone. Congenital cardiac defects; increased risk for tumors. Long-term survival possible.

Precautions before anesthesia

Assessment of severity of syndrome with particular consideration of airway and endocrine abnormalities—all children should have endocrine assessment and exclusion of glucose intolerance and thyroid dysfunction. Assessment of associated abnormalities such as cardiac or scoliosis, including investigations and appropriate referrals. Assess for obstructive sleep apnea.

Anesthetic considerations

A major problem with these children is the high rate of behavioral disorder with hyperactive and aggressive behavior. Premedication is recommended and is well tolerated orally. Parental presence has been required despite premedication to control some of these children for induction. Although there are no reports of difficult tracheal intubation, it should be anticipated because of the presence of significant macroglossia. Spontaneous respiration should be maintained until confirmation that assisted ventilation is possible or tracheal intubation is achieved. Endocrine (thyroid function) and cardiac considerations if appropriate. Patient may require intraoperative glucose monitoring. Regional anesthesia feasible.

Pharmacological implications

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