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At a glance

Nanism caused by functional growth hormone deficiency.

Synonyms:

Pituitary Dwarfism Type IV Syndrome; Biodefective Growth Hormone Syndrome; Pituitary Dwarfism with Normal Immunoreactive Growth Hormone Low Somatomedin Syndrome.

History

Allen Avinoam Kowarski et al described the first two cases of the Kowarski Syndrome in 1978.

Incidence

The exact incidence remains unknown. Less than 10 cases have been reported in the literature.

Genetic inheritance

Autosomal recessive inheritance trait is suspected. A presumed mutation in the growth hormone gene on chromosome 17 has been suggested.

Pathophysiology

A structural abnormality of growth hormone causes low levels of somatomedin, which results in delayed bone age and growth retardation. Administration of exogenous growth hormone results in normal somatomedin levels and a significant increase in growth rate.

Diagnosis

Phenotypical findings and laboratory investigation of the growth hormone. Low levels of somatomedin confirm the diagnosis.

Clinical aspects

Typical clinical findings in patients with achondroplastic dwarfism may be absent in patients with Kowarski Syndrome who have been treated with exogenous growth hormone. Neurological findings in achondroplastic dwarfs include foramen magnum stenosis and odontoid hypoplasia causing spinal cord compression, central sleep apnea, and obstructive hydrocephalus. Facial features are short maxilla, large tongue, and flat nose, which may predispose to obstructive sleep apnea. Pulmonary hypertension and cor pulmonale secondary to kyphoscoliosis and sleep apnea have been reported.

Precautions before anesthesia

Although none of the typical findings of achondroplasia are described in the referenced cases, any patient with abnormal growth should be carefully evaluated for potential difficult airway management, unstable cervical spine and/or spinal cord compression, and potential adverse effects of delayed growth on the respiratory and cardiovascular systems.

Anesthetic considerations

No specific considerations for isolated short stature are required, especially if treated. If untreated, considerations may include difficult laryngoscopy and avoidance of excessive airway manipulation, which may further compress the spinal cord. If the patient is at risk for apnea, judicious use of sedating medications and close postoperative monitoring may be necessary. Respiratory and cardiovascular compromise may increase complication rates and necessitate admission to an intensive care unit postoperatively. Thick, lax skin can make vascular access challenging.

Other condition to be considered

Other types of dwarfism, especially the following:

  • Laron Syndrome: Features of this autosomal-recessive transmitted disorder include severe dwarfism with sparse hair caused by primary (not acquired) abnormally high concentrations of immunoreactive serum growth hormone and insensitivity to exogenous growth hormone. Other features include craniofacial abnormalities, relative obesity (mostly reflected by excess of adipose tissue in the context of thin bones and diminished muscle mass), ...

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