Pendred Syndrome

At a glance

A developmental abnormality of the cochlea resulting in bilateral sensorineural hearing loss and diffuse thyroid enlargement. The hypothyroidism may be severe enough to cause mental and physical impairment.

Synonyms

Goiter-Deafness Syndrome; Goiter Sensorineural Deafness Syndrome.

History

First described by English surgeon Vaughn Pendred, in 1896, in two deaf sisters with goiter.

Incidence

7:100,000 live births; M = F. Risk factors are familial.

Genetic inheritance

Autosomal recessive with variable expression.

Pathophysiology

Caused by biallelic mutation of the SLC26A4 gene on chromosome 7q22.3. Gene mutation affects sulfate transport resulting in defective sulfated proteins in the thyroid, including thyroglobulin. The affected gene codes for an ion transporter protein named pendrin, most abundantly expressed in the thyroid, inner ear, and kidney.

Diagnosis

Clinical features; biochemical (normal or low T4 levels, high thyroid-stimulating hormone [TSH] levels, perchlorate discharge test positive, indicating defective organic binding of iodine in the thyroid gland, exaggerated response to thyrotropin-releasing hormone [TRH]).

Clinical aspects

Sensorineural hearing loss caused by cochlear malformation, is present at birth or detected in early infancy, and accounts for 10% of all childhood deafness. May have impaired vestibular dysfunction because of widened vestibular aqueduct. Goiter usually appears in middle or late childhood but can present in the newborn, causing airway obstruction and respiratory distress. The goiter is usually euthyroid but occasionally hypothyroidism may be severe. There is a very small risk of malignant neoplasm. Mental retardation has also been reported. Normal life span can be expected.

Precautions before anesthesia

Thyroid function should be evaluated (TSH, T₄ = high TSH and low T4 would confirm the presence of hypothyroidism). A perchlorate test should be performed to determine the extent of the thyroid dysfunction. However, it is not consistently positive in affected individuals. A medical consultation with the endocrine service is essential before any elective and emergency (if possible) surgical procedures.

Anesthetic considerations

The presence of hypothyroidism should be an indication to postpone elective surgery until corrected. Deafness and vestibular dysfunction contribute to a patient’s anxiety. Preoperative evaluation of thyroid function and correction of hypothyroidism is necessary. Airway assessment is mandatory in the presence of large or long-standing goiter. Airway obstruction and respiratory distress in neonatal goiter may require emergency airway access. Possibility of postoperative tracheomalacia after excision of long-standing goiter.

Pharmacological implications

Delayed metabolism of anesthetic drugs and opioids in case of hypothyroidism.

References