Muscular Pseudohypertrophy-Hypothyroidism Syndrome

Muscular pseudohypertropy - hypothyroidism, also known as Kocher-Debre-Semelaigne syndrome is a rare disorder characterized by pseudohypertrophy of muscles due to longstanding hypothyroidism (see this term).

Epidemiology

Prevalence is unknown.

Clinical description

The syndrome usually presents between 18 months and 10 years but has been reported at earlier ages including during the neonatal period. Patients present with clinical features of hypothyroidism, including decreased activity and increased sleep, feeding difficulty and constipation, prolonged jaundice, myxedematous facies, large fontanels (especially posterior), macroglossia, a distended abdomen with umbilical hernia, and hypotonia, along with muscle pseudohypertrophy. Pseudohypertrophy involves the muscles of the extremities, limb girdle, trunk, hands and feet but is more prominent in the limbs, resulting in an athletic appearance.

Etiology

The etiology of the muscle pseudohypertrophy is not known but it is thought to be a result of long standing hypothyroidism. Hypothyroidism, or thyroid hormone deficiency, may be congenital and may be permanent or transient (see these terms).

Diagnostic methods

Diagnosis is based on the presence of clinical features and myopathic changes. In countries with newborn screening programs (with either a primary thyroxine (T4)-follow-up thyroid-stimulating hormone (TSH) or primary TSH test), infants with congenital hypothyroidism are diagnosed after detection by screening tests.

Management and treatment

Treatment is based on thyroid supplements. With treatment, reversal of the pseudohypertrophy and clinical symptoms is possible.