Unusual muscle abnormalities associated with thalidomide treatment in a rhesus monkey: a case report

Unusual musculotendinous abnormalities were observed in the forelimbs of a rhesus monkey treated prenatally with thalidomide (10 mg/kg maternal body weight, gestation days 33, 34, and 35). Although the hindlimbs exhibited malformations typical of thalidomide dysmelia, the forelimbs appeared relatively normal externally. However, dissection revealed totally anomalous insertions of preaxial muscles of both forearms. Extensor muscles inserted on flexor surfaces even though normal sites of insertion were present and unoccupied. Radiographs revealed only minor ossification deficiencies in the carpus and distal radius. These observations suggest that thalidomide, given at the appropriate time, can disrupt condensation and splitting of pre-muscle masses without greatly disturbing condensation of corresponding preskeletal elements. These types of musculoskeletal relationships are unusual findings in congenital malformations of the limbs and have not been widely associated with thalidomide teratogenesis.