Thalidomide embryopathy

Thalidomide embryopathy (also known as thalidomide syndrome) is a pattern of birth defects caused by in utero exposure to the drug thalidomide during a critical window of embryonic development, typically between days 20 and 36 after fertilization. Thalidomide was widely prescribed as a sedative and anti-nausea medication for pregnant women in the late 1950s and early 1960s before its teratogenic effects were recognized. The condition is not inherited but results from the direct toxic effect of the drug on the developing embryo. The hallmark feature of thalidomide embryopathy is limb reduction defects, most characteristically phocomelia (absence or severe shortening of the long bones of the limbs, with hands or feet attached close to the trunk) and amelia (complete absence of one or more limbs). Upper limbs are more frequently and severely affected than lower limbs, and the involvement is often bilateral but asymmetric. Beyond the limbs, thalidomide embryopathy can affect multiple organ systems. Ear anomalies (including microtia and anotia) with associated hearing loss are common, as are eye abnormalities (such as coloboma, microphthalmos, and abnormal lacrimation). Facial nerve palsy (often bilateral), cardiac defects (particularly septal defects and conotruncal malformations), gastrointestinal anomalies (including duodenal atresia and anal atresia), and renal malformations may also occur. The specific pattern of malformations depends on the precise timing of thalidomide exposure during organogenesis. There is no cure for thalidomide embryopathy, and management is supportive and multidisciplinary. Treatment focuses on surgical correction of congenital anomalies where possible, prosthetic limb fitting, physical and occupational therapy, hearing aids or cochlear implants for hearing loss, and psychosocial support. Many affected individuals have normal intelligence and life expectancy, though the severity of physical disabilities varies widely. Since the recognition of thalidomide's teratogenicity, strict prescribing regulations and pregnancy prevention programs have been implemented worldwide, though new cases have occasionally been reported in countries where thalidomide is used to treat conditions such as leprosy and multiple myeloma.

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