PROSPECTIVE ASSESSMENT OF RISKS FOR CERVICOMEDULLARY-JUNCTION COMPRESSION IN INFANTS WITH ACHONDROPLASIA

Achondroplasia, the most common heritable skeletal dysplasia, may resu lt in abnormality at the craniocervical junction, which is a potential ly lethal problem in a subset of young infants with this disorder. We evaluated and followed an unbiased and unselected consecutive series o f infants with achondroplasia, to better document the occurrence, freq uency, and clinical presentation of craniocervical abnormalities. Of 5 3 prospectively ascertained infants, 5 were judged to have sufficient craniocervical junction compression to require surgical decompression. Intraoperative observation always showed marked abnormality of the ce rvical spinal cord, and all operated-on children showed marked improve ment of neurological function. The most frequent clinical abnormalitie s within this subset were those expected for high cervical myelopathy. The best predictors of need for suboccipital decompression included l ower-limb hyperreflexia or clonus, on examination; central hypopnea de monstrated by polysomnography; and foramen magnum measures below the m eans for children with achondroplasia. Infants with achondroplasia are at risk for potentially lethal sequelae of craniocervical junction ab normalities; selective intervention can be life and health saving, but individuals at high risk will be identified only if all affected infa nts undergo comprehensive assessment in infancy.