Congenital neural abnormalities presenting with mirror movements in a patient with Klippel-Feil syndrome. Case report.

A young girl with Klippel-Feil syndrome presented with the onset of mirror movements in early childhood. Computerized tomography studies of her cervical spine and brain revealed fibrous diastematomyelia with duplication of the cervical spinal cord and an extra-axial midline posterior fossa cyst, together with the multiple cervical vertebral anomalies. Exploration of the posterior fossa lesion revealed it to be a dermoid cyst. The congenital spinal and cord abnormalities found in this case support the hypothesis that the Klippel-Feil syndrome may be associated with variable duplication of the spinal cord and that mirror movements may be related to impairment of pyramidal tract decussation.