Segmental spinal dysgenesis (SSD) is a rare congenital abnormality in which a segment of the spine and spinal cord fails to develop properly. Segmental vertebral anomalies involve the thoracolumbar, lumbar, or lumbosacral spine. We report two cases of SSD associated with other spinal dysraphism. Radiologic investigations revealed segmental dysgenesis of thoracic spinal cord without an associated vertebral bony anomaly in one case and segmental dysgenesis of the cervico-thoracic cord with diastematomyelia in the other case. The neurologic picture depends on the severity of the malformation and on its segmental level along the longitudinal embryonic axis. The pathogenesis of SSD syndrome is not clear but its cause is probably related to a segmental maldevelopment of the neural tube. (J Korean Acad Rehab Med 2007; 31: 127-130)
