Neural arch stenosis and spinal cord injury in thanatophoric dysplasia.

Bony abnormalities caused by thanatophoric dysplasia affect the base of the skull and the vertebrae as well as the ribs and appendicular long bones. We present our findings in a full-term infant with thanatophoric dysplasia in whom the posterior fossa, the rostral vertebral column, and the neuraxis at and adjoining the craniovertebral junction were studied by dissection, roentgenography, and histologic examination. In this infant, malformations of the vertebral laminae, most prominent in the basiocciput and atlas vertebra, led to compression of the rostral cervical spinal cord, causing gliosis and focal necrosis. Stenosis of the foramen magnum and spinal canal may contribute to the ventilatory insufficiency that often causes death in patients with thanatophoric dysplasia. We suggest that the causes of death in patients with thanatophoric dysplasia and other severe forms of osteochondrodysplasia should be sought in neuraxial injury rather than attributed solely to pulmonary hypoplasia.