Congenital spondylolysis of cervical vertebrae with spondylolisthesis anf frontal narrowing of the spinal canal. Report of two cases.

Two cases of cervical spondylolisthesis, due to a congenital defect in the pars interarticularis of C6, associated with spina bifida and elongation of the contralateral pars interarticularis, are reported. Tomography showed an abnormal direction of the articular facets of C6 and demonstrated a narrow frontal diameter of the cervical spinal canal at the level of the malformation. Gas myelography showed a slight compression of the cord. Unlike previously reported cases the patients had neurological findings which, in one case at least, were certainly referable to the spinal cord.