Assessment and neurologic involvement of patients with cervical spine congenital synostosis as in Klippel-Feil syndrome: study of 19 cases.

We reviewed 19 children and adolescents with cervical spine congenital synostosis as in Klippel-Feil syndrome (KFS), with an average follow-up of 12.5 years. We paid particular attention to neurologic complications associated with cervical spine abnormalities. Five patients were affected by neurologic complications; four underwent a surgical procedure; and 14 had no neurologic finding. Two had hypermobility at one level, and one had hypermobility at two levels. We found that the more numerous the occipito-C1 abnormalities, the more significant the neurologic risk. In contrast, this risk was not related to the number of "mobile blocks" or to age. Various mechanisms of neural complications have been studied in the literature: medullary abnormality, spinal instability, narrowing of the cervical canal, and vascular dysfunction. Surgery is usually thought to be required in cases with neurologic complications. The indication for surgery is, however, less clear in cases of pure instability without neurologic involvement because surgery is likely to increase the future risks at mobile disks either above or below the fuse level. Careful clinical and radiologic observation is necessary in such patients. Magnetic resonance imaging (MRI) with lateral views in flexion and extension seem to be the best method for detecting impingement of the spine on the cord.