Structural scoliosis model in dogs with experimentally induced syringomyelia.

STUDY DESIGN

Animal scoliosis model associated with syringomyelia.

OBJECTIVE

To investigate the pathogenesis of scoliosis produced in dogs with kaolin-induced syringomyelia.

SUMMARY OF BACKGROUND DATA

Kaolin injected into the cisterna magna produces basilar arachnoiditis, leading to hydrocephalus and syringomyelia. There have been no reports on scoliosis associated with kaolin-induced syringomyelia.

METHODS

Kaolin was injected percutaneously into the cisterna magna of 11 beagles 6-8 weeks after birth. Roentgenograms, computed tomography, and magnetic resonance imaging were obtained. The spinal cord and the paraspinal muscles were examined histologically. Structural changes of the vertebral column were analyzed with calcein and tetracycline labeling.

RESULTS

Hydrocephalus occurred in nine dogs. A communicating syringomyelia appeared in five dogs. Mild scoliosis developed in two dogs, and severe cervical scoliosis in one dog. In the syringomyelia cases, acute or subacute inflammatory changes were found in the spinal cord. Damage of the anterior and posterior horn cells was more marked in the scoliotic animals than in the nonscoliotic animals. In three of the syringomyelia cases, including two scoliosis cases, the paraspinal muscles revealed neurogenic changes. The deformed vertebrae appeared to diminish rather than to increase the deformity in severe scoliosis.

CONCLUSION

The exact mechanism of the development of scoliosis could not be identified, although an etiologic relation with malfunction of the central nervous system was noted. This model may be useful to study scoliosis experimentally.