Craniovertebral anomalies: a study of 82 cases.

Eighty-two cases of craniovertebral anomalies have been analysed. Fifty of these were operated upon. Congenital atlanto-axial dislocation was the commonest anomaly encountered (56.1%). Multiple anomalies were frequently seen (48.8%). Common combinations were atlanto-axial dislocation with occipitalisation of atlas, basilar invagination with Arnold-Chiari malformation and basilar invagination with occipitalisation of atlas. There was a high incidence (50%) of neck deformity and/or a low hairline which provided a good clue to the diagnosis. Precipitating factors, paroxysmal symptoms and an acute onset were common in cases of atlanto-axial dislocation. Cranial nerve and cerebellar dysfunction were common in cases with multiple anomalies. Thirty-six (72%) patients improved following surgery, and three died.