Basilar impression and Arnold-Chiari malformation. Surgical findings in 209 cases.

The surgical findings observed in a series of 209 consecutive patients with craniovertebral anomaly are presented. The high prevalence of basilar impression in the Northeast of Brazil is noteworthy. There were 28 (13.3%) patients with basilar impression alone, 10 (4.7%) cases of pure Arnold-Chiari malformation and in 171 (81.8%) cases the basilar impression was associated with Arnold-Chiari malformation. This study reflects our surgical experience of the pathology in a 17-year period (1971-1987). It reflects also the peculiarities of neurosurgical practice in an undeveloped region of this Country. The literature is extensively reviewed.