Chiari malformation and atlantoaxial instability: problems of co-existence.

Abstract

Association of Chiari malformation and atlantoaxial subluxation varies. There is a complex relationship between the two, bony and soft tissue pathologies. This is a review of various articles available from the literature on the management of Chiari and its association with atlantoaxial instability. We have an experience of operating on 86 cases of paediatric atlantoaxial subluxation, of which 12 had Chiari malformation diagnosed preoperatively (13.95%). Of the 76 children with Chiari malformations operated on by us, 11 had associated atlantoaxial subluxation diagnosed on imaging (14.47%). Re-alignment and reduction with fixation may be effective in achieving decompression in cases where reduction is possible from posterior approach. In these cases, posterior fixation is all that is required. If reduction is not possible from posterior and there is "fixed" ventral compression, anterior decompression needs to be combined with posterior fixation. In most cases, direct posterior decompression is warranted.