Experience with revision craniovertebral decompression in adult patients with Chiari malformation type 1, with or without syringomyelia.

Failure of primary craniovertebral decompression for Chiari malformation most often results from the formation dense scar tissue at the operation site, obstructing CSF movement. Revision cranio-vertebral decompression can provide early symptomatic relief in most patients and this benefit is sustained in at least two thirds of cases, in the medium term at least. Patients with concomitant syringomyelia appear to derive most benefit from revision surgery.