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

Background Craniovertebral decompression is performed for symptomatic Chiari malformation type 1, with or without syringomyelia. In a few patients the symptoms and/or syrinx persist or recur, in which case revision surgery may be offered. The aim of this study was to examine the cause of failure of primary surgery and to assess the outcomes for revision cranio-vertebral decompression. Methods We retrospectively reviewed all revision cranio-vertebral decompressions performed in our centre over an eighteen-year period. A total of 35 patients were identified (23 females; 12 males). Twenty patients had isolated Chiari malformation type 1 and a further fifteen had associated syringomyelia. The mean follow up period was 4-years (range:1-12 years). Results The mean time to revision was 7 years after the primary surgery. The commonest operative finding was that of dense arachnoid scar tissue, obstructing movement of CSF across the craniovertebral junction. Overall, 32 of the 35 patients reported improvement after surgery, including all 15 patients with syringomyelia. Improvement was maintained in the longer term in more than two thirds of those patients who underwent revision craniovertebral decompression. Conclusions 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.