Study Design: Retrospective case review

Summary of Background Data: The Chiari malformation is a condition characterised by herniation of the posterior fossa contents below the level of the foramen magnum.

Objectives: To present the long term outcome and complication rate following hindbrain decompression for this condition.

Methods: We retrospectively analysed the results of patients who underwent hind brain decompression between 1994 and 2003. There were 70 cases with a mean age of 32 years. Follow up was carried out with clinical examination and repeat MRI scans. The mean follow up was 4.7 years. Thirty-six patients had associated syringomyelia. Patients underwent hind brain decompression through a small posterior fossa craniectomy, opening of the foramen magnum with or without removal of arch of C1.

Results: One patient died and one had a stroke which resolved except for mild facial weakness. Long term follow up revealed that 50% of the patients were asymptomatic following surgery and another 26% had marked improvement in their symptoms. One patient deteriorated post-operatively and the remainder (23%) had unchanged condition. Of the patients presenting with scoliosis 67% had no further progression in their curve.

Conclusion: This is the largest series presented from a single centre with pre- and postoperative MRI fol1ow up. Our results compare favourably with previously published literature.