Prospective study of outcome of foramen magnum decompressions in patients with syrinx and non-syrinx associated Chiari malformations.

OBJECTIVE: To assess the outcome in patients with syrinx and non-syrinx associated Chiari malformations undergoing Foramen Magnum Decompression (FMD).
METHODS: Sixty-one patients undergoing FMD for Chiari malformations were prospectively studied with disease specific, generic (SF 36) and subjective (patient reported) outcomes. Of these, 34 patients had objective outcome data including SF36, visual analogue pain scores, Neck and Myelopathy disability indices and the Hospital anxiety and depression score. SF 36 scores were compared to normative data. Data were collected pre-operatively, at 3 months and during long-term follow up (12-60 months).
RESULTS: Patient reported improvements in headache and neck pain post-operatively was reported in both syrinx and non-syrinx associated patients. Visual Analogue scores showed improvements in arm pain, paresthesia and hand tingling at 3 months in the syrinx group only. Non-syrinx patients showed significant improvements post-operatively in the Neck disability index and the SF-36 domains for physical function, role physical and bodily pain. Comparison with SF-36 normative data indicates that patients still have significantly impaired quality of life 12 months post-operatively.
CONCLUSION: FMD is able to relieve symptoms and improve quality of life in patients with both syrinx and non-syrinx associated Chiari malformations. In syrinx patients we observed symptomatic improvement in limb symptoms as well as radiological resolution of the syrinx. The use of SF-36 allows the health gain associated with FMD to be quantified. SF 36 is not adequate as a stand alone measure of outcome in this complex disorder and we advocate the concurrent use of disease specific measures and post-operative imaging of the syrinx.