Radiological outcome after surgical treatment of syringomyelia-Chiari I complex in adults: a systematic review and meta-analysis

Foramen magnum decompression (FMD) is widely accepted as the standard treatment for syringomyelia associated with Chiari type I malformation (CMI). Despite extensive clinical investigations, relevant surgical details are still matter of debate. The authors performed a systematic review and meta-analysis of the literature examining the radiological outcome of syringomyelia in adult patients with CMI after different surgical strategies. PRISMA guidelines were followed. A systematic search of three databases was performed for studies published between 1990 and 2018. Our systematic review included 13 studies with a total of 276 patients with CMI associated with syringomyelia. Overall, the rate of post-operative radiological improvement at last follow-up was 81.1% (95% CI 73.3-88.9%; p < 0.001; I² = 71.4%). The rate of post-operative syrinx shrinkage did not differ significantly among both groups of decompression with the extra-arachnoidal technique and arachnoid dissection (90%, 95% CI 85.1-94.8%, I² = 0% vs 79.8%, 95% CI 61.7-98%, I² = 85.5%). A lower rate of post-operative radiological syrinx shrinkage was observed after decompression with splitting of the outer layer of the dura (55.6% 95% CI 40.5-70.8%, I² = 0%). CSF-related complications and infections were similar among the different groups. Our meta-analysis found that FMD with the extra-arachnoidal technique and arachnoid dissection provides similar results in terms of post-operative shrinkage of syringomyelia. Patients undergoing decompression with splitting of the dura presented the lower rate of syrinx reduction. These data should be considered when choosing the surgical approach in adult patients with CMI associated with syringomyelia.