107. Systematic Review And Meta-Analysis Of Imaging Characteristics In Chiari I Malformation: Does Anything Really Matter?

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Authors: Travis Atchley, MD; Elizabeth Alford, MD; Brandon Rocque, MD (Birmingham, AL)

Introduction: Previous studies have attempted to evaluate the utility of preoperative MRI parameters to predict outcomes in Chiari I malformation. We reviewed the extant literature and performed a meta-analysis to determine what preoperative imaging features may predict 1) presence of preoperative symptoms or associated findings, 2) need for surgical decompression, or 3) improvement after surgical decompression?

Methods: The systematic review and meta-analysis was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Publications through June 2018 on PubMed, Embase, and Cochrane Library databases were searched using the keywords “Chiari I malformation” AND “decompression” OR “imaging”. 1210 publications were identified. 20 were included for systematic review; nine were included in the meta-analysis. Included publications were grouped by outcome studied

Results: All individual studies in the systematic review were Level III evidence. Tonsil position, clivus gradient, scoliotic curve of >20° were all associated with the presence of preoperative syrinx (p<0.05). Degree of scoliotic curve was associated with length of syrinx. Pre-operative findings of central syrinx morphology, shorter syrinx, and scoliotic curve < 20° were associated with post-operative stability/improvement (p<0.05). Post-operative symptomatic improvement was associated with preoperative pB-C2 line 3mm, absence of scoliosis, and presence of syrinx (p<0.05). By meta-analysis, there was no significant difference in post-operative improvement between patients with and without syrinx (OR=0.89; 95%CI: 0.58–1.37) or between patients with and without basilar invagination (OR=1.31; 95%CI: 0.72–2.36).

Conclusion: Prior studies have attempted to identify objective preoperative imaging parameters to predict post-operative improvement, but no consistently reliable criteria have been determined across multiple studies. This review and meta-analysis highlights the importance of considering each patient’s clinical history and physical exam within the context of associated radiographic abnormalities