Minimally Invasive Decompression for Chiari I Malformation: A Systematic Review and Meta-analysis

Introduction: Chiari I malformation is a structural defect in the cerebellum which is defined as herniation of the cerebellar tonsils into the foramen magnum. While the traditional approach for that condition is through open foramen magnum decompression, some surgeons practice a minimally invasive technique. This procedure involves endoscopic surgery through a small incision made at the foramen magnum or the posterior atlas followed by suboccipital craniectomy and C1 laminectomy. Our paper intends to further elucidate the differences in outcomes between the traditional and minimally invasive surgery (MIS) to treat CIM.

Methods: Article selection was from PubMed database on July 24th, 2024. Included studies had symptomatic patient populations requiring surgical intervention via minimally invasive foramen magnum decompression, and whose complications were explicitly reported and described.

Results: 200 patients who had undergone MID were reported by 10 studies. Surgical incision area ranged from 6.25 cm² to 12 cm². Meta-analysis revealed that operative time was highly heterogeneous (I² = 99%). Neurological testing included VAS, KPS, mJOA, and CCOS, measured pre and postoperatively. 8 studies reported improvement (reduction) in syrinx volume of at least 60% and the average rate of patient syringomyelia improvement was 84%. Meta-analysis of complication rates showed a moderate heterogeneity (I² = 61%) with common and random effect models yielding proportions of .16 and .12, respectively. The most and least common complications were dural tear (8) and superficial wound infection (1).

Conclusion : Statistical analysis demonstrated that operation time varied highly per institution and surgeon. All studies reported improvements in neurological testing postoperatively. Syringomyelia improvement rates demonstrated that MIS is effective. Complication rates were found to be favorable and superior to those of open surgery. These results demonstrate that this technique is effective for the treatment of symptomatic Chiari I malformation and at least as efficacious as open surgery.