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

Chiari I malformation (CIM) is a structural defect in the cerebellum, which is characterized by herniation of the cerebellar tonsils into the foramen magnum. While open foramen magnum decompression is traditional, some surgeons practice a minimally invasive technique. Our paper intends to further elucidate the differences in outcomes between the traditional and minimally invasive foramen magnum decompression (MID). Article selection was from PubMed. Included studies had symptomatic patient populations requiring surgical intervention via MID, and whose complications were explicitly reported and described. A total of 200 patients were reported by 10 studies. Surgical incision area ranged from 2.5 cm² to 12 cm². Meta-analysis revealed that operative time was highly heterogeneous (I² = 99%). Neurological testing included visual analogue scale (VAS), Karnofsky performance scale (KPS), modified Japanese Orthopaedic Association score (mJOA), and Chicago Chiari outcome scale (CCOS). 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 0.16 and 0.12, respectively. The most and least common complications were dural tear (eight occurrences) and superficial wound infection (one occurrence). Averages of neurological testing scales confirmed improvement in function. Syringomyelia improvement rates demonstrated that MID 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 CIM and that MID is at least as efficacious as open surgery.