BACKGROUND AND OBJECTIVES: While neurosurgical posterior fossa decompression with duraplasty (PFDD) may provide clinical and radiological improvement for Chiari malformation-I (CM-I)-syringomyelia, the comparative efficacy and safety of PFDD without vs with intradural tonsillar manipulation (posterior fossa decompression with tonsil resection) has remained controversial for over 5 decades. METHODS: We conducted a retrospective cohort study of 1231 CM-I-syringomyelia patients treated at our institution from 2003 to 2024, comparing 2 techniques: standard PFDD and foramen magnum and foramen of magendie dredging (FMMD, a modified posterior fossa decompression with tonsil resection procedure). Propensity score matching was used to balance baseline characteristics between the 2 groups. The primary outcomes were syrinx regression >50%, while secondary outcomes encompassed symptom-related parameters, syrinx regression, complication-related parameters, and reoperation rate. RESULTS: A total of 1231 patients with CM-I were included, of whom 310 (25.2%) were in the PFDD group, and 921 (74.8%) were in the FMMD group. Per treatment analysis demonstrated no increase in odds of complications for FMMD (P > .05). PFDD was noninferior to FMMD in clinical improvement and syrinx regression (P = .147, P = .169, respectively). Syrinx regression (>50% reduction) was superior following FMMD (78% vs 60%, P 50% reduction), a lower rate of revision surgery, and no increase in complications compared with PFDD. Nonetheless, PFDD was similar to FMMD regarding clinical improvement and syrinx regression.
Yuan et al. (Mon,) studied this question.