Keyhole retrosigmoid approach for microvascular decompression surgery: systematic review and single-arm meta-analysis

Microvascular decompression (MVD) surgery is traditionally performed via a retrosigmoid craniotomy. Recently, neurosurgeons have increasingly adopted smaller approaches; however, the available evidence has not yet been systematically compiled. This is the first systematic review and meta-analysis on the efficacy and safety of ≤ 2-cm-keyhole retrosigmoid MVD. PubMed and Embase databases were searched for studies involving adults with trigeminal neuralgia (TN), hemifacial spasm (HFS), or glossopharyngeal neuralgia (GPN), who underwent first-time retrosigmoid keyhole MVD (diameter ≤ 2 cm). Primary outcomes were symptom relief and complications. Study quality was assessed using the Methodological Index for Non-Randomized Studies (MINORS). Pooled estimates were calculated using a random-effects single-arm meta-analysis. 32 publications met the inclusion criteria. 93.7% had a retrospective design. The mean MINORS score was 9.9 ± 1.4 out of 16. Among 5,883 patients, 37.7% had TN, 61.6% HFS, and 0.7% GPN. The complete symptom resolution rate was 89.8% (95% CI [0.855-0.930]) for TN, 91.1% (95% CI [0.871-0.940]) for HFS and 88.7% (95% CI [0.746-0.954]) for GPN. The overall complication rate was 13.9% (95% CI, 0.107-0.180), with a permanent neurological deficit rate of 4.7% (95% CI, 0.030-0.074), all involving cranial nerves (CN). In patients with TN, the most frequent permanent neurological deficit was a sensory CN V deficit, occurring in 2.6% (95% CI, 0.013-0.050), followed by a CN VIII deficit in 1.9% (95% CI, 0.011-0.035). Among HFS patients, the most frequent permanent deficits were CN VIII in 5.0% (95% CI, 0.026-0.094) and CN VII in 2.1% (95% CI, 0.008-0.050). None of the studies described cases requiring conversion from a keyhole approach to a standard craniotomy. The keyhole retrosigmoid approach for MVD appears to be safe and effective. Comparative studies are needed to evaluate potential advantages of a keyhole approach over a standard craniotomy.