Predictive value of intraoperative bulbocavernosus reflex monitoring for postoperative voiding dysfunction after lumbosacral spine surgery: a systematic review and meta-analysis

PURPOSE: Postoperative voiding dysfunction (POVD) is a significant complication of spinal dysraphism and lumbosacral spinal tumor resection. Conventional intraoperative neurophysiological monitoring modalities primarily assess the descending motor pathway and may not fully evaluate the integrity of the sacral reflex pathway. Intraoperative bulbocavernosus reflex (BCR) monitoring provides a real-time assessment of the sacral reflex arc's afferent and efferent pathways and may predict postoperative urinary function. However, its diagnostic performance and clinical utility remain incompletely defined. Therefore, this study aimed to evaluate the predictive value and diagnostic accuracy of intraoperative BCR monitoring for POVD in patients undergoing lumbosacral spine surgery. METHODS: PubMed, Medline, Scopus, and Web of Science were searched comprehensively through March 2026. Random-effects models were used to pool BCR feasibility, diagnostic performance (sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV)), and the association between end-of-surgery BCR status and POVD. Leave-one-out sensitivity analyses and meta-regression were conducted to explore potential sources of heterogeneity. RESULTS: Intraoperative BCR monitoring was feasible with a success rate of 94%. BCR demonstrated moderate sensitivity of 62% (95% CI: 0.38-0.81) and high specificity of 99% (95% CI: 0.95-1.00) for predicting POVD. The pooled PPV, NPV, and accuracy were 93% (95% CI: 0.63-0.99), 94% (CI: 0.88-0.97), and 93% (CI: 0.87-0.96), respectively. End-of-surgery BCR maintenance was significantly associated with lower likelihood of POVD (OR: 0.02; 95% CI: 0.00-0.32; P = 0.0019). Conversely, BCR disappearance showed an imprecise trend towards higher likelihood of POVD (OR: 6.91; 95% CI: 0.87- 54.85; P = 0.0642). CONCLUSION: Intraoperative BCR monitoring is feasible and may provide clinically useful predictive information for POVD after lumbosacral spine surgery. Its high specificity and NPV support its use as a part of a multimodal neuromonitoring protocol for assessing sacral pathway integrity. Further prospective studies are needed to validate its predictive performance and standardize monitoring protocols and outcome definitions.