Can triggered electromyography thresholds assure accurate pedicle screw placements? A systematic review and meta-analysis of diagnostic test accuracy

Abstract

Objective: Triggered electromyography (t-EMG) for pedicle screw placement was introduced to prevent the misplacement of screws; however, its diagnostic value is still debated. This study aimed to clarify the diagnostic value of t-EMG and to compare thresholds. Methods: We searched MEDLINE, EMBASE, and the Cochrane Library, and 179 studies were identified. Among them, 11 studies were finally enrolled. The pooled sensitivity, specificity, diagnostic odds ratio (DOR), and summary receiver operating characteristics (SROC) plots were analyzed. Results: The enrolled studies included 13,948 lumbar and 2070 thoracic screws. The overall summary sensitivity/specificity/DOR values of t-EMG were 0.55/0.97/42.16 in the lumbar spine and 0.41/0.95/ 14.52 in the thoracic spine, respectively, indicating a weak diagnostic value. However, subgroup analysis by each threshold value showed that the cutoff value of 8 mA in the lumbar spine indicated high sensitivity (0.82), specificity (0.97), and DOR (147.95), thereby showing high diagnostic accuracy of identifying misplaced screws. Conclusion: The most useful application of t-EMG may be as a warning tool for lumbar pedicle screw malpositioning in the presence of positive stimulation at a threshold of 68 mA. Significance: t-EMG by screw stimulation may be valuable in the lumbar region at a threshold of 68 mA. (C) 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.