A systematic review with meta‑analysis of the diagnostic test accuracy of pedicle screw electrical stimulation

European Spine Journal, 2022

A systematic review with meta‑analysis of the diagnostic test accuracy of pedicle screw electrical stimulation

Pedro Fonseca1,2 · Márcio Goethel1 · João Paulo Vilas‑Boas1,3 · Manuel Gutierres1,4 · Miguel Velhote Correia1,2,5

1 LABIOMEP: Porto Biomechanics Laboratory, University of Porto, Porto, Portugal

2 FEUP: Faculty of Engineering, University of Porto, Porto, Portugal

3 FADEUP: Faculty of Sports, University of Porto, Porto, Portugal

4 FMUP: Faculty of Medicine, University of Porto, Porto, Portugal

5 INESC TEC: Institute for Systems and Computer Engineering, Technology and Science, Porto, Portugal

Abstract

Purpose To provide a systematic review with meta-analysis providing evidence of the current diagnostic test accuracy (DTA) of pedicle screw electrical stimulation.

Methods 

A systematic search on PubMed, Scopus and Web of Science was performed according to the PRISMADTA guidelines, and eligibility criteria applied to reduce the results to: (1) only journal articles reporting electrical stimulation of the pedicle screw head, (2) screw position confirmation by imaging techniques, and (3) enough information allowing the calculation of a 2 × 2 contingency table. Sample characteristics, image confirmation method, electrical current threshold and stimulation results were retrieved and analyzed using according to appropriate DTA analysis methods, and allowing the calculation of specificity, sensitivity for pedicle screws insertion at the lumbar and thoracic levels.

Results 

Lumbar screw stimulation presents a higher sensitivity (0.586 [0.336, 0.798] and specificity (0.984 [0.958, 0.994]) than thoracic screws (sensitivity: 0.270 [0.096; 0.562]; specificity: 0.958 [0.931, 0.975]). The same is observed in terms of the diagnostic odds ratio for lumbar (88.32 [32.136, 242.962]) and thoracic (8.460 [2.139, 33.469]) levels. When performing a sub-group analysis, it is possible to divide the lumbar stimulation threshold as 8 and 10–12 mA, and the thoracic threshold as 6 and 9–12 mA. A threshold of 8 mA at the lumbar level provides higher sensitivity and specificity. Increasing the threshold results in higher specificity but not sensitivity. In fact, at the range of 10–12 mA, the diagnostic validity is too low to confer this technique any robust diagnostic validity. Similarly, at the thoracic level, lower threshold currents are associated with increased sensitivity, but their diagnostic validity is very low.

Conclusion 

Electrical stimulation of the pedicle screw can be used as an adequate diagnostic capability at the lumbar level with a threshold of 8 mA. However, thoracic stimulation is currently not reliable, with very low sensitivity and diagnostic validity at 6 mA or higher.

Keywords 

Diagnostic accuracy · Pedicle screw · Intraoperative · Neuromonitoring · Electrical stimulation · Spine surgery