Application of different thresholds for instrumentation device testing in minimally invasive lumbosacral spine fixation

Wu, Yunfen; Cohen, Douglas; Téllez, María J.; DiGiacinto, George V.; Barquero, Alfonso Vázquez; Ulkatan, Sedat

doi:10.1016/j.jocn.2019.11.036

Cited by 3 publications

(2 citation statements)

References 17 publications

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“…To minimize this spread of current, some investigators use either a plastic tube or apply a surface insulative treatment on the pedicle access probe. [13][14][15][16][17][18][19][20] They then test the pilot hole by continuously stimulating a moving focal probe before PPS placement. Screw stimulation, as a final test, however, must employ the uninsulated metallic instruments because insulating the screw/extender sleeve assembly poses a practical difficulty.…”

Section: Discussionmentioning

confidence: 99%

“…Threshold-based CMAP monitoring, therefore, should play a more important role for safe screw placement in PPS procedures than in the conventional open techniques. Only a limited number of PPS studies [13][14][15][16][17][18][19] and reviews 20,21 have, however, dealt with this type of neuromonitoring, probably for two reasons. First, percutaneous surgical techniques inevitably rely on fluoroscopy at the expense of radiation exposure.…”

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confidence: 99%

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Threshold-based Monitoring of Compound Muscle Action Potentials for Percutaneous Pedicle Screw Placement in the Lumbosacral Spine

Tani

Saito

Taniguchi

et al. 2021

Spine

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Study Design. A prospective analysis. Objective. To test if threshold-based monitoring of compound muscle action potentials (CMAPs) by stimulating the screw loaded to uninsulated extender sleeve provides a valid safety warning for percutaneous pedicle screw (PPS) placements in the lumbosacral spine. Summary of Background Data. Utility of the CMAP monitoring to PPS procedures remains controversial. Methods. A series of 202 patients underwent a total of 1664 lumbosacral PPS placements under CMAP monitoring without fluoroscopic guidance. The monitoring consisted of stimulating the PPS assembled to uninsulated extender sleeve and recording CMAPs from the vastus medialis, biceps femoris, tibialis anterior, and medial gastrocnemius. Automated steps of a threshold hunting algorithm using 0.2-ms duration pulses of increasing intensities delivered at 2/s allowed quick determination of a minimum stimulation current to evoke >100-μV amplitude CMAPs. Results. At L2 through S1 spines, postoperative CT scans identified 51 medial or inferior pedicle wall breaches of 1536 screws (3.3%) without neurologic complications. The receiver operating characteristic curve analysis determined the critical cutoff threshold value of 27 mA (74% sensitivity and 95% specificity) for predicting 35 breaches of 627 screws (5.6%) at L2 and L3, and of 17 mA (100% sensitivity and 98% specificity) for 16 of 909 (1.8%) at L4 through S1. While advancing the screw, three breaches (5.9%) showed a particularly low threshold of ≤6-mA, allowing the surgeon to immediately redirect the screw and retest the new trajectory as safe. Conclusion. Screw stimulation with threshold hunting algorithm has a distinct advantage over the time-consuming insulated pilot hole stimulation, allowing an uninterrupted flow of the surgery. The present findings have documented practical usefulness and reliability of CMAP monitoring using direct stimulation of the PPS assembled to uninsulated extender sleeve.

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