Optimal “Low” Pedicle Screw Stimulation Threshold to Predict New Postoperative Lower-Extremity Neurologic Deficits During Lumbar Spinal Fusions

Intraoperative Electromyography in Awake Minimally Invasive Transforaminal Lumbar Interbody Fusion: A Case Study on Nerve Activation Under the Effects of Local Anesthesia

“…5–7 As demonstrated across various studies, incorporation of pedicle screw stimulation during instrumentation allows surgeons to adjust suboptimal screw trajectories accordingly, further reducing incidence of postoperative neurologic deficits. 12,13…”

“…[5][6][7] As demonstrated across various studies, incorporation of pedicle screw stimulation during instrumentation allows surgeons to adjust suboptimal screw trajectories accordingly, further reducing incidence of postoperative neurologic deficits. 12,13 Although the rationale behind pedicle screw stimulation applies to nerve detection during percutaneous decompression, very little literature demonstrates its use in this nature. In their analysis of EMG monitoring during TLIF procedures, both Calencie et al and Bindal and Ghosh used t-EMG during pedicle screw placement, but solely relied on free-run EMG to detect spontaneous nerve irritation during decompression.…”

Screw Stimulation Thresholds for Neuromonitoring in Minimally Invasive Oblique Lateral Lumbar Interbody Fusion (OLLIF): A Correlational Study

“…Though typical amplitudes used for a stimulation threshold are not universally agreed upon, amplitudes of 7-8mA are generally accepted, with any response below this value indicating that the screw is too close to any adjacent nerve or has breached the insulating cortical bone [4][5][6]. More specifically, the threshold of 6 milliamps or below is considered a breach of the pedicle screw, between 6 and 8 is considered a possible breach, above 8 is generally considered safe, and above 12 it is rare that the pedicle screw has contact with neural structure [7,8]. In open surgery, the screw is directly placed into the bone with no significant contact with the surrounding soft tissue and minimal energy dispersion, while in minimally invasive surgery (MIS), a pedicle screw is placed and a significant portion of the screw has contact with the soft tissue, dissipating energy of the stimulation probe [9][10][11].…”

Commentary: Safe Electromyography Stimulation Thresholds Within Kambin's Triangle During Endoscopic Transforaminal Lumbar Interbody Fusion

“…The reviewers believe, however, that as the authors gather more data and gain more experience, this threshold is subject to change, and the sensitivity and specificity for said threshold are expected to improve. For example, in a 2021 study involving 8584 pedicle screws by Melachuri et al, 5 a direct stimulation threshold of 8 mA was found to have a specificity of 90%, and in a Parker et al 2 study of 2450 pedicle screws, stimulation thresholds of less than 5.0 mA, 5.0 to 8.0 mA, and > 8.0 mA, had a positive specificity response of 99.9%, 97.9%, and 95.9%, respectively. In addition, when the threshold was set to less than 5.0 mA, 91% of tested screws with a positive EMG response were determined to be actual medial breaches, but at thresholds between 5.0 and 8.0 mA or greater than 8.0 mA, a positive response was associated with 89% and 100% false, respectively.…”