Diagnostic accuracy of perioperative electromyography in the positioning of pedicle screws in adolescent idiopathic scoliosis treatment: a cross-sectional diagnostic study

Correlation between Single-pulse and Pulse-train stimulation during Neuromonitoring of Thoracic Pedicle Screws in Scoliosis Surgery

BACKGROUND

The use of thoracic pedicle screws (TPS) during scoliosis surgery entails an inherent risk of neurological deficit. Triggered electromyography (t-EMG) is an accurate neuromonitoring test for the detection of malpositioned TPS. However, single-pulse t-EMG (SP t-EMG) stimulation has shown variable capability for detecting medial pedicle breaches while pulse-train t-EMG (PT t-EMG) could be more accurate. The aim is to analyze the correlation between SP t-EMG and PT t-EMG.

METHODS

Retrospective study including 20 patients of scoliosis correction with 294 TPS placed. A total of 588 tests with both SP t-EMG and PT t-EMG were performed, analyzed, and compared. The results of both t-EMG techniques were stratified into three different groups according to threshold obtained: Group 1 (≤6 mA), Group 2 (6.1 - 11.9 mA) and Group 3 (=12 mA). Generalized Linear Model was performed to analyze the correlation between the methods.

RESULTS

SP t-EMG elicited response in 5 screws (1.7%) at ≤ 6 mA; 28 screws (9.5%) at 6.1 - 11.9 mA; and 261 screws (88.8%) at =12 mA. PT t-EMG elicited response in 16 screws (5.4%) at ≤6 mA; 30 screws (10.2%) at 6.1 - 11.9mA; and 248 screws (84.4%) at =12 mA. There is a strong positive and significant association between SP t-EMG and PT t-EMG with a decrease ratio of 2% (95% CI: 1% to 3%).

CONCLUSIONS

SP t-EMG and PT t-EMG stimulation techniques had similar results when the stimuli were applied the TPS, but PT t-EMG may have better efficacy in low-threshold group.

Does robot-assisted navigation influence pedicle screw selection and accuracy in minimally invasive spine surgery?

OBJECTIVE

The accuracy of percutaneous pedicle screw placement has increased with the advent of robotic and surgical navigation technologies. However, the effect of robotic intraoperative screw size and trajectory templating remains unclear. The purpose of this study was to compare pedicle screw sizes and accuracy of placement using robotic navigation (RN) versus skin-based intraoperative navigation (ION) alone in minimally invasive lumbar fusion procedures.

METHODS

A retrospective cohort study was conducted using a single-institution registry of spine procedures performed over a 4-year period. Patients who underwent 1- or 2-level primary or revision minimally invasive surgery (MIS)–transforaminal lumbar interbody fusion (TLIF) with pedicle screw placement, via either robotic assistance or surgical navigation alone, were included. Demographic, surgical, and radiographic data were collected. Pedicle screw type, quantity, length, diameter, and the presence of endplate breach or facet joint violation were assessed. Statistical analysis using the Student t-test and chi-square test was performed to evaluate the differences in pedicle screw sizes and the accuracy of placement between both groups.

RESULTS

Overall, 222 patients were included, of whom 92 underwent RN and 130 underwent ION MIS-TLIF. A total of 403 and 534 pedicle screws were placed with RN and ION, respectively. The mean screw diameters were 7.25 ± 0.81 mm and 6.72 ± 0.49 mm (p < 0.001) for the RN and ION groups, respectively. The mean screw length was 48.4 ± 4.48 mm in the RN group and 45.6 ± 3.46 mm in the ION group (p < 0.001). The rates of “ideal” pedicle screws in the RN and ION groups were comparable at 88.5% and 88.4% (p = 0.969), respectively. The overall screw placement was also similar. The RN cohort had 63.7% screws rated as good and 31.4% as acceptable, while 66.1% of ION-placed screws had good placement and 28.7% had acceptable placement (p = 0.661 and p = 0.595, respectively). There was a significant reduction in high-grade breaches in the RN group (0%, n = 0) compared with the ION group (1.2%, n = 17, p = 0.05).

CONCLUSIONS

The results of this study suggest that robotic assistance allows for placement of screws with greater screw diameter and length compared with surgical navigation alone, although with similarly high accuracy. These findings have implied that robotic platforms may allow for safe placement of the “optimal screw,” maximizing construct stability and, thus, the ability to obtain a successful fusion.