[Study on the consistency between lumbar neuroelectrophysiological pedicle screw detection and the integrity of the inner wall of the pedicle].

OBJECTIVE

To investigate the consistency between the intraoperative triggered electromyographic(T-EMG) monitoring of pedicle screw and the lumbar pedicle breach.

METHODS

A total of 1 538 patients with posterior pedicle screw fixation for lumbar interbody fusion surgery were enrolled between December 2018 to December 2023, including 854 males and 684 females, aged 26 to 85 years old, with an average age of (65.4±5.6) years old. A total of 8 684 pedicle screws were monitored by T-EMG monitoring. Intraoperative C-arm X-ray hawk-eye fluoroscopy was performed, and conventional postoperative CT was performed to determine whether the pedicle screw had penetrated the medial cortex, to investigate the consistency between the intraoperative T-EMG monitoring of pedicle screw and the lumbar pedicle breach.

RESULTS

Of the 8 684 screws in this study, 312 were positive, the positive rate was 3.59%. Among the 312 screws, intraoperative fluoroscopy suggested correct placement for 42 screws, which were not replaced. Postoperative CT confirmed minor medial breach in 8 of these (patients asymptomatic);the remaining 34 were false positives. For the other 270 screws, fluoroscopy suggested potential breach, prompting replacement. Postoperative CT still showed minor breach in 16 replaced screws (patients asymptomatic). 328 screws were found to be suspiciously positive, with a rate of 3.78%. Among 328 screws, fluoroscopy suggested correct placement for 301 screws, which were not replaced. Postoperative CT revealed minor breach in 18 (asymptomatic). For the remaining 27 screws, fluoroscopy suggested potential breach, leading to replacement. Postoperative CT showed minor breach in 3 of these (asymptomatic). The 8 044 screws were negative, the negative rate was 92.6%. However, postoperative CT identified 127 medial breaches (false negatives). Of these, 86 were minor (asymptomatic) and 41 were significant. Among the significant breaches, 32 patients were asymptomatic, while 9 exhibited obvious nerve root irritation symptoms, which resolved after screw revision.

CONCLUSION

T-EMG is a valuable tool in improving the accuracy of screw placement and reducing the screw revision rate.