Assessment of intraoperative neurophysiological monitoring techniques in lumbosacral pedicle screw placement surgery

Study Design: Retrospective observational study. Purpose: To evaluate intraoperative neurophysiological monitoring techniques in lumbosacral (L1-S1) pedicle screw placement surgery in University Medical Center Ho Chi Minh City, Vietnam. Overview of Literature: Intraoperative neurophysiological monitoring (IONM) in lumbosacral pedicle screw placement surgery helps the neurosurgeon detect early warning signs, reducing or preventing permanent postoperative neurological deficits. Methods: The authors carried out a retrospective study of 120 consecutive patients who underwent lumbosacral pedicle screw placement surgery and monitored neurophysiological intraoperative between May 2020 and December 2020, at the University Medical Center Hospital in Ho Chi Minh City, Viet Nam. Clinical assessment before and after surgery, intraoperative neurophysiological changes in Raw electromyogram (rEMG), somatosensory evoked potential (SSEP), triggered electromyogram (tEMG), pedicle screw testing (PED) were collected to calculating for sensitivity, specificity, positive predictive value, and negative predictive value of these techniques. Results: Of the 120 patients, 6 (5%) had postoperative new neurological deficits, of which a total of 666 pedicle screws were placed. The sensitivity and specificity of intraoperative rEMG monitoring in detecting postoperative nerve deficits were 83.3%, and 41.8%, respectively. The sensitivity and specificity of intraoperative SSEP monitoring in detecting postoperative nerve deficits were 50.0%, and 94.7%, respectively. The sensitivity of tEMG and PED were equal to 66.7%. The specificity of tEMG and PED were 85.4% and 98.1%, respectively. The positive predictive value of rEMG, SSEP, tEMG and PED were 10%, 33.3%, 21.1% and 66.7%, respectively. The negative predictive value of rEMG, SSEP, tEMG and PED were 98.6%, 97.2 %, 97.8% and 98.1%, respectively. Conclusions: rEMG has a high sensitivity (83.3%) in detecting postoperative nerve deficits. In opposite, SSEP, tEMG, PED have high specificity. These techniques help to predict and possibly prevent postoperative neurologic deficits in lumbosacral pedicle screw placement surgery.