Rate and prediction of outcomes after neuromonitoring signal changes in somatosensory evoked potentials in lumbar spine surgery: A 10-year experience

Data: Intraoperative neuromonitoring changes of somatosensory evoked potentials (SSEPs) may portend postoperative neurological deficits. We assessed the predictive power of SSEP changes during lumbar spinal surgery for postoperative neurological deficits and recovery rates. In a retrospective multi-surgeon review of neuromonitoring logs, we identified all lumbar spine surgery patients (2011-2021) from our institution. We collected demographic, clinical, surgical and follow-up data on only subjects with intraoperative SSEP changes categorizing them into Group A (intraoperative SSEP changes without postoperative neurological deficits) and Group B (intraoperative SSEP changes with postoperative neurological deficits) for statistical analysis. 2398 subjects underwent lumbar spine surgery. 37 patients (1.54%) identified with intraoperative SSEP signal changes (two patients excluded due to insufficient follow-up data (n=35; Group A=19, Group B =16). Patients followed for at least 24 months. At latest follow-up, 10 patients (62.5%) in Group B either returned to baseline or improved; 6 patients continued to have some neurological deficit. Of significance, Group B patients were younger (p = 0.04) and use of an interbody was higher (p=0.01). No significant differences found for gender, body mass index, preoperative mean arterial pressure, CCI, number of levels decompressed, or estimated blood loss. We observed a positive predictive value of 45.7% with intraoperative SSEP changes. SSEP changes during lumbar spine surgery that are irreversible portend a higher rate of neurological injury. We observed reliable motor recovery in patients who experienced postoperative neurological deficits in an average of 3.9 months. Secondly, use of an interbody was associated with poorer recovery rates. • Irreversible somatosensory evoked potential changes can portend a higher rate of neurological injury. • Of 2398 surgeries, 1.54% had SSEP changes (without deficit=19, with deficit=16). • Age (p=0.05) and use of an interbody (p=0.01) was significant between the two groups. • At 2 years, 8 patients (without deficit=2, with deficit=6) had a neurological deficit. • The positive predictive value of intraoperative SSEP changes was 45.7%.