Prevention of Neurological Deficit With Intraoperative Neuromonitoring During Anterior Lumbar Interbody Fusion

Study Design: This was a retrospective cohort study. Objective: While intraoperative neuromonitoring (IONM) has been increasingly used in spine surgery to have a real-time evaluation of the neurological injury, we aim here to assess its utility during anterior lumbar interbody fusion (ALIF) and its association with postoperative neurological deficit. Summary of Background Data: ALIF is a beneficial surgical approach for patients with degenerative disease of the lower lumbar spine who would benefit from increased lordosis and restoration of neuroforaminal height. One risk of ALIF is iatrogenic nerve root injury. IONM may be useful in preventing this injury. Materials and Methods: We performed a retrospective cohort study of 111 consecutive patients who underwent ALIF at a tertiary care academic center by 6 spine surgeons. We aimed to describe the association between IONM, postoperative weakness, and factors that predispose our center to using IONM. Results: The 111 patients had a median age of 62 years [interquartile range (IQR): 53-69 y]. Neuromonitoring was used in 67 patients (60.3%) and not used in 44 patients. Seven neuromonitoring patients had IONM changes during the surgery. Three of these patients' surgeries featured intraoperative adjustments to reduce iatrogenic neural injury. The IONM cohort underwent significantly more complex procedures [5 levels (IQR: 3-7) vs. 2 levels (IQR: 2-5), P=0.001]. There was no difference in rates of new or worsened postoperative weakness (IONM: 20.6%, non-IONM: 20.5%). Conclusions: We demonstrate evidence of the potential benefits of IONM for patients undergoing ALIF. Intraoperative changes in neuromonitoring signals resulted in surgical adjustments that likely prevented neurological deficits postoperatively. IONM was protective so that more complex surgeries did not have a higher rate of postoperative weakness.