Is there an association between digital oximetry desaturation and changes in somatosensory evoked potentials during anterior lumbar interbody fusion?

Purpose: To determine whether a causal relationship exists between somatosensory evoked potential (SSEP) changes digital oximetry (DO) desaturation events during anterior lumbar interbody fusion (ALIF), investigating whether vascular compression from surgical retraction induces neural ischemia. Methods: We conducted a prospective observational study of 30 consecutive patients undergoing ALIF for refractory lumbar spondylodiscoarthropathy, employing intraoperative SSEP monitoring and digital pulse oximetry. Digital desaturation episodes (SpO₂ < 90%) and SSEP changes (amplitude reduction or latency increase) were recorded. Clinical data, postoperative complications, and pain scores (Verbal Numeric Scale – VNS) were systematically collected. Associations between desaturation and SSEP changes were analyzed using Fisher’s exact test. Results: Peripheral desaturation and SSEP alteration occurred independently in one patient each (3.3%), with no statistical association between the events (p > 0.999). No major vascular injuries were observed. Digital oximetry and SSEP monitoring allowed early detection and prompt reversal of perfusion and neurological changes. The procedure demonstrated a favorable safety profile, with low complication rates and no intraoperative deaths. Postoperatively, all patients showed significant improvement in lumbar pain (VAS reduced from median 8 to 2; p < 0.001). Sensory improvement was observed in 69% of patients with preoperative deficits, and motor function improved in one of two patients with paresis. Conclusion: A causal association between DO desaturation and intraoperative SSEP changes during ALIF appears to be uncommon. Nevertheless, continuous neurophysiological and oximetry monitoring enhances surgical safety, supporting its use in procedures involving vascular manipulation. ALIF has demonstrated favorable outcomes, particularly regarding the reduction of postoperative low back pain.