Prompt recognition of acute or delayed vascular insults during anterior spinal reconstructive surgery of the lower lumbar levels is paramount for successful intervention and prevention of sequelae. Although surgical exposure of the lower lumbar levels requires mindful dissection and cautious retraction of abdominal vessels, ischemic insult due to partial or complete occlusion of the iliac arteries may go undetected without adequate surgical monitoring. We present a case of progressive thrombotic occlusion of the left common iliac artery detected by intraoperative spinal cord monitoring using somatosenory evoked potentials (SSEPs) at the peripheral and central levels. Surgical monitoring using palpation of vessels and pulse oximetry of the great toe were initially proposed as simple and relatively inexpensive modalities for routine surgical monitoring. Subsequently, monitoring cortical SSEPs were combined with great toe pulse oximetry to advance continuous routine surgical monitoring. However, using only cortical SSEPs predisposes such protocols to an inherently higher risk of false positives. Neuromonitoring protocols should rely heavily on the replication of waveforms recorded at multiple sites along the neural pathway.