ALIF Retraction Causes SSEP Changes, Resolved With Adjustment
By Admin | February 29, 2024
Special considerations have to be made when surgeons operate. Variables like patient history, the approach, and who needs to be in the operating room are just a few of the things that need to be considered. For example, in cases of lumbar spine surgery where the surgeon chooses an anterior approach, collaboration between spine and vascular surgeons is crucial. The vascular surgeon is needed to assist the spinal surgeon to mobilize large blood vessels, particularly when dealing with the aorta and its branches. The intricacies of anterior lumbar interbody fusion (ALIF) highlight the importance of neurophysiological monitoring in preventing potential postoperative complications.
This case involves a 64 year-old-female patient who presented with chronic lower back pain and pain in the left buttocks region. She had a history of multiple previous spine surgeries at the L4-L5 level which included the placement of hardware. The patient was diagnosed with hypertension, radiculopathy, foraminal stenosis, central stenosis and pseudoarthrosis.
During ALIF procedures, the aorta typically bifurcates into the left and right common iliac arteries at L4. This often means that the vascular surgeon must retract the iliac artery on the left so that the surgeon can remove the disc at this level and place an interbody cage. If retraction is too great, the vessel is unable to perfuse the lower extremity.
To prevent thrombosis of the common iliac artery during ALIF procedures, it’s recommended to monitor SPO2 (oxygen saturation) and lower extremity somatosensory evoked potentials to identify if intermittent release of the retractors on the vessel is necessary.
Our 64-year-old patient’s planned ALIF at L3-L5 involving hardware removal at L4-L5 and fusion at L3-L5, required careful consideration of her vascular health due to proximity to the bifurcation of the aorta.
During the ALIF portion of the procedure and during retraction of the left common iliac artery, significant SSEP changes were observed, including an increase in latency (>10%) and decrease in amplitude (>50%) for the left posterior tibial nerve (PTN) and left peroneal nerve (PN) SSEPs. The neuromonitoring technologist alerted the vascular surgeon who was assisting and the surgeon released retraction of the left common iliac artery so that it could perfuse the left lower extremity. After doing so, the waveforms returned to normal limits and blood flow was restored to the left leg.
Fortunately, with the timely adjustment of the retractor, the left lower extremity SSEP changes were reversed. This intervention prevented a potentially severe consequence—impaired blood perfusion to the lower extremity—underscoring the critical role of neurophysiological monitoring in lumbar anterior approaches. Without the aid of neurophysiology monitoring, leg perfusion changes might be missed. Vasospasm and thrombosis, though rare, could go undetected, leading to severe postoperative complications.
The adjustment of the retractor not only resolved the immediate issue but also averted the possibility of more extensive surgical interventions that may have been required if complications had escalated.
The case of the 64-year-old female highlights the significance of neurophysiological monitoring in lumbar anterior approaches. Collaborative efforts between spine and vascular surgeons, coupled with vigilant monitoring, can prevent catastrophic consequences and enhance patient outcomes. For more information on the transformative benefits of neuromonitoring, please contact us at 888-344-2947.
