Left Lower SSEP Decrease During ALIF
August 07, 2024
Spinal disc issues can drastically affect one’s mobility and quality of life. For many patients, anterior lumbar interbody fusion (ALIF) is a transformative solution. This procedure not only has the potential to alleviate pain but also correct spinal alignment. A successful surgery, for many patients, means reclaiming a more active lifestyle.
ALIF is a sophisticated surgery where a bone graft replaces the damaged disc and two or more bones are fused together, stabilizing the spine and preventing painful motion. However, the procedure carries significant risks, including potential nerve damage and complications with abdominal organs among others. This case study delves into the importance of intraoperative neurophysiological monitoring (IONM) during ALIF, showcasing how it plays a pivotal role in safeguarding patient outcomes and enhancing surgical success.
The Patient
The 60-year-old woman had a history of experiencing chronic lower back pain and pain in her left lower extremity, extending to the buttock, lateral thigh, and lateral leg. While she hadn’t experienced any weakness, she did report that her leg pain was more severe than her back pain. Her radiology images revealed multi-level lumbar spondylosis and foraminal stenosis at the L3-S1 levels.
The surgeon decided on an L5-S1 ALIF and L5-S1 posterior instrumentation and fusion to minimize the extent of the surgery, focusing only on the segments causing the most symptoms. And, to maximize the potential for the best patient outcomes, the surgical team used intraoperative neuromonitoring.
Neurophysiology During Surgery
For the ALIF part of the procedure, the patient was positioned supine, and positioned prone for the posterior instrumentation and fusion. During the ALIF, a significant decrease in the somatosensory evoked potentials (SSEPs) was observed in the left posterior tibial nerve (PTN). Notably, a pulse oximeter was not placed on the patient's left toe before draping.
The absence of a pulse oximeter on the left toe meant that the only method to detect a loss of circulation in the left leg was through intraoperative neurophysiological monitoring (IONM). The IONM detected a significant loss of amplitude from the left posterior tibial nerve somatosensory evoked potentials. The technologist promptly informed the surgeons about the significant decrease in the left PTN SSEP. In response, the surgeons then released the retraction, returning the left lower SSEPs to normal limits. Following the adjustment, no significant changes were noted for the remainder of the surgery.
Possible Consequences Without Neurophysiology
Without this neurophysiological monitoring, the potential post-operative neurological deficits could have included changes in sensation in the bottom of the foot and toes, pain in the ankle and bottom of the foot and toes and weakness.
This case study highlights the critical role of intraoperative neurophysiological monitoring in complex spinal surgeries like ALIF. The ability to detect and respond to changes in nerve function in real time can prevent serious postoperative complications and improve patient outcomes.
For more information on the benefits of neuromonitoring and its role in enhancing patient care, please contact us or sign up for our newsletter.
