Preoperative SSEP and MEP Changes Prior to Draping, Patient Positioning Is Key
By Admin | February 29, 2024
In a large-scale study of approximately 4,000 anterior cervical spine surgeries, neuromonitoring detected impending neurologic injury due to patient positioning in approximately 2% of cases. The most common cause of impending brachial plexopathy was shoulder taping for counter-traction, while the second most common cause was neck extension. These kinds of positional injuries can result in conditions such as brachial plexopathy or ulnar neuropathy without intervention making it imperative to obtain intraoperative neuromonitoring (IONM) baseline signals as early as possible to detect potential positional changes and provide improved patient outcomes.
In the case of this 52-year-old male’s procedure, IONM changes of the left ulnar nerve somatosensory evoked potentials (SSEPs) and left upper extremity motor-evoked potentials (MEPs) occurred prior to draping the patient for the procedure.
The patient presented with numbness and tingling in their upper left arm and pain with certain neck movements but denied any gait issues or lower extremity symptoms. He had a history of a prior ACDF at C5-C6 over twenty years ago and had hypertension in addition to being diabetic. The patient was diagnosed with central stenosis, foraminal stenosis, radiculopathy, spondylosis, and degenerative disc disease.
The surgeon elected to perform an ACDF C4-C5 on the patient with hardware removal at C5-C6.
Before initiating the surgery, the surgeon obtained pre-extension and post-extension baselines. In this case, the pre-extension baselines were present and reliable, allowing the surgical team to proceed with positioning the patient for the procedure. As the patient’s arms were fully tucked and taped for retraction, a notable change occurred in the left ulnar nerve SSEPs along with a significant decrease in left upper extremity MEPs.
Quick to respond, the neuromonitoring team alerted the surgeon, who removed the left arm and shoulder tape and requested that the patient’s mean arterial pressure (MAP) be increased to 85 or higher. After a pause to allow for improvements, left ulnar nerve SSEPs and left upper extremity MEPs recovered, and the surgery proceeded with stabilized waveforms.
Without the proactive measures taken during this surgery, the patient's positioning could have led to left-sided ulnar neuropathy or brachial plexopathy postoperatively. The case underscores how baseline signals, coupled with vigilant neuromonitoring, act as early warning systems, enabling surgeons to intervene promptly and mitigate potential nerve damage during ACDF procedures.
This case serves as a compelling example of the transformative benefits of neuromonitoring. The acquisition and interpretation of baseline signals empower surgical teams to navigate complexities, ensuring patient safety and reducing the risk of postoperative complications. For more information on the transformative benefits of neuromonitoring, please contact us at 888-344-2947.
Cited:
Schwartz, D. M., Sestokas, A. K., Hilibrand, A. S., Vaccaro, A. R., Bose, B., Li, M., & Albert, T. J. (2006). Neurophysiological identification of position-induced neurologic injury during anterior cervical spine surgery. Journal of clinical monitoring and computing, 20(6), 437–444. https://doi.org/10.1007/s10877-006-9032-1
