Use of somatosensory evoked potentials to detect peripheral ischemia and potential injury resulting from positioning of the surgical patient: case reports and discussion.

BACKGROUND: Somatosensory evoked potentials (SSEPs) have long been recognized as an excellent tool for detecting neural and vascular compromise during vascular, neurosurgical and orthopedic procedures. SSEPs have the ability to localize, central versus peripheral, the area of compromise. Many surgeons use only lower-limb SSEP monitoring when performing lumbar spinal surgery. The upper extremities are usually not monitored during such procedures, and monitoring oxygen saturation does not detect neural compromise. PURPOSE: To report that the expanded use of SSEP monitoring during surgery can be beneficial in detecting peripheral ischemia or neural compromise resulting from positioning. STUDY DESIGN: Three case reviews of orthopedic spine surgeries where SSEP monitoring provided early warnings of vascular and neural compression. METHODS: The cases review three different lumbar procedures in which evidence of peripheral ischemia and nerve compression were detected by SSEP monitoring. RESULTS: By the use of upper- and lower-extremity monitoring during lumbar procedures, early detection of ischemia and nerve compression were noted intraoperatively. These changes prompted examination of the patient and repositioning to correct the ischemia or compression. The repositioning in these cases corrected the problem, and no lasting effects were found. CONCLUSIONS: Including SSEP monitoring of the bilateral upper extremities should be considered during lumbar spinal procedures. Such monitoring can be offered for a slightly increased expense and only minimal time delay to place the additional required electrodes by the technician. As a direct result of the early warning of the SSEP monitoring, we were able to avoid potential ischemic injuries and improve patient outcomes.