Intraoperative spinal cord monitoring using combined motor and sensory evoked potentials recorded from the spinal cord during surgery for intramedullary spinal cord tumor.

Objectives: The risk of postoperative neurological impairment mandates the use of intraoperative spinal cord monitoring (IOM) during intramedullary spinal cord tumor (IMSCT) surgery. We have used spinal cord evoked potential after electrical stimulation of the cord(Sp-SCEP) to monitor the sensory tract, and SCEP after electrical stimulation to the brain (Br-SCEP) to monitor the motor tract. Both Sp-SCEP and Br-SCEP are stable under general anesthesia. We assessed the clinical utility of these multimodal spinal cord monitoring methods in a retrospective study of a cohort of patients undergoing IMSCT surgery.

Methods: Thirteen patients with IMSCTs underwent tumor resection using Sp-SCEP and/or Br-SCEP.

Results: Four patients underwent surgery using only Sp-SCEP monitoring, resulting in two false negatives. Nine patients underwent surgery monitored by Br-SCEP and Sp-SCEP. In three of the nine cases, Br-SCEP amplitude fell by 50% from control levels, despite there being no change in Sp-SCEP. In one of the nine cases, Sp-SCEP amplitude fell to 50% of control levels, but Br-SCEP amplitude was stable.

Conclusions: During IMSCT surgery, localized regions of the cord may be damaged. Multimodal monitoring should be used to monitor.Combining Sp-SCEP and Br-SCEP is a useful means of monitoring the sensory and motor tracts.