Objective
Intraoperative monitoring using somatosensory evoked potential (SEP) study has been used increasingly to monitor neurological function during scoliosis surgery and other high-risk spinal surgeries. However, there are few studies related to this intraoperative monitoring, particularly in severe spinal deformity surgery, in Korea. So we evaluated the clinical efficacy of intraoperative SEP monitoring and considered the risk factors related to spinal surgery.

Method
We performed a posterior tibial nerve somatosensory evoked potential study for intraoperative monitoring during surgical procedures in 101 patients (male 46, female 55).

Results
Neurologic damage occurred in 16 patients (10 congenital scoliosis cases, 5 tuberculous kyphosis cases, and 1 degenerative spondylosis case) after surgical procedures. Delayed postoperative neurologic damage occurred in 4 patients (2 mild damage cases, 2 severe damage cases) among 85 cases which showed normal responses during surgical procedures. Sensitivity of this study was 75%, and specificity was 95.3%.

Conclusion
Somatosensory evoked potential study for intraoperaive monitoring is a sensitive and very useful method to detect iatrogenic lesions during spinal deformity surgery with satisfactory specificity. However, to improve the sensitivity and specificity of the intraoperative monitoring, combination of motor evoked potentials is recommended.