Abstract
Somatosensory evoked potentials evoked with tibial nerve stimulation were analyzed in patients of central type lumbar spinal canal stenosis. Analysis was performed according the guidelines for evoked potentials described by American electroencephalographic society. Average Lp peak latency recorded with surface electrodes applied on the skin on T12 or L1 spinatus process were 23.8ms in patients group and 22.0ms in control group. Lp peak latency had positive correlation with patients' height. Significant result was obtained by discrimination analysis performed using Lp latency and patients' height as parameters. According the result of the analysis, both groups were divided with the sensitivity of 72% and the specificity of 80%. The delay of Lp latency in patients group is thought to reflect pathophysiological change of cauda equina caused by narrow lumbar spinal canal. Lp peak latency is thought to be useful as a noninvasive examination in diagnosis of lumbar spinal canal stenosis.
