title: Short latency somatosensory evoked spinal and scalp-recorded potentials following posterior tibial nerve stimulation in man.
abstract: Short latency somatosensory evoked potentials (SEPs) following posterior tibial nerve stimulation at the ankle were studied by using surface electrodes placed on the spine and scalp with a non-cephalic reference (unipolar recording) in normal young adults. In order to improve recording technique, ECG was used to trigger the stimulator, and bilateral simultaneous stimulation was employed. A triphasic (positive-negative-positive) or biphasic (negative-positive) potential was recorded at each spinal electrode. Latency of this potential was longer in the more rostral channels. Conduction velocity of the spinal cord from the 12th thoracic to the 2nd cervical spine was 73.4 +/- 7.53 m/sec. At scalp electrodes, 4 components (P25, N27, P28 and N31) were identified preceding the major positive peak (P36). These 4 components showed similar latency and amplitude at all 4 electrodes investigated (Fs, Fz, C3 and C4) and are considered to be generated in the deep structure. Especially, P25 is estimated to be generated in the ascending sensory pathway of the upper cervical cord, but generator sources of other components remain to be determined. P36 appears to be generated in the somatosensory foot area.
mesh_terms: D000328:Adult; D004558:Electric Stimulation / Q000379:methods*; D004562:Electrocardiography; D004566:Electrodes; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008297:Male; D009431:Neural Conduction; D011930:Reaction Time; D012535:Scalp / Q000502:physiology; D013131:Spine / Q000502:physiology; D013979:Tibial Nerve / Q000502:physiology*