The Study Of The Contact Heat Evoked Potentials Of Face In Normal Subjects

ObjectiveIn order to investigate feature of contact heat evoked potentials (CHEPs) with different face site in Normal Subjects. To establish clinical utility of CHEPs in measurement of sensation small fiber function of cranial nerves.Subjects and methodsCHEPs were recorded from 116 normal subjects, which included male 56, female 60;age from 20y to 66y, mean age(39.2y±11.8), in the Affiliated Shao Yi Fu Hospital of Zhejiang University Medical College, from september in 2013 to february in 2014. The subjects were set on supine position, which prefrons skin temperature were 36～37℃ by infrared temperature meter. All operations were completed by the same doctor. The CHEPS device (Medoc, Israel) with a thermode contacting a cutaneous area of 573 mm2 (27mm in diameter) was used for heat stimulation, which heating rate up to 70℃/s, the baseline temperature was 32℃, and stimulation peak heat intensity was 51℃. Heat stimuli were applied at peak intensity of 51℃ to four sites:above right the eyebrow, side of nasal ala, perioral, preauricula. Stimulus intensity was rated by normal subjects according visual analogue scales (VAS) after every stimulus. Electrodes were placed on the Cz (vertex) position in accordance with the extended 10-20 International System, CHEPs were recorded by electromyography(Keypoint). Linked middle of forehead electrodes provided a reference, and the ground electrode was placed on the right forearm. The N wave latencies, P wave latencies and N-P amplitudes of CHEP was recorded at the Cz (vertex) position. All numerical data are presented as mean±SEM values. Pearson Chi-square test was applied to compare rate; Independent-sample T test was applied to compare the visual analogue scales(VAS); One-way analysis of variance and non-parametric test were applied to compare N wave latencies, P wave latencies and N-P amplitudes from different site; Fisher exact test was applied to compare elicit rate of male and female; In cases where the data were not normally distributed, the Wilcoxon rank-sum test was used to determine differences between study groups. SPSS version 18.0 software was used for all statistical analyses. Significance was accepted at the P< 0.05 level.ResultsThe elicit rate of CHEPs from above right the eyebrow, side of nasal ala, perioral, preauricula were:87.93%,87.93%,82.75%,84.48%(all P>0.05); The VAS were:6.14+1.36,6.78±1.63,6.46±1.49,6.26±1.42; There were no statistical differences between the VAS、the latencies of N wave and P wave. The amplitudes were: 20.52±7.06μV、23.15±7.09μV、19.55±7.65μV、19.70±7.68μV,there was a highest amplitude of the side of nasal ala (P< 0.05). There were no statistical differences between the elicit rate, the latencies of N wave, P wave, VAS and amplitudes of CHEPs from different sites in male and female (P>0.05)ConclusionCHEPs could be elicited reliably on different facial sites, e.g. above right the eyebrow, side of nasal ala, perioral, preauricula. The VAS were not correlated with the elicited or non-elicited of CHEPs. The thermode of CHEPs device could more closerly contact with the side of nasal ala skin. Our tests suggested the latencies of N wave, P wave of CHEPs to provide well own control. No gender differences were observed for the elicit rate, the latencies of N wave, P wave, the VAS and amplitudes of CHEPs from different sites.