Patterns of contact heat evoked potentials (CHEP) in neuropathy with skin denervation: correlation of CHEP amplitude with intraepidermal nerve fiber density.
OBJECTIVE
Contact heat evoked potentials (CHEPs) provide an objective approach to investigate cerebral responses to thermal stimuli mediated by Adelta fibers. Skin denervation is often associated with reduced thermal sensibilities. We aimed to investigate the influences of skin denervation on CHEPs in neuropathic patients.


METHODS
CHEPs were recorded at the vertex area by applying contact heat stimuli of 51 degrees C on the distal leg of neuropathic patients with sensory symptoms and pathological evidence of skin denervation in the distal leg. Patterns and parameters of CHEPs in the neuropathic group were compared with those in the control group of age- and gender-matched subjects.


RESULTS
There were 25 neuropathic patients with reduced intraepidermal fiber (IENF) density (1.46+/-1.70fibers/mm, range: 0-5.32). In the control group, well-defined averaged tracings of CHEPs with an initial negative peak (N-wave) followed by a positive peak (P-wave) were consistently recorded in all 25 subjects. The peripheral conduction velocities of CHEPs were 9.92+/-4.06m/s (range: 6.06-16.60), in the range of Adelta fibers. The group of neuropathic patients had markedly reduced N-P amplitudes (p<0.0001) and prolonged N-wave latencies (p=0.049) compared to the control group. IENF density was the only neuropathic parameter correlated with N-P amplitude on multiple linear regression analysis (p=0.010) compared to large-fiber parameters.


CONCLUSIONS
In neuropathic patients with pathological evidence of skin denervation, there were reduced amplitude and prolonged latencies in CHEPs mediated by Adelta fibers. The reduction of CHEP amplitude corresponded to the degree of skin denervation.


CONCLUSIONS
CHEP offers electrophysiological evidence of thermal responses and provides an objective, non-invasive approach to assess the physiological counterparts of skin denervation in neuropathic patients.
Chao
Chi-Chao
CC
Department of Neurology, National Taiwan University Hospital, 7 Chung-Shan South Road, Taipei 10002, Taiwan.
Hsieh
Song-Chou
SC
Department of Internal Medicine, National Taiwan University Hospital, Taipei 10002, Taiwan.
Tseng
Ming-Tsung
MT
Section of Neurology, Department of Internal Medicine, Far Eastern Memorial Hospital, Taipei 22060, Taiwan.
Chang
Yang-Chyuan
YC
Department of Neurology, National Taiwan University Hospital, 7 Chung-Shan South Road, Taipei 10002, Taiwan.
Hsieh
Sung-Tsang
ST
Department of Neurology, National Taiwan University Hospital, 7 Chung-Shan South Road, Taipei 10002, Taiwan; Departments of Anatomy and Cell Biology, National Taiwan University College of Medicine, Taipei 10051, Taiwan. Electronic address: shsieh@ntu.edu.tw.
D000328:Adult; D000368:Aged; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D004817:Epidermis / Q000294:innervation* / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006358:Hot Temperature; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology / Q000528:radiation effects; D010523:Peripheral Nervous System Diseases / Q000473:pathology* / Q000503:physiopathology; D011930:Reaction Time / Q000502:physiology; D012189:Retrospective Studies; D043222:Ubiquitin Thiolesterase / Q000378:metabolism
C482860:UCHL1 protein, human; D043222:Ubiquitin Thiolesterase