Coexistence of ipsilateral pain-inhibitory and facilitatory processes after high-frequency electrical 'Stimulation

摘要

Background: High-frequency electrical stimulation (HFS) of the human forearm evokes analgesia to blunt pressure in the ipsilateral forehead, consistent with descending ipsilateral inhibitory pain modulation. The aim of the current study was to further delineate pain modulation processes evoked by HFS by examining sensory changes in the arm and forehead; investigating the effects of HFS on nodceptive blink reflexes elicited by supraorbital electrical stimulation; and assessing effects of counter-irritation (electrically evoked pain at the HFS-conditioned site in the forearm) on nodceptive blink reflexes before and after HFS.Methods: Before and after HFS conditioning, sensitivity to heat and to blunt and sharp stimuli was assessed at and adjacent to the conditioned site in the forearm and on each side of the forehead. Nodceptive blink reflexes were also assessed before and after HFS with and without counter-irritation of the forearm.