Enhancement of Analgesic Effect by Combination of Non‐Noxious Stimulation and Noxious Stimulation in Humans

Abstract

The aim of the this study was to investigate the combined effects of heterosegmental non-noxious and noxious stimulation on electrically induced tooth pain. The late component of somatosensory-evoked potentials (SEP), induced by electrical tooth stimulation and pain intensity, were examined under electrical stimulation to forearms. Noxious, non-noxious, and combined non-noxious and noxious electrical stimulation were applied to median nerves on the forearms. Four experimental sessions (ie, control session, combined non-noxious and noxious stimulation session, non-noxious stimulation session, and noxious stimulation session were performed for each subject at each 10-minute interval for 30 minutes. The amplitudes of the SEP and VAS scores in the combined stimulation session decreased significantly compared with those in the control session and the reduction rates were 51.1% (13.4 μV) and 41.0% (23.5 mm), respectively. These results show that the combined stimulation has a more potent analgesic effect than that of either the non-noxious or the noxious stimulation. It is suggested that a potent analgesia was produced by an activated central mechanism, including endogenous opioid and descending pain inhibitory systems due to combined non-noxious and noxious stimulation.

New method for postoperative pain relief using a combination of noxious and non-noxious stimuli after impacted wisdom tooth extraction

“…A previous study had shown that a combination of non-noxious and noxious stimuli had a potent analgesic effect on tooth pain (13). The present findings support this previous observation, and suggest that the potent analgesic effect of combined non-noxious and noxious stimuli is elicited by segmental control and an activated central mechanism, including the endogenous opioid and descending pain inhibitory pathways (23) (Le Bars D et al, Opioids and diffuse noxious inhibitory control Fig.…”

“…The patients comprised 21 males and 23 females aged between 20 and 34 years, with a mean age of 26.3 ± 6.36 years (± SD) (Table1). As in the previous study (13), the 44 patients were randomly allocated to four groups, each comprising 11 patients: noxious stimuli (CPM), non-noxious stimuli (TENS), combined noxious and non-noxious stimuli (combined), and a sham group. Chi-squared test revealed no significant inter-group differences in gender ratio.…”

“…The stimulation procedures employed were all carried out by a single dental anesthesiologist using an originally developed device (Ohyou Keisoku Kenkyuusyo, Tokyo, Japan) described previously (13). According to Svensson et al (22), conditioning stimulation exerts hypoalgesic effects when applied both contralateral and ipsilateral to a remote site.…”

“…The phenomenon of "pain inhibiting pain" is a concept referred to collectively as CPM or, formerly, diffuse noxious inhibitory control (DNIC) (9). A series of CPM studies in humans (10)(11)(12)(13) have shown that somatosensory evoked potentials (SEP) induced by painful electrical tooth stimulation were reduced by noxious stimulation of the forearm, accompanied by a decrease of tooth pain intensity, as estimated using a visual analog scale (VAS) (10-13). The last of those studies demonstrated reductions in the magnitudes of both SEP amplitudes and VAS values using a combination of non-noxious and noxious stimuli (13).…”

“…Although there have been many independent reports of pain relief with respect to TENS (5,7,8,14,15) and CPM (9,(10)(11)(12)(13)(16)(17)(18)(19), few reports (20,21) have described the combined effects of TENS and CPM in humans.…”