Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale
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Randomized Controlled Trial
Effects of local anesthetics on somatosensory function in the temporomandibular joint area.
There is a need for systematic studies regarding the pathophysiology and pain mechanisms of somatosensory function in the temporomandibular joint (TMJ). So far, the effects on somatosensory functions of local anesthetics (LA) applied to the auriculotemporal (AT) nerve or intraarticularly (IA) into the TMJ have not been studied systemically. This study aimed to examine in a double-blinded, placebo-controlled manner the effects of LA on mechanical and thermal sensitivity in the TMJ area. ⋯ No other measures showed a significant change after the injections. Our results showed that IA bupivacaine injection in healthy subjects has no effect on the sensitivity of the TMJ or surrounding area, while AT nerve block has a more pronounced effect on deep mechanical, but not on superficial mechanical or thermal sensitivity. Further research to investigate the effect of LA on somatosensory functions in TMJ patients in comparison with this study results will give valuable information about the sensitivity in the TMJ area.
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Randomized Controlled Trial Comparative Study Clinical Trial
GABAergic modulation of diffuse noxious inhibitory controls (DNIC): a test by use of lorazepam.
Diffuse noxious inhibitory controls (DNIC) are an important supra-spinal mechanism of pain inhibition. Neurotransmitters and modulators involved in DNIC are serotonin and endogenous opioids. The influence of substances binding to the GABA(A) receptor complex, which has been suggested to play an important role in descending pain inhibition on DNIC has not yet been investigated. ⋯ This pain-specific inhibitory effect did not differ significantly between sessions with lorazepam and placebo. Accordingly, lorazepam did not modify the inhibitory action of DNIC although lorazepam generally increased heat pain threshold. The results of the present study provided no evidence for DNIC being mediated by activation of the GABA(A) receptor complex.
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Randomized Controlled Trial Clinical Trial
Ketamine attenuates glutamate-induced mechanical sensitization of the masseter muscle in human males.
The purpose of the present study was to determine whether glutamate-induced mechanical sensitization of the masseter muscle in human volunteers involves activation of peripheral N-methyl-D-aspartate (NMDA) receptors. Healthy male volunteers (n=18) participated in this randomized, two-session study. During each session, the volunteers received two injections into the right masseter muscle. ⋯ Co-injection of ketamine with glutamate also completely blocked the glutamate-induced mechanical sensitization 15 min post-injection as compared with glutamate alone. The lack of spread of mechanical sensitization outside the area of glutamate injection is consistent with the view that glutamate-induced mechanical sensitization results from a peripheral mechanism. The attenuation of glutamate-induced mechanical sensitization by ketamine suggests that this effect is mediated, in part, through activation of peripheral NMDA receptors.