Undersøgelse af temporal summation og naturlig smertehæmning hos raske forsøgsdeltagere før og under muskelømhed

Abstract

Introduktion: Patienter med kroniske smerter behandles ofte ens i sundhedsvæsenet uden differentiering af, hvilke centrale smertemekanismer, der er påvirkede. Ved at skelne mellem mekanismerne vil behandlingen heraf kunne målrettes. Temporal summation (TS) og conditioned pain modulation (CPM) er smertemekanismer, der er påvirkede ved flere kroniske smertetilstande, men interaktionen imellem de to mekanismer er sparsomt belyst. Formålet med dette studie er at undersøge interaktionen hos raske forsøgsdeltagere før og under delayed onset muscle soreness (DOMS). Metode: 20 raske forsøgsdeltagere (10 mænd og 10 kvinder, gennemsnitsalder 28,9±8,52 år) deltog i fire forsøgs-sessioner. DOMS blev induceret i musklerne quadriceps femoris og triceps surae i randomiseret rækkefølge. Forsøgsdeltagerne blev undersøgt ud fra randomiserede quantitative sensory testing (QST) paradigmer med håndholdt tryk algometer og computer-kontrolleret cuff algometer. Resultater: DOMS blev detekteret perifert ved kvantificering med håndholdt algometer, men ikke med cuff-algometer. Visuel analog skala (VAS) score under TS steg før og under DOMS. Pressure pain threshold faldt under CPM. Ved quadriceps femoris var der signifikant forskel for VAS score under TS før (p<0,01) og under CPM (p<0,05) både før og under DOMS. Ved triceps surae var der signifikant forskel på VAS score for TS under CPM (p<0,001) under DOMS, men ikke før (p<0,146). Diskussion/konklusion: TS inhiberes af CPM i det raske smertesystem. Det smertefulde respons af TS under DOMS blev intensiveret, hvilket indikerer at centrale mekanismer kan spille en rolle i facilitering af smerter. Resultaterne tyder på, at interaktionen mellem CPM og TS ændrede sig under DOMS. Der er behov for yderligere kliniske studier omkring interaktionen mellem TS og CPM. Keywords: Temporal summation, conditioned pain modulation, delayed onset muscle soreness, quantitative sensory testing.

Introduction Chronic pain patients are often treated equally not taking into consideration, which of the central pain mechanisms are affected. The treatment can be individualized by distinguishing between the mechanisms. Temporal summation (TS) and conditioned pain modulation (CPM) are affected in many chronic pain conditions, but the interaction between the mechanisms is sparsely assessed. The aim of the study was to examine this interaction in healthy volunteers before and during delayed onset muscle soreness (DOMS). Methods Twenty healthy subjects (10 males and 10 females, mean age 28,9±8,52) participated in four experimental sessions. DOMS was randomly induced in quadriceps femoris and triceps surae muscles. The subjects were assessed using randomized quantitative sensory testing (QST) paradigms with handheld pressure algometry and computer controlled cuff algometry. Results DOMS was detected by assessment with handheld algometer but there was no significant reduction in pain thresholds when using the cuff-system. Visual analogue scale (VAS) scores were increased during TS before and during DOMS. Pressure pain thresholds were reduced during CPM. In quadriceps femoris there was a significant difference in VAS scores for TS before (p<0,01) and during CPM (p<0,05) both before and during DOMS. In the triceps surae there was a significant difference in the VAS scores for TS during CPM (p<0,001) during DOMS, but not before (p<0,146). Conclusion TS seems to be inhibited by CPM in the healthy pain system, but both facilitated and inhibited during DOMS. The pain response of temporal summation during DOMS was intensified indicating that central mechanisms may play a role in pain facilitation. These findings suggest that the interactions of CPM and TS shifted during DOMS. Further clinical studies on the interaction between TS and CPM are needed. Keywords: Temporal summation, conditioned pain modulation, delayed onset muscle soreness, quantitative sensory testing.

A master thesis from Aalborg University

Undersøgelse af temporal summation og naturlig smertehæmning hos raske forsøgsdeltagere før og under muskelømhed

[Assessment of temporal summation and conditioned pain modulation in healthy subjects before and during delayed onset muscle soreness]