An extensive amount of studies indicate that conditioned pain modulation (CPM) test paradigms can be of use to evaluate the efficacy of the endogenous pain inhibition pathway in healthy controls and pain patients. A number of studies indicate that the autonomic nervous system (ANS) responds to painful stimulation by parasympathetic activity withdrawal and up-regulation of sympathetic activity (flight-or-fight mode), but it remains unknown whether these responses predict individual pain susceptibility or CPM efficacy and whether different pain modalities evoke different physiological stress responses, i.e. do individuals with low pain tolerance exhibit more vigorous ANS responses when subjected to controlled acute pain stimuli, and do high ANS responsiveness to pain coincide with altered psychophysical pain levels/CPM efficacy. This study aims to investigate the effect of ANS responsiveness on CPM paradigms and to investigate if an exogenous, pharmaceutically induced decrease in the sympathetic drive of the ANS will yield decreased CPM efficacy.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
DOUBLE
Enrollment
25
Reduction of the ANS response
Center for Sensory Motor Interaction, Aalborg University
Aalborg East, Denmark
CPM efficacy
A test stimuli will be applied and compared with a test stimuli simultaneous a condition stimuli.
Time frame: 1-2 hours after propranolol/placebo and after 10 minutes break.
Temporal summation of pain
10 stimuli will be applied and subjects will back asked to rate the pain for each individual stimuli.
Time frame: 1-2 hours after propranolol/placebo and after 10 minutes break.
Heart-rate variability
Two-point Heart-rate variability recording will be conducted using the Polar RS800CX heart rate monitor.
Time frame: 1-2 hours after propranolol/placebo and after 10 minutes break.
Offset analgesia
Temperatures ranging from 45-48°C will be applied to the forearm in three phases (phase 1: 5 seconds, phase 2: 5 seconds, and phase 3: 20 seconds). The subjects will be asked to assess the pain of the thermal stimuli using the electronic VAS scale.
Time frame: 1-2 hours after propranolol/placebo and after 10 minutes break.
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