University of Twente Student Theses


Observing Electrical Brain Responses during Processing of Nociceptive Stimuli around the Detection Threshold combined with a Cold Pressor Test

Dollen, R. (2020) Observing Electrical Brain Responses during Processing of Nociceptive Stimuli around the Detection Threshold combined with a Cold Pressor Test.

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Abstract:Introduction: Conditioned pain modulation (CPM) evaluates the effect of a painful conditioning stimulus on a test stimulus. In this study, the technical feasibility of the NDT-EP method combined with a painful conditioning stimulus, chosen as the cold pressor test (CPT), was explored in a clinical environment. Also, the effect of CPT on nociceptive detection thresholds (NDTs) and evoked potentials (EPs) was investigated. Methods: Two groups of subjects were included in this study. The first group involved healthy pain-free subjects and the second group comprised chronic low back pain patients diagnosed with failed back surgery syndrome (FBSS). Healthy subjects underwent two measurement sessions to perform a test-retest analysis. Intra-epidermal stimuli were applied as a test stimulus, while CPT was used as a conditioning stimulus (1°C for 7 minutes). A test-retest reliability analysis was performed on healthy subjects by comparing NDTs of test measurements to retest measurements. Also, EP amplitudes of test measurements were compared to retest measurements for each CPT phase (i.e. pre-, per-, and postCPT), separately. Additionally, the effect of CPT on NDTs and EPs for test, retest and FBSS measurements was explored. Also the contribution of age to the effect of CPT on NDTs and EPs was investigated in healthy subjects. Results: Twenty healthy subjects (median age: 40.5 years, eleven females) and six FBSS patients (median age 61.5 years, four females) were included in this study. No difference was found in detection probability for retest measurements following single pulse stimulation compared to test measurements of healthy subjects. However, detection probabilities of retest measurements following double pulse stimulation differed from test measurements (P = 0.048). EP amplitudes perCPT and postCPT of test measurements for double pulse stimuli differed from retest measurements (P = 0.022 and P = 0.036, respectively). No differences were found for EP amplitudes preCPT and all CPT phases for single pulse stimuli between test and retest measurements. Detection probabilities of test and retest measurements were significantly modulated by condition and interactions where condition was involved. The effect of CPT on NDTs obtained during application of CPT was moderate, while NDTs obtained after termination of CPT were significantly modulated compared to pre- and perCPT NDTs (P < 0.010). Moderate to poor effect of CPT was found in FBSS patients and age analysis. Conclusion: Results demonstrated that both healthy subjects and FBSS patients seem to be able to properly execute the experiment and tolerate the intensity of the conditioning stimulus. Good reliability of single pulse stimulation in detection probabilities, NDTs and EP amplitudes was observed. Detection probabilities and average group NDTs in both stimulus properties were modulated by CPT in healthy subjects. Average group NDTs were moderately affected by CPT in FBSS patients and age analysis. EP amplitudes were poorly affected by CPT in all study groups. Effects of psychological factors, such as expectancies and distraction, in pain modulation cannot be excluded. Additional research, including subject training and application of control CPT experiment, is recommended to investigate the influence of psychological factors on pain modulation. Keywords: Evoked potential, failed back surgery syndrome, conditioned pain modulation, cold pressor test, linear mixed regression, nociceptive threshold, conditioning stimulus, descending modulatory pathways, pain inhibition
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:02 science and culture in general, 42 biology, 44 medicine, 50 technical science in general
Programme:Technical Medicine MSc (60033)
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