EPV 13. Pain-related evoked potentials depict the effect of conditioned pain modulation in healthy subjects

• Published in: Clinical neurophysiology Vol. 127; no. 9; pp. e218 - e219
• Main Authors: Höffken, O, Özgül, Î, Enax-Krumova, E, Tegenthoff, M, Maier, C
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.09.2016
• Subjects: Neurology
• ISSN: 1388-2457; 1872-8952
• DOI: 10.1016/j.clinph.2016.05.033

Background Conditioned pain modulation (CPM) evaluates the pain modulating effect of a noxious conditioning stimulus (CS) on another noxious test stimulus (TS), mostly based on subjective pain ratings ( Yarnitsky et al., 2015 ). We now use electrical stimulation (TS) of intraepidermal nerve fibres, reflecting the nociceptive A δ -fibre transmission ( Katsarava et al., 2006 ), to investigate whether cortically recorded pain-related evoked potentials (PREP) can depict the CPM-effect. Methods We examined 17 healthy subjects using a novel CPM-protocol. We recorded PREP (including the assessment of the PREP-induced pain) over Cz referred to linked ear lobes, stimulating the dominant hand with the two-fold of the individual pain threshold (2PT) using three custom-built concentric surface electrodes. We than evaluated the CPM-effect in a cross-over design with immersion of the non-dominant hand into either 10 °C or 24 °C (control) cold water as CS. As TS we recorded PREP stimulating with pain intensity of 40–60 on the NRS 0–100 before, and repeatedly during and after CS application. Statistics: Pearson correlation, ANOVA, paired t -test, linear regression. Result At 2PT the PREP-induced pain and PREP-amplitude did not correlate. With increasing stimulus intensity from 2.3 ± 0.3 mN to 6.7 ± 1.4 mN, the PREP-induced pain raised from 24.5 ± 3.8 to 52.1 ± 1.1 ( p < 0.001), while the PREP-amplitude remained unchained. Only in the 10 °C-condition, both PREP-induced pain intensity (52.6 ± 4.4 vs. 30.3 ± 12.5) and PREP-amplitude (42.1 ± 13.4 μ V vs. 28.7 ± 10.5 μ V) decreased during and increased after CS termination (all p < 0.001). The changes of PREP-induced pain and PREP-amplitudes correlated only in the 10 °C-condition ( r = 0.5; p = 0.042). Discussion The presented novel CPM-protocol with hand immersion in painful cold water as conditioning stimulus can be used to modulate the PREP-induced pain intensity in healthy subjects and, more importantly, the PREP-recordings are able to depict quantitatively the CPM-effect electrophysiologically in an objective way.