Auditory evoked potentials (AEPs) are reduced during the cold pressor test

D. TORTA; F. A. JURE; J. A. BIURRUN MANRESA; O. K. ANDERSEN

Copenhagen

Congreso; 10th European Pain Federation Congress; 2017

European Pain Federation EFIC

Background and aims. During the cold pressor test (CPT) somatosensory nociceptive and non-nociceptive brain responses are reduced [1,2]. The aim of the study was to assess the effect of CPT on the processing of auditory stimuli, which are not conveyed through the spinal cord. Whereas a reduction of the NWRs can be explained by DNIC-like effects, a reduction of AEPs during the task should involve other mechanisms. Methods. AEPs, NWRs and the perceived intensity of auditory and electrical stimuli were recorded before, during, and after CPT. AEPs were elicited by loud sounds presented via loudspeakers and were recorded using 64-channel EEG. NWRs were elicited by single electrical stimulus at twice the reflex threshold intensity at the arch of the sole of the foot and were recorded from the biceps femoris muscle. NWRs were used to control for the suppression of nociceptive processing at the level of the spinal cord during CPT. Results. The probability of eliciting NWRs and the perceived intensity of the electrical stimuli were reduced during the CPT and remained suppressed in the after measurement. The amplitude of the negative vertex potential of the AEPs was reduced during the CPM, but returned to baseline level in the post-session. The perceived intensity of auditory stimuli did not change significantly. Conclusion. Our results suggest that CPT induces multiple mechanisms leading to a short-lasting suppression of cortical responses to non-nociceptive and non-somatosensory stimuli in conjunction with a longer lasting suppression of the NWRs.