Effect of Pain Perception on the Heartbeat Evoked Potential

Abstract

Pain as an unpleasant sensory and emotional experience, if uncontrolled or undertreated, can seriously impair the quality of life. In many cases, the failure to adequately treat pain is due to the lack of accurate pain assessment tools, especially when subjective self-report methods are not applicable due to patients’ inability to formulate their pain experience (e.g. young children, incapacitating brain conditions). Therefore, there is a need for measures of pain which do not rely on patients’ ability to self-report. In this study, the relationship between the Heartbeat Evoked Potential(HEP) and acute pain perception was investigated. The aim was to examine the effect of acute tonic cold pain on the HEP and to test whether or not pain perception can be reflected by the HEP. Simultaneous electroencephalogram (EEG) and electrocardiogram (ECG) were recorded from 21 healthy young adults in three conditions: passive no-task control, no-pain control and cold pain induced by cold pressor test (CPT). The HEP was obtained by using ECG R-peaks as event triggers. Prominent HEP deflection was observed in both control conditions mainly over the frontal and central locations, while it was significantly sup-pressed in the cold pain condition over the right-frontal, right-central and midline locations. A comparison of the data in the first and last 5 minutes of cold pain condition showed that lower subjective pain ratings were accompanied by higher HEP magnitudes. A correlation analysis showed that the mean HEP magnitude over the midline locations was significantly negatively correlated with subjective pain ratings. In conclusions, cold pain induces significant suppression of the HEP across a number of scalp locations, and the suppression is correlated with self-report of pain, indicating the potential of the HEP to serve as an alternative pain measure.