Electrophysiological investigation of the contribution of attention to altered pain inhibition processes in patients wit
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The Journal of Physiological Sciences Open Access
ORIGINAL PAPER
Electrophysiological investigation of the contribution of attention to altered pain inhibition processes in patients with irritable bowel syndrome Nabi Rustamov1,2, Alice Wagenaar‑Tison1,2, Elysa Doyer1,2 and Mathieu Piché1,2*
Abstract Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder associated with chronic abdominal pain and altered pain processing. The aim of this study was to examine whether attentional processes contribute to altered pain inhibition processes in patients with IBS. Nine female patients with IBS and nine age-/sex-matched controls were included in a pain inhibition paradigm using counter-stimulation and distraction with electroencephalogra‑ phy. Patients with IBS showed no inhibition of pain-related brain activity by heterotopic noxious counter-stimulation (HNCS) or selective attention. In the control group, HNCS and selective attention decreased the N100, P260 and highgamma oscillation power. In addition, pain-related high-gamma power in sensorimotor, anterior cingulate and left dorsolateral prefrontal cortex was decreased by HNCS and selective attention in the control group, but not in patients with IBS. These results indicate that the central pain inhibition deficit in IBS reflects interactions between several brain processes related to pain and attention. Keywords: Irritable bowel syndrome, Selective attention, CPM, DNIC, Electroencephalography, Pain Background Irritable bowel syndrome (IBS) is a functional gastrointestinal (GI) disorder characterized by chronic abdominal pain and bowel dysfunction [1]. IBS may be associated with psychological distress, impaired quality of life, and disability, and it constitutes a serious societal and economic burden due to its high prevalence [2]. Although several mechanisms have been proposed, the underlying physiopathology of chronic pain in IBS remains unclear. A consistent finding reported in several studies in patients with IBS is the alteration of central pain inhibition mechanisms [3–10]. Considering that altered pain *Correspondence: [email protected] 1 Department of Anatomy, Université du Québec à Trois-Rivières, 3351 Boul. Des Forges, C.P. 500, Trois‑Rivières, QC G9A 5H7, Canada Full list of author information is available at the end of the article
inhibition is associated with widespread hyperalgesia, it is possible that mechanisms related to diffuse noxious inhibitory controls (DNIC) or conditioned pain modulation (CPM) may be disrupted in IBS. Indeed, DNIC produce diffuse analgesia [11–16] and their dysfunction may cause diffuse pain hypersensitivity. Other factors that may contribute to chronic pain in IBS include altered cognitive functions and attentional processes, which may also lead to widespread pain hypersensitivity independently of the original source of pain. Regarding cognitive functions, cognitive performance is lower in patients with chronic pain [17] and decreased cognitive inhibition may be associated with reduced pain inhibition [18]
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