Novel techniques to study visceral hypersensitivity in irritable bowel syndrome

Abstract

Visceral hypersensitivity has emerged as a key hypothesis in explaining the painful symptoms of irritable bowel syndrome (IBS), and it has been proposed as a "biologic marker" for the condition. Visceral hypersensitivity can be influenced by peripheral and central mechanisms affecting pain perception. The optimal method for its assessment in humans has not been determined. Current techniques include stimulation via the computerized barostat and electrical stimulation, response measures including the lower limb reflex, and brain imaging modalities such as functional MRI and positron emission tomography. It has been shown that IBS patients have decreased sensory thresholds to colonic and rectal balloon distention by barostat. Studies using electrical stimulation and the RIII lower limb reflex have further confirmed enhanced visceral perception in IBS. Evidence from more recent neuro-imaging studies suggests that IBS patients have abnormal activation of brain circuits involved in emotional and cognitive modulation of sensory information, resulting in ineffective pain modulation; these circuits may have a pathophysiologic role in enhancing visceral perception. There are few effective pharmacologic treatments that relieve IBS symptoms, and improved understanding of brain-gut interactions and factors relating to enhanced visceral perception may guide us in developing more efficacious treatments.

One-year course and predictors of abdominal pain in children with autism spectrum disorders: The role of anxiety and sensory over-responsivity

“…Converging evidence from studies using different physiological and imaging modalities indicates that functional GI problems may be associated with visceral pain hypersensitivity (VPH) in some individuals (for review, see Azpiroz et al, 2007;Keszthelyi, Troost, & Masclee, 2012;Truong, Naliboff, & Chang, 2008;Zhou & Verne, 2011). VPH is defined as enhanced pain sensitivity in the gut that occurs in response to painful and non-painful (e.g., food) stimuli.…”

Editorial: Irritable Bowel Syndrome and the Elusive Mast Cells

“…However, it is important to note that mast cell numbers in volunteers were high with a wide range of values. Th ere is no evidence that the diff erence found in their study, which were 370 ± 165 / mm 2 and salivary cortisol level are not regarded as biological markers of IBS ( 18 ), they are of course useful to identify hypersensitive IBS patients as used here. Whether mast cell functions were altered in the intestine or colon remains to be investigated.…”

“…Currently, no optimal method for its assessment in humans has been proven ( 18 ). Braak et al ( 8 ) make the interesting observation that the number of immune cells in the colonic mucosa is not associated with the presence of visceral hypersensitivity assessed by rectal sensitivity to distention.…”

Pain Perception during Menstrual Cycle

“…Although menstrual cycle effects on symptoms were similar in healthy women and women with IBS, symptom severity was greater in women with IBS [58]. The etiology of IBS is multifaceted, with potential abnormalities in central and peripheral neural pathways and neurotransmitter systems and disturbed neuromodulation at central level [59,60]. In this sense, the imbalance toward excitatory control may be taken into account for the occurrence of worsening of visceral pain during menses.…”