RESUMEN
BACKGROUND AND AIM: Irritable bowel syndrome (IBS) and fibromyalgia syndrome (FMS) are common conditions with some similarities, but different perceptual responses to somatic and visceral stimuli. The purpose of this study was to assess in a large group of IBS patients the somatic perception by transcutaneous electrical nerve stimulation (TENS) and its relation to the level of severity and presence of FMS. METHODS: In 99 patients grouped by the validated functional bowel disorder severity index (FBDSI) in mild, moderate, and severe IBS and in 33 healthy controls (HC), we studied discomfort thresholds and perception of somatic stimuli at control (hands and elbows) and active (trapezius) sites by TENS and by using a specific questionnaire. RESULTS: The use of TENS showed that IBS showed significant higher thresholds and lower perception cumulative score compared to HC. The severity of IBS is significantly associated with age and mean control site values for discomfort and borderline associated with gender in the ordinal model constructed for the ascending series protocol. The severity of IBS is also significantly associated with the active cumulative perception score in the long stimulus protocol. Due to limited sample size of IBS men with FMS, analyses of discomfort thresholds and cumulative perception score by FMS were done only for women. IBS women without FMS had significantly higher mean control site values for discomfort and significantly lower active cumulative perception score than HC. IBS women with FMS had significantly lower mean active site values for discomfort thresholds than IBS women without FMS (Dunn's test p < 0.05). CONCLUSIONS: IBS patients showed somatic hypoalgesia to electrical stimuli. The severity of IBS and the presence of FMS influence the perception of somatic stimuli induced by TENS.