Impact of visceral pain on migraine symptoms in comorbid patients: a retrospective observational study

Background: Visceral pain and migraine, especially at a high frequency/chronic, are frequent comorbidities, but little is known about their mutual influences. This study investigated if visceral pain-migraine comorbidity involves higher migraine pain and somatic hyperalgesia than migraine-only and if effective visceral pain treatment also improves migraine and hyperalgesia parameters. Methods: Retrospective analysis of 2,903 charts of migraine patients presenting at a Hospital Headache Center for a first visit over 3 years, + 1 follow-up year. Selected charts of female patients meeting inclusion criteria were: 117 migraine-only and 139 migraine + visceral pain, including 50 dysmenorrhea, 48 irritable bowel syndrome (IBS), 41 painful bladder syndrome/recurrent infectious cystitis (PBS/C). They were reviewed for migraine parameters: monthly attacks, symptomatic consumption and pain intensity, for visceral pain: painful menstrual cycles, IBS and bladder pain days, and for sensory parameters: muscle, subcutis and skin electrical pain thresholds, pressure pain thresholds at three sites (trapezius, deltoid and quadriceps), all routinely part of the visit. Migraine-only (M) and migraine + visceral pain (M + VP) patients were compared. In comorbid subgroups, all under the same migraine prophylaxis, the effects of visceral treatment, i.e., 21 hormonal/laser for endometriosis in primary/secondary dysmenorrhea, 25 dietary in IBS, 23 bladder instillations in PBS or antibiotics in infectious cystits, or no treatment were also reviewed on both migraine and visceral pain parameters over 6 months. Results: Migraine + visceral pain vs. migraine-only patients had: higher number and intensity of migraine attacks and symptomatic consumption for migraine and lower pain thresholds in all somatic tissues (p < 0.0001). In comorbid patients, all migraine and sensory parameters improved after migraine prophylaxis (0.0001 < p < 0.002), but patients undergoing effective visceral treatment, i.e., decreased visceral episodes/days, presented a higher reduction of migraine attacks, symptomatic consumption and migraine intensity and a higher increase in pain thresholds than patients not undergoing visceral treatment (0.0001 < p < 0.04). Conclusions: Visceral pain comorbidity involves higher levels of migraine pain and somatic hyperalgesia than migraine-only. Treatment of the visceral condition vs. no treatment results in a better outcome of migraine and sensory parameters, suggesting that management of visceral pain should represent an integral part of the therapeutic regimen in comorbid migraine patients.