Reversal of visceral and cutaneous hyperalgesia by local rectal anesthesia in irritable bowel syndrome (IBS) patients

Irritable bowel syndrome (IBS) is one of the most common gastrointestinal illnesses and is characterized by altered visceral perception. The aim of the study was to determine if local anesthetic blockade of peripheral visceral nociceptive input reduces both visceral and cutaneous secondary hyperalgesia in IBS patients. Ten women with IBS (mean age 30±10 years) and ten control subjects (all women) (mean age 29±7 years) rated pain intensity and unpleasantness to distension of the rectum (35 mmHg) and thermal stimulation (47 °C) of the foot before and after rectal administration of either lidocaine jelly or saline jelly in a double blind crossover design. Intrarectal lidocaine (300 mg) reduced reported rectal and cutaneous pain in all of the IBS patients. The effects were statistically much greater than those of placebo and most of the effects were present within 5–15 min after the onset of the treatment. In the control subjects, rectal lidocaine did not decrease pain report from visceral and cutaneous stimuli. The results of this study support the hypothesis that local anesthetic blockade of peripheral impulse input from the rectum/colon reduces both visceral and cutaneous secondary hyperalgesia in IBS patients. The results provide further evidence that visceral hyperalgesia and secondary cutaneous hyperalgesia in IBS reflects central sensitization mechanisms that are dynamically maintained by tonic impulse input from the rectum/colon. Rectal administration of lidocaine jelly may also be a safe and effective means of reducing pain symptoms in IBS patients.