Visceral afferents: what role in post-inflammatory pain?

Several weeks to several months after a bout of inflammation or an infectious event in a visceral organ, while inflammation or infection has resolved, defective nociceptive functions are sometimes still present, characterized by chronic pain symptoms, visceral hyperalgesia and allodynia. Visceral afferents which convey nociceptive messages have been shown to be hyperexcitable in inflammatory states. Only recently, studies have addressed visceral afferent electrical properties and neuroplastic changes in post-inflammatory situations. This review tries to appraise in post-inflammatory hypersensitive states, the most recent advances in the knowledge of visceral afferent inputs, together with in vivo recordings of visceral hyperalgesia and allodynia. Copyright 2009 Elsevier B.V. All rights reserved.