Nociplastic pain: controversy of the concept

Abstract

Classically, pain can be of a nociceptive or neuropathic nature, which refers to non-neural or neural tissue lesions,respectively. Chronic pain in conditions such as migraine, fibromyalgia, and complex regional pain syndrome (CRPS),is thought to perpetuate without a noxious input. Pain in such patients can be assigned neither to the nociceptivenor neuropathic category. Therefore, a third pain descriptor, named “nociplastic pain”, has been adopted by theInternational Association for the Study of Pain. The current controversy-focused narrative review updates littledebatedaspects of the new pain concept. The most disputable feature of nociplastic pain is its autonomouspersistence, i.e., existence without causative tissue damage, presumably because of a malfunction of pain pathwaysand processing. This contradicts the fact that nociplastic pain is accompanied by persistent central sensitizationthat has been shown to require a continuing noxious input, e.g ., nerve injury. Even if sensitization occurs withouta lesion, e.g ., in psychogenic and emotional pain, peripheral stimulus is necessary to produce pain. A logicalweakness of the concept is that the word “plastic” in biology refers to adaptation rather than to maladaptation. The pathophysiologic mechanism of nociplastic pain may, in fact, be associated with background conditions thatelude diagnosis because of the limitations of current diagnostic means. Misapplication of the nociplastic paincategory may weaken diagnostic alertness toward occult causes of pain. Possible diagnostic errors could be avoidedby understanding that nociplastic pain is a mechanism of pain rather than a diagnosis. Clinical use of this paindescriptor deserves a wider critical discussion.