Conditioned pain modulation pathway (CPM)

Conditioned pain modulation (CPM) is a centrally mediated, endogenous pain inhibitory process in which pain from one stimulus is reduced by the application of a second, often remote, noxious stimulus ("pain inhibits pain"). CPM is considered the human analog of diffuse noxious inhibitory controls (DNIC) described in animals, involving descending pain control pathways that engage cortical and subcortical brain regions (including the orbitofrontal cortex, anterior cingulate cortex, periaqueductal gray, and brainstem), and spinal dorsal horn neurons. The efficiency of CPM is believed to reflect the integrity of endogenous pain inhibition and is often altered in chronic pain disorders such as fibromyalgia and irritable bowel syndrome. CPM is measured as a reduction in pain perception during or following a heterotopic noxious conditioning stimulus. Neurotransmitters involved include noradrenaline, serotonin, and endogenous opioids, among others. While CPM is not itself a molecular target, its measurement provides a valuable phenotypic biomarker for pain research and potential patient stratification in clinical practice.

Other names

Conditioned pain modulationCPMDiffuse noxious inhibitory controls (in animals)DNICEndogenous analgesia pathwayHeterotopic noxious conditioning stimulation (HNCS)

Modulation by noradrenergic, serotonergic, opioidergic, and possibly other neurotransmitter systems influencing the descending inhibitory pain pathway