Nociplastic Pain

Original Editor - Kapil Narale

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Top Contributors - Kapil Narale, Kim Jackson, Ewa Jaraczewska, Candace Goh, Melissa Coetsee and Sehriban Ozmen  

IASP Definition

Until 2017, pain mechanisms have been divided into “nociceptive pain” and “neuropathic pain”. Since these only include pain from two specific sources, there are a large group of patients without a valid pathophysiological identification for their experience of pain. This pain experienced is neither nociceptive nor neuropathic. Thus, this group comprises people who have neither obvious activation of nociceptors nor neuropathy, but clinical and psychophysical findings suggest altered nociceptive function.

Recommended by the IASP, "Nociplastic Pain is a term used to describe persistent pain that arises from altered nociception, despite no clear evidence of actual or threatened tissue damage causing the activation of peripheral nociceptors, or evidence for disease or lesion of the somatosensory system causing the pain."

Types of conditions that fall under the umbrella of Nociplastic Pain include: fibromyalgia, complex regional pain syndrome, other types of musculoskeletal pain such as chronic low back pain, visceral pain disorders such as irritable bowel syndrome and bladder pain syndrome.

It is seen that there isn't a single term that is fully suitable for describing someone's pain, and the pain experience can overlap between the 3 terms of nociceptive, neuropathic, and nociplastic pain. The terms describe one element or dimension o fthe pain experience.

Nociplastic Pain is not a diagnosis, but a descriptor of the pain that is being experienced.

Pathophysiology

Nociplastic Pain is often mixed with central sensitisation.

Nociplastic pain does not involve tissue damage that can activate nociceptors. It also does not involve nerve damage which would lead to neuropathic pain. However, it is present in chronic conditions.

Nociplastic Pain can be divided into 3 categories:

• Supraspinal mechanism - hyperresponsiveness to pain stimuli, hyperactivity, connectivity between regions of the brain in charge of pain perception
  • Nociplastic pain is believed to be equipped with decreased connectivity and activity of brain areas for pain inhibition.
  • There is an increased concentration of Substance P and glutamine levels in cerebrospinal fluid, with inhibition of GABAergic transmission
  • Variance also exists n the shape and size of grey and white matter in areas relating to pain

• Spinal mechanisms - this involves regional clustering and narrowing of signals from different pain loci spinal cord reorganisation, amplified spinal reflex transmission, and decreased spinal inhibition
• Peripheral Mechanisms - this is related to the proliferation of sodium channels and sympatho-afferent coupling

Generally, the experience of pain involves contribution from all 3 categories. Feel free to see Table 1 in Buldy's et al (2023) for an outline of the 3 pathophysiological mechanisms of nociplastic pain.

Testing and Diagnosis

Diagnostic tools for neuropathic pain such as the painDETECT and Douleur Neuropathique 4 questionnaire can be used to detect nociplastic pain.

Comparison of Definitions

As can be seen, Nociplastic Pain is a 3rd dimension of Pain classification.

Nociception, Neuropathic, and Nociplastic Pain can be described by the IASP in the definitions on the following pages..

The definitions are explained in the following video:

Resources

• IASP Website
• WHO Website