Nociplastic Pain–Nerves Gone Rogue

Central sensitization syndromes (CSS) are a group of medical conditions that share the common abnormality of nerve sensitization or nociplastic pain. They affect as many as 30 million adults in the United States. Examples include chronic migraine, back pain, bladder pain, pelvic pain, and irritable bowel syndrome. The individual conditions differ in many ways but all share the feature of sensitization.

 

Common sensitization syndromes

Chronic back pain and neck pain
Chronic muscle pain (myofascial pain syndrome)
Fibromyalgia
Temporomandibular disorders
Chronic stomach pain
Irritable bowel syndrome
Migraine headaches
Chronic bladder pain (i.e., interstitial cystitis)
Chronic pelvic pain

 

How sensitization increases pain levels

Nerve sensitization arises from abnormalities in how pain signals are processed and perceived in the brain, spinal cord, and nerves. Sensitization makes the nerves more sensitive and more reactive to stimuli which increases pain levels. There is increased reactivity to normal sensory inputs, such as touch and movement.

 

Sensitized nerves exaggerate the pain signal when reporting it to the brain. The reactive nerves send more pain signals, more often. They are like tattletales, constantly telling the brain something is wrong. The person then perceives something serious is wrong. It’s what I call a “maladaptive biologic process.” The nerves get confused and adjust in an unhelpful way; the brain believes the tattletale nerves.

 

Three ways sensitization exaggerates pain levels

1. Pain hypersensitivity is increased sensitivity to sensory inputs, such as touch, pressure, and movement. Let’s consider two people, one with sensitization and the other without it. They both lift a 50-pound box and feel a pull in the back. The person without sensitization reports the pain as a “three out of ten.” Meanwhile, the person with sensitization reports the pain as a “seven out of ten.” The nerves are telling the brain it hurts more than what a person without the condition feels. It’s not the person overreacting; the intensity is very real. The sensation is because the nerves are hypersensitive.

2. Allodynia-Pain in response to things that aren’t normally painful. Light pressure on the back muscles shouldn’t cause discomfort outside of an injury. With nerve sensitization, a mild touch can prompt a substantial pain response. And, after being touched, there can be unpleasant sensations, like burning or tingling.

3. The pain spreads to more parts of the body. With sensitization, pain spreads beyond the injured area, such as the joint or nerve. One example is with back pain. Instead of a small area of the back hurting, a person with nerve sensitization may feel pain across the back and down into the thighs. Another example is with nerves, someone with a pinched nerve may feel their entire leg is numb, instead of just the area supplied by the irritated nerve.

 

In addition to affecting how pain is experienced, sensitization causes symptoms that affect the entire body. Called “non-pain symptoms,” these include activity-limiting fatigue, disrupted sleep, and thinking difficulties. Tattletale nerves throw the entire nervous system off.

 

The whole body is affected

Between the pain condition—such as headaches or back pain—and the non-pain symptoms, nerve sensitization affects the function of the entire body. Your brain and nervous system are in charge of helping you think clearly, be active, and regulate sleep. If that system is not working normally, all of its functions are affected. With sensitization syndromes, the disorder does not stem from just the back or head or stomach, but from the entire nervous system.

 

References

Muhammad B. Yunus, “Editorial Review (Thematic Issue: An Update on Central Sensitivity Syndromes and the Issues of Nosology and Psychobiology),” Current Rheumatology Reviews 11, no. 2 (July 2015): 70–85.

Jo Nijs et al., “Nociplastic Pain Criteria or Recognition of Central Sensitization? Pain Phenotyping in the Past, Present and Future,” Journal of Clinical Medicine 10, no. 15 (July 21, 2021): 3203.