Nociplastic Pain: Why Nonspecific Is Not a Diagnosis

Nociplastic pain is pain produced by a nervous system that has changed, not by damaged tissue or an injured nerve. It is also the kind most likely to be missed, because a chart that already says chronic low back pain has stopped looking.

The video for Chapter 2 of The Pained Brain, Pain Is Not a Diagnosis, makes the case that pain is a signal. The book is by Dr. Gurpreet Singh Padda, MD, MBA, MHP, and Dr. KrisJay Fucanan, MD. This page goes further into the three questions every signal demands before anyone treats it: which structure, which mechanism, which terrain. The broader argument is in why pain is the signal and not the disease.

When the label becomes the disease

In ICD-11, the World Health Organization’s disease classification, chronic primary pain means pain lasting more than 3 months with significant distress or disability that is not better accounted for by another condition. As a coding tool it works. In field tests fewer than 3% of cases fell into the leftover categories, and the World Health Assembly endorsed the classification in 2022. What no paper supplies is a biological criterion that separates primary from secondary pain. The line is drawn by exclusion.

The system pushed the same way. Among 1,294,247 opioid-naive adults, 6.0 percent were still taking opioids a year after a first prescription, and 29.9 percent were if that first supply ran 31 days or more. And 83 percent of academic pain-center leaders reported administrative pressure over satisfaction scores. The incentive rewarded quieting the alarm, not finding its cause.

Question one: which structure is hurting?

The major reviews say that for nearly all people with low back pain, no specific nociceptive cause can be identified. Look at what specific means in those papers: fracture, malignancy, infection. That triage is designed to catch the rare and dangerous, and it does. It was never designed to find a facet joint.

Finding one takes a controlled block. The small nerves to a joint are numbed with a short-acting anesthetic, then on another day with a long-acting one, and the question is whether the pain follows the drug. The case for doing it twice does not rest on one research group. In 176 consecutive patients with no prior lumbar surgery, 47 percent responded to a single screening block, but only 15 percent were confirmed on the second drug, a false-positive rate of 38 percent. When one tertiary practice worked 170 cases to a conclusion, the disc was the source in 42 percent, the facet joint in 31 percent and the sacroiliac joint in 18 percent. There is more on how a medial branch block confirms facet joint pain.

The technique has limits. There is no non-interventional gold standard to check a block against, and false positives by comparative blocks still run 17 to 41 percent. A positive dual block names a structure with more confidence than anything else available, yet it has not been shown to predict a long-term treatment result. That is the reason I block before I ablate, never after.

Question two: nociplastic pain, nerve pain or tissue pain?

Nociceptive pain comes from damaged or inflamed tissue. Neuropathic pain comes from damage to the nerve itself. Nociplastic pain arises from altered nociception despite the absence of tissue damage, and it shows decreased responsiveness to treatments aimed at the periphery: anti-inflammatory drugs, opioids, surgery and injections. The three often coincide in one person, which is part of why chronic pain is so stubborn. We have written about how pain is classified and why the category changes the treatment.

There are bedside criteria for it. Possible nociplastic musculoskeletal pain requires pain for more than 3 months, a regional, multifocal or widespread pattern rather than a discrete spot, pain not entirely explained by tissue or nerve mechanisms, and clinical signs of hypersensitivity in the painful region. Those criteria are expert consensus, not validated tests. Fibromyalgia is the clearest example. Chronic low back pain can carry a nociplastic component mixed with a structural one.

Skipping this question has a measurable cost. Among 27 trials of nerve-pain drugs for back pain and spine-related leg pain, 59 percent either excluded people with neuropathic pain or never considered it, and only 22 percent enrolled patients at the level where those drugs are recommended. Where neuropathic pain was probable, short-term pain fell 10.45 points on a 100-point scale. Where it was only possible, 5.50. The subgroup differences were not statistically significant, so this does not prove that sorting patients by mechanism improves outcomes. It shows that most of the field never sorted them.

The calendar will not sort them either: in one clinic, a neuropathic component had essentially no correlation with how long the pain had lasted. How a sensitized system produces pain a scan cannot explain is covered in why your scan does not match your pain.

Question three: what state is the body in?

The third question is the one pain care rarely asks. When one joint replacement program screened all 1,461 incoming patients, 58.9 percent had diabetes or prediabetes, and 40.9 percent of those with diabetes had never been told. Universal screening before knee replacement in Hong Kong found undiagnosed prediabetes in 36.4 percent.

That number predicts the result. In 4,778 elective lumbar operations, a preoperative HbA1c above 8 percent carried 0.64 times the odds of a meaningful functional improvement. Across 17,472 knee replacements, diabetes blunted early pain relief. The other side deserves its place. In 587 hip and knee replacements, once body mass index and other illnesses were adjusted, 12-month pain and function scores were similar. Obesity with multiple illnesses is still terrain, but that study does not back the narrower claim that HbA1c alone predicts the pain result.

The guidelines leave this gap open. The 2022 federal opioid guideline runs 95 pages and names HbA1c, insulin, vitamin D or an inflammatory marker 0 times, and the word laboratory appears 4 times, each about urine toxicology. The British guidance on assessing chronic pain sets out 23 recommendations and names no blood test, although it does direct clinicians to ask about sleep, work, housing and income. Those belong in the history, because pain travels with them. When no guideline asks for a measurement, no payer builds around it, and it goes undone. The case for the one number almost nobody draws is in the post on fasting insulin and your nerves.

What changes when the terrain changes

Treat the imbalance and pain moves, in trials that never touched the joint. In 407 adults with obesity and knee osteoarthritis, weekly semaglutide cut knee pain by 41.7 points against 27.5 on placebo over 68 weeks. The placebo arm improved on counseling alone, so roughly a third of the total was the drug’s increment.

What is eaten matters, not only how much. In 129 patients on two calorie-set diets, weight loss did not differ, yet pain was lower on the Mediterranean pattern than on low-fat. In a 24-person pilot that first removed ultra-processed food from everyone’s diet, adding carbohydrate restriction lowered pain 17.9 millimeters against 11.0, and hsCRP fell only in the restricted arm. That points to the route: the pain change traveled with a fall in inflammation. Where the terrain did not change, neither did pain: a telephone referral that moved weight by 0.4 kilograms produced no pain change.

The needle has a place in that plan. In one cervical epidural cohort, arm pain fell from 8.7 to 3.5 at 3 months in a within-group measure, not a placebo-adjusted one, and 92 percent of the diabetic patients had transient high blood sugar afterward. As the whole plan, repeated indefinitely, an epidural buys under five points against placebo, and bone density reductions appear past a cumulative 200 mg of methylprednisolone in a year. As a bridge that makes sleep, movement and diet change possible, the relief earns its cost. Here is what an epidural steroid injection actually does.

Before any procedure, ask three things. Which structure, and will it be confirmed with two blocks? Which mechanism, and has anyone screened for nerve or nociplastic pain? Which terrain, and what are my HbA1c and fasting insulin? The studies and what each can and cannot show are in the Technical Supplement to Chapter 2, written to hand to your physician. Why an untreated terrain costs years is in the post on how chronic pain shortens life, and why the picture of your spine so often misleads is in the post on what an abnormal MRI really means.

Frequently asked questions

What is nociplastic pain?

Nociplastic pain arises from altered processing in the nervous system without tissue damage or nerve injury to explain it. It tends to be widespread or multifocal, often travels with fatigue, poor sleep and fog, and responds poorly to injections, surgery, anti-inflammatory drugs and opioids. It can exist alone or alongside tissue pain in the same person, so naming it early changes the plan. Why normal test results are expected in fibromyalgia.

What are examples of nociplastic pain?

Fibromyalgia is the clearest example. Chronic low back pain can carry a nociplastic component mixed with a structural one, which is one reason treatment aimed only at the spine can fall short. Clinicians look for pain lasting more than 3 months, spread beyond one discrete area, not fully explained by tissue or nerve injury, and showing signs of hypersensitivity. Why chronic back pain keeps coming back.

Why was pain called the fifth vital sign?

In 1999 the Veterans Health Administration asked for a 0-to-10 pain rating at every visit, and hospital accreditation standards followed in 2001. The number did not improve care: across 600 visits no quality indicator changed, and 52 percent of patients reporting substantial pain received no new therapy at that visit. A rating proves someone asked. It does not prove anyone looked for the cause. Why pain scores alone can mislead care.

Is one diagnostic block enough to find the source of back pain?

Usually not. In one lumbar series, a single uncontrolled block would have labeled 67.9 percent of patients positive, a false-positive rate of 49.8 percent, and an independent group found 38 percent. The evidence supports repeating the block on a separate day with a different anesthetic, under imaging, and trusting the result only when both answers agree. When low back pain is actually the sacroiliac joint.

Can losing weight reduce joint pain?

In trials, pain fell roughly as much as the metabolic terrain changed. Semaglutide in adults with obesity and knee osteoarthritis cut pain 41.7 points against 27.5 on placebo. After bariatric surgery, 77.1 percent of patients with severe knee pain improved meaningfully at one year. Programs too light to move weight did not move pain, and any drug decision belongs with your physician. What Wegovy and Ozempic do to knee pain.

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Medically reviewed by Dr. Gurpreet Singh Padda, MD, MBA, MHP, board certified in anesthesiology, pain medicine, interventional pain management, addiction medicine and obesity medicine. Adapted from Chapter 2 of The Pained Brain by Dr. Padda and Dr. KrisJay Fucanan, MD. Last reviewed September 2026.

Dr. Gurpreet Singh Padda, MD, MBA, MHP