Central Sensitization Inventory: What Your Score Can and Cannot Say

The central sensitization inventory is a symptom questionnaire. A score at or above the classic cutoff of 40 says your symptoms fit a nervous system that turns pain up. It is a screen, not a measurement. A high score is a reason to test with a pressure algometer (a pressure gauge). It is never a verdict about your character.

A replaced knee can look perfect on an X-ray and still hurt, and the proof of why often sits in the forearm. When healthy skin hurts at half the pressure a healthy person can stand, the problem has left the joint. Many patients first meet that problem as a number: a score on the central sensitization inventory, handed back with no explanation of what it means.

The video above, Chapter 9 of The Pained Brain, explains how the nervous system becomes an amplifier. Below: how the amplifier is measured, how far to trust each tool, and what a positive result predicts. The book is by Dr. Gurpreet Singh Padda, MD, MBA, MHP, and Dr. KrisJay Fucanan, MD.

The amplifier, in one cascade

Central sensitization is a lasting but reversible rise in how excitable the pain neurons of the spinal cord and brain become. Lasting means it outlives the injury. Reversible means it is not damage. Nothing is broken. Something has been learned.

The learning follows a chain. An inflamed joint keeps firing into the cord. The NMDA receptor on the receiving neuron, normally plugged by a magnesium ion, opens. The synapse strengthens the way a practiced skill strengthens. Then activated microglia, the resident immune cells of the nervous system, release a growth factor that disables the chloride pump the brakes depend on, so the inhibitory signal stops inhibiting. Inputs that never counted as pain now do. Light touch hurts. A pinprick repeated once a second climbs with every tap.

How strongly a nervous system turns pain up is a personal trait. Fifty healthy men were sensitized on four separate days. Each man’s own result barely moved, a correlation of 0.85. The correlation between different men was 0.03.

What the central sensitization inventory measures

The inventory is a symptom questionnaire. The classic cutoff is 40. At one Dutch pain center, 2,890 patients filled it out before their first visit. Their average score sat right at that line, at 40.2, against 16.4 in healthy volunteers. And 59.9 percent reported at least one central sensitivity syndrome.

The same data suggest the classic line is too high. The value that best separated patients from healthy controls was 30, with an area under the curve of 0.95, and it was 33 in women and 25 in men. That comes from one center and a Dutch-language version, and its authors warn against carrying the cutoffs elsewhere. Read a borderline score with that in mind.

Now the limit. Across 66 studies and 13,284 people, inventory scores tracked depression, anxiety and catastrophizing (expecting the worst) strongly. They tracked lab measures of nerve sensitivity only weakly. So the score is a screen for the syndrome. It is not a measure of the nerve connection itself. A high score is a reason to measure, never a verdict about your character.

The measurement: pressure, wind-up and the brakes

Three bedside tests look at the body directly. A pressure algometer, a calibrated gauge, is pressed on a spot far from the pain until you first say pain. A stimulus repeated once a second shows temporal summation, the spinal cord’s wind-up. Conditioned pain modulation applies one pain while testing another. It shows whether your body’s own pain brakes kick in.

• Pressure threshold: reliability of 0.77 or better across 88 people with rheumatoid arthritis, back pain or no pain. Different testers checked them one to three weeks apart.
• Temporal summation: 0.76 or better in the same study. It scored better as a difference than as a ratio.
• Conditioned pain modulation: the noisy one. Its best same-session reliability was 0.64 in healthy people and 0.77 in patients. And 24 of 25 studies were rated poor on reporting.

One abnormal reading is a research measurement, so the test gets repeated. The point of an instrument is the second reading.

Why the blood test missed it

In 160 people, 40 with degenerative disc pain and 40 with disc herniation plus two control groups, 34 inflammatory proteins ran high in the spinal fluid of each patient group. In the same patients’ blood, the inflammatory proteins ran below the controls. A normal CRP does not mean nothing is inflamed. It means the blood was the wrong place to look.

The drivers are metabolic, and at least two can be measured. In 265 adults with knee pain, low pressure thresholds went with more visceral fat (deep belly fat), a median 130 against 95 square centimeters. They also went with more leptin, 22.2 against 13.3 ng/mL. Both held in people with a normal BMI: thin outside, inflamed inside. CRP, fasting glucose and HbA1c showed no link at all. And in 302 healthy, pain-free adults, a heavier heart and metabolic load already went with more spinal wind-up and weaker brakes, before any of them had a pain condition. The gut is part of that terrain. That is why the gut’s reach into the spine belongs in the same conversation.

The third driver is social. Being disbelieved is a stressor, and chronic stress lowers the pain threshold. Invalidation by one’s own family raised the odds of the fibromyalgia phenotype 1.81-fold, separate from depression.

What sensitization predicts before a procedure

This is why I test before I schedule. In 103 knee replacement patients sorted before surgery, those with both extra wind-up and failed brakes got 52.0 percent relief at a year. Those with only one problem got 81.1 and 79.6 percent. In 464 hip and knee replacements, each point on a widespread-pain score raised the odds of failing to cut the pain in half by 17.8 percent. Failure ran 26.97 percent in the lowest third against 60.68 percent in the highest. In 37 patients over 65 given genicular radiofrequency plus a joint injection, a score of 40 or more dulled the pain relief by 2.1 points.

The opposite finding matters as much. After discectomy for a herniated disc, 100 patients improved whatever their score, and the average score itself fell from 22.3 to 13.7. Where there is a true mechanical lesion, fix it. The test does not cancel a procedure. It tells me whether the plan for the months after the procedure needs to be ready before the needle goes in, which also explains why each injection can buy less time than the last.

Turning the amplifier down

Input keeps the amplifier running. In 53 people with chronic whiplash, radiofrequency neurotomy (heat treatment of the nerves to the neck joints) cut body-wide sensitivity to pressure and heat at one and three months. When the nerves regrew and the pain came back at about ten months, the central signs came back with it. That is the bridge seen from the spinal cord. A block or an ablation does not cure the amplifier. It stops feeding it.

The quiet has to be used. In 110 adults who lost 7.9 percent of their weight by diet over three months, chronic muscle and joint pain fell from 51 percent to 25 percent, with no change in hsCRP. It had no control group and was short. It is the weakest design in the research and the biggest effect in it. Food, sleep and movement are prescribed like a procedure, because they cut off the fuel. Exercise is dosed like a drug, since the pain relief a healthy person gets from a workout does not reliably show up in a sensitized one. Fear is treated too, with Acceptance and Commitment Therapy given in-house.

The drugs aimed at the amplifier are modest: pregabalin in fibromyalgia has a number needed to treat of 7 to 14. Any medication change belongs with your own physician. The humility here is mine: my specialty built its tools for the joint, and the problem moved into the cord.

Related reading: Glial Cells & Central Sensitization Pain

Questions to bring to your appointment

• Can an algometer be pressed on a part of me that does not hurt, and repeated?
• Before this procedure, has anyone checked my wind-up and my brakes?
• Can we measure visceral fat and leptin, not only weight?
• What is the plan for the months a procedure buys?

The Deep Dive to Chapter 9 lays out every study cited here. It gives each number with its population and what each study does and does not show. It is written to hand to your doctor. When the amplifier drives someone to the emergency room at two in the morning, what that room can and cannot find is the next chapter.

Frequently asked questions

Is central sensitization real, or is the pain in my head?

It is a physical state of the nervous system. PET scan tracers have shown activated glia (support cells) in the brains of people with chronic back pain, fibromyalgia and knee arthritis. Spinal fluid in disc patients carries high levels of inflammation proteins. The pain is made by the brain and cord, as all pain is. But the amplification can be measured with an algometer. Here is why a scan so often fails to match the pain you feel.

What is a high score on the central sensitization inventory?

The classic cutoff is 40. At one Dutch pain center, a lower value of 30 best separated patients from healthy volunteers, with 33 for women and 25 for men. A high score shows that the symptom pattern fits sensitization. But the questionnaire also tracks mood and being on high alert. So it should lead to direct testing, not end the talk. See why normal test results are expected in fibromyalgia.

Why does my knee still hurt after a successful replacement?

About one in five knee replacements leaves chronic pain even when the implant is perfect. Patients with both extra wind-up and failed pain brakes before surgery got far less relief than those with just one problem. When the pain has moved into the nervous system, a new joint does not switch it off. The next step is to find the real driver. Read how persistent pain after knee replacement is worked up.

Can a blood test show central sensitization?

Not reliably. In disc patients, inflammation proteins were high in spinal fluid, while the same proteins in blood ran below healthy controls. In adults with knee pain, CRP, fasting glucose and HbA1c were not linked to low pain thresholds, but visceral fat (deep belly fat) and leptin were. Measuring the fat that sends signals tells you more than the marker in the blood. Learn how leptin resistance runs pain hotter than scans suggest.

Can central sensitization be reversed?

Often, yes. After knee replacement, neck radiofrequency and hip replacement, body-wide sensitivity eased once the painful input stopped. In whiplash it came back when the pain came back. In a minority, it lasts. Removing the input buys a window. The metabolic, sleep and movement work done inside that window is what keeps the volume down. Pain is the signal, not the disease, and that changes the treatment.

Sources

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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 9 of The Pained Brain by Dr. Padda and Dr. KrisJay Fucanan, MD. Last reviewed September 2026.

Dr. Gurpreet Singh Padda, MD, MBA, MHP