Central Sensitization and Hyperalgesia Are Bogus Medical Terms

By Dr. Forest Tennant

Some 15 years ago, “central sensitization” was a term I first started seeing when I was editor of Practical Pain Management. It was defined as experiencing a pain level above what was normally expected from arthritis, fibromyalgia, neuropathy, and other peripheral (outside the brain) pain conditions. 

When central sensitization was present, it was an indication to more aggressively treat the pain with opioids and/or other measures. Unfortunately, this simple, well-meaning term has been transformed by some unscrupulous practitioners to imply that patients with central sensitization don’t need opioids or other treatment.

Central sensitization also became synonymous with the term “hyperalgesia” – meaning the patient was overreacting or feeling too much pain for their condition. What’s more, opioids were supposedly the cause of hyperalgesia, so they need to be stopped. 

Let’s be very clear. Neither “central sensitization” nor “hyperalgesia” are bonafide medical conditions. A medical condition is one in which there is a common set of symptoms and physical findings, and the condition can be confirmed by a diagnostic test such as an MRI or blood test. 

Central sensitization and hyperalgesia are bogus medical conditions that can’t be objectively identified, quantified, or diagnosed. They are simply terms that sound scientific and authoritative, when in reality they have become fraudulent terms used to justify withholding opioids and other treatments.

It is time patients, families, and physicians reject these terms and the medical practitioners who use them.

Central sensitization is not to be confused with the term “central pain.” This is a serious condition that more likely than not requires opioids, along with great care and concern on the part of the medical practitioner.

“Central pain” initially referred to the emergence of pain after a stroke. Strokes can wipe out and destroy brain tissue that contain opioid receptors and the normal biologic apparatus which shuts down and relieves pain. One especially severe post-stroke pain condition is known as the Dejerine-Roussy Syndrome, which damages the thalamus. 

Opioid drugs, sometimes in high or unusual formulations, are required for post-stroke central pain.

Although central pain was first associated with strokes, it soon became appropriate to include brain tumors, hydrocephalus, and scarring from meningitis infections, since these conditions can also wipe out brain tissue and cause pain.

In recent times, central pain has come to include those pain patients who have developed neuroinflammation and tissue destruction in the brain concomitantly with a peripheral pain problem that may involve the joints, muscles, nerves, or spine.

It is interesting to note that central pain in the past was often called “secondary pain” as it tends to occur after someone has developed a peripheral pain condition. 

The first investigator to elucidate peripheral pain conditions with brain tissue destruction was Apkarian in 2004.He and his colleagues found decreased prefrontal gray matter deficiencies in the brain scans of persons with chronic back pain. 

Since that time, a plethora of brain scan and glial cell studies have found that persons with a peripheral pain condition may experience brain inflammation involving glial cells and tissue destruction — akin to what occurs after a stroke. 

Bona fide central pain is clinically typical and obvious. It is characterized by constant (24/7) pain and high pulse rates, hypertension, episodes of excess sweating, and cold hands and feet.

Prescription opioids, including long-acting opioids, may be required to control bonafide central pain. In addition to opioids, central pain has what is called descending pain, which requires dopamine stimulating drugs to adequately control it. 

The cause of central pain that accompanies or follows the development of a peripheral pain condition is now believed to be related to an autoimmune process and/or viral reactivation, especially from the Epstein-Barr virus.

In summary, central sensitization and hyperalgesia are not bonafide medical conditions. To use these bogus labels to justify the withholding of medications is unscientific, fraudulent and inhumane. 

These terms and the practitioners who use them should be summarily rejected. Central pain is a serious condition characterized by severe constant pain which often requires opioids for pain control. 

Forest Tennant, MD, DrPH, is retired from clinical practice but continues his research on the treatment of intractable pain and arachnoiditis. Readers interested in learning more about his research should visit the Tennant Foundation’s website, Arachnoiditis Hope. You can subscribe to its research bulletins here.   

The Tennant Foundation gives financial support to Pain News Network and sponsors PNN’s Patient Resources section. 

Do You Have Central Sensitization or Intractable Pain?

By Forest Tennant, PNN Columnist

Chronic pain patients may now be told by their doctor, nurse practitioner or pharmacist that they have “central sensitization” (CS). This vague, non-descriptive term is unfortunate in many ways. Nevertheless, it appears to be here to stay. 

Since Intractable Pain Syndrome (IPS) is a far more serious condition that requires an aggressive, multi-component treatment approach, it is essential to know the difference between IPS and CS. 

Going forward, we believe that it will be increasingly difficult to obtain some medications unless you have IPS. Therefore, it is of vital importance to not only know if you have IPS, but you must be able to clearly explain it to your physicians, family and insurance carrier. If you have simple chronic pain or CS, you could be quite limited in obtaining many prescription medications. 

Definition of Central Sensitization: Amplification or heightened pain above what would normally be expected from tissue damage or injury. 

CS occurs when brain tissue starts to alter due to excess electric currents that originate in damaged or injured tissue. Brain tissue alteration is referred to as neuroplasticity. CS can often be recognized if pain advances, because it begins to cause insomnia and requires daily, rather than “as-needed” medication. 

CS is the forerunner or precursor of IPS. Almost all persons with IPS have had or currently have CS. There is a movement among medical practitioners to recognize CS and treat it with drugs like duloxetine (Cymbalta) or pregabalin (Lyrica) to prevent it from advancing to IPS. 

Definition of Intractable Pain Syndrome: Constant, incurable pain with cardiovascular, endocrine and autoimmune complications.

Only some medical conditions cause IPS. The most common are arachnoiditis, Ehlers-Danlos syndrome, brain injury and Reflex Sympathetic Dystrophy (RSD or CRPS). 

Levels of estradiol and testosterone often go down with IPS, causing symptoms which include amenorrhea in women (missed menstrual periods), impotence in men, fatigue, loss of sex drive, osteoporosis and loss of teeth.

Your autoimmune system will also be affected by IPS, causing elevation of inflammatory markers, cytokines, proteins, and white blood cells.

This could result in symptoms of fibromyalgia, thyroiditis, carpel tunnel syndrome, TMJ, mast cell activation, and migratory joint pains.  

Pain from IPS will cause elevations of pulse and blood pressure. Cortisone and insulin levels will also go up, causing elevations in glucose and cholesterol.

“Going forward, we believe that it will be increasingly difficult to obtain some medications unless you have IPS... If you have simple chronic pain or CS, you could be quite limited in obtaining many prescription medications.”

— Forest Tennant

It is up to the pain patient with IPS to educate all concerned parties that their CS has turned into IPS and that it is a serious syndrome with cardiovascular, endocrine, and auto-immune complications. 

Each person with constant pain needs to catalogue the above manifestations and make a record to give to your medical practitioners and pharmacist. If you haven’t had blood tests for hormone and autoimmune dysfunction, you must request these be done. Please review our website and obtain materials on IPS for your medical practitioners and pharmacist. 

Forest Tennant is retired from clinical practice but continues his research on intractable pain and arachnoiditis. This column is adapted from newsletters recently issued by the IPS Research and Education Project of the Tennant Foundation. Readers interested in subscribing to the newsletter can sign up by clicking here.

The Tennant Foundation gives financial support to Pain News Network and sponsors PNN’s Patient Resources section.