Ask the Expert: Central Sensitization
Q: How do you clinically determine if a chronic pain patient has centralized pain? Do you record this in the patient's chart?
The question prejudices the answer by implying that centralization is an active process by the patient. Centralization is a neuro-inflammatory event with a genetic (possibly epigenetic or microbiome-related) predisposition and a peripheral trigger. It is not under the behavioral control of patients.
Unfortunately, no standardized, validated set of diagnostic criteria exists for centralized pain, but there are some good discussions of its characterization in the work of Daniel Clauw. CRPS (complex regional pain syndrome) is the quintessential centralized pain disorder. Centralization generally is associated with chronic pain, but the experience of acute and subacute pain is altered by central biochemistry, physiology, and states of consciousness. The science is incomplete.
My clinical interest is focused on pain related to spinal impairments and on CRPS (which always is centralized). When I’m persuaded to think that pain is mediated by central phenomena, I record the specific behavior that expresses and reveals the centralization. I also record, without blaming the patient, a theoretical mechanism by which it occurs but only when that mechanism implies a diagnostic or therapeutic option for the patient. If the theoretical mechanism does not lead to a diagnostic or therapeutic choice, then it is pure speculation that would serve only to “get me off the hook” for not being able to diagnose or address the peripheral pain generator.
Peter A. Moskovitz, MD
Clinical Professor of Orthopaedic Surgery and Neurological Surgery
George Washington University Washington, DC Chairman, Board of Directors RSDSA (Reflex Sympathetic Dystrophy Syndrome Association), www.rsds.org
Central sensitization occurs after repeated stimuli to peripheral nerves. The central nervous system (CNS) becomes excitable, and neurons acquire memory of the pain. Wind-up (neural excitability) occurs, with the CNS maintaining a state of high reactivity. Once central sensitization occurs, the CNS does not need input from the periphery to fire.
Clinically, central sensitization usually involves an increased sensitivity to touch or pain (allodynia and hyperalgesia, respectively). The presence of allodynia usually implies central sensitization has occurred. In addition, other senses may be heightened, such as reactions to light, sound, and smells. Cognitive deficits and concentration problems may be present. Anxiety and/or depression are more likely in those with central sensitization.
Central sensitization usually is present with many common conditions, such as chronic migraine, fibromyalgia, CRPS, irritable bowel syndrome, chronic pelvic pain, chronic low back and neck pain, and nervous system injuries, etc.
Once central sensitization occurs, it is more difficult to treat the condition. The usual preventive medications may not be as effective, and many patients overuse analgesics. Theoretically, if we effectively treat pain early in the process, the likelihood of central sensitization diminishes. For instance, if a 20 year-old-woman has 3 headaches per week, instituting preventive medications may decrease the chance that she will have daily headaches by the age of 25.
Regarding charting, I do not write central sensitization. It is implied that central sensitization is part of the problem in those with long-standing chronic pain.
Lawrence Robbins, MD
Robbins Headache Clinic
In general, I do not distinguish between centralized and neuropathic pain because they tend to be similar in their effects and respond similarly. And they are indeed similar to so-called thalamic pain.
They may respond to TENS (transcutaneous electrical nerve stimulation), especially applied to the opposite limb, as well as to intravenous magnesium, cranial electrical stimulation, biofeedback training, and hypnotherapy.
C. Norman Shealy, MD, PhD
Holos Energy Medicine Education
I make a diagnosis of centralized pain when the patient states their pain is constant, causes severe insomnia, interferes with intellectual functions, and exhibits central sensitization. I determine that the latter is present if the patient reports waves or episodes of allodynia and/or hyperalgesia. I have begun to notate the presence of centralization in my charts along with my usual diagnosis of intractable or chronic pain. Furthermore, I now use the term “centralized” on prescriptions, reports, and written communications in an effort to educate my circle of contacts that a patient may have peripheral and central components to their pain.
Forest Tennant, MD, DrPH
Editor in Chief
Practical Pain Management