Dr. Daniel Clauw set the tone in his keynote address on central and peripheral mechanisms. He presented on the degree of “fibromyalgia-ness” as measured on the Modified American College of Rheumatology Fibromyalgia Diagnostic Criteria (Mod ACR-FDC)(1) in conditions such as knee osteoarthritis, which historically have been equated with dominant nociceptive drivers, not central pain mechanisms.
Fibromyalgia-ness is a term coined by Wolfe (2009). (2) He writes that the symptoms of fibromyalgia (central sensitization) occur as a continuum in the population, rather than simply being present or absent (2). In disorders such as rheumatoid arthritis, lupus, low back pain, and pelvic pain to name a few, the Fibromyalgia (FM) score is more predictive of pain levels and disability compared to more objective measures of the disease and/or the tissues themselves(2,3).
Nineteen of the 31 points on the Mod ACR-FDC are based on how widespread the pain is, and the other 12 points are derived from co-morbid symptoms that accompany central sensitization including lack of sleep, fatigue, brain fog, headaches, lower abdominal pain and depression. A total score is created by adding up the two subscales. The cut-off for Fibromyalgia is 13 or greater. (1)
For anyone who knows me, it will not surprise you to hear that I have a love affair with questionnaires. Questionnaires help inform treatment, and allow us to direct appropriate treatment to the phenotypes of central pain mechanisms.
Dr. Clauw recommended that we use the Mod ACR-FDC to first reliably identify central pain mechanisms within conditions not historically linked with this clinical picture, such as knee osteoarthritis. The Mod ACR-FDC is a quick screen to assess how widespread the pain problem is, which is strongly correlated with central sensitization.
In Dr. Clauw’s study on knee osteoarthritis and total knee replacement (TKR), each one point increase in fibromyalgia-ness on the Mod ACR-FDC led to nine mg greater oral morphine requirement during post-surgical hospitalization, and 20-25 percent greater likelihood of failed pain relief from surgery. These phenomena were linear across the entire scale up to a total score of approximately 18, and equally strong even after individuals who met criteria for FM (total score of 13 or greater) were excluded. This phenomenon was much stronger than, and largely independent of, classic psychological factors for predicting central sensitization.
Dr. Clauw reported that the most prevalent pain conditions in younger individuals are now thought to be more “central” than “peripheral.” Central pain mechanisms can also be identified within individuals who present with concurrent nociceptive or neuropathic pain states. Patients often present with a mixed pain state, and both nociceptive drivers and the nervous system need to be evaluated.
This still remains deeply unappreciated in clinical practice so there is marked overuse of tissue-based treatments for persistent pain (opioids, injections, surgery, mobilizations) when the target should be the central nervous system (CNS). Rather than thinking of FM as a disease, think of it as a CNS-driven pathophysiological process that can co-exist with many other disease processes.
Identification of central sensitization is vitally important. But what happens next? In the example above, which patients need to strengthen their quadriceps? Who should be operated on? Who should be mobilized or manipulated? Who needs pain education? Who would benefit from yoga, qi gong, or tai chi?
Let’s not create a “label” of central sensitization and get trapped in the same research quagmire as we have for the past few decades with non-specific low back pain (LBP). Low Back Pain is not non-specific, and neither is central sensitization. However, they are both complex disorders with characteristics significant to the individual and their presentation.
Long et al (2004) published an RCT in Spine demonstrating that 74 percent of 312 acute and chronic LBP patients have an identifiable directional preference by using a standardized mechanical assessment. (4) Their conclusions stated, “regardless of subjects” direction of preference (DP), the response to contrasting exercise prescriptions was significantly different: exercises matching subjects’ DP significantly and rapidly decreased pain and medication use and improved in all other outcomes. If repeatable, such subgroup validation has important implications for LBP management.” Despite the reliability of identifying directional preference, and the matched response in decreased pain and medication, mechanical pain has not become a recognized phenotype of LBP to assist research to target efficacious exercise prescription.
Let’s not get stuck in this same dilemma with central sensitization. We need to create phenotypic characteristics of central pain mechanisms and investigate the best interventions for each phenotype. This starts with utilizing validated questionnaires such as the Pain Catastrophization Scale (PCS), Tampa Scale of Kinesiophobia (TSK), Depression, Anxiety and Stress Scale (DASS-21), Positive Affect, Negative Affect Scale (PANAS) and Fremantle Back Questionnaire (FreBAQ) to identify the phenotypes of a sensitized state. There is already a cache of well-validated treatment modalities for the sensitized nervous system such as pain education, yoga, mindfulness meditation and qi gong/tai chi, all based on strong therapeutic alliance and self-efficacy, two further potential targets.
By way of example, mindfulness meditation is not going to be the panacea for everyone with central sensitization; however, certain phenotypic patient characteristics such as rumination, magnification, and a high degree of secondary suffering may be clinical indicators for those who would respond best to mindfulness meditation. However, if we don’t specifically measure rumination and magnification, how will we know?
And, if we don’t measure central pain mechanisms, we will remain focused on treating the nociceptive drivers. I, for one, will take Dr. Clauw’s recommendation and start looking at my persistent pain patient’s fibromyalgia-ness, and start assessing the clinical relevance of this new piece of research. I will compare it to using the Central Sensitization Inventory (CSI) for persistent pain, and assess which provides more clinically relevant and measurable information. They both measure the degree of central sensitization. Evaluate both in the clinic for yourself to see which best fits your practice and practice style.
Thank you Dr. Clauw for your inspiring lecture!
- Wolfe, F., Clauw, D., Fitzcharles, M., Goldenberg, D. Hauser, W. Katz, R., Mease, P., Russel, A., Russell, I., and Walitt, B. (2016). 2016 Revisions to the 2010/2011 fibromyalgia diagnostic criteria. Seminars in Arthritis and Rheumatism, 46(3), pp. 319-329.
- Wolfe, F. (2009). Fibromyalgianess. Arthritis & Rheumatism, 61(6), pp.715-716.
- Clauw, D. (2014). Fibromyalgia. JAMA, 311(15), P.1547.
- Long, A., Donelson, R, and Fung, T. (2004). Does it matter which exercise? Spine, 29(23), pp.2593-2602.
About the Author
Carolyn Vandyken, BHSc (PT), Pelvic Health Physiotherapist, has practiced in a wide variety of clinical settings and has spoken at over 50 conferences and presentations throughout Canada and the United States. She owns a Canadian-based teaching company, Pelvic Health Solutions, and manages her own clinic, Huntsville Pelvic Health and Pain Centre in Huntsville, Ontario.