What is central sensitization?

By Karen Bang, PT

Central sensitization is defined as the amplification of pain by mechanisms of the central nervous system. It is now understood that it can occur independent of peripheral injury or inflammation and it is widely recognized that central sensitization is involved with nearly all chronic pain conditions (Harte et al., 2018).

What does central sensitization involve?

There are several signs that may lead you or your clinician into thinking that you are experiencing a component of central sensitization (Vandyken, 2021).

Pain that is lasting longer than 3 months
When you sustain an injury, whether it is a bone fracture, a muscle strain, or an ankle sprain, your tissue should be healed within the normal healing time frame of 12 weeks. Any pain that lasts longer than the normal tissue healing time is often labeled as chronic pain.

Pain that is widespread
Pain associated with an acute injury is often contained to a local area of the body or follows a specific nerve distribution. A hallmark sign of central sensitization is having pain that is diffuse and occurs in more than one area.

Hyperalgesia and allodynia
Hyperalgesia is defined as experiencing pain that is disproportionately severe compared to the intensity of the stimulus. Allydonia is when you have pain in response to a previously non-pain producing stimulus. For example, a moderate slap on the skin may produce intense pain (hyperalgesia) or a gentle stroke over the skin could result in discomfort (allyodynia) (Coutaux et al, 2005).

Pain that is not related to a specific mechanical factor
In a centrally sensitized individual, their pain is often confusing with an ill-defined pattern of triggers.

Depression, catastrophization, and/or fear of re-injury
Psychological factors including fear and catastrophization have been found to be highly correlated with central sensitization. Catastrophizing is when you assume that the worst thing will happen and in the context of pain or injury, it is having the feeling of a poor prognosis related to recovery.

Who might be experiencing central sensitization?

Central sensitization is often present in conditions such as urinary chronic pelvic pain syndromes, endometriosis, fibromyalgia, irritable bowel syndrome, depression and/or anxiety, headaches, temporomandibular joint disorder, and low back pain (Harte et al., 2018). It is sometimes present in conditions including shoulder pain, rheumatoid arthritis, non-traumatic neck pain, tendinopathies, pain following cancer, tennis elbow, and patella femoral pain syndrome (Nijs et al., 2019).

Questionnaires that can help you or your clinician determine if you may have central sensitization include the Central Sensitivity Inventory and the Depression, Anxiety, and Stress Scale. These questionnaires will include questions about your sleep quality, energy levels, ability to wind down, level of positive affect, and many other factors affecting your well-being.

The Good News

Your central nervous system is capable of change! This means that you and your clinician can partake in the process of central de-sensitization or central nervous system down-regulation. The central nervous system actually has the ability to change much quicker than your tissues can! Your physiotherapist can help you address lifestyle factors that are involved in the process of central sensitization including physical activity, stress, sleep, beliefs, and diet (Nijs et al., 2019).

References:

Coutaux, A., Frederic, A., Willer, JC., Le Bars, D. Hyperalgesia and allodynia: peripheral mechanisms. Joint Bone Spine. 2005:72, 359-371. doi:10.1016/j.jbspin.2004.01.010

Harte SE, Harris RE, Clauw DJ. The neurobiology of central sensitization. J Appl Behav Res. 2018;23:e12137. https://doi.org/10.1111/jabr.12137

Nijs, J., Polli, A., Willaert, W., Malfliet, A., Huysmans, E., & Coppieters, I. (2019). Central sensitisation: another label or useful diagnosis?. Drug And Therapeutics Bulletin, 57(4), 60-63. doi: 10.1136/dtb.2018.000035

Vandyken, C. (2021, September). Biopsychosocial Reframed: Using Distress Questionnaires to Create Psychologically Informed Practice.