Chronic Pain: What Can be the Cause?

Contents

• What is central sensitization? How does it produce pain?

• Conditions that can be caused by central sensitization

• Causes of central sensitization

• Treatment of central sensitization

• How osteopathic manipulative treatment can help central sensitization

What is central sensitization? How does it produce pain?

Central sensitization is a condition that affects the nervous system (including the brain). It’s associated with patients diagnosed with several chronic pain conditions from whiplash to fibromyalgia and chronic fatigue syndrome (CFS).

In central sensitization the nervous system, like a computer, goes through a process where it alters it’s pain settings resulting in it turning up it’s pain sensing volume. This heightened state of alertness makes your nerves far more susceptible to feeling pain. It can, but not always, occur along side an injury and maintains the sensation of pain even after the injury may have healed.

In addition to your nerves registering every bump and touch as a painful stimulus central sensitization has some other characteristic traits. These are associated with heightened sensitivity across all the senses including:

• Sensitivities to climate factors such as light, draught, noise and odors(1).

• Cognitive deficits: poor concentration and memory(2).

• Emotional distress: anxiety(3), depression(3), poor quality of life(3), somatization(4), catastrophizing(4), hypervigilance(4), fear avoidane(4), obsessive compulsive disorder(10), bipolar disorder(10), panic attacks(10)and post-traumatic stress disorder(10)

Conditions that can be caused by central sensitization

Central sensitization has been associated with many different chronic disorders such as:

• Low back pain(5)

• Chronic neck pain(10)

• Whiplash injury to the neck(6)

• Headaches(7,10) including those associated from ‘digestive problems’(8)

• Migraine(7,10)

• Rheumatoid arthritis(9)

• Osteoarthritis(5)

• Over active bladder(10)

• Fibromyalgia(5, 10)

• Restless leg syndrome(10)

• Endometriosis(10)

• Irritable Bowel Syndrome (IBS)(10)

• Painful muscles (Myofascial Pain Syndrome)(10)

• Jaw (TMJ) pain from painful muscles(10)

• Primary functional dyspepsia(10)

• Periodic limb movement disorder(10)

• Primary dysmenorrhea(10)

• Painful bladder syndrome/ interstitial cystitis(10)

• Primary chronic tinnitus/primary chronic hearing loss(10)

• Vulvodynia/vulvar vestibulitis(10)

• Chronic prostatitis/chronic male pelvic pain(10)

• Post-traumatic stress disorder(10)

• Multiple chemical sensitivity (chemical intolerance)(10)

• Primary burning mouth syndrome(10)

• Primary chronic cough(10)

Causes of central sensitization

Central sensitization can come on following any injury or illness that affects the nervous system or causes pain and distress. This needn’t be just from an injury but also from an illness affecting your organs such as the pain from Irritable Bowel Syndrome (IBS).

Psychological stress has been associated with and known to exacerbate central sensitization(10). This is due to the intimate link with the parts of the brain that senses pain and controls aspects of our stress response, nervous system, hormones and body organs(11). This is partly how pain can literally make us feel sick, give us anxiety or just make us feel depressed. This whole body and mind response to pain is hypothesised as being a primitive response to ensure that we become vigilant so we don’t put ourselves in a situation that could lead to further harm(11).

The anxiety associated with these psychological stresses can, in turn, make the nervous system more sensitive exacerbating central sensitization.  This is especially true when compounded with insomnia.

Treatment Of Central Sensitization

The treatment options that should only be prescribed by an appropriate health care provider include(12):

• Medication: e.g., opioids, combined μ-opioid receptor agonist and noradrenaline reuptake inhibitor drugs.

• Topically applied analgesic therapies have strong potential for (temporally) decreasing painful inputs.

• Address metabolic factors e.g. ketogenic diets in some studies have been shown to reduce pain(13).

• Address neurotrophic factors e.g., decreasing brain-derived neurotrophic factor.

• Conservative treatments e.g. osteopathy(15) to help manage the pain.

• Education program for patients on how their pain’s caused.

• Cognitive behavioural therapy (CBT) to pragmatically assess pain and a patient’s behavior to their pain.

• Exercise therapy.

• Testosterone gel(14).

How osteopathic manipulative treatment can help central sensitization

Central sensitization can be initiated by an injury especially when compounded by an emotional stressor. Undoubtedly, to a varying degree, this is a phenomena present in all pain conditions as all pain involves some level of emotional response even if very mild and only transient.

In patients with recognised conditions such as Fibromyalgia central sensitization seems to hold a key to understanding their acute and disabling symptoms. However even in the case of a sprained ankle we see patients who over compensate disproportionate to their pain because of the fear and anxiety of exacerbating their problem. This form of central sensitization is of course very mild and short lived.

The only potential downside to understanding central sensitization is that injuries, which can be easily treat, can end up being undiagnosed. Why take the time in examining a patient to find an injury when you can just say ‘there’s no injury there it’s just your brain creating an illusion of an injury and pain – it’s central sensitization’!

Osteopaths are trained not just to find and fix injuries that can cause or are compounded by central sensitization but they can educate the patient as to what their injury is and what they can do at home. By reducing pain and getting you moving again the nervous system turns down it’s pain volume, it in essence resets itself to factory settings so it’s not sensing pain so readily.

A more complete review of the role of osteopathy for central sensitization(15) can be read for free on PubMed.

References

(1) Central Sensitization and Perceived Indoor Climate among Workers with Chronic Upper-Limb Pain: Cross-Sectional Study (2015). Emil Sundstrup, Markus D. Jakobsen, Mikkel Brandt,  Kenneth Jay, Roger Persson, Lars L. Andersen 

(2) Effects of Stress and Relaxation on Central Pain Modulation in Chronic Whiplash and Fibromyalgia Patients Compared to Healthy Controls (2016). Iris Coppieters, Barbara Cagnie, Jo Nijs, Jessica van Oosterwijck, Lieven Danneels, Robby De Pauw, Mira Meeus.

(3) Association between pain, central sensitization and anxiety in postherpetic neuralgia (2015).Schlereth T, Heiland A, Breimhorst M, Féchir M, Kern U, Magerl W, Birklein F.

(4)  Central sensitization: A biopsychosocial explanation for chronic widespread pain in patients with fibromyalgia and chronic fatigue syndrome (2007). Meeus M., & Nijs, J.

(5) Evidence for shared pain mechanisms in osteoarthritis, low back pain, and fibromyalgia (2011). Staud R.

(6) Lack of evidence for central sensitization in idiopathic, non-traumatic neck pain: a systematic review. (2015). Malfliet A, Kregel J, Cagnie B, Kuipers M, Dolphens M, Roussel N, Meeus M, Danneels L, Bramer WM, Nijs J.

(7) Sleep features and central sensitization symptoms in primary headache patients (2014). Marina de Tommaso, Marianna Delussi, Eleonora Vecchio, Vittorio Sciruicchio, Sara Invitto, and Paolo Livrea

(8) Gastrointestinal Headache; a Narrative Review (2016).Majid T Noghani, Hossein Rezaeizadeh, Sayed Mohammad Baqer Fazljoo and Mansoor Keshavarz

(9) Central Sensitization: A Generator of Pain Hypersensitivity by Central Neural Plasticity. Alban Latremoliere and Clifford J. Woolf

(10) Does central sensitization help explain idiopathic overactive bladder? (2016). W. Stuart Reynolds, Roger Dmochowski, Alan Wein and Stephen Bruehl

(11) Central Sensitization and Descending Facilitation in Chronic Pain State (2012). Emiko Senba, Keiichiro Okamoto, Hiroki Imbe

(12) Treatment of central sensitization in patients with 'unexplained' chronic pain: an update (2014). Nijs J, Malfliet A, Ickmans K, Baert I, Meeus M.

(13) Ketogenic Diets and Pain (2013). Susan A. Masino, David N. Ruskin

(14) A novel use for testosterone to treat central sensitization of chronic pain in fibromyalgia patients. White HD, Robinson TD.

(15) Sensitization and Interoception as Key Neurological Concepts in Osteopathy and Other Manual Medicines (2016). Giandomenico D'Alessandro, Francesco Cerritelli, Pietro Cortelli