Should chronic pain be treated as a disease in its own right?

Monday 16 November 2009, London – A new review of brain imaging studies on patients with chronic pain discusses recent findings showing that after several years of suffering and enduring chronic pain there are functional, chemical and structural changes to the brain. The review of this growing literature poses the question as to whether chronic pain should be treated as a disease in its own right, rather than as a symptom¹.

The review, published in The Journal of Pain¹, outlines and addresses the complexities involved in chronic pain, and raises the issue that improvements in the assessment and management of pain for the 7.8 million people in the UK who have to live with chronic pain² are desperately needed. 

“Improving our understanding of chronic pain and its mechanisms will lead to better treatments that hopefully will enable people to regain their independence as well as significantly enhance their quality of life”, said Professor Irene Tracey, co-author of the article and Director of the Functional Magnetic Resonance Imaging of the Brain (FMRIB) Centre and Nuffield Professor of Anaesthetic Science at the University of Oxford.

Professors Tracey and Bushnell reviewed a number of functional, structural and molecular brain imaging studies on patients suffering chronic pain, even if the underlying cause of the pain differed, examining conditions such as: irritable bowel syndrome (IBS), chronic back pain, fibromyalgia, neuropathic pain, rheumatoid arthritis, osteoarthritis of the knee and stroke pain.  Although these painful conditions affect a range of different parts of the body, similar changes were observed in the brain and the authors examine the evidence against the current definition of a disease¹.

Summary of results observed¹:

Functional changes: Experiencing pain for a long duration of time, results in the brain being less able to cope, ultimately resulting in functional changes.  These changes include a reduced ability to inhibit the painful stimuli and over activity in brain areas that make the experience of pain more unpleasant.

Structural changes: The changes seen to the structure of the brain provide the best evidence that chronic pain should be regarded as a disease in its own right.  Chronic pain affects the brain structurally by causing grey matter (areas dense with nerve cell bodies) in the thalamus and lateral prefrontal cortex of the brain, as well as other areas, to reduce in size.  It is hypothesised that the reduction in grey matter in chronic pain may be due to excitotoxicity (continuous nerve stimulation) and nerve loss.

Chemical changes: Brain imaging studies have shown that healthy brains respond differently to pain compared to people living with pain over a prolonged period of time.  In people with chronic pain there appears to be a drop in the concentration of chemicals namely glutamate, N-Acetyl aspartate and dopamine.

About chronic pain:

Chronic pain affects approximately 20% of the world’s population¹ and has a large impact on people’s emotional and physical wellbeing.  There is also a large financial cost associated with chronic pain, estimated to be around 200 billion Euros per year in Europe¹ and in the UK alone, £3.8 billion a year is spent on incapacity benefit payments to those diagnosed with chronic pain².

Chronic pain is persistent and can be progressive. In contrast to acute pain, which arises suddenly in response to a specific injury and is usually treatable, chronic pain persists over time and is often resistant to medical treatments³.

There are a number of different medical conditions that can cause chronic pain including (but not limited to) diabetes, arthritis, migraine, fibromyalgia, cancer, shingles, sciatica, and previous trauma or injury³.

About the FMRIB Centre

The FMRIB Centre is a recognised world-class MR imaging laboratory that integrates research into key neurological and neuroscientific problems with cutting-edge developments in MR physics and data analysis (http://www.fmrib.ox.ac.uk). The Centre has a large number of scientists and clinicians and is highly multidisciplinary.

All media services undertaken by Galliard Healthcare Communications to increase awareness of this research have been funded by MSD.

References:

1. Tracey I and Buschnell MC. How Neuroimaging studies have challenged us to rethink: Is chronic pain a disease? J Pain. 2009; 10 (11): 1113-1120
2. Chronic Pain in the UK . Pain Coalition. Accessed 19 October 2009: http://www.paincoalition.org.uk/
3. Definition of Chronic pain. MedicineNet.com. Accessed 19 October 2009: http://www.medterms.com/script/main/art.asp?articlekey=22430

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 20/11/09