Pain management: From a disease-oriented to a mechanism-based strategy
Traditionally, the treatment of chronic pain has relied on the particular diagnosis of the illness. Nevertheless, multiple current studies suggest that chronic pain sufferers tend to share a pattern of increased central response to pain, and limited central analgesic regulation. Therefore, it is proposed to move to a pain management strategy aimed at understanding and modifying the mechanisms that maintain chronic pain and explain the ineffectiveness of treatments.
Given that about 70% of patients with chronic pain have deficiencies in the central mechanisms of pain generation and inhibition, knowledge of these mechanisms is essential to provide effective care for patients who suffer pain and are resistant to drug treatments (e.g. opioids).
Central sensitization: a useful construct to better understand pain
An intense and continuous experience of pain can cause changes in our nervous system that explain an exaggerated response to the sensations we receive and a reduced protective response to pain. These changes, which first appear in the spinal cord and are known as central sensitization, can change the connections in the brain (or in other words, can produce non-adaptive neuroplasticity).
Many scientists and medical professionals believe that the best way to combat these negative neuroplastic changes is to understand them. If we are able to speak the same language as the brain and convince it to return to a healthy and normal state of functioning, we could reduce or even eliminate chronic/bad pain. The evidence supports this premise. For example, in a study conducted in Dr. Graven-Nielsen´s 1 laboratory, when researchers corrected abnormal pain mechanisms prior to total knee replacement surgery, patients were less likely to develop knee pain after surgery and more likely to recover successfully.
Tools to measure central response to pain
The good news is that there are many tools available for researchers to understand how bad pain is generated and maintained. Some of these tools are:
1) Electroencephalography (EEG), a non-invasive way of measuring the electrical activity of the brain to know its response to painful stimuli.
2) Transcranial magnetic stimulation (TMS), a way of activating different neurons in the brain, probe their function and even stimulate healthy changes.
3) Quantitative sensory evaluation (QST). These methods use different sensations (e.g., pressure, heat and cold) to see how the brain responds to them, and to measure changes over time.
All of these tools are of great value to our exploration and understanding of how chronic pain works, and how we can treat it.
1 Graven-Nielsen T, Wodehouse T. Normalization of widespread hyperesthesia and facilitated spatial summation of deep-tissue pain in knee osteoarthritis patients after knee replacement. Arthritis &. Epub 2012.