Unlocking The Reasons for Chronic Pain
We have all experienced pain at some stage in our lives and anticipate pain as a consequence of injury. Despite this anticipation though we expect that with healing and time, pain will resolve. However, acute pain can persist for many months or years, becoming chronic in its nature; a prospect difficult for many of us to imagine.
People who suffer from chronic pain often don’t understand why they still have ongoing pain even though their injury has healed. Therefore, some of them ask me if there is a “pain centre” within our body, particularly in the brain, where pain is generated. One of my chronic pain patients actually quipped: “If you tell me where the pain hub is I will go to a surgeon and get them to cut it out”.
Unfortunately, there is no simple answer as multiple factors play a role in the development and the ongoing nature of chronic pain. Older theories about the causes of chronic pain focused on the periphery (e.g. damage in a body part) or on the processing of nociception (signals from the periphery that signal damage or the potential of damage) at the level of the spinal cord. There now is consistent and compelling evidence that treatments based on these theories are not effective in reducing pain. Central brain processes are now recognised as playing a key role in the experience of pain.
I have been at the forefront of discovering the critical role of the brain in the development and sustainment of chronic neuropathic pain. We have shown that chronic neuropathic pain is associated with altered thalamic anatomy, biochemistry and activity. This can disturb central processing and play a key role in the persistent experience of ongoing pain. Our research shows that inhibitory brain cells (which are normally blocking out pain) within the thalamus stop functioning in individuals with ongoing pain. As a result the amount of GABA (the chief inhibitory messenger of neurologic information from one cell to another) is decreased. This loss of inhibition mean that the brain itself is altered which results in brain activity changes that then are perceived as pain. So the brain has lost its ability to inhibit sensory information, is more sensitive and therefore pain and sensory signals are amplified resulting in the experience of chronic pain.
In our present study we also found a decrease in GABA in the prefrontal cortex among people with chronic neuropathic pain. The prefrontal cortex is known to be involved in emotional processing. This decrease in GABA (which represents a loss of inhibition) might explain why people with chronic neuropathic pain also suffer from emotional disorders such as anxiety and depression. A loss of inhibition within the prefrontal cortex can mean that people with chronic pain can’t stop thinking about their pain and constantly anticipate pain with pessimistic, negative and fearful thoughts. They can’t stop these ruminations as the prefrontal cortex has lost parts of its ability to inhibit these thoughts.
In a new study we would like to target these brain alterations using a neuromodulatory approach that can provide pain relief via the primary source of pain: the human brain. We would like to modulate these functional, structural and biochemical changes via electroencephalography based neurofeedback which may lead to significant and sustained pain reduction. Neurofeedback teaches individuals to gain control over their brain states via electroencephalography biofeedback.