In an earlier article we considered changes to the brain in people with CRPS solely in the context of poor memory or ‘brain fog’. In this regard, in addition to factors such as poor sleep and the side-effects of medication, there has long been speculation in the medical profession that memory loss for those suffering CRPS may also be the result of a malfunction in a part of the brain known as the Limbic System, which is involved in the control of our mood and instinct.
However, in recent years, more advanced medical imaging techniques have meant that, for the first time, there is actually now visual evidence that people with CRPS undergo significant changes in certain areas of the brain.
The studies undertaken involve complex neuroscience, much of which can be difficult to fathom. Before considering the results of these studies further, a brief glossary may be helpful. My apologies to anyone in the science community for the over-simplification, which is entirely for my benefit!
Grey (or gray) and white matter
The brain essentially consists of grey matter and white matter, named for their respective shades (actually pinkish-grey and white). The shade comes down to the fat content and the presence of blood vessels.
Grey matter comprises neurons (commonly referred to as ‘brain cells’) and glial cells, which hold neurons in place, insulate them from one another, supply them with essential oxygen and nutrients and remove waste.
White matter comprises the nerve fibres which connect areas of grey matter and along which nerve signals pass. If an area of white matter is damaged, the brain may eventually be able to rewire itself; finding an alternative route to replace the lost connection(s).
Such rewiring is an example of brain plasticity. Brain plasticity (or neuroplasticity) is the brain’s ability to change itself over time by modifying its connections. These changes do not just occur in order to repair damaged connections. They are essential to our development, allowing us to develop from a child to an adult, as well as helping us to adapt to new situations and environments.
But brain plasticity can also have a negative effect.
Research published recently in the Journal of Pain is just the latest to suggest that people with CRPS undergo significant brain plasticity resulting in marked structural and functional changes in certain areas of the brain.
The researchers found that people newly diagnosed with CRPS showed both reduced blood flow and a lower volume of grey matter in regions of the brain associated with both pain and movement. This indicated the occurrence of brain plasticity during the early stages of CRPS.
In patients with long term CRPS, whilst there did not appear to be a further reduction in the volume of grey matter, the study found that there was a clear negative relationship between average levels of pain and the volume of grey matter in regions of the brain associated with pain processing. In other words, the lower the volume of grey matter in those areas, the higher the average levels of pain reported.
Graded Motor Imagery
However, the ability of the brain to change can provide hope in the form of targeted therapy. Perhaps the best example of this familiar to people with CRPS is Graded Motor Imagery (GMI).
The idea behind GMI is to train the brain to re-connect to the part of the body affected by pain. The accepted theory is that in a person with CRPS, their brain effectively disowns the part of the body affected, seeing it instead as a threat. Normally, when we injure ourselves the brain perceives this threat and, as a protection mechanism, produces pain as an alarm signal, which allows us to deal with and treat the injured area. However, in cases of CRPS, this alarm system is faulty.
GMI focuses on the areas of the brain responsible for sensation and movement. In each area there is a particular space for each part of the body. When somebody suffers pain for a long time the space associated with the painful part of the body can become ‘fuzzy’, creating confusion in the brain, which in turn continues to produce pain as a protection mechanism. In essence, this is the brain’s way of attempting to identify the affected part of the body. GMI involves a series of steps aimed at helping the brain to re-identify the affected part and thereby reduce pain. The step in the GMI process that most people are familiar with is of course mirror therapy.
Whilst there has been considerable research on the efficacy of GMI as a treatment for CRPS, the results reported can at best be described as variable. Interestingly, however, in terms of a reduction in levels of pain, results for GMI have generally been more positive for people suffering CRPS than for people suffering other chronic pain conditions.