Who is at risk for chronic back pain? For many, back pain occurs for a few days or weeks and then disappears. Sometimes acute pain develops into chronic pain because the cause was not discovered and treated properly; undiagnosed back pain is the most common type. However, sometimes two people with identical injuries have drastically different outcomes – one walks away pain free while the other is steeped in pain for years.
The link between physical and emotional pain has been substantiated through years of study. It is known that areas of the brain like the amygdala are involved in both physical and emotional processing and that the same neurotransmitters are used to communicate both. This means that emotional reaction to pain can indicate whether it will worsen or reside.
A new study conducted by neuroscientist Vania Apkarian of Northwestern University shows that, when it comes to the brain, the amygdala isn’t the only player in chronic pain. His study solidified a connection between the development of chronic pain and the level of communication between two brain regions: the insula and the nucleus accumbens. The study can be found in the July 1 issue of Nature Neuroscience.
The study consisted of 39 participants who had new back pain for between 1 and 4 months. Brain scans were taken of the patients at the study’s beginning, and then a few more times throughout the period of a year. 19 people still had pain by the end of the year, which constitutes chronic pain, while 20 had recovered. The brain scans of almost every participant whose pain became chronic showed elevated communication between the insula and nucleus accumbens.
Like the amygdala, these two components of the brain are players in our emotional response to situations. They are also involved in how the brain learns. When the activity in one of these areas increases, the activity in the other increases.
What does this heightened communication mean? The nucleus accumbens is responsible for teaching the brain how to judge and respond to situations. It is also the final stop in what is called the reward pathway. Dopamine is released into the nucleus accumbens to produce a feeling of pleasure after a fulfilling act. Whether chronic pain and the addiction cycle have a connection is unclear, but this study merits further consideration of this possibility. Since the nucleus accumbens teaches the brain how to respond to situations, a hyperactive one may teach the brain to continue responding to pain, even if the cause is no longer there. This could be especially relevant to people seeking fibromyalgia treatment.
The insula is responsible for inhibitory feelings. The nucleus accumbens senses rewards and shows the brain how to respond to situations while the insula checks the nucleus accumbens’ teachings and tries to weigh the situation. (See the interesting article at www.wired.com, which explains how the nucleus accumbens and insula interact when confronted with a shopping decision.)
Though the exact reasons for the relationship between this heightened brain communication and chronic pain are theoretical now, the relationship points to a possible new treatment path for people with nonspecific chronic back pain and fibromyalgia. For many, chronic pain is the result of undiagnosed and untreated biomechanical dysfunctions like muscle imbalance and myofascial pain. For others who have sought various forms of treatment to no avail or physically recovered from an injury but are still feeling pain, this study may lend insight.
The source of chronic pain isn’t always in the same area as the pain itself; sometimes brain function – or dysfunction – can cause pain sensations where none should be present. Keep up-to-date on research to ensure you and your doctor are considering all possible back pain causes.