Structural MRIs Can Be Used to Detect Chronic Low Back Pain

Low back pain is a significant problem, afflicting between 60% and 80% of adults in the United States. A significant number of these episodes will continue to develop into a chronic condition.  Each year, chronic back pain sends approximately 13 million people to the doctor, second only to the common cold.

Back pain is the main reason why people under 45 years of age experience physical limitations, and causes disability in almost 5 million people, half of whom are permanently disabled.

The incidence of chronic low back pain is rising in the United States, and it costs more than $100 billion a year, two-thirds of which is from lost wages and productivity.

Although low back pain is a common condition, its causes are not well understood in 85% to 90% of all cases. This can make it difficult to diagnose and treat the problem adequately.

Pain researchers are beginning to understand that the brain plays a significant role in causing and maintaining chronic pain. Using an MRI machine, we can look at the structure and function of the brain to see where pain is processed and how it structurally changes the brain.

There have now been many studies that have shown abnormalities in brain function and brain structure in people with chronic pain. However, to date, no one has ever demonstrated that a pattern of brain activity or brain structure can be used to determine whether someone is in chronic pain. Accomplishing this yet elusive goal would take us one step closer toward having a more objective measure of chronic pain.

We studied 47 healthy patients and 47 patients with chronic low back pain and captured  magnetic resonance imaging scans (MRIs) of the gray matter in the brains of both groups. Both groups had substantially equal numbers of men and women, and averaged about 37 years of age. In addition, the study participants with low back pain were not taking any prescription pain medication at the time of the test, nor did they have any other painful or psychiatric conditions.

Our study was able to successfully identify whether someone was experiencing chronic low back pain in 76% of the cases, based just on their brain imaging patterns. We also identified specific changes in the gray matter in people suffering from chronic low back pain. These changes were distributed throughout the various areas of the brain that have been found to be associated with chronic pain. These results are a promising advance in our understanding of the brain’s role in chronic low back pain and in our ability to classify the disease and pinpoint its various causes.

While these are exciting first steps in using brain imaging to detect the presence or absence of pain, we are still a long way away from using this has a clinical “pain detector”. These participants were very specifically and carefully chosen and don’t necessarily represent the typical patient with chronic low back pain. Further studies will need to be conducted and the techniques refined. Nonetheless, we are enthusiastic about these preliminary results in helping us to take further steps towards a personalized approach to pain management.

Ung H, Brow JE, Johnson KA, Younger J, Hush J, Mackey S. Multivariate classification of structural MRI data detects chronic low back pain. Cerebral Cortex Advance Access published December 17, 2012.