A German researcher1 has found evidence that chronic pain after whiplash may affect the actual structure of the brain.
Dr. Mark Obermann, a neurologist, found that he had many whiplash patients with chronic pain, and wondered if brain scans would show any evidence of what was causing the long-term symptoms.
He used high resolution MRI to check the brain density of 30 whiplash patients and 30 control subjects. The researchers took three MRIs of each patient: one within 14 days of the injury, another at three months, and a final image one year after the collision.
At the three-month mark, 10 patients (33%) had daily headaches.
The 14-day MRIs were normal; but at three months, the MRI images, “…showed reduced gray matter in the anterior cingulate and dorsal lateral prefrontal regions in only patients who continued to have headache pain at three months.”
One year later, the gray matter changes were not found in any patients. At this time only two patients still had headaches, and one of these was medication-related.
The article states:
“The areas where the change was noted…are involved with pain and the affective experience of it.”
The findings seem to show that the anatomical changes in the brain are related to chronic pain, and when the pain is resolved, the changes in the brain disappear.
Chronic Pain and the Brain
Why is this study important?
For years, researchers have been convinced that chronic pain after whiplash is much more complicated than “injury to the spine” = “chronic pain.” While clearly the trauma of a rear-end collision results in objective injury to the tissue, the long-term effects of this local trauma can end up being much more widespread and debilitating.
This has been the basis of the work on “central hypersensitivity” – or the concept that localized trauma results in brain changes that can, in turn, affect how the body processes pain in general.
In central hypersensitivity, a traumatic event “activates” the brain to be hypersensitive to painful stimulus. In whiplash patients, this results in reduced pain thresholds, and has been shown to result in fibromyalgia-like symptoms over time in certain patients.
These disturbances in the central nervous system can result in long-term problems in some patients. A 2003 study found:
“These sensory disturbances occurred independently of psychological distress, within a month of injury and persisted unchanged to 6 months post-injury. It is likely that such changes in sensory function reflect altered nociception within the central nervous system.” 2
This latest study shows that these nervous system changes can also affect the brain. This can be especially important because the anterior cingulated has been linked to depression in other studies. It’s possible that depression after an injury may be related to actual changes in the chemistry of the brain caused by chronic pain.