Chronic Pain Correlates with Brain Region Enlargement

Pain: a seemingly simple four-letter word, but healthcare providers know that pain is anything but simple. While there has been ample research elucidating the pathways and mechanisms of neuropathic pain, a recent analysis successfully identified a key brain region that plays in a role in complex regional pain syndrome (CRPS).

A collaborative effort from researchers at Aalto University, Helsinki University Hospital, and Harvard Medical School revealed that a difference in a particular region of the brain, choroid plexus, could help explain pain conditions. Limited information is available about the choroid plexus. It is known that its function is to produce cerebrospinal fluid, which creates a protective buffer for the brain. In addition, it controls the substances which pass through blood into the brain, spinal cord, and cerebrospinal fluid. But beyond that, the area has been largely neglected, partly due to the fact that it’s not typically a target in routine brain scans.

“As the choroid plexus is known to mediate the interaction between inflammation in the periphery of the body and in the brain, it is an interesting and important target for future research of chronic pain and CRPS in particular,” one of the researchers Riitta Hari, a professor at Aalto University, said in a news release.

By using 3-tesla structural magnetic resonance images, the team was able to study the choroid plexus (located in the walls of the brain ventricles). More specifically, they looked at the size and volume of the region in 32 subjects, half of which had CRPS and the other half being health controls. After examining 29 subcortical brain regions, it became apparent that an enlarged choroid plexus was associated with CRPS — a finding that the authors describe as “unexpected.”

“When studying magnetic resonance images of the brains of patients suffering from CRPS, we noticed that the choroid plexus was nearly one-fifth larger in patients than in healthy control subjects,” confirmed first author Guangyu Zhou, a postdoctoral researcher in the Department of Neuroscience and Biomedical Engineering at Aalto University.

As described in Scientific Reports, the data revealed a 21.1% larger right lateral-ventricle choroid plexus in patients with CRPS when compared to healthy controls. Those patients had a 12.6% larger region even when compared to patients with chronic pain with other etiologies.

The data suggests a new channel for therapeutic strategies, but further investigation is needed to support the relationship of the choroid plexus in pain conditions.