Finnish researchers identify a link between the choroid plexus and complex regional pain syndrome (CRPS)
Neuroscientists at Aalto University, working together with colleagues at Helsinki University Hospital and Harvard Medical School, report a previously unrecognized association between enlargement of the choroid plexus and complex regional pain syndrome (CRPS). The findings, published in the journal Scientific Reports, highlight a potential central nervous system contribution to this debilitating chronic pain condition.
“When we inspected structural magnetic resonance images of brains from CRPS patients, the choroid plexus appeared substantially larger—approximately one-fifth greater in volume—compared with healthy control subjects,” says Postdoctoral Researcher Guangyu Zhou from Aalto University’s Department of Neuroscience and Biomedical Engineering (NBE), who led the image analyses.
The choroid plexus sits along the walls of the brain ventricles and is best known for producing cerebrospinal fluid (CSF), which cushions and protects the brain and spinal cord. Beyond CSF production, the choroid plexus regulates the passage of molecules between the blood, cerebrospinal fluid and nervous tissue and participates in neuroimmune signaling. Despite these important roles, its structural features are rarely quantified in routine clinical brain imaging.
“Clinical neuroscience has long focused on neurons and major brain structures, but the choroid plexus has received surprisingly little attention,” explains Professor Riitta Hari, who supervised the research team. “Because the choroid plexus can mediate communications between peripheral inflammation and brain immune responses, its enlargement in CRPS patients merits focused study as a possible contributor to chronic pain mechanisms.”
Complex regional pain syndrome is a chronic condition that often begins after relatively minor injury—such as a hand trauma—and can spread locally to involve an entire limb or, in some cases, extend to the opposite side of the body. The disease produces persistent pain and a range of sensory, motor and autonomic symptoms, and its mechanisms remain incompletely understood. Because CRPS can involve altered nerve signaling and immune responses, the central nervous system has long been suspected to play a role. The present findings add new evidence pointing specifically to the choroid plexus as a structural and potentially functional locus of interest.
Using high-resolution 3-tesla structural magnetic resonance imaging, the research team measured choroid plexus volume and compared it across groups. The published analysis reports a significant increase in choroid plexus volume in CRPS patients relative to matched healthy subjects. Importantly, enlargement was not observed in patients with chronic pain from other causes, suggesting a degree of specificity for CRPS. These morphometric results complement growing interest in neuroimmune interactions and the role of brain barrier systems in chronic pain disorders.
The authors emphasize that choroid plexus enlargement does not by itself establish causation. Instead, the observation raises several testable hypotheses: enlarged choroid plexus might reflect ongoing neuroimmune signaling, altered CSF production or clearance, or increased trafficking of immune cells and inflammatory mediators between blood and brain. Any of these processes could influence central pain processing and contribute to CRPS symptoms. Future investigations should combine imaging with molecular and immunological measures to clarify mechanisms and potential therapeutic targets.
Funding: The study received support from the Academy of Finland, the European Research Council and Tekes – the Finnish Funding Agency for Innovation.
Source: Riitta Hari – Aalto University
Image Credit: The image is credited to the researchers/Aalto University
Original Research: Full open access research for “Enlargement of choroid plexus in complex regional pain syndrome” by Guangyu Zhou, Jaakko Hotta, Maria K. Lehtinen, Nina Forss and Riitta Hari in Scientific Reports. Published online September 21, 2015. doi:10.1038/srep14329
Abstract
Enlargement of choroid plexus in complex regional pain syndrome
In clinical brain morphometry the choroid plexus has been largely overlooked. In this work, the authors report a measurable increase—approximately 21%—in choroid plexus volume in patients with complex regional pain syndrome compared with age- and gender-matched healthy individuals. No similar enlargement was found in a comparison group of patients with chronic pain of other causes. These observations suggest that the choroid plexus may be involved in CRPS pathogenesis. Given the choroid plexus’s role in mediating interactions between peripheral inflammation and brain immune activity, the finding identifies this structure as a promising target for future research into central mechanisms of chronic pain.