Introduction: Chronic Pain is a difficult entity to define and treat. The usual definition is that of pain that persists beyond expected healing period of 3-6 months . The pathophysiology, in particular changing neural connections, are still not widely agreed on. In recent years neuroimaging has shown evidence of structural reorganization and change . These new developments can further improve understanding of the brains plasticity and potentially new strategies to either help identify those experiencing acute pain at risk of transition to chronic pain, but also as a potential target for therapy.
Methods: The study population of 67 patients includes: a group of 26 selected from a pain management service and a group of 41 normal controls. The participants were matched on age, gender and ethnicity. Each patient has undergone structural and diffusion-weighted MRI scans. Voxel based morphometry was used to investigate differences in grey matter volumes between the groups, as well as to investigate correlations with neurocognitive outcomes. Cortical thickness was also calculated. Tract-based spatial statistics (TBSS) were used to investigate differences and correlation with neurocognitive outcomes between diffusion metrics (fractional anisotropy, mean diffusivity).
Results: The chronic pain group showed smaller cerebellar grey matter volume relative to healthy controls. There was no difference in cortical thickness observed. Furthermore, those experiencing chronic pain exhibited significantly decreased FA and increased MD in multiple white matter tracts, relative to controls.
Conclusions: These findings suggest that cerebellar atrophy maybe involved in chronic pain.
Patient Care: Pathophysiology of chronic pain is not well understood and with the use of new advanced neuroimaging techniques we are able to study in vivo the brain changes caused by chronic pain. These new developments can further improve understanding of the brains plasticity and potentially new strategies to either help identify those experiencing acute pain at risk of transition to chronic pain, but also as a potential target for therapy.
Learning Objectives: By the conclusion of this session, participants should be able to;
1) Define chronic pain
2) Describe chronic pain pathophysiology
3) Describe brain changes seen in chronic pain in relation to pathophysiology
References: Treede R, Rief W, Barke A et al. A Classification of chronic pain for ICD-11. Pain. June 2015:156 (6)
Apkarian A, Balinki M, Farmer M. Predicting transition to chronic pain. Current Opinion Neurology. August 2013. Vol 26 (4)
Geha P, Baliki M, Harden R et al. The Brain in Chronic CRPS Pain: Abnormal Gray-White Matter Interactions in Emotional and Autonomic Regions. Neuron. November 26, 2008. 60;570-581
Rodriguez-Raecke R, Nieneier A, Ihle K. Structural Brain Changes in Chronic Pain Reflect Probably Neither Damage Nor Atrophy. PLOS One. February 2013 Vol 8 (2)