Brain Morphological Signatures for Chronic Pain

Abstract

Chronic pain can be understood not only as an altered functional state, but also as a consequence of neuronal plasticity. Here we use in vivo structural MRI to compare global, local, and architectural changes in gray matter properties in patients suffering from chronic back pain (CBP), complex regional pain syndrome (CRPS) and knee osteoarthritis (OA), relative to healthy controls. We find that different chronic pain types exhibit unique anatomical ‘brain signatures’. Only the CBP group showed altered whole-brain gray matter volume, while regional gray matter density was distinct for each group. Voxel-wise comparison of gray matter density showed that the impact on the extent of chronicity of pain was localized to a common set of regions across all conditions. When gray matter density was examined for large regions approximating Brodmann areas, it exhibited unique large-scale distributed networks for each group. We derived a barcode, summarized by a single index of within-subject co-variation of gray matter density, which enabled classification of individual brains to their conditions with high accuracy. This index also enabled calculating time constants and asymptotic amplitudes for an exponential increase in brain re-organization with pain chronicity, and showed that brain reorganization with pain chronicity was 6 times slower and twice as large in CBP in comparison to CRPS. The results show an exuberance of brain anatomical reorganization peculiar to each condition and as such reflecting the unique maladaptive physiology of different types of chronic pain.

Structural Brain Alterations in Community Dwelling Individuals with Chronic Joint Pain

“…Previous studies that examined structural brain alterations in pain consisted mostly of small and very specific clinical patient populations. [6][7][8][9][10][11][12][13]15 We used a hierarchical approach in studying brain structural differences. We first examined global brain tissue volumes and lobar volumes.…”

“…The hippocampus has previously been suggested as one of the altered structures in the brain in several pain states. 6,7 In women, this involvement of the limbic system, therefore, could indicate a more emotional coping of pain.…”

“…Previous studies that examined structural brain alterations in chronic pain focused on a variety of pain phenotypes, such as migraine, back pain, osteoarthritis, and fibromyalgia. [6][7][8][9][10][11][12][13][14][15] Typically, the study size was small; the largest studies included approximately 100 subjects. The small sample sizes of these studies led to a modest statistical power, thereby influencing the reproducibility of the results.…”

[P3–344]: Effect of Kidney Dysfunction on Cerebral Cortical Thinning in an Elderly Population

“…Although the function of the insula was not fully understood, it was usually linked to emotional process, autonomic function and interoception 39,40 . Abnormal changes in insular cortical thickness have been found in patients with chronic musculoskeletal pain, abdominal pain, migraine or smoking addiction 39,[41][42][43] . In patients with mild AD, depression and anxiety symptoms were found to be associated with thinning of the insular cortex 44 .…”

Complex regional pain syndrome: The matter of white matter?

“…More recently, morphometric changes have been found in the CRPS patients' brains with anatomical T1 MRI (Baliki, Schnitzer, Bauer, & Apkarian, 2011; Barad, Ueno, Younger, Chatterjee, & Mackey, 2014; Geha et al., 2008; Pleger et al., 2014), and we have observed the enlargement of choroid plexus (Zhou, Hotta, Lehtinen, Forss, & Hari, 2015), in line with the suggestion that neuroinflammation might play a role in the pathophysiology of CRPS (Linnman, Becerra, & Borsook, 2013). In neuroinflammatory diseases, brain's white matter can possess microstructural abnormalities although it appears normal in anatomical T1 MRI (Filippi et al., 2012).…”