Brain white matter structural properties predict transition to chronic pain

• Published in: Pain (Amsterdam) Vol. 154; no. 10; pp. 2160 - 2168
• Main Authors: Mansour, Ali R., Baliki, Marwan N., Huang, Lejian, Torbey, Souraya, Herrmann, Kristi M., Schnitzer, Thomas J., Apkarian, A. Vania
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Elsevier B.V 01.10.2013; Lippincott Williams & Wilkins, Inc; Elsevier
• Subjects: Adult; Biological and medical sciences; Brain; Brain - pathology; Brain - physiopathology; Chronic pain; Chronic Pain - diagnosis; Chronic Pain - metabolism; Chronic Pain - physiopathology; Connectivity; Diffusion Tensor Imaging - methods; Disease Progression; DTI; Female; Fundamental and applied biological sciences. Psychology; Humans; Longitudinal Studies; Male; Middle Aged; Nerve Fibers, Myelinated - metabolism; Nerve Fibers, Myelinated - pathology; Prediction; Predictive Value of Tests; Somesthesis and somesthetic pathways (proprioception, exteroception, nociception); interoception; electrolocation. Sensory receptors; Vertebrates: nervous system and sense organs; DTI; Brain; Connectivity; Chronic pain; Prediction; Chronic; Pain; Central nervous system; Predictive factor; White matter; Encephalon
• ISSN: 0304-3959; 1872-6623; 1872-6623
• DOI: 10.1016/j.pain.2013.06.044

White matter fractional anisotropy differences accurately predicted back pain persistence over 1year, and showed minimal alterations over the 1-year period. Neural mechanisms mediating the transition from acute to chronic pain remain largely unknown. In a longitudinal brain imaging study, we followed up patients with a single sub-acute back pain (SBP) episode for more than 1year as their pain recovered (SBPr), or persisted (SBPp) representing a transition to chronic pain. We discovered brain white matter structural abnormalities (n=24 SBP patients; SBPp=12 and SBPr=12), as measured by diffusion tensor imaging (DTI), at entry into the study in SBPp in comparison to SBPr. These white matter fractional anisotropy (FA) differences accurately predicted pain persistence over the next year, which was validated in a second cohort (n=22 SBP patients; SBPp=11 and SBPr=11), and showed no further alterations over a 1-year period. Tractography analysis indicated that abnormal regional FA was linked to differential structural connectivity to medial vs lateral prefrontal cortex. Local FA was correlated with functional connectivity between medial prefrontal cortex and nucleus accumbens in SBPr. As we have earlier shown that the latter functional connectivity accurately predicts transition to chronic pain, we can conclude that brain structural differences, most likely existing before the back pain–inciting event and independent of the back pain, predispose subjects to pain chronification.