Presented at the 2012 AAPM Annual Meeting « Back

Chronic Low Back Pain Patients (CLBP) Display Altered Brain Connectivity in the Default Mode Network—An Arterial Spin Labeling (ASL) MRI Study

Marco Loggia, PhD, mloggia@partners.org¹, Jieun Kim, PhD², Jian Kong, MD¹, Randy Gollub, MD PhD¹, Vitaly Napadow, PhD², Ajay D. Wasan, MD MSc³, (1) Harvard Medical School, Charlestown, Massachusetts, (2) Martinos Center for Biomedical Imaging, Charlestown, Massachusetts, (3) Harvard Medical School, Chestnut Hill, Massachusetts

Introduction: The default mode network (DMN) is a network of brain areas that includes: medial prefrontal (MPFC), posterior cingulate, and lateral temporal cortices, hippocampal formation and inferior parietal lobule.(1) ASL measures cerebral blood flow to specific brain regions and assesses neural activity. As DMN activity has been shown to be altered in chronic pain, (2,3) we hypothesized that functional connectivity within the DMN, such as the MPFC, would be altered in CLBP versus controls. Methods: After IRB informed consent, 16 CLBP subjects with discogenic pain (avg. pain 4.8/10, avg. duration 6.2 yrs.) and 16 matched healthy controls underwent two resting-state 6-minute pulsed ASL scans, at separate visits, in a 3T MRI. Tag and Control images were acquired interleaved, and subtracted to create perfusion time series. Probabilistic independent component analysis (4) identified the DMN, and T-tests contrasted DMN connectivity patterns between groups (cluster-corrected at Z≥2.3, p<0.05).(5) Results: In both sessions, in comparison to the healthy controls, CLBP patients exhibited stronger connections between the DMN and the MPFC, demonstrating high test-retest reliability (p<.05, see figure). Conclusions: In this study we show, for the first time, that resting state connectivity is altered in patients suffering from discogenic CLBP, i.e., baseline brain functioning is altered in CLBP. Increased DMN-MPFC connectivity suggests increased prefrontal contributions to cognitive processing. The MPFC is a key area processing pain and mood. Our novel ASL approach evaluates brain connectivity in a chronic pain condition, and future studies should link such connectivity to changes in pain over time. References: 1)Buckner RL, Andrews-Hanna JR, Schacter DL: The brain's default network: Anatomy, function, and relevance to disease. Ann N Y Acad Sci 1124: 1-38, 2008. 2)Baliki MN, Geha PY, Apkarian AV, Chialvo DR: Beyond feeling: Chronic pain hurts the brain, disrupting the default-mode network dynamics. J Neurosci 28: 1398-403, 2008. 3)Napadow V, LaCount L, Park K, As-Sanie S, Clauw DJ, Harris RE: Intrinsic brain connectivity in fibromyalgia is associated with chronic pain intensity. Arthritis Rheum 62: 2545-55, 2010 4)Beckmann CF, DeLuca M, Devlin JT, Smith SM: Investigations into resting-state connectivity using independent component analysis. Philos Trans R Soc Lond B Biol Sci 360: 1001-13, 2005 5)Worsley KJ, Statistical analysis of activation images, in Functional mri: An Introduction to Methods, P. Jezzard, Matthews, P.M., and Smith S.M., Editor Oxford University Press: New York, NY, 2001. 6)Worsley, K.J., Statistical analysis of activation images, in Functional MRI: An Introduction to Methods, P. Jezzard, Matthews, P.M., and Smith S.M., Editor 2001, Oxford University Press: New York, NY

Funding: NIH