Alterations in Somatomotor Network Functional Connectivity in Painful Diabetic Neuropathy—A Resting State Functional Magnetic Resonance Imaging Study

Abstract

Aims: Painful diabetic neuropathy (Painful-DN) is a common disabling condition, with no objective biomarkers and less than optimal treatments. RS-fMRI is a quick (5 minute) functional imaging method that evaluates regional cortical interactions that occur when a subject is at rest. The aim of this study was to explore resting functional connectivity of the somotomotor network in painful DN as a possible objective biomarker for neuropathic pain. Methods: 46 patients with diabetes (No DN, n=16; Painful DN, n=15; Painless DN, n=15) and 16 healthy volunteers underwent detailed clinical and neurophysiological assessments. RS-fMRI data were acquired at 3T (Philips Healthcare) and functional connectivity analysis was performed using FSL (www.fmrib.ox.ac.uk/fsl). Results: There was reduced functional connectivity in the sensorimotor network (postcentral gyrus -42,-22,56; all TFCE, corrected p<0.05) and default mode network (precuneus -6,-46,40; p<0.05), superior frontal gyrus (34,62,60; p<0.05), Heschl’s gyrus (-42,-22,12; p<0.05), insular cortex (34,62,60; p<0.05) and superior parietal lobule (-22,-42,68; p<0.05). Somatomotor network functional connectivity significantly correlated with quantitative pain assessments (Short Form 36, r=-0.52; p=0.03 and Chronic Pain Acceptance Questionnaire r=-0.55, p=0.045). Conclusion: These findings demonstrate that chronic pain has a widespread impact on overall brain function in diabetes, and suggests that disruptions of the resting state networks may underlie the cognitive and behavioural impairments accompanying chronic pain. Specifically within the somatomotor network, we have demonstrated abnormal functional connectivity in painful DPN which correlates with clinical measures of pain and behaviour. RS-fMRI has the potential to serve as an objective biomarker for the chronic pain condition in DPN. Disclosure D. Selvarajah: None. M. Awadh: None. R. Gandhi: None. I.D. Wilkinson: None. S. Tesfaye: Speaker's Bureau; Self; Pfizer Inc.. Other Relationship; Self; Janssen Pharmaceuticals, Inc., Takeda Development Centre Europe Ltd.. Advisory Panel; Self; Wörwag Pharma GmbH & Co. KG.