EEG and Functional MRI on Back Pain
Authors: Hu Yong 
Published: May 2014

Pain is a major health care problem worldwide. It affects the well-being of millions of individuals, and its financial burden upon our societies is considerable.1 Back pain (BP) is a particularly substantial health problem. It affects up to 70% of the adult population, and poses a considerable health care and socioeconomic burden. The diagnosis, evaluation, and treatment of BP is a major challenge, which leads to the limited effectiveness for the most commonly applied interventions and approaches.2 Evidence showing significant changes within the brain in chronic BP patients indicated that BP may be accompanied by cognitive abnormalities3 brain chemical changes,4 and cortical reorganization or degeneration.5 In recent years, this has been investigated using both advanced neuroimaging and electrophysiology. The advent of modern neuroimaging and electrophysiological techniques has enabled researchers to examine the pain processing network. There is important evidence that local cerebral blood flow (CBF) changes reflect variations in local synaptic activity, as measured using positron emission tomography (PET).6,7 This dramatic change in blood flow during neuronal activity is also detected using functional magnetic resonance imaging (fMRI), in which signal changes reflect alteration in local CBF and, more specifically, variations in the ratio of deoxyhemoglobin to oxyhemoglobin (termed blood oxygenation level dependent [BOLD] contrast). The BOLD fMRI, which has been widely successful in brain functional research, is based on the biological mechanism that neurovascular coupling exists between neuronal activity and the cerebral vascular response. Using a type of BOLD fMRI that shows when certain parts of the brain are activated, Wager et al recently addressed the critical question of the existence of a specific brain activity pattern for heat pain.8 The authors assessed this question in a rigorous and systematic approach. Their research leads to more objective assessments of pain. In addition to fMRI neural image technology, electroencephalography (EEG) is a more practical and cost effective technology to investigate the brain activity, which is generated by the firing of neurons within the brain.9 EEG is a direct measurement of neuronal activity with a sampling frequency as high as dozens of kHz (e.g., short-latency somatosensory evoked potentials),10,11 thus resulting in extremely high temporal resolution (only a tenth of a millisecond). Recently, we developed a new method to achieve robust single-trial estimate of even smaller ERP components.12 More advanced single-trial approaches, which make use of the temporal, frequency, and spatial information of multichannel EEG recordings based on this approach, will be developed to detect single-trial parameters and brain network accurately and reliably. In this new method, we may investigate those pain-related EEG features for specific EEG signature of pain perception, which may be used for objective and quantitative assessment for BP. Disclosure of Interest None declared References Brooks J, Tracey I. From nociception to pain perception: imaging the spinal and supraspinal pathways. J Anat 2005;207(1):19–33 Papageorgiou AC, Rigby AS. Review of UK data on the rheumatic diseases—7. Low back pain. Br J Rheumatol 1991;30(3):208–210 Giesecke T, Gracely RH, Grant MA, et al. Evidence of augmented central pain processing in idiopathic chronic low back pain. Arthritis Rheum 2004;50(2):613–623 Baliki MN, Chialvo DR, Geha PY, et al. Chronic pain and the emotional brain: specific brain activity associated with spontaneous fluctuations of intensity of chronic back pain. J Neurosci 2006;26(47):12165–12173 Wand BM, O’Connell NE. Chronic non-specific low back pain - sub-groups or a single mechanism? BMC Musculoskelet Disord 2008;9:11 Apkarian AV, Bushnell MC, Treede RD, Zubieta JK. Human brain mechanisms of pain perception and regulation in health and disease. Eur J Pain 2005;9(4):463–484 Disbrow E, Baron R, Baron Y. Examination of the role of the cerebral cortex in the perception of pain using functional magnetic resonance imaging. Curr Rev Pain 1999;3(4):281–290 Wager TD, Atlas LY, Lindquist MA, Roy M, Woo CW, Kross E. An fMRI-based neurologic signature of physical pain. N Engl J Med 2013;368(15):1388–1397 Niedermeyer E, Lopes da Silva FH. Electroencephalography: basic principles, clinical applications, and related fields. 5th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2005 Inoue K, Hashimoto I, Nakamura S. High-frequency oscillations in human posterior tibial somatosensory evoked potentials are enhanced in patients with Parkinson's disease and multiple system atrophy. Neurosci Lett 2001;297(2):89–92 Ozaki I, Suzuki C, Yaegashi Y, Baba M, Matsunaga M, Hashimoto I. High frequency oscillations in early cortical somatosensory evoked potentials. Electroencephalogr Clin Neurophysiol 1998;108(6):536–542 Hu L, Mouraux A, Hu Y, Iannetti GD. A novel approach for enhancing the signal-to-noise ratio and detecting automatically event-related potentials (ERPs) in single trials. Neuroimage 2010;50(1):99–111