Abstract
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.
None declared
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