Characterization of Source-Localized EEG Activity During Sustained Deep-Tissue Pain

Abstract

Musculoskeletal pain is a clinical condition that is characterized by ongoing pain and discomfort in the deep tissues such as muscle, bones, ligaments, nerves, and tendons. In the last decades, it was subject to extensive research due to its high prevalence. Still, a quantitative description of the electrical brain activity during musculoskeletal pain is lacking. This study aimed to characterize intracranial current source density (CSD) estimations during sustained deep-tissue experimental pain. Twenty-three healthy volunteers received three types of tonic stimuli for three minutes each: computercontrolled cuff pressure (1) below pain threshold (sustained deep-tissue no-pain, SDTnP), (2) above pain threshold (sustained deep-tissue pain, SDTP) and (3) vibrotactile stimulation (VT). The CSD in response to these stimuli was calculated in seven regions of interest (ROIs) likely involved in pain processing: contralateral anterior cingulate cortex, contralateral primary somatosensory cortex, bilateral anterior insula, contralateral dorsolateral prefrontal cortex, posterior parietal cortex and contralateral premotor cortex. Results showed that participants exhibited an overall increase in spectral power during SDTP in all seven ROIs compared to both SDTnP and VT, likely reflecting the differences in the salience of these stimuli. Moreover, we observed a difference is CSD due to the type of stimulus, likely reflecting somatosensory discrimination of stimulus intensity. These results describe the different contributions of neural oscillations within these brain regions in the processing of sustained deep-tissue pain.

Low Back Pain Assessment Based on Alpha Oscillation Changes in Spontaneous Electroencephalogram (EEG)

“…However, such brief stimuli may be limited in their ability to reliably simulate natural and clinically painful experiences, even when considering acute pain [8]. Therefore, a growing number of studies have focused on developing an objective approach to measuring chronic pain by using sustained pain stimulation, which may evoke nonphase-locked cortical responses similar to those observed in EEG data associated with chronic pain [10][11][12].…”

“…EEG at different frequency bands including theta, beta, and gamma has been reported to be related to pain perception [13][14][15][16], even though there has not been a clear consensus determining which rhythmic band has the most reliable correlation with different levels of elicited pain. Compared with other frequency domains, alpha band oscillations (8)(9)(10)(11)(12)(13) are the most commonly explored [17] (considering that gamma waves are generated deep in the brain and are therefore not easy to record with scalp EEG [18], while data concerning pain-related beta EEG activity are scarce [16,19,20]). Furthermore, resting-state EEG recording of alpha oscillations is found to be stable over time [21], highly heritable [22], and unique to an individual to the extent that it could serve as a "statistical signature" [23].…”

Translational Applications of Neuroimaging

“…There is accumulating evidence that specific oscillatory activity patterns in anatomically defined brain regions, as well as the synchronization between them, play a key role in acute and chronic pain processing. The use of source localization algorithms for highdensity EEG recordings, in particular, is an emerging technical development in the pain field that has enabled insights into cortical mechanisms of both acute and chronic pain in human subjects (Stern et al, 2006;Prichep et al, 2018;Teixeira M. et al, 2021;Teixeira P. E. P. et al, 2021;Völker et al, 2021;Mussigmann et al, 2022;Bott et al, 2023;Rockholt et al, 2023). In this study, we have focused on the cortical response to evoked stimuli rather than resting measurements.…”

Mechanisms and manifestations in musculoskeletal pain: from experimental to clinical pain settings

“…Recently, painful cuff pressure stimulation maintained for 3 minutes compared with nonpainful cuff pressure evoked an increased global electroencephalographic power in several regions (eg, contralateral anterior cingulate cortex, primary somatosensory cortex, dorsolateral prefrontal cortex, and posterior parietal cortex), where the increase in the alpha power may be a result of increased cortical inhibition by the deep-tissue pain. 258 The cortical excitability in tonic pain models has also been studied by sensory-evoked potentials in electroencephalographic recordings after electrical stimulation of peripheral nerves. Inhibition of early sensory-evoked potentials was found after tonic chemically induced muscle pain, with lasting depression several minutes after the pain vanished.…”

“…Recently, painful cuff pressure stimulation maintained for 3 minutes compared with nonpainful cuff pressure evoked an increased global electroencephalographic power in several regions (eg, contralateral anterior cingulate cortex, primary somatosensory cortex, dorsolateral prefrontal cortex, and posterior parietal cortex), where the increase in the alpha power may be a result of increased cortical inhibition by the deep-tissue pain. 258…”