Background & Aims
Chronic pain (CP) is a major public health issue worldwide, with high treatment failure rate and heavy burden. Among strategies proposed to improve analgesia, a better characterization and classification of CP syndromes can be achieved through association of objective indicators to the currently validated subjective pain scales. Resting-state EEG indicators were recently proposed to be biomarkers of chronic neuropathic pain (CNP) as defined by the IASP. However, their relationship with clinical neuropathic features of pain (found also in other pain types) was not questioned.
Methods
In this new retrospective analysis of existing data, two lower-limb radiculopathy-related CNP populations (CNP1, n=9; CNP2, n=10; all right-handed males), 16 fibromyalgia (FM) female and right-handed patients were investigated regarding mainly VAS and DN4 scores, while mood (HAD) and sleep (ISI) scales were only used to characterize the studied populations. High-density (64 electrodes) resting-state EEG recording data were also analyzed. The Global power spectrum (GPS) derived from a Fast Fourier Transform-based spectral analysis of preprocessed data was used to characterize each frequency domain: high ? (H?; 20-30 Hz), low ? (L?; 13-20 Hz), ? (8-12 Hz), ? (7-8 Hz) and ? (2-4 Hz). Standard statistical descriptive and inferential parametric tests were performed, and significance set at p<0.05 (95% CI, two-tailed). All results presented below are beyond statistical significance.
Results
All 3 groups (CNP1, CNP2 and FM) had similar age, ongoing pain (VASd~4/10) and DN4 (~6), subclinical anxiety and insomnia; FM patients showed higher general pain (VASg~6/10) and depression sub-score. The CNP1 group displayed correlations between DN4 and VASg and between VASd and VASg, whereas no correlation was seen in the CNP2 group. In the FM group, DN4 was correlated with VASg. The CNP1 (contrary to CNP2 and FM) patients with significant pain (VASd?3) showed a correlation between L? GPS and VASd (r=-0.909).
Discrepancies between CNP1 and CNP2 populations were analyzed in relation with past back surgery as the only discriminating element (22 % vs 80% and 1042(42) vs 260(358) days delay to evaluation). In the non-back surgery group, correlations between DN4 and VASd; between VASd and VASg and between H? GPS and both VASd (r=-0.682) and DN4 (-0.690) were found, in contrast to absence of correlation in the back surgery group.
Conclusions
High and low ? GPS seem to be related to ongoing pain intensity in CNP, but not to the clinical neuropathic character of pain (which is associated to the general pain level). Recent back surgical intervention vanishes most clinical associations in CNP, while a link appears now between H? GPS and the clinical neuropathic feature of pain; suggesting some impact beyond the desired therapeutic effect.
References
Mussigmann, T et al. (2022), NeuroImage, 258:119355,
Mouraux, A et al. (2018), Brain, 141:3290-3307
Presenting Author
Joelle N. Chabwine
Poster Authors
Joelle Chabwine
MD, PhD
University of Fribourg
Lead Author
Igor Gossuin
Department of Orthopedics, Fribourg Hospital, Fribourg, Switzerland
Lead Author
Renato Gondar
Department of Orthopedics, Fribourg Hospital, Fribourg, Switzerland
Lead Author
Franziska Peier
MSc
Laboratory for Neurorehabilitation Science, Medicine Section, University of Fribourg, Switzerland
Lead Author
Naima L. Mory
MSc
Laboratory for Neurorehabilitation Science, Medicine Section, University of Fribourg, Switzerland
Lead Author
Gianluca Maestretti
MD
Department of Orthopedics, Fribourg Hospital, Fribourg, Switzerland
Lead Author
Michael De Pretto
PhD
Laboratory for Neurorehabilitation Science, Medicine Section, University of Fribourg, Switzerland
Lead Author
Michael Mouthon
PhD
Laboratory for Neurorehabilitation Science, Medicine Section, University of Fribourg, Switzerland
Lead Author
Topics
- Specific Pain Conditions/Pain in Specific Populations: Neuropathic Pain - Peripheral