Beta Electroencephalographic Oscillation Is a Potential GABAergic Biomarker of Chronic Peripheral Neuropathic Pain

This preliminary investigation aimed to assess beta (beta) oscillation, a marker of the brain GABAergic signaling, as a potential objective pain marker, hence contributing at the same time to the mechanistic approach of pain management. This case-control observational study measured beta electroencephalographic (EEG) oscillation in 12 right-handed adult male with chronic neuropathic pain and 10 matched controls (similar to 55 years). Participants were submitted to clinical evaluation (pain visual analog scale, Hospital Anxiety, and Depression scale) and a 24-min high-density EEG recording (BIOSEMI). Data were analyzed using the EEGlab toolbox (MATLAB), SPSS, and R. The global power spectrum computed within the low (L beta, 13-20 Hz) and the high (H beta, 20-30 Hz) beta frequency sub-bands was significantly lower in patients than in controls, and accordingly, L beta was negatively correlated to the pain visual analog scale (R = -0.931, p = 0.007), whereas H beta correlation was at the edge of significance (R = -0.805; p = 0.053). Patients' anxiety was correlated to pain intensity (R = 0.755; p = 0.003). Normalization of the low and high beta global power spectrum (GPS) to the GPS of the full frequency range, while confirming the significant L beta power decrease in chronic neuropathic pain patients, vanished the significance of the H beta decrease, as well as the correlation between L beta power and pain intensity. Our results suggest that the GABAergic L beta EEG oscillation is affected by chronic neuropathic pain. Confirming the L beta GPS decrease and the correlation with pain intensity in larger studies would open new opportunities for the clinical application of gamma-aminobutyric acid-modifying therapies.