EEG-based cortical alterations in individuals with chronic knee pain secondary to osteoarthritis: a cross-sectional investigation.

Chronic painful knee osteoarthritis (OA) is a disabling physical health condition. Alterations in brain responses to arthritic changes in the knee may explain persistent pain. This study investigated source localised, resting-state electroencephalography (rsEEG) activity and functional connectivity in people with knee OA, compared to healthy controls (HC). Adults aged 44-85 years with knee OA (n=37) and HC (n=39) were recruited. rsEEG was collected for 10 minutes and decomposed into infraslow frequency (ISF) to gamma frequency bands. Standard low-resolution electromagnetic brain tomography (sLORETA) statistical non-parametric maps were conducted, current densities of regions of interest were compared between groups and correlation analyses were performed between EEG measures and clinical pain and functional outcomes in the knee OA group. sLORETA non-parametric maps revealed higher (p=0.006) gamma band activity over the right insula (RIns) in the knee OA group. A significant (p<0.0001) reduction in ISF band activity at the pregenual anterior cingulate cortex (pgACC), whereas higher theta, alpha, beta, and gamma band activity at the dorsal anterior cingulate cortex (dACC), pgACC, the somatosensory cortex (SSC), and RIns in the knee OA group were identified. ISF activity of dACC was positively correlated with pain measures and psychological distress scores. Theta and alpha activity of RIns were negatively correlated with pain interference. In conclusion, aberrations in infraslow and faster frequency EEG oscillations at sensory-discriminative, motivational-affective, and descending inhibitory cortical regions were demonstrated in people with chronic painful knee OA. Moreover, EEG oscillations were correlated with pain and functional outcome measures. PERSPECTIVE: This study confirms alterations in the rsEEG oscillations and its relationship with pain experience in people with knee OA. The study provides potential cortical targets and the EEG frequency bands for neuromodulatory interventions for managing chronic pain experience in knee OA.