Evaluation of dynamic brain function in patients with different degrees of chronic pain by EEG microstate analysis

Chronic pain is closely associated with functional remodeling of the central nervous system. The neuroplasticity in the brain can be characterized by the electroencephalography (EEG) microstate analysis of the static topological features of resting-state functional brain networks.

Seventy-four patients undergoing spinal surgery for chronic pain were included. Preoperative resting-state EEG recordings were obtained, and patients were stratified into two groups according to their preoperative Numerical Rating Scale (NRS) pain scores. From the EEG data, four specific microstates (labeled A, B, C, and D) were extracted, and their temporal characteristics were analyzed. Statistical analysis was performed to compare the microstate characteristics between the two groups, and to examine the correlation between microstate characteristics and pain intensity.

In the high-pain (HP) group, microstate D exhibited significantly reduced occurrence frequency, time coverage, and duration compared with the low-pain (LP) group. In addition, differences in microstate transition patterns were observed between the two groups. A significant correlation was also observed between the temporal characteristics of microstate D and the preoperative pain intensity, as measured by the NRS.

Alterations in microstate dynamics during the preoperative resting state may reflect changes in brain functions among patients with chronic pain. EEG microstate analysis may be recommended for identifying changes in brain dynamics associated with chronic pain.

This study was registered on ClinicalTrials.gov prior to patient enrollment (Registration number: NCT03761576; Registration date: November 30, 2018).