Resting-state EEG spectral power alterations following traumatic brain injury: a comprehensive systematic review and meta-analysis of clinical and injury-related moderators.

BACKGROUND: Traumatic brain injury (TBI) is a major global health concern associated with diverse neurophysiological alterations. Resting-state electroencephalography (rs-EEG) provides a noninvasive measure of post-injury neural oscillations, yet reported spectral power findings remain inconsistent, potentially due to differences in TBI etiology. OBJECTIVE: We systematically reviewed and quantified rs-EEG spectral power changes following TBI and evaluated whether TBI etiology, time since injury, age, sex, and injury severity moderated these effects. METHODS: Following PRISMA guidelines, we included case-control and longitudinal studies reporting rs-EEG spectral power metrics. Meta-regression models examined the influence of moderators. RESULTS: Twenty-four studies (1,236 participants; 713 TBI, 523 controls) met inclusion criteria; 14 studies contributed 39 effect sizes to the meta-analysis. General TBI demonstrated more consistent slow-wave increases and fast-wave suppression than sport-related concussion (SRC). TBI was associated with increased theta power relative to controls (g = 0.50, p = 0.03), although substantial heterogeneity and publication bias were present. TBI etiology and sex moderated theta effects (p = 0.03, each), but neither remained significant after false discovery rate correction. CONCLUSION: TBI was associated with increased slow-wave activity, particularly theta power, although methodological heterogeneity warrants cautious interpretation. Standardized protocols and incorporation of aperiodic spectral metrics are needed to improve mechanistic understanding of post-injury brain dynamics.