Neuroimaging correlates of symptom burden and functional recovery following mild traumatic brain injury: A systematic review.

BACKGROUND: Mild traumatic brain injury (mTBI) represents 95% of all traumatic brain injuries. Despite being classified as "mild," mTBI can lead to persistent symptoms that impact quality of life. Diagnostic and management strategies rely heavily on subjective symptom reporting due to a lack of validated biomarkers. Identifying neuroimaging biomarkers to characterise the pathophysiological features underlying symptom burden and poor recovery is critical for improving mTBI management. OBJECTIVE: To synthesise evidence on cross-sectional, longitudinal, and prognostic links between Magnetic Resonance Imaging (MRI) features and mTBI symptom burden and functional recovery. METHODS: The review followed PRISMA guidelines. Systematic searches of MEDLINE, SCOPUS, and Cochrane Library identified mTBI studies with acute MRI data, measures of symptom burden or functional recovery, and at least one follow-up clinical timepoint, covering publications to July 18, 2025. Risk of bias was evaluated using the Quality in Prognostic Studies tool, and findings were synthesised narratively. RESULTS: Sixty-two of 7,232 articles were included. The review identified heterogeneous evidence across MRI modalities. Structural MRI findings showed limited correlation with clinical outcomes, while changes in white matter and functional connectivity were more strongly associated with symptom burden and recovery. Disruptions of integrative regions and association pathways such as the thalamus, superior longitudinal fasciculus, and cingulate cortex were linked to worse symptom burden and recovery outcomes. CONCLUSIONS: Acute MRI, when contextualised with clinical data, helps delineate correlates of mTBI symptom burden and functional recovery. To strengthen inference, future neuroimaging studies should prespecify and report symptom burden and functional recovery as core endpoints.