Defining significant acute traumatic intracranial injuries in adult patients with traumatic brain injury: a narrative review

PURPOSE OF RESEARCH: The objectives of this narrative review were (1) to identify in recent literature the definition of a significant acute traumatic intracranial injury in adults with traumatic brain injury (TBI) and (2) to discuss the relevance of the elements within each definition. METHODS: A literature review was conducted to identify relevant publications from the past 25 years (2000-2025) including original research articles, systematic reviews, clinical guidelines, and consensus statements that addressed the concept of significant acute intracranial traumatic injuries. RESULTS: While the definition established during the development of the Canadian CT Head Rule remains the most widely utilized, its validity in aging populations is still uncertain. Currently, the BIG (uBIG, mBIG) criteria represent the most extensively validated classification systems. Mild Traumatic Brain Injury Risk Score and the QueBIC decision tool are the first rules specific to mild TBI, external validation is still required. Recent advancements in neuroimaging, such as the NIRIS, HITS, and SBNS TBI CT classifications, underscore the critical importance of precise lesion characterization. Positive correlation between biomarkers (GFAP and UCH-L1) and TBI severity is promising, further research is necessary to establish specific biomarker thresholds for identifying significant acute traumatic intracranial injuries. CONCLUSION: To date, there is no contemporary consensus definition of a significant acute traumatic intracranial lesion in patients presenting with TBI. Several factors appear essential for defining a significant lesion, including comorbidities, clinical presentation, CT scan injury characteristics and biomarkers.