Continuum of Irreversible and Potentially Reversible Traumatic Brain Injury Sequelae: Axonal Injury and Hydrocephalus

Chronic traumatic encephalopathy (CTE) is a neurodegenerative tauopathy linked to repetitive head trauma and definitively diagnosed postmortem. Its proposed clinical correlate in living patients is traumatic encephalopathy syndrome (TES). Within this spectrum, diffuse axonal injury (DAI) and post-traumatic hydrocephalus (PTH) represent interacting mechanisms contributing to long-term neurocognitive decline after traumatic brain injury (TBI). While DAI reflects largely irreversible axonal damage, PTH constitutes a potentially reversible disturbance of cerebrospinal fluid (CSF) dynamics. Their coexistence and pathophysiological interplay remain underrecognized. Understanding this continuum is essential to guide therapeutic strategies targeting both structural injury and CSF circulation abnormalities. A narrative review of PubMed-indexed literature (1980-2025) was conducted, focusing on pathophysiological correlations, neuroimaging features, and management strategies for CTE/TES, DAI, and PTH. Case series, clinical trials, and review articles addressing post-traumatic CSF disturbances were prioritized. A total of 100 records were identified (85 via database search, 15 through citation tracking). After screening, 32 were excluded, and 62 articles were included following full-text review. No duplicates were identified. Studies not relevant to pathophysiology, diagnosis, or management were excluded. Persistent ventriculomegaly after TBI is frequently misinterpreted as cerebral atrophy rather than hydrocephalus, leading to missed opportunities for surgical intervention. Advanced neuroimaging improves differentiation between DAI-related atrophy and treatable PTH. Selected patients demonstrate meaningful functional recovery following CSF diversion procedures, including programmable shunts and endoscopic third ventriculostomy. This continuum highlights the importance of recognizing reversible components of post-traumatic injury. Early identification and appropriate management of PTH may significantly improve functional outcomes in patients with chronic TBI.