Cerebrospinal fluid dysregulation and post-traumatic hydrocephalus after paediatric traumatic brain injury.

Post-traumatic hydrocephalus after paediatric traumatic brain injury is commonly framed as a delayed structural complication, yet the clinical literature indicates that this model is incomplete. Across paediatric neurocritical care and imaging studies, traumatic injury was associated with disturbed cerebrovascular autoregulation, impaired intracranial compliance, altered cerebral perfusion pressure targets, abnormal cerebrovascular reactivity, oxygenation abnormalities, and evolving glymphatic or perivascular changes. Normative paediatric studies likewise showed that cerebrospinal fluid physiology is developmentally dynamic, with age-dependent variation in aqueductal and spinal flow, glymphatic-associated indices, craniospinal compliance, and the relationship between brain and cerebrospinal fluid volumes. Together, these observations support the hypothesis that paediatric post-traumatic hydrocephalus may, in some patients, represent a downstream clinical expression of disturbed cerebrospinal fluid and intracranial fluid homeostasis, rather than a purely structural disorder of obstruction or absorption failure. The most direct clinical evidence came from infusion-study data in post-traumatic ventriculomegaly, in which resistance to cerebrospinal fluid outflow was higher in shunted cases, compliance was reduced, and structural imaging alone did not reliably distinguish probable hydrocephalus from ex vacuo ventricular enlargement. However, direct paediatric studies of incidence, physiology-based classification, and treatment selection remain limited. Current evidence supports consideration of a physiology-informed reframing of post-traumatic hydrocephalus, while also underscoring the need for longitudinal paediatric studies that link acute disturbances in cerebrospinal fluid dynamics with delayed ventriculomegaly, treatment response, and neurodevelopmental outcome.