Neurologists while treating soldiers who had survived explosions in the warfront came across a medical paradox. Evidences of memory deficits, speech problems and difficulties with decision-making were seen in these patients. The paradox was that most of these patients had not suffered a direct head injury even though their scan reportssuggested enlargement of brain ventricles with minor bleeding in certain cases. Such medical conditions are called Blast Induced Traumatic Brain Injury (TBI). There have been studies in the past showing the development of stress in various parts of the brain due to explosions, though none of them directly correlate the expansion of Cerebrospinal fluid (CSF) pathways and brain ventricles, believed to be the indication of TBI. Our work primarily explores the role of intracranial CSF pressure dynamics in the genesis of TBI, emphasizing the evolution of the unsteady pressure field within CSF pathways, ventricular and the subarachnoid regions of the brain. The pressure gradient between the ventricles and the porous parenchyma is found to be considerably high and occurs within few milliseconds of blast application, which is indicative of the ventricular expansion. Our work also qualitatively evaluates the CSF pressure instabilities at various instants of time.