PTH and Hydrocephalus: Acute PTH, that develops days to weeks after injury, can be the result of one of two processes: i) obstruction of normal CSF flow leading to ventricular enlargement and elevated ICP or ii) “external hydrocephalus”, due to CSF absorption impairment from the pacchionian granulations, leading to enlargement of cranial subarachnoid spaces with normal-sized ventricles (Manet et al., 2017).