OBJECTIVE: The management of post-traumatic ventriculomegaly (PTV) is controversial. This is due to the difficulty to determine whether PTV is related to an atrophic process or to a true "active" hydrocephalus. The purpose of this study is to analyze the CSF-dynamics in patients with PTV and, possibly, to identify parameters that correlate with prognosis. METHODS: 15 patients with PTV were treated following this protocol: 1-frontal ventriculostomy (with Rickham reservoir); 2-CSF-dynamics evaluation; 3-ventriculo-peritoneal shunt. CSF dynamics evaluation was based on an intraventricular infusion test (performed three to five days after ventriculostomy). Outflow Resistance (R-out) and Intracranial Elastance Index (EI, i.e. the reciprocal of intracranial compliance) were calculated. Patients were classified according to response to shunt into: 1-fast responders: rapid clinical improvement, i.e. within days/one month from surgery; 2-slow responders: patients presenting little clinical improvement occurring after months (despite neurorehabilitation); 3-non responders: no clinical improvement. RESULTS: Seven patients (46.7%) were classified as fast-responders, three patients were classified as slow-responders (20%) and five patients were classified as non-responders (33.3%). Opening CSF pressure was less than 15mmHg for all patients. R-out (cut-off >10mmHg/ml/min) had 100% sensitivity, 50% specificity, 100% negative predictive value and 63.6% positive predictive value. EI (cut-off value >0.3) had 100% specificity, 42.4% sensitivity, 100% positive predictive value and 66.7% negative predictive value. CONCLUSIONS: Based on these considerations, we can suggest that, for patients with normal pressure PTV, analysis of CSF dynamics could be of help in selecting patients for CSF-shunt. A combination of Intracranial Elastance and of R-out could help predicting shunt responsiveness.