The diagnosis and management of patients with idiopathic normal-pressure hydrocephalus (NPH) remain somewhat controversial and there is no clear guideline for assessing the post-shunt outcome. The objective of this study was to investigate whether cerebrospinal fluid (CSF) flow dynamics is linked to post-shunt improvement. Fourteen NPH patients (nine males and five females; mean age, 68 years) investigated by magnetic resonance imaging (MRI) before surgical diversion of CSF were retrospectively reviewed. Phase-contrast sequences were added to the morphological clinical protocol for quantification of CSF oscillations, which were recorded at the level of the cerebral aqueduct and the C2 and C3 subarachnoid spaces (SAS). The phase-contrast images were analysed with custom-designed dedicated flow segmentation software. The oscillations measured in this hydrocephalus population were compared to a previously studied healthy population. A difference of at least two standard deviations was used to define a hyperdynamic or hypodynamic state of CSF flow. The cervical CSF flow of the hydrocephalus patients was not significantly different from those of the volunteer population. Of the 14 hydrocephalus patients, 12 had a good response to the shunt. Of these, 10 presented an increased ventricular CSF flow, one a low ventricular CSF flow, and the last one had a normal ventricular CSF flow. Phase-contrast MRI can help develop guidelines for surgical management of NPH. The shunt responders appear to be the patients with hyperdynamic ventricular CSF flow and normal cervical CSF flow.