Brain Pulsatility

This will be a single-center, prospective, analytical cohort study. All included patients will undergo transcranial ultrasound (TPI) with measurement of cerebral pulsatility parameters prior to subtractive lumbar puncture during hospitalization in the neurosurgery department, followed by a second ultrasound assessment either at one year after surgery for operated patients, or at one year after the initial ultrasound assessment for non-operated patients. This ultrasound evaluation will be integrated into the routine work-up, which is already systematically performed in cases of suspected idiopathic normal pressure hydrocephalus (iNPH). The neurosurgical team's decision to perform cerebrospinal fluid (CSF) shunting will be made blinded to the ultrasound measurements and based solely on the standard clinical protocol. The primary objective of the study is to demonstrate that the mean amplitude of cerebral pulsatility (MeanBTP) prior to subtractive lumbar puncture is significantly higher in patients who show clinical improvement 12 months after CSF shunting compared with those who do not, with a type I error risk (alpha) of 0.05."