Cerebrospinal fluid and blood flow patterns in idiopathic normal pressure hydrocephalus

Objectives Increased aqueduct cerebrospinal fluid (CSF) flow pulsatility and, recently, a reversed CSF flow in the aqueduct have been suggested as hallmarks of idiopathic normal pressure hydrocephalus (INPH). However, these findings have not been adequately confirmed. Our objective was to investigate the flow of blood and CSF in INPH, as compared to healthy elderly, in order to clarify which flow parameters are related to the INPH pathophysiology. Materials and Methods Sixteen INPH patients (73 years) and 35 healthy subjects (72 years) underwent phase‐contrast magnetic resonance imaging (MRI). Measurements included aqueduct and cervical CSF flow, total arterial inflow (tCBF; i.e. carotid + vertebral arteries), and internal jugular vein flow. Flow pulsatility, net flow, and flow delays were compared (multiple linear regression, correcting for sex and age). Results Aqueduct stroke volume was higher in INPH than healthy (148±95 vs 90±50 mL, P