Intracranial hypertension (IIH) is a disorder producing a syndrome of increased intracranial pressure secondary to a compressive intracranial lesion or said to be idiopathic. The most common symptoms are headaches, blindness, pulsatile tinnitus or papillary edema. There are many options for the treatment of IIH, especially neurosurgery (derivation of cerebrospinal fluid or stent placement). Currently, idiopathic IIH has no clear etiology but the hypothesis of sino-venous insufficiency is more and more recognized. The assumption of venous insufficiency has not been demonstrated so far. Therefore the investigators propose to demonstrate that cerebral venous drainage pathways are altered in adult patients with idiopathic intracranial hypertension in comparison to healthy individuals having normal circulation. Assessment will be performed using Magnetic Resonance Imaging which is part of the patient care.

The investigator working hypothesis is an impairment of the cerebral venous drainage in IIH compared to the circulation observed in healthy volunteers considered as the reference. The research will focus on adult patients referred to the imaging department for intracranial hypertension assessment. MRI support is common for this type of request The reference will be established in a population of healthy volunteers for whom MRI blood flow measurements will be performed. In addition to the primary objective, the investigators assess the impact of IIH on CSF dynamics The study does not present any risk for the subject, any contraindication to MRI examination being respected. The subjects will undergo MRI examination including morphological and flow sequences without contrast injection. The flow sequences, in planes located at the C2-C3 and aqueductal levels, will be used to measure vascular flows (venous and arterial) and CSF oscillatory volumes. Image post-processing will be performed on a semi-automatic software allowing to extract fluid dynamics parameters.

Inclusion Criteria:

• Age : >18 years old
• adult patients referred to the imaging department for intracranial hypertension assessment
• adult control subjects without history of cerebral or vascular pathology

Exclusion Criteria:

• history of cerebral or vascular pathology for the control subjects
• pregnant woman
• claustrophobia
• major obesity
• any contraindication to MRI exam