MRI scans reveal hidden brain drains in rare headache disorder

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * For all participants: Age \> 18 years and ≤ 40 years female gender Absence of previous neurosurgical or endovascular neurological history Participant able to express her consent Medical insurance * For participants with IIH No required criterion of severity or evolution of IIH Definite diagnosis of IIH according to Dandy's modified criteria. All of the following criteria must be met and verified by medical reports or certificates from a neurologist, especially the value of the CSF opening pressure measured during the lumbar puncture must be clearly noted on the reports * History of papilledema * Normal neurological examination, except for paralysis of the VIth cranial nerve * Neuroimaging: normal cerebral parenchyma without hydrocephalus, intracranial expansive process, or structural anomaly, and absence of meningeal contrast enhancement in MRI without and with contrast product. A venous angio-MRI is necessary in atypical patients; if MRI is unavailable or contraindicated, a brain scan without and with contrast product can be done in combination with a venous angioscan with contrast injection * Normal CSF composition * High CSF opening pressure (≥ 25 cm of water) obtained from a lumbar puncture performed in lateral decubitus * For healthy volunteers No previous history of neurological or neurosurgical disorder Exclusion Criteria: * For all participants Pregnant or breastfeeding woman Contraindication to cerebral MRI: metallic implant, pacemaker, artificial heart valve, cerebral vascular malformation, aneurysm clips, metallic fragments, artificial implants, peripheral or neural pacemaker, insulin pump, intravenous catheter, epilepsy , metallic contraceptive device, claustrophobia, refusal to be informed in case of abnormal MRI (with a significant medical abnormality) Hypersensitivity to the active substance of the contrast agent or to any of the excipients (Sodium calcobutrol, Trometamol, 1N hydrochloric acid (pH adjustment), Water for injections) lumbar puncture in the month preceding the brain MRI Neurological tumoral, degenerative, vascular, inflammatory or progressive pathology Renal or hepatic impairment MRI with gadolinium injection performed in the 7 days preceding the inclusion visit Person subject to a measure of legal protection (safeguard of justice, curatorship, guardianship), deprived of liberty by judicial or administrative decision * For participants with IIH Participants with a probable but not definite diagnosis of IIH according to the Dandy modified criteria * For healthy volunteers Chronic headaches (\>15 days per month) Uncorrected and/or unlabeled visual symptoms (visual blurriness, diplopia, visual eclipses, papilledema, optic atrophy)