title: Choroidal fissure acts as an overflow device in cerebrospinal fluid drainage: morphological comparison between idiopathic and secondary normal-pressure hydrocephalus.
abstract: To clarify the pathogenesis of two different types of adult-onset normal-pressure hydrocephalus (NPH), we investigated cerebrospinal fluid distribution on the high-field three-dimensional MRI. The subarachnoid spaces in secondary NPH were smaller than those in the controls, whereas those in idiopathic NPH were of similar size to the controls. In idiopathic NPH, however, the basal cistern and Sylvian fissure were enlarged in concurrence with ventricular enlargement towards the z-direction, but the convexity subarachnoid space was severely diminished. In this article, we provide evidence that the key cause of the disproportionate cerebrospinal fluid distribution in idiopathic NPH is the compensatory direct CSF communication between the inferior horn of the lateral ventricles and the ambient cistern at the choroidal fissure. In contrast, all parts of the subarachnoid spaces were equally and severely decreased in secondary NPH. Blockage of CSF drainage from the subarachnoid spaces could cause the omnidirectional ventricular enlargement in secondary NPH.
authors.affiliation: Normal Pressure Hydrocephalus Center, Rakuwakai Otowa Hospital, Kyoto, Japan.|Department of Neurosurgery and Stroke Center, Rakuwakai Otowa Hospital, Kyoto, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Yamada
authors.affiliation: Normal Pressure Hydrocephalus Center, Rakuwakai Otowa Hospital, Kyoto, Japan.|Department of Neurosurgery and Stroke Center, Rakuwakai Otowa Hospital, Kyoto, Japan.
authors.forename: Masatsune
authors.initials: M
authors.lastname: Ishikawa
authors.affiliation: Department of Neurosurgery and Stroke Center, Rakuwakai Otowa Hospital, Kyoto, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Iwamuro
authors.affiliation: Department of Neurosurgery and Stroke Center, Rakuwakai Otowa Hospital, Kyoto, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D065634:Cerebrospinal Fluid Leak / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002831:Choroid Plexus / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000145:classification / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology; D020547:Lateral Ventricles / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D013346:Subarachnoid Space / Q000002:abnormalities* / Q000000981:diagnostic imaging / Q000503:physiopathology