title: Disproportionately Enlarged Subarachnoid Space Hydrocephalus in Idiopathic Normal-Pressure Hydrocephalus and Its Implication in Pathogenesis.
abstract: Idiopathic normal-pressure hydrocephalus (iNPH) has become socially significant in Japan. Japanese guidelines for iNPH in 2011 described the diagnostic importance of "disproportionately enlarged subarachnoid space hydrocephalus" (DESH) on magnetic resonance imaging (MRI). However, some patients with iNPH have equivocal or no features of DESH. To clarify the diversity of MRI findings in iNPH, we classified iNPH into three types based on MRI findings. Using this, we investigate predictable MRI findings for shunt effectiveness in iNPH. A total of 83 patients with suspected iNPH who were treated with shunt surgery were reviewed in this study. All patients had a positive cerebrospinal fluid (CSF) tap test. Among the 83 patients, DESH was noted in 64 %, incomplete DESH in 23 %, and no DESH in 13 % (see Fig. 3). Among the three types of incomplete DESH, incomplete DESH-v (ventricle) was 0 %, DESH-c (convexity) in 13 %, and DESH-s (Sylvian fissure) in 10 %. A high improvement rate after the shunt surgery was noted in the DESH and incomplete DESH-s groups, showing 73.5 % and 87.5 %, respectively. The non-DESH group showed a fairly large improvement of 63.6 %. A common MRI finding in DESH and incomplete DESH-s was high convexity tightness with ventriculomegaly. This combination was promising for shunt effectiveness in patients with suspected iNPH. Further study is necessary to elucidate the pathogenesis.
authors.affiliation: Normal Pressure Hydrocephalus Center, Otowa Hospital, 2 Chinjicho, Yashina, Otowa, Kyoto, Japan. rakuwadr1001@rakuwadr.com.
authors.forename: Masaatsune
authors.initials: M
authors.lastname: Ishikawa
authors.affiliation: Department of Neurosurgery, Otowa Hospital, Otowa, Kyoto, Japan.
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Oowaki
authors.affiliation: Department of Neurosurgery, Otowa Hospital, Otowa, Kyoto, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takezawa
authors.affiliation: Department of Neurosurgery, Otowa Hospital, Otowa, Kyoto, Japan.
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Takenaka
authors.affiliation: Department of Neurosurgery, Otowa Hospital, Otowa, Kyoto, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Yamada
authors.affiliation: Department of Neurosurgery, Otowa Hospital, Otowa, Kyoto, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamamoto
authors.affiliation: Stroke Center, Otowa Hospital, Otowa, Kyoto, Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Okamoto
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002557:Cerebrospinal Fluid Shunts; D005260:Female; D006801:Humans; D006850:Hydrocephalus, Normal Pressure / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D008279:Magnetic Resonance Imaging; D008297:Male; D013346:Subarachnoid Space / Q000000981:diagnostic imaging*; D016896:Treatment Outcome
keywords: Dementia; Gait disturbance; Hydrocephalus; MRI; The elderly