Copyright ©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Jun 6, 2023; 11(16): 3706-3713
Published online Jun 6, 2023. doi: 10.12998/wjcc.v11.i16.3706
Current research of idiopathic normal pressure hydrocephalus: Pathogenesis, diagnosis and treatment
Tetsuro Ishida, Tomonori Murayama, Seiju Kobayashi
Tetsuro Ishida, Department of Psychiatry, Japan Health Care College, Sapporo 062-0053, Hokkaido, Japan
Tomonori Murayama, Department of Psychiatry, Asahikawa Keisenkai Hospital, Asahikawa 078-8208, Hokkaido, Japan
Seiju Kobayashi, Department of Psychiatry, Shinyukai Nakae Hospital, Sapporo 001-0022, Hokkaido, Japan
Author contributions: Ishida T was responsible for the conception and design of the study and writing of the manuscript; Murayama T and Kobayashi S assisted in the critical review and editing of the manuscript; All authors gave their approval for the final version to be submitted.
Conflict-of-interest statement: All the authors declare that they have no conflict of interest.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See:
Corresponding author: Tetsuro Ishida, MD, Chief Doctor, Department of Psychiatry, Japan Health Care College, Higashi 3-11-1-55 Toyohira-ku Tsukisamu, Sapporo 062-0053, Hokkaido, Japan.
Received: December 27, 2022
Peer-review started: December 27, 2022
First decision: January 20, 2023
Revised: February 18, 2023
Accepted: May 4, 2023
Article in press: May 4, 2023
Published online: June 6, 2023

Idiopathic normal pressure hydrocephalus (iNPH) is caused by impaired cerebrospinal fluid absorption in the elderly; it is a surgically treatable form of dementia. Gait disturbance, dementia, and urinary incontinence are the triad of signs for iNPH. In addition to these clinical findings, imaging studies show characteristic ventricular enlargement. High Evans Index and ‘disproportionately enlarged subarachnoid hydrocephalus’ are other well-known imaging findings of iNPH. If the tap test shows improved symptoms, shunt surgery is performed. The disease was first described by Hakim and Adams in 1965, followed by the publication of the first, second, and third editions of the guidelines in 2004, 2012, and 2020, respectively. Recent studies signal the glymphatic system and classical cerebrospinal fluid (CSF) absorption from the dural lymphatics as aetiological mechanisms of CSF retention. Research is also underway on imaging test and biomarker developments for more precise diagnosis, shunting technique options with fewer sequelae and complications, and the influence of genetics. Particularly, the newly introduced ‘suspected iNPH’ in the third edition of the guidelines may be useful for earlier diagnosis. However, less well-studied areas remain, such as pharmacotherapy in non-operative indications and neurological findings other than the triadic signs. This review briefly presents previous research on these and future issues.

Keywords: Review, Idiopathic normal pressure hydrocephalus, Treatable dementia, Shunt surgery, Drug therapy

Core Tip: Idiopathic normal pressure hydrocephalus (iNPH) presents with gait disturbance, dementia, and urinary incontinence. Improvement in these symptoms by tap testing, and imaging studies showing characteristic ventricular enlargement, are important for the diagnosis. iNPH is a dementia that is treatable by shunt surgery. This review describes recent pathophysiology, diagnosis, and treatment in iNPH.