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Volume 12 Supplement 1

Abstracts from Hydrocephalus 2015

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Epidemiological characteristics of patients with idiopathic normal pressure hydrocephalus in Japan: analysis of the treatment


To clarify the epidemiological and clinical characteristics of idiopathic normal pressure hydrocephalus (iNPH) in Japan, a nationwide epidemiological survey was conducted, focusing on treatment analysis.


Study participants were selected according to hospital bed capacity, using a random sampling method. In a primary survey, the number of iNPH patients in each hospital department during the year 2012 was estimated for stratification of institutions and next, in a secondary survey, selected patients provided detailed information, determining the clinical and epidemiological features of interest.


In the primary survey 1804 clinical departments responded (recovery rate: 42.7% ) for 3079 individuals, including 1815 individuals who underwent shunt surgery. The estimated annual number of patients receiving treatment was 13,000 (95% CI: 10000 to 16000). The estimated prevalence rate for hospital-based patients in 2012 was 10.2 individuals per 100,000.

Analyses were conducted on 1495 respondents (885 males (59.2%): age 77.9±6.30(SD) years; and 610 females (40.8%): age 78.0±6.41 years. Results showed 992 iNPH patients (66.1%) treated with shunt surgery, 547 patients (77.6±6.12yo) with lumboperitoneal (LPS), 428 patients (76.51±6.19yo) with ventriculoperitoneal (VPS) and 17 with vetriculoatrial (VAS) shunting. Four patients having both LPS and VPS.

In 120 out of 992 shunted patients were recorded complications (12.1%), including 77 out of 547 patients with LPS and 43 out 428 patients with VPS, without statistically significant difference between the two subgroups (p=0.092).

Therapeutic efficacy exceeded 90% with improvement of 1 point or higher on the modified Rankin Scale (mRS) in 56%. Age and Alzheimer's Disease were factors with a negative impact on the therapeutic prognosis, with odds ratio of 1.029 95%CI (1.013-1.047) p=0.001, and 1.365 95% CI (1.008-1.849) p=0.044, respectively. They had significant impact on the prognosis of improvement according to mRS.


We reported hospital based survey study in Japan, providing the main characteristics of iNPH epidemiology and management for 2012.


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Correspondence to Madoka Nakajima.

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This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.

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Nakajima, M., Miyajima, M., Akiba, C. et al. Epidemiological characteristics of patients with idiopathic normal pressure hydrocephalus in Japan: analysis of the treatment. Fluids Barriers CNS 12 (Suppl 1), O39 (2015).

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