Prevalence of idiopathic normal pressure hydrocephalus: A prospective, population-based study

Abstract

Background Idiopathic normal pressure hydrocephalus (iNPH) causing gait impairment, dementia and urinary incontinence among the elderly, is probably under-diagnosed and under-treated. Despite being known since the 1960s, there is still a lack of prospective, population-based studies on the prevalence of iNPH. Such studies are warranted to minimize selection bias and estimate the true prevalence of the disease. Methods The prevalence of iNPH was determined in a randomly selected sample of residents, aged 65 years and older, in the Swedish county of Jämtland. Out of 1,000 individuals invited to participate, 673 (67.3%) completed a questionnaire with seven questions on iNPH symptoms. A subgroup, with and without self-reported symptoms, participated in clinical and radiological evaluations and were diagnosed according to international guidelines. Measurement of cerebrospinal fluid opening pressure was not performed as it was considered too invasive. Results Those who reported at least two symptoms in the questionnaire (n = 117) and 51 randomly selected individuals with 0–1 symptom participated in further examinations. Out of them, 25 individuals received the diagnosis probable iNPH according to American-European guidelines (except for the criterion of CSF opening pressure) corresponding to a prevalence of 3.7%. The prevalence of iNPH was four times higher among those aged 80 years and older (8.9%) than among those aged 65–79 years (2.1%) (p <0.001). The difference in prevalence between men (4.6%) and women (2.9%) was not significant (p = 0.24). When iNPH was diagnosed according to the Japanese guidelines the prevalence was 1.5% Conclusions In this prospective, population-based study the prevalence of iNPH was 3.7% among individuals 65 years and older, and more common in the higher age group, 80 years and above. INPH should be increasingly recognized since it is a fairly common condition and an important cause of gait impairment and dementia among the elderly that can be effectively treated by shunt surgery.

Diagnostic accuracy of the iNPH Radscale in idiopathic normal pressure hydrocephalus

“…1. Preoperative brain CT within eight days prior to surgery, with maximum 1 mm slice thickness stored in the picture archiving The control group consisted of 55 individuals, 65 years or older from the general population, who participated in a previous study on the prevalence of iNPH [2]. Those without symptoms of iNPH, defined as at least 90 points on the iNPH symptom scale [7] were included in the present study, regardless of findings on a non-contrast enhanced brain CT. No lumbar puncture was performed as it was considered too invasive for volunteers from the general population.…”

“…However, it is interesting to speculate why men are overrepresented in the shunted group. There are indications that iNPH is more common in men [2], but it could also be influenced by gender differences in patient selection for surgery as well as in the patients' health care seeking behavior.…”

“…Idiopathic normal pressure hydrocephalus (iNPH), is a neurological condition affecting gait, balance, cognition and continence [1]. The disease is more common than previously expected, with a prevalence of 3.7% for those over 65 years old, and is increasing with age [2]. The clinical symptoms of iNPH may overlap with those of other neurological conditions such Alzheimer's disease and Parkinson disease.…”

In Vivo Evidence for Impaired Glymphatic Function in the Visual Pathway of Patients With Normal Pressure Hydrocephalus

“…The prevalence of iNPH is strongly associated with age. 47,48 Age has been shown to influence the flow of CSF and the glymphatic function. 49 It is therefore possible that some of the differences between the groups represent age effects.…”

Pathogenesis and pathophysiology of idiopathic normal pressure hydrocephalus

“…INPH is not a rare clinical entity. The prevalence of iNPH has been estimated to be 10 per 100 000 to 22 per 100 000 overall, with 1.30% in those aged ≥65 years and 5.9% in those aged ≥80 years 3,4 . One of the core features of iNPH is that the cerebrospinal fluid (CSF) pressure of an iNPH patient is within normal ranges 2 .…”