Normal-pressure hydrocephalus has its highest prevalence in the seventh and eighth decades and is rare in people younger than 60 years (Fisher 1982). However, young patients ranging from neonates to young adults with secondary normal-pressure hydrocephalus have been reported (Barnett et al 1987). The prevalence in the general population is unknown because some patients may manifest only with gait impairment and without cognitive deficits. A door-to-door survey in Germany of subjects older than 65 years found the prevalence of normal-pressure hydrocephalus to be 0.41% (Trenkwalder et al 1995). A survey of medical records in Olmsted County, Minnesota, established the incidence of normal-pressure hydrocephalus as 1.19/100,000 per year (Klassen and Ahlskog 2011). Clinical and radiologic assessment of more than 1000 subjects aged 70 years and older estimated prevalence of normal pressure hydrocephalus at 0.2% in individuals with the age range of 70 to 79 years, and it dramatically increased to 5.8% in octogenarians (Jaraj et al 2014). Several authors consider prevalence and incidence of normal-pressure hydrocephalus to be overestimated, and data from the Netherlands suggest the incidence of normal-pressure hydrocephalus responding to shunt at about 2.2 per million per year (Vanneste et al 1992b).