[Idiopathic normal pressure hydrocephalus: High incidence in people over 80 years of age]. / Hidrocefalia normotensiva idiopática: alta incidencia en mayores de 80 años.

INTRODUCTION: Idiopathic normal pressure hydrocephalus is usually observed in adults over 60 years of age. The highest incidence of cases is between 70 and 80 years-old, and it could be under-diagnosed in over 80 year-olds. OBJECTIVE: A description is presented on the overall incidence and age group incidence, the delay in the diagnosis, and main outcomes. PATIENTS AND METHODS: A descriptive study was performed on patients with idiopathic normal pressure hydrocephalus, in the population of Osona County during the years 2010-2015. RESULTS: The annual incidence rate was 4.43 per 100,000 inhabitants. The incidence increased with age; from 8.09 per 100,000 in the 60 to 69 years age group, to 23.61 per 100,000 in the 70-79 years age group of, and to 37.02 per 100,000 in the 80-89 years age. The delay in the diagnosis was 15.01 ± 10.35 months. All the patients improved after surgery, but only 73.3% of the patients maintained the improvement after one year. CONCLUSIONS: Idiopathic normal pressure hydrocephalus is an age related disease and probably underdiagnosed in the elderly. An early diagnosis and a clinical suspicion are essential in patients over 80 years old.