[Epidemiology of chronic subdural hematomas].

BACKGROUND AND PURPOSE: The Japanese population is aging faster than any other population in the world, affecting the epidemiology of which frequently occurs in the elderly. In this study, the epidemiological aspect of chronic subdural hematoma (CSDH) is investigated, using data of the Miyagi Traumatic Head Injury Registry Project.

PATIENTS AND METHODS: From January 2005 to December 2007, 1,445 patients with CSDH were registered in the project (M:F=1,021:424, mean age 71.2±12.8 y.o.). Using these patient's records, the incidence of CSDH was investigated, as well as causes of head injury, severity, and outcome.

RESULTS: The overall incidence of CSDH was 20.6/100,000/year, with 76.5 in the age group of 70-79 y.o. and 127.1 in the over 80 y.o. group. Ground level fall was the most frequent cause of trauma in the elderly, in contrast to traffic accident, which was the most frequent cause in the younger generation. Compared to the younger generation, neurological condition was severer in the elderly at the time of admission, and the outcome was poorer at the time of discharge.

CONCLUSION: Compared to previous reports, this study demonstrates a marked increase in the incidence of CSDH. Not only population aging but also current medical trends (such as increases of the elderly patients who receive hemodialysis, anticoagulant, and/or antiplatelet therapy) may influence the increase of CSDH incidence.