[Mechanism of injury in acute subdural hematoma and diffuse brain injury: analysis of 587 cases in the Japan Neurotrauma Data Bank].

OBJECTIVE: The aim of this study was to analyze and compare the epidemiology of injury mechanisms in acute subdural hematoma (ASDH) with those of diffuse brain injury (DBI) in the Japan Neurotrauma Data Bank.

METHODS: Data in the Japan Neurotrauma Data Bank were reviewed for 1,002 patients with severe head injury treated at hospitals between 1998 and 2001 (ASDH, n=246; DBI, n=341). Clinical variables including mechanisms of injury were evaluated.

RESULTS: Patients with DBI were significantly younger, with higher incidence of skull fracture, lower Glasgow coma scale score and higher injury severity score than patients with ASDH. Different mechanisms of injury were involved, with ASDH occurring much more commonly in non-vehicular injuries, particularly falls (47.2%), while DBI resulted almost exclusively from vehicular injuries (79.7%). Impact sites on the head with ASDH were more commonly occipital or temporal, while those for DBI were frontal, temporal or facial. Alcohol use was involved in 13.8% of drivers with ASDH and 33.6% of drivers with DBI.

CONCLUSION: The principal mechanical damage in DBI was to the brain itself, while primary damage in ASDH occurred to surface blood vessels. ASDH and DBI remain the two worst and most-important types of traumatic brain injury, although the pathogenesis differs with age and mechanism injury.