Posttraumatic cerebral atrophy as a risk factor for delayed acute subdural hemorrhage.

It has long been appreciated that chronic alcoholics and the elderly with generalized cerebral atrophy are at increased risk for the development of acute subdural hematomas. The reported incidence of cerebral atrophy after severe head injury is significant. However, the incidence of late morbidity and mortality from acute subdural hematoma is not well documented. Acute subdural hemorrhage is attributed to rupture of bridging cerebral veins. In the presence of cerebral atrophy, the bridging veins are stretched and traverse a greater distance in the subdural space. They are therefore more susceptible to tearing with minor trauma. In addition, there is a delayed tamponade effect since the atrophied brain is shrunken away from the inner table of the skull. A case report is presented which suggests that survivors of severe head injury may be at increased risk for the development of acute subdural hematomas from relatively minor injuries months or even years after their initial trauma.