Acute Subdural Hematomas
An acute subdural hematoma (SDH) is a clot of blood that develops between the surface of the brain and the dura mater, the brain’s tough outer covering, usually due to stretching and tearing of veins on the brain’s surface. These veins rupture when a head injury suddenly jolts or shakes the brain.
- Traumatic acute SDHs are among the most lethal of all head injuries. Associated with more severe generalized brain injury, they often occur with cerebral contusions.
- SDHs are seen in 10 percent to 20 percent of all traumatic brain injury cases and occur in up to 30 percent of fatal injuries.
- SDHs are best diagnosed by computed tomography (CT) scan. They appear as a dense, crescent-shaped mass over a portion of the brain’s surface.
- Most patients with acute SDHs have low Glasgow Coma Scale (GCS) scores on admission to the hospital.
- SDHs greater than 1 cm at the thickest point generally require rapid surgical treatment. Smaller SDHs may not require surgery. A large craniotomy, surgery through an opening created in the skull, is often required to remove the thick blood clot and to reach bleeding sites.
- Cerebral contusions underlying an SDH are often removed at the same surgery.
- Recovery after brain injury varies widely.
- The mortality rate for patients with an acute SDH ranges from 50 percent to 90 percent. A significant percentage of these deaths result from the underlying brain injury and pressure on the brain that develops in the days after injury.
- Approximately 20 percent to 30 percent of patients will recover full or partial brain function. Postoperative seizures are relatively common in these patients.
- Favorable outcomes are most common in patients who receive rapid treatment, younger adults, patients with a GCS score above 6 or 7 and reactive pupils, and those without multiple cerebral contusions or unmanageable pressure on the brain.