Clinical Definition

A subdural hematoma (SDH) is an intracranial blood clot between the dura mater and arachnoid layer of the meninges. The hematoma often develops due to shearing of the bridging veins, a breakage caused by head trauma. A subdural hematoma often causes an increase in intracranial pressure, which may result in damage to the brain tissue.

In Our Own Words

A subdural hematoma (SDH) is a blood clot that develops in the space between two layers that cover the brain: the dura mater and the arachnoid membranes. When an injury to the head occurs, it is usually the veins traveling from the dura to the brain that tear and bleed to cause an SDH, but small arteries can also rupture to cause the SDH.

The tearing or rupturing of the vessels results in a pooling of blood, and this collection of blood can cause pressure inside the head. Pressure inside the skull can become so great it injures the brain and causes damage or even death. The most common cause of a subdural hematoma is some type of trauma to the head, typically a motor vehicle accident. Although symptoms can develop minutes after an injury to the head, they can also occur hours later, or more slowly over time, as is sometimes the case with chronic subdural hematomas in elderly people.