Subdural Hematoma (SDH)

Anatomy of the injury

Illustration showing blood clot underneath the dura.

The covering of the brain is called the dura. When a hemorrhage occurs from bleeding underneath the dura, a blood clot forms between the brain and the dural.

What is a subdural hematoma?

In the animation, one can see the blood clot underneath the dura. It pushes the brain inward resulting in pressure on the brain. Since the hemorrhage is under the dura, it is called a subdural hematoma (SDH).

How does a subdural hematoma form?

Brain illustration showing bridging veins

There are veins connecting the dura covering the brain and the brain itself. These are called bridging veins. When the brain shifts within the skull during trauma, bridging veins can get stretched and tear. This results in bleeding on the surface of the brain, under the dura forming a subdural hematoma. Clinically, patients will become progressively lethargic and may rapidly lapse into a coma with an acute subdural hematoma.

The brain is inside the skull. When the skull moves forward and hits something solid, for example, falling onto the floor, the skull stops first, but the brain is still traveling. Bridging veins get stretched, tear and bleed as is seen in this video.