When bleeding around the brain is new.

What “acute” means

Acute describes timing. The blood is recent—often minutes to a few days old—rather than a collection that has been evolving for weeks. Many acute subdural hematomas follow a fall, motor-vehicle crash, or other head injury. Some occur in people taking blood thinners, even after trauma that seemed modest.

Acute bleeding is not the setting in which MMA embolization is used as a substitute for decompression. If pressure must be relieved now, that is a surgical and intensive-care decision.

Why it can be an emergency

Because the skull cannot expand, a rapidly enlarging collection raises pressure inside the head. That pressure can reduce alertness, cause weakness or speech difficulty, and, in severe cases, shift the brain (herniation).

How it looks on CT

On a non-contrast head CT, acute blood is often bright (hyperdense) and shaped like a crescent along the inner table of the skull. The team also looks for midline shift, compression of nearby structures, additional injuries, and skull fracture.

A crescent shape is typical of subdural blood. A lens-shaped collection above the dura is more typical of an epidural hematoma. Mixed pictures occur, which is why a specialist reviews the images rather than a single descriptive word on a report.

How it is treated

Small collections in a stable patient may be observed in a hospital setting with repeat imaging. Larger collections, declining alertness, or significant mass effect often require surgical evacuation, commonly a craniotomy when the clot is solid.

The team may reverse anticoagulation, treat seizures, support breathing and blood pressure, and watch intracranial pressure. Those decisions are made in an emergency department, operating room, or neuro-intensive care unit—not through an outpatient form.

After the acute phase

Some patients later develop a more chronic collection, and some acute bleeds evolve on subsequent scans. Follow-up imaging and a clear return-precaution plan matter after discharge.

MMA embolization is a consideration primarily for chronic subdural hematoma, especially to reduce recurrence after drainage. It is not an emergency replacement for acute decompression.