Middle meningeal artery embolization

The brain is covered by several thin layers. The toughest outer layer, just under the skull, is called the dura. A subdural hematoma is a collection of blood that forms between the dura and the brain. A chronic subdural hematoma (cSDH) builds up slowly, over weeks, often after a minor bump to the head that you may not even remember.

It is most common in people over 65. As we age, the brain shrinks a little and the small veins bridging to the dura stretch and tear more easily. Blood thinners, antiplatelet medicines such as aspirin, frequent falls and heavy alcohol use raise the risk.

Once a chronic subdural starts, the body forms a thin, inflamed lining around it, called a membrane, full of fragile new blood vessels. These vessels keep leaking small amounts of blood, so the collection can grow or come back even after it is drained. Many of these vessels are fed by the middle meningeal artery (MMA), an artery that runs along the inside of the skull and feeds the dura.

Embolization means blocking a blood vessel on purpose. In MMA embolization, we guide a thin catheter into the middle meningeal artery and fill its branches with a liquid embolic agent that hardens like soft glue, or with tiny particles. This cuts off the blood supply to the leaky membrane. With the leak stopped, the body can slowly absorb the old blood over the following weeks to months.

The dura has other sources of blood, so blocking the MMA does not harm the brain. The brain itself is fed by different arteries that are not touched.

What we see

Decisions are made together with a neurosurgeon. MMA embolization does not remove the blood that is already there, so it does not give fast relief from pressure on the brain. When a large collection is causing significant symptoms, surgery comes first, and embolization is often added a day or two later.

Large studies published in 2024 found that adding MMA embolization to standard treatment, including surgery, cut the chance of the hematoma coming back or needing another operation roughly in half or more. Some small collections without symptoms are simply watched, sometimes after pausing blood thinners when safe to do so.

1. 1
   Getting ready

   An IV is placed, and you receive moderate sedation or general anesthesia so you can lie very still. We review your blood thinners with you and your neurosurgeon beforehand. See blood thinners.

2. 2
   Reaching the artery

   We numb the wrist or groin and place a small tube in the artery. Using X-ray, a catheter is guided up to the external carotid artery in the neck, and a very thin microcatheter into the middle meningeal artery.

3. 3
   Blocking the branches

   Contrast dye maps the artery and checks for connections to the eye or brain. We then slowly inject the liquid embolic agent or particles to fill the branches feeding the membrane, on one or both sides.

4. 4
   Finishing

   A final picture confirms the branches are closed. The tube is removed and the pinhole is sealed with a wrist band or closure device.

The part of this procedure I spend the most time on is the map. Before I inject anything, I look for small connections between the middle meningeal artery and the arteries to the eye and face, because protecting those is what keeps the procedure safe. I remind families that the blood collection does not disappear overnight. It shrinks over the next few months, and that slow change on the follow-up scans is what we are hoping to see.

Fabio Komlos, MD, interventional radiologist · About Dr. Fabio Komlos

1. First few hours
   You rest while nurses check the puncture site and do regular neurological checks: strength, speech and alertness.
2. Night after
   Most people stay 1 night for observation, often longer if embolization was done together with surgery.
3. First 1–2 weeks
   Some people have a headache, jaw or temple ache for a few days. Avoid heavy lifting, straining and driving until your doctors clear you. Take steps to prevent falls at home.
4. 2–6 weeks
   A follow-up CT scan checks the collection. It may look the same at first, which is expected.
5. 3–6 months
   Repeat CT scans usually show the collection shrinking or gone. Your neurosurgeon will guide when blood thinners can be restarted, if needed.

Do not drive until your neurosurgeon clears you, especially if you have had a seizure or symptoms from the hematoma. Rules for driving after a seizure vary by state.

Most people have a steady shrinking of the collection over 3 to 6 months. When embolization is added to surgery, the chance of needing another operation drops substantially. A small number of people still need drainage later if the collection grows or symptoms get worse.