Aneurysmal subarachnoid hemorrhage

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Synonyms

aSAH,

Overview

Subarachnoid hemorrhage (SAH) is bleeding in the space below one of the thin layers that cover and protect your brain. SAH is a medical emergency that requires immediate treatment. It’s often caused by head trauma and/or a ruptured brain aneurysm. The most common sign is a sudden, severe headache.

Symptoms

  • a sudden severe headache unlike anything you’ve experienced before.
  • a stiff neck.
  • feeling and being sick.
  • sensitivity to light (photophobia)
  • blurred or double vision.
  • stroke-like symptoms – such as slurred speech and weakness on one side of the body.

Causes

  • A brain aneurysm that bursts. A brain aneurysm is a bulge in a blood vessel in the brain. …
  • Head injury. Another common cause is a head injury. …
  • A tangle of blood vessels in the brain, known as an arteriovenous malformation. …
  • Swelling of the blood vessels, known as vasculitis.

Prevention

It is almost impossible to prevent a subarachnoid hemorrhage caused by an aneurysm or AVM. These blood vessel abnormalities usually do not cause any symptoms before the hemorrhage occurs. Smoking has been shown to increase the risk of forming an aneurysm, so avoiding smoking may prevent some cases.

Diagnosis

To diagnose a subarachnoid hemorrhage, you may need the following tests:

  • CT scan. This imaging test is very effective at detecting bleeding in the brain. But it may not detect bleeding if you have a low red blood cell count or if there is a small amount of bleeding. Your healthcare professional may inject a contrast dye to view your blood vessels in greater detail, known as a CT angiogram.
  • MRI. This imaging test also can detect bleeding in the brain. An MRI scan may show signs of a subarachnoid hemorrhage in rare cases when it’s not detected by a CT scan. Your healthcare professional might inject a dye into a blood vessel to view the arteries and veins in greater detail, known as an MR angiogram.
  • Cerebral angiography. You may have a cerebral angiography to get more-detailed images. Angiography also may be done if a subarachnoid hemorrhage is suspected, but the cause isn’t clear or doesn’t appear on other imaging. A long, thin tube known as a catheter is inserted into an artery and threaded to your brain. Dye is injected into the blood vessels of your brain to make them visible under X-ray imaging. Sometimes a cerebral angiogram does not show an aneurysm. If this happens, you may have a second angiogram if your healthcare professional thinks an aneurysm is likely.

For some people with an aneurysm that caused a subarachnoid hemorrhage, the bleeding may not appear on initial imaging. If this happens, you may need a lumbar puncture. During this procedure, a needle is inserted into the lower back. A small amount of the fluid that surrounds the brain and spinal cord, known as cerebrospinal fluid, is removed. The fluid is then studied to look for blood, which may mean that you have a subarachnoid hemorrhage.

Prognosis

Prehospital mortality rates have been reported to be between approximately 22% and 26%, while inpatient mortality rates were reported to be between approximately 19% and 20%. Furthermore, although reported studies are sparse, approximately 36% to 42% of patients report a poor long-term outcome.

Treatment

Treatment of a subarachnoid hemorrhage focuses on stabilizing the condition. Your healthcare team checks your breathing, blood pressure and blood flow.

If you have a burst aneurysm, you’re treated for it and your healthcare team works to prevent complications.

To treat a ruptured brain aneurysm, your healthcare professional might recommend:

  • Surgery. The surgeon makes an incision in the scalp and locates the brain aneurysm. A metal clip is placed on the aneurysm to stop the blood flow to it.
  • Endovascular embolization. The surgeon inserts a catheter into an artery and threads it to your brain. Detachable platinum coils are guided through the catheter and placed in the aneurysm. The coils reduce blood flow into the aneurysm and cause the blood to clot. Different types of coils have been developed to treat aneurysms.
  • Other endovascular treatments. Certain aneurysms can be treated with endovascular embolization that uses newer technology. These newer techniques include stent-assisted or balloon-assisted coiling or devices that divert blood flow.

Treating the ruptured aneurysm quickly can help prevent bleeding from happening again.

It’s also important to prevent other complications. A subarachnoid hemorrhage may lead to low salts such as sodium in the blood. It also may cause high or low blood sugar. Your healthcare team monitors these levels and treats them if needed.

There also may be poor blood flow to the brain. A common complication of a subarachnoid hemorrhage due to a burst aneurysm is a constriction and narrowing of the blood vessels in the brain, known as vasospasm. This can cause a stroke if blood flow decreases to a certain level. A stroke may be avoided by raising blood pressure or by widening blood vessels in the brain with medicines. The medicine nimodipine (Nymalize) also can lower the risk of vasospasm.

Another common complication is a buildup of fluid in cavities within the brain, known as hydrocephalus. This can be treated with drains inserted in the head or lower back.

Sometimes, procedures need to be repeated. After your initial treatment, follow-up appointments with your healthcare team are important to watch for any changes. You also may need physical, occupational and speech therapies.