What causes an aneurysm to bleed?
We usually don’t know why an aneurysm bleeds or exactly when it will bleed. We do know what increases the chance for bleeding:
High blood pressure is the leading cause of subarachnoid hemorrhage. Heavy lifting or straining can cause pressure to rise in the brain and may lead to an aneurysm rupture.
Strong emotions, such as being upset or angry, can raise blood pressure and can subsequently cause aneurysms to rupture.
Blood “thinners” (such as warfarin), some medications and prescription drugs (including diet pills that act as stimulants such as ephedrine and amphetamines), and harmful drugs like cocaine can cause aneurysms to rupture and bleed.
What are the chances that an unruptured aneurysm may bleed?
Many factors determine whether an aneurysm is likely to bleed. These include the size, shape and location of the aneurysm and symptoms that it causes. Smaller aneurysms that are uniform in size may be less likely to bleed than larger, irregularly shaped ones. Once an aneurysm has bled, there’s a very high chance of re-bleeding. That’s why we recommend treatment as soon as possible.
What happens if an aneurysm bleeds?
If an aneurysm ruptures, it leaks blood into the space around the brain. This is called a “subarachnoid hemorrhage.” Depending on the amount of blood, it can produce:
a sudden severe headache that can last from several hours to days
nausea and vomiting
drowsiness and/or coma
The hemorrhage may also damage the brain directly, usually from bleeding into the brain itself. This is called a “hemorrhagic stroke.” This can lead to:
weakness or paralysis of an arm or leg
trouble speaking or understanding language
vision problems
seizures
What is the usual damage to the brain after an aneurysm bleeds?
Once an aneurysm bleeds, the chance of death is 30 to 40 percent and the chance of moderate to severe brain damage is 20 to 35 percent, even if the aneurysm is treated. Fifteen to 30 percent of patients have only mild difficulties or almost none. If the aneurysm isn’t treated quickly enough, another bleed may occur from the already ruptured aneurysm.
In 15 to 20 percent of patients, vasospasm (irritation by the leaked blood causing narrowing of the blood vessels) may occur. This can lead to further brain damage. Other problems may include hydrocephalus (enlargement of the spaces within the brain that produce cerebrospinal fluid), difficulty breathing that requires a mechanical ventilator, and infection. Heart and lung problems may result due to extensive brain damage that can affect the body’s normal functions.
Why is the damage so extensive after bleeding?
After blood enters the brain and the space around it, direct damage to the brain tissue and brain function results. The amount of damage is usually related to the amount of blood. Damage is due to the increased pressure and swelling from bleeding directly into the brain tissue, or from local cellular damage to brain tissue from irritation of blood in the space between the brain and the skull.
Blood can also irritate and damage the normal blood vessels and cause vasospasm (constriction). This can interrupt normal blood flow to the healthy brain tissue and can cause even more brain damage. This is called an “ischemic stroke.”
Will treating a ruptured aneurysm reverse or improve brain damage?
Once an aneurysm bleeds and brain damage occurs, treating the aneurysm will not reverse the damage. Treatment helps prevent more bleeding, which can cause more damage to the brain and, consequently, to the body’s functions. If bleeding has already caused brain damage, patients may benefit from rehabilitation therapy after the aneurysm has been treated.
How is a treatment method for an aneurysm chosen?
Each patient and each aneurysm is different. Doctors must evaluate the risk factors that favor treatment vs. non-treatment and decide which technique may be best.
It’s important to consult with experts in this field. This should include a discussion with a cerebrovascular neurosurgeon who specializes in surgically clipping aneurysms, a neurosurgeon with endovascular expertise and training, a neurointerventionalist (a neurologist with endovascular training) or a neuroradiologist who specializes in the less invasive treatment of cerebral aneurysms by coiling. These types of medical specialists have different expertise and training backgrounds. We recommend you consult with several types of physicians.
How should an aneurysm be treated?
The best treatment depends on many things, including whether the aneurysm has ruptured or not. A ruptured aneurysm usually requires treatment right away, because the re-bleeding rate remains quite high. However, the treatment time and options for treatment depend on the size, location and shape of the aneurysm, as well as the patient’s overall medical condition. If an aneurysm hasn’t ruptured, the treatment decision depends on its size, location and shape, and the patient’s symptoms. Each factor is important and requires consultation with a neurosurgeon and a neurointerventionalist or a neuroradiologist who has special skills and training in treating these types of aneurysms.