What Is a Brain Aneurysm?
A brain aneurysm, also known as a subarachnoid hemorrhage (SAH), Other names: Cerebral aneurysm, brain aneurism, brain aneurysm, cerebral aneurism, is a weak spot in the wall of a blood vessel inside the brain. Think of a weak spot in a balloon and how it feels stretched out and thin. A brain aneurysm is like that.
That area of the blood vessel gets worn out from constant flow of blood and bulges out, almost like a bubble. It can grow to the size of a small berry.
Brain Aneurysm Causes
Brain aneurysms usually develop as people age, becoming more common after 40. It’s also possible to have a blood vessel defect at birth.
Women tend to have higher rates of aneurysms than men.
Aneurysms tend to form at the fork of blood vessels, places where they branch off, because those sections tend to be weaker. They are most commonly found at the base of the brain.
Four major blood vessels supply blood to the brain. They join together at the Circle of Willis at the base of the brain. Smaller arteries leave the circle and branch out to supply brain cells with oxygen and nutrients.
Artery junction points may become weak, causing a ballooning of the blood vessel wall to potentially form a small sac or aneurysm.
Cerebral aneurysms are common, but most are asymptomatic and are found incidentally at autopsy.
There are different types:
- Saccular aneurysms are the most common type of brain aneurysm. They bulge out in a dome shape from the main artery. They’re connected to that artery by a narrow “neck.”
- Fusiform aneurysms aren’t as common as saccular aneurysms. They don’t pouch out in a dome shape. Instead, they make a widened spot in the blood vessel.
Although brain aneurysms sound alarming, most don’t cause symptoms or health problems. You can enjoy a long life without ever realizing that you have one.
But in rare cases, aneurysms can grow big, leak, or explode. Bleeding in the brain, known as a hemorrhagic stroke, is serious, and you’ll need medical care right away.
A ruptured aneurysm quickly becomes life-threatening and requires prompt medical treatment.
Most brain aneurysms, however, don’t rupture, create health problems or cause symptoms. Such aneurysms are often detected during tests for other conditions.
Treatment for an unruptured brain aneurysm may be appropriate in some cases and may prevent a rupture in the future. Talk with your caregiver to ensure you understand the best options for your specific needs
Symptoms of Ruptured Brain aneurysm
A sudden, severe headache is the key symptom of a ruptured aneurysm. This headache is often described as the “worst headache” ever experienced.
Common signs and symptoms of a ruptured aneurysm include:
- Sudden, extremely severe headache
- Nausea and vomiting
- Stiff neck
- Blurred or double vision
- Sensitivity to light
- A drooping eyelid
- Loss of consciousness
Symptoms of ‘Leaking’ Brain aneurysm
In some cases, an aneurysm may leak a slight amount of blood. This leaking (sentinel bleed) may cause only a:
- Sudden, extremely severe headache
A more severe rupture often follows leaking.
Symptoms of Unruptured Brain aneurysm
An unruptured brain aneurysm may produce no symptoms, particularly if it’s small. However, a larger unruptured aneurysm may press on brain tissues and nerves, possibly causing:
- Pain above and behind one eye
- A dilated pupil
- Change in vision or double vision
- Numbness of one side of the face
Brain Aneurysms in Children
Rarely, kids under 18 can have a brain aneurysm. Boys are eight times more likely to get them than girls. Of the few cases in children, about 20% are “giant” aneurysms (larger than 2.5 centimeters).
Aneurysms in kids can come on for no reason. But they’re also sometimes related to:
- Head trauma
- Connective tissue disorders
- Genetic disorders
- Family history
Risk factors of Brain Aneurysm present at birth
Selected conditions that date to birth can be associated with an elevated risk of developing a brain aneurysm. These include:
- Inherited connective tissue disorders, such as Ehlers-Danlos syndrome, that weaken blood vessels
- Polycystic kidney disease, an inherited disorder that results in fluid-filled sacs in the kidneys and usually increases blood pressure
- Abnormally narrow aorta (coarctation of the aorta), the large blood vessel that delivers oxygen-rich blood from the heart to the body
- Cerebral arteriovenous malformation (brain AVM), an abnormal connection between arteries and veins in the brain that interrupts the normal flow of blood between them
- Family history of brain aneurysm, particularly a first-degree relative, such as a parent, brother, sister, or child
Brain Aneurysm Risk Factors
Smoking and high blood pressure are the things that put you at the most risk of having a brain aneurysm. But several other things in your medical history and lifestyle also increase your odds.
Things in your medical history that can play a role include:
- High blood pressure
- Atherosclerosis, a disease in which fat builds up inside the walls of your arteries (blood vessels that deliver oxygen-rich blood throughout your body)
- Diseases affecting your blood or blood vessels:
- Connective tissue disorders such as Ehlers-Danlos syndrome
- Polycystic kidney disease
- Injury or trauma to your head
- Cancer or tumors in your head and neck
- Abnormalities at birth, such as tangled blood vessels in your brain, abnormally narrow aorta (coarctation of the aorta), or cerebral arteriovenous malformation (brain AVM)
- Family history of brain aneurysms
Complications of Brain Aneurysm
When a brain aneurysm ruptures, the bleeding usually lasts only a few seconds. The blood can cause direct damage to surrounding cells, and the bleeding can damage or kill other cells. It also increases pressure inside the skull.
If the pressure becomes too elevated, the blood and oxygen supply to the brain may be disrupted to the point that loss of consciousness or even death may occur.
Complications that can develop after the rupture of an aneurysm include:
- Re-bleeding. An aneurysm that has ruptured or leaked is at risk of bleeding again. Re-bleeding can cause further damage to brain cells.
- Vasospasm. After a brain aneurysm ruptures, blood vessels in your brain may narrow erratically (vasospasm). This condition can limit blood flow to brain cells (ischemic stroke) and cause additional cell damage and loss.
- Hydrocephalus. When an aneurysm rupture results in bleeding in the space between the brain and surrounding tissue (subarachnoid hemorrhage) — most often the case — the blood can block circulation of the fluid surrounding the brain and spinal cord (cerebrospinal fluid). This condition can result in an excess of cerebrospinal fluid that increases pressure on the brain and can damage tissues (hydrocephalus).
- Hyponatremia. Subarachnoid hemorrhage from a ruptured brain aneurysm can disrupt the balance of sodium in the blood. This may occur from damage to the hypothalamus, an area near the base of the brain.A drop in blood-sodium levels (hyponatremia) can lead to swelling of brain cells and permanent damage.
Brain Aneurysm Diagnosis
Several types of scans and tests can be used to figure out whether you have a brain aneurysm. They include:
- CT scan: This exam creates images of your brain. You will lie on a table that slides into a CT scanner. A technician will inject contrast dye into one of your veins to make it easier to see the blood flow and spot aneurysms in your brain.
- MRI: This exam is similar in that you lie on a table that slides into a scanner. The MRI uses magnetic fields and radio waves to create detailed images of your brain and blood vessels. MRIs and CT scans can detect aneurysms larger than 3 to 5 millimeters. The following tests are more invasive than CT or MRI scans. But they could give you and your nurses and doctors a more complete picture of what’s going on:
- Angiogram: This test, considered the most reliable way to detect aneurysms, shows the weak spots in your blood vessels. During the test, you lie on an X-ray table, and you will be given something to numb any pain. Your doctor will insert a small flexible tube through a blood vessel in the leg. They’ll guide that tube, called a catheter, into the blood vessels in your neck that reach the brain. Then they’ll inject a contrast dye into you, and X-rays will be taken that show all the blood vessels in the brain. This gives your nurses and doctor a map of your blood vessels, pinpointing the aneurysm.
- Cerebrospinal fluid test: Your doctor may order this test if they think an aneurysm may have ruptured. You’ll be given something to block any pain. A technician will put a needle into you to draw spinal fluid. That fluid is tested to see whether it contains blood, which could mean an aneurysm has ruptured.
What is the treatment for brain aneurysm?
Treatment for a symptomatic aneurysm is to repair the blood vessels. Clipping and coiling are two treatment options.
- Clipping: A neurosurgeon can operate on the brain by cutting open the skull, identifying the damaged blood vessel and putting a clip across the aneurysm. This prevents blood from entering the aneurysm and causing further growth or blood leakage.
- Coiling: An interventional neurologist, neurosurgeon, or interventional radiologist can thread a tube through the arteries, as with an angiogram, identify the aneurysm, and fill it with coils of platinum wire or with latex. This prevents further blood from entering the aneurysm and resolves the problem.
- Flow diverter surgery: This option is for larger brain aneurysms in which neither clipping nor coiling would work. In this procedure, your doctor inserts a stent, usually made of metal mesh, inside the artery. It becomes a wall inside the vessel to divert blood away from the aneurysm.
Both these options have the risk of damaging the blood vessel and causing more bleeding, damaging nearby brain tissue, and causing the surrounding blood vessels to go into spasm; depriving brain tissue of blood supply and causing a stroke.
Prior, during, and after surgery, attention is paid to protect the brain and its blood vessels from potential further damage. Vitals signs are monitored frequently, and heart monitors are used to watch for abnormal heart rhythms.
What is the outcome/statistics of brain aneurysm?
Brain aneurysms are deadly. About 10% of patients with a ruptured aneurysm die before receiving medical care. If untreated, another 50% will die within a month, with a 20% risk of rebleed by the end of the first two weeks. Aside from the bleeding issues, there is significant risk of artery spasm leading to stroke.
Survival rates are increased in patients who present early to the hospital. Early diagnosis, aneursym repair, and control of blood vessel spasms with appropriate medications are all associated with increased survival.