What is Cerebral Aneurysm (Brain Aneurysm)?
Cerebral aneurysms are essentially bulges that form at weak spots in the brain’s arteries. Their size can differ: they can be small (less than 0.5 mm), medium (6 to 25 mm), or large (more than 25 mm). Most of them are saccular, or berry-shaped, and these often come with a thin or even missing middle layer and a much-damaged or absent inner elastic layer. Some less common ones are fusiform or circular, and mycotic or caused by an infection. Most of the time, cerebral aneurysms don’t show symptoms and are only discovered during brain imaging tests or autopsies. Around 85% of these aneurysms are found in the front part of the brain, mostly at junctions or branch points along a structure known as the circle of Willis. If these aneurysms rupture, they usually cause a type of stroke called subarachnoid hemorrhage, which comes with a high risk of severe disability or even death.
What Causes Cerebral Aneurysm (Brain Aneurysm)?
Cerebral aneurysms, which are abnormal bulges in the walls of the brain’s blood vessels, usually develop as a result of certain conditions or behaviors. These can include getting older, high blood pressure, smoking, drinking alcohol excessively, and hardening of the arteries (known as atherosclerosis).
Other contributors to cerebral aneurysms can be cocaine use, tumors, injuries to the head, and certain types of infections that can cause clots to form in the heart, like endocarditis.
Family history also plays a part, as people with more than one family member who has had an aneurysm are at a higher risk.
Examples of genetic disorders that can increase the likelihood of developing an aneurysm include polycystic kidney disease (where multiple cysts form in the kidneys), Ehlers-Danlos syndrome (a group of inherited disorders that affect skin, joints, and blood vessels), fibromuscular dysplasia (a condition that causes arteries to narrow), tuberous sclerosis (a genetic disorder where benign tumors can grow in multiple organs), abnormal connections between arteries and veins (known as arteriovenous malformations), and coarctation of the aorta (a narrowing of the large blood vessel that leads from the heart).
Risk Factors and Frequency for Cerebral Aneurysm (Brain Aneurysm)
Cerebral aneurysms, a bulge in a blood vessel in the brain, affect about 3.2% of people globally. Generally, aneurysms are more common in people around 50 years old, with an equal chance for both men and women to have them. However, after the age of 50, there are twice as many women with aneurysms as there are men, possibly because falling estrogen levels lead to changes in blood vessel structure.
There are about 10 cases per 100,000 people of aneurysms rupturing and causing a specific type of stroke known as a subarachnoid hemorrhage (SAH). This rate is higher in Finnish and Japanese populations, but it’s not because aneurysms are more common in these groups.
- Around the world, about 3.2% of people have cerebral aneurysms.
- The average age of people with an aneurysm is 50.
- Men and women have an equal chance of having an aneurysm, until age 50.
- After 50, women are twice as likely as men to have an aneurysm.
- The rate of aneurysms breaking and causing a SAH is about 10 in 100,000 people.
- People in Finland and Japan have higher rates of SAH, but not necessarily of aneurysms.
- About 0.4 to 0.6% of all deaths are due to aneurysm-related SAH.
- Of people who experience a rupture, about 20% die and an additional 30 to 40% experience other health complications.
Signs and Symptoms of Cerebral Aneurysm (Brain Aneurysm)
An unruptured brain aneurysm often doesn’t cause symptoms, so it can be hard to detect with just a physical exam. However, when an aneurysm ruptures, it usually causes a sudden, severe headache – often described as the “worst headache of my life”. For about 30% of patients, this harsh headache is felt on the same side as the aneurysm. Other symptoms that could accompany the headache are brief unconsciousness, signs of meningitis, or nausea and vomiting. Seizures are rare, seen in fewer than 10% of patients, and sudden death can also occur in about 10 to 15% of patients. There are instances where 30 to 50% of patients with a major subarachnoid hemorrhage (a type of stroke caused by bleeding on the surface of the brain) report a severe, sudden headache 6 to 20 days beforehand. This is known as a “sentinel headache”, which acts as a warning sign of a minor bleeding or “warning leak”. Physical exam findings may reveal high blood pressure, dilated pupils, changes in vision, changes in consciousness, sensitivity to light, motor or sensory deficits, stiff neck, and lower back pain when the neck is bent.
Doctors may use the Hunt and Hess grading system to predict the outcome of the patient based on their initial neurological state. This system has 5 grades reflecting the severity of symptoms, which are associated with the overall death rate. Patients with a mild headache and slight stiffness of the neck are assigned Grade 1. Those with a severe headache, stiff neck, but no other neurological deficits except cranial nerve palsy are assigned Grade 2. Grade 3 is for patients who are drowsy or confused with a mild focal deficit. Those who are halfway unconscious with moderate to severe weakness on one side of the body are assigned Grade 4. Lastly, Grade 5 includes patients who are in a coma with decerebrate posturing (abnormal body movements).
Testing for Cerebral Aneurysm (Brain Aneurysm)
Unruptured brain aneurysms are often found unexpectedly when a patient gets a brain scan for a different reason. However, those at high-risk might have tests such as magnetic resonance imaging (MRI), computerized tomographic angiography (CTA), or traditional angiography to check for them. If it’s thought a brain aneurysm has ruptured and caused a subarachnoid hemorrhage (SAH), or bleeding in the brain, a non-contrast CT scan of the brain is usually the first step, sometimes coupled with a lumbar puncture (LP), also known as a spinal tap.
If the patient arrives promptly, the CT scan alone is often sufficient to identify a SAH, but its effectiveness reduces over time. It’s highly effective within the first 6 hours of symptom onset, but drops significantly after that.
If the CT scan comes back negative but a SAH is still suspected, an LP is the next step. Some signs to look for in an LP are high pressure when the procedure is initiated and a high red blood cell count that doesn’t decrease in subsequent collections of spinal fluid. The presence of xanthochromia, a pinkish or yellowish discoloration of the cerebrospinal fluid (CSF) caused by the breakdown of hemoglobin, strongly suggests a SAH. The sensitivity of xanthochromia detection increases significantly if it’s done 12 hours or more after the suspected brain bleed time.
Once the diagnosis of SAH is confirmed, it’s important to identify where the bleeding is coming from. Techniques like CTA, MRA, or digital subtraction angiography (DSA) can help to locate the source of bleeding. DSA involves inserting a flexible tube into the blood vessel and injecting a contrast dye, allowing for clear imaging under fluoroscopy. It’s considered the “gold standard” for detecting a ruptured brain aneurysm.
Treatment Options for Cerebral Aneurysm (Brain Aneurysm)
The choice of treatment depends on several factors such as the patient’s age, other existing health conditions, and the size and location of the aneurysm. It also matters if the aneurysm has burst or not. There are generally two types of treatment: surgical and endovascular.
In surgical treatment, a small clip is placed on the neck of the aneurysm to stop blood from entering it and reduce the risk of bleeding. This procedure is done under general anesthesia in the operating room. It involves temporarily removing a piece of the skull to access the aneurysm, using a microscope to separate it from nearby blood vessels, and applying the clip. The piece of the skull is then replaced and secured with tiny metal plates and screws, before closing the wound. Over time, the aneurysm will get smaller and scar over, but the clip usually stays in place for life.
Endovascular coiling is another, less invasive treatment. This procedure involves inserting a thin tube called a catheter through an artery in the groin. The catheter is guided up to the artery containing the aneurysm. A smaller catheter that carries a platinum coil is then inserted through the main catheter. The coil is released into the aneurysm with an electric current, which promotes clotting and eventually eliminates the aneurysm. The risks of this procedure include the formation of blood clots and the rupture of the aneurysm during the procedure.
If the aneurysm has ruptured, additional treatments are needed to manage complications. This care typically occurs in an intensive care unit (ICU) to monitor for problems like rebleeding, spasms in blood vessels, excessive fluid in the brain, seizures, and a decrease in sodium levels in the blood. A type of medicine called a calcium channel blocker, often nimodipine, is commonly used to prevent a lack of blood supply to the brain due to spasms following a rupture.
What else can Cerebral Aneurysm (Brain Aneurysm) be?
- Abnormal connections between arteries and veins
- Problems related to a group of veins in the brain
- Tears in the walls of major arteries in the neck
- Clots in the brain’s veins
- An unusual, non-atherosclerotic disease that affects medium-sized arteries
- Severe types of headaches like migraines and clusters
- A rare, progressive cerebrovascular disorder
- Bleeding or obstruction in the pituitary gland
- A condition caused by a blockage or bleeding in the brain, called a stroke
- A rare type of vascular anomaly in the brain occurring during infancy
There are many different conditions that can affect the blood vessels in and around the brain. It’s always essential to get the right diagnosis from a medical professional.
What to expect with Cerebral Aneurysm (Brain Aneurysm)
If a cerebral aneurysm, a bulge or ballooning in the brain’s blood vessels, ruptures, the health risks are extremely high. About 25% of people die within the first day and half of them will die within the following three months. Even with treatment, the death rate is about 40%.
Several factors affect these outcomes:
* Age
* Where the aneurysm is located in the brain
* How much narrowing (vasospasm) is present in the blood vessels
* Whether high blood pressure and other health conditions are present
* The person’s neurological condition when they are admitted to the hospital
* The amount of bleeding within the ventricles, the fluid-filled spaces inside the brain.
Possible Complications When Diagnosed with Cerebral Aneurysm (Brain Aneurysm)
Here are some potential complications associated with certain medical conditions:
- Recurrent bleeding
- Vasospasm – narrowing of the blood vessels
- Seizures – sudden, uncontrolled electrical disturbance in the brain
- Syndrome of inappropriate antidiuretic hormone secretion – a condition that results from high levels of antidiuretic hormone in the body
- Hydrocephalus – an increase in fluid in the brain
- Arrhythmias – irregular heartbeats
- Congestive cardiac failure – a chronic condition in which the heart doesn’t pump blood as well as it should
- Gastrointestinal bleeding – bleeding in the digestive tract
- Deep vein thrombosis – a blood clot in a deep vein, usually in the leg
- Neurogenic pulmonary edema – fluid in the lungs caused by a nervous system condition
Recovery from Cerebral Aneurysm (Brain Aneurysm)
After leaving the hospital, the majority of patients often need physical, speech, and occupational therapy. It’s also important for these patients to take precautionary measures against deep vein blood clots, urinary tract infections, and seizures. Additionally, regular imaging is performed to verify that the aneurysm, or the enlarged blood vessel, has been successfully eliminated.
Preventing Cerebral Aneurysm (Brain Aneurysm)
It’s crucial to educate people about brain aneurysms, as approximately 10% don’t survive long enough to reach the emergency room. Making people aware can help save lives.
