Brain aneurysm - Symptoms, Causes, Preventions and Treatment

Brain aneurysm definition

A brain aneurysm, medically known as a cerebral or intracranial aneurysm, is an unusual bulging or swelling that emerges from a weakened area of the blood vessel wall in the brain. It may occur in any blood vessel; however, it is most often seen in an artery rather than a vein.

Aneurysms can develop anywhere in the circulatory system, including the blood vessels of the neck, intestines, kidneys, and legs. Still, they most commonly occur in the brain's blood vessels and along the aorta (the largest artery that carries oxygenated blood from the heart to the other parts). If an aneurysm in the brain expands and makes the blood vessel wall too thin, it ruptures and bleeds into the space around the brain, which is dangerous. 

Brain aneurysm meaning

Cerebral derived from Latin word “cerebrum” which means “the brain”. Aneurysm derived from Medieval Latin word called “aneurisma” and from Greek “aneurysmos” which means “dilation of an artery” or “widening”.

Types of brain aneurysms

Usually, aneurysms occur on larger blood vessels where an artery branches. Aneurysm is categorized into the following based on multiple factors, which include:

• Saccular: This is the most common type, a rounded sac containing blood, an aneurysm that bulges from one side of the artery. It is also called “Berry” because it resembles a berry hanging from a vine. Saccular aneurysms are usually found in arteries at the base of the brain and most often occur in adults.
• Fusiform: This aneurysm bulges in all directions (all sides) of the artery and has no distinct neck.
• Giant: It may be fusiform or saccular and measure more than 2.5cm in diameter. The neck is often wide and may involve more than one artery.
• Traumatic: It is caused by a closed head injury or penetrating trauma.
• Mycotic: It is the ballooning or swelling of a blood vessel caused by a fungal or bacterial infection that affects the arteries in the brain.
  

Brain aneurysm prevalence

A cerebral aneurysm is one of the significant cerebrovascular diseases and is much more common than many think. According to the Brain Aneurysm Foundation,1 in 50 persons suffers from an unruptured brain aneurysm at any given time.

Brain aneurysms may occur in anyone at any age. They are most common in adults aged 30 to 60 and more frequent in women than men . This condition may cause sudden death, with nearly 500,000 victims dying worldwide every year. Most of these people may never notice any of the tell-tale signs of a ruptured cerebral aneurysm, including an extremely severe headache indicative of a brain bleed.

Fortunately, most aneurysms are small, and 50 to 80% do not rupture during a person’s lifetime. However, some brain aneurysms cause harmful effects on individuals’ health and performance due to rupturing and creating subarachnoid haemorrhage (SAH). Aneurysm rupture is one of the most challenging complications of cerebral aneurysms. About 80% of non-traumatic SAHs result from the rupture of cerebral aneurysms, with a mortality rate as high as 45%. Prompt detection and timely treatment are crucial for good recovery and outcomes in patients with nontraumatic SAH.

The annual incidence of aneurysmal SAH is estimated at 6 to 16 cases per 100,000 people, resulting in approximately 76,500 to 204,100 new cases in India each year. Even though basilar artery aneurysms are rare (3-5% of all brain aneurysms), they are the most common type in the posterior circulation, where the aneurysms that present at posterior circulation (back part of the brain- basilar artery, vertebral arteries and posterior communicating artery) are more likely to rupture compared to other areas. 

Brain aneurysm causes

Brain aneurysm causes encompass a range of factors that weaken arterial walls, leading to potential ruptures and potential complications, which include:

• High blood pressure: Elevated blood pressure can increase the pressure on the walls of the blood vessels inside the brain, eventually resulting in an aneurysm.
• Family history: Having a first-degree relative, such as a parent, sister or brother, with a history of a brain aneurysm may make it more suspectable to develop one than someone with no family history of the condition. 
• Pre-existing blood vessel weakness: In some people, brain aneurysms can occur due to blood vessel weaknesses present from birth.
• Trauma or severe head injury: A brain aneurysm can develop after a trauma or severe head injury due to the damage of the blood vessels in the brain.
• Drug abuse: It is considered to be another risk factor for brain aneurysms because drug abuse inflames the walls of the blood vessels and raises blood pressure. The combination of these factors may cause a brain aneurysm.
• Autosomal dominant polycystic kidney disease: It is a genetic condition that causes multiple cysts (small sacs filled with fluid) to develop in the kidneys. Brain aneurysms are more common in people with ADPKD due to elevated blood pressure affecting the weakened blood vessel walls.
• Body tissue disorders: Conditions that affect the tissues, including Ehlers-Danlos syndrome or Marfan syndrome, can cause and increase the risk of brain aneurysms because these conditions can sometimes cause weaknesses in the blood vessel walls.
• Coarctation of the aorta: Individuals with coarctation of the aorta may also have a small risk of developing a brain aneurysm. This condition describes a narrowing of the main artery in the body (the aorta) present from the person's birth (congenital), a common type of congenital heart disease.
  

Brain aneurysm symptoms

Brain aneurysm symptoms are often unnoticeable by patients until the aneurysm either becomes large or ruptures, which causes leakage of blood from the aneurysm into the blood. Many patients only detect aneurysms when they have a brain scan for other reasons. The following are the early symptoms of brain aneurysm: 

• Headache: It can be caused by larger unruptured cerebral aneurysms, when it pushes the nerves and tissue in the brain, which feels like pounding in time with the pulse (pulsatile)
• Weakness: Less frequently, individuals may exhibit dilated pupils and sometimes brain stroke symptoms, such as weakness or paralysis on one side of the body.
• Neurological Symptoms: A large aneurysm exerts pressure on surrounding brain tissue or on a nerve, causing the following
• Vision changes
• Eye pain
• Numbness or tingling on head or face
• Seizures 
• Other symptoms: The following are the symptoms of a ruptured brain aneurysm symptoms, and they can be seen If the brain aneurysm ruptures:
• Sudden onset of severe headache
• Stiff neck
• Sensitivity to light
• Changes in mental state or loss of consciousness
• Numbness or weakness of the body
• Vision or speech impairment
  

Brain aneurysm risk factors

Multiple risk factors have been linked with aneurysm growth, development and rupture. The following are some of the factors that contribute to the risk of developing brain aneurysms: 

• Older age: Most patients with brain aneurysms are over the age of 40, and more commonly occurs in adults between the ages of 30 and 60. 
• Gender: As per a research, it was stated that women are more likely to develop a brain aneurysm. 
• Family history: If the person's parents or siblings have had brain aneurysms, it can increase the particular risk of developing brain aneurysms.
• Cigarette smoking: Smoking isn't known as a direct causative factor for brain aneurysms; however, it can increase the risk of other potential medical conditions, such as atherosclerosis, which can directly increase the risk of brain aneurysms. 
• Traumatic brain injuries: Severe head injury can increase the risk of brain aneurysm due to the damage of blood vessels. 
• Specific conditions: Connective tissue diseases such as Ehlers-Danlos syndrome, polycystic kidney disease, and Marfan's syndrome can weaken the blood vessels, resulting in an increased risk for cerebral aneurysms.
• Infections: Infection of artery walls in the brain can increase the risk of mycotic aneurysm.
• Chronic high blood pressure: According to the American Stroke Association, Hypertension is the leading cause of subarachnoid haemorrhage. Obesity is considered one of the potential risk factors for aneurysms. Having an unhealthy, high-fat diet causes hyperlipidaemia, burdening the cardiovascular system, and contributes to atherosclerosis, damaging blood vessels.     
• Previous brain aneurysm: As per the American Stroke Association, having one aneurysm puts the person at a 15 to 20% risk of having another in the future. 
• Alcohol abuse: Excessive consumption of alcohol is associated with an increased risk of death and cardiovascular disease (CVD). It causes cerebral aneurysm development and rupture, resulting in aneurysmal subarachnoid haemorrhage.
  

Frequently Asked Questions (FAQs) on Brain aneurysm

What is a brain aneurysm?

A brain aneurysm is characterized by abnormal bulging or swelling that arises from a weakened area in the blood vessel wall in the brain, resulting in abnormal ballooning or widening of the vessel's width (normal diameter). It may occur in any blood vessel; however, it is most often seen in an artery rather than a vein.

What does an aneurysm look like?

It looks like a bubble or blister in a blood vessel. Healthy arteries appear pink, while an aneurysm looks reddish due to a muscle wall defect in the middle layer. Most aneurysms have two general shapes: saccular (berry), which has a rounded shape that extends from one side of a vessel wall, and fusiform (spindle-shaped), which looks like a snake that swallowed a rat with ballooning on both sides instead of one. 

How common are brain aneurysms?

Brain aneurysms are relatively uncommon. One research paper analysed 68 studies on brain aneurysms from 21 countries and found the prevalence to be about 3 percent, or around 3 out of every 100 persons in the general population.

Can brain aneurysms shrink?

Unruptured brain aneurysms do not shrink on their own. If an aneurysm is noticed before it ruptures, treatment approaches (options), including surgical clipping or endovascular coiling, are usually recommended to prevent the rupture and further growth. Neurosurgeons perform coiling by placing a special stent called a flow-diverting stent across the base of the brain aneurysm, which leads to clotting and shrinkage of the aneurysm. 

Do all aneurysms need treatment?

No, not all aneurysms need to be treated immediately. Aneurysms that are very small (less than 3 mm at their largest point) and have never bled do not need to be treated immediately because small aneurysms are less likely to rupture. If an aneurysm in the brain ruptures, it is an emergency that requires medical treatment in the hospital. Often, a rupture is treated with surgery, especially endovascular surgery.

What happens after a brain aneurysm?

A ruptured aneurysm in the brain can cause serious problems such as haemorrhagic stroke (internal bleeding), brain damage, coma, and even death. Some cerebral aneurysms, especially those that are very small, do not bleed or cause other problems. These types of aneurysms are usually detected during imaging tests (radiological examination) for different medical conditions. 

Are brain aneurysms painful?

Most of the time, brain aneurysms do not cause any symptoms (including pain) until they rupture. In case of a rupture, the patient may experience a sudden, excruciating headache, resulting in intense pain unlike anything previously felt. Other symptoms include a sudden feeling of being sick, vomiting, sensitivity to light, and neck stiffness.

Department of Neurology