top of page
Ishwari Mulay
Mar 263 min read

Understanding Cerebral Aneurysms

A cerebral aneurysm (also known as a brain aneurysm) is a weak or thin spot on an artery in the brain that balloons or bulges out and fills with blood. The bulging aneurysm can put pressure on the nerves or brain tissue. 


Fig.1- brain aneurysm


Experts think brain aneurysms form and grow because blood flowing through the blood vessel puts pressure on a weak area of the vessel wall. This can increase the size of the brain aneurysm. If the brain aneurysm leaks or ruptures, it causes bleeding in the brain, known as a hemorrhagic stroke. Most often, a ruptured brain aneurysm occurs in the space between the brain and the thin tissues covering the brain. This type of hemorrhagic stroke is called a subarachnoid hemorrhage.


Some cerebral aneurysms, particularly those that are very small, do not bleed or cause other problems. These types of aneurysms are usually detected during imaging tests for other medical conditions. Cerebral aneurysms can occur anywhere in the brain, but most form in the major arteries along the base of the skull. All cerebral aneurysms have the potential to rupture and cause bleeding within the brain or surrounding area.



Types-


  1. Saccular aneurysm, also known as a berry aneurysm- This type of aneurysm looks like a berry hanging from a vine. It's a round, blood-filled sac that protrudes from the main artery or one of its branches. It usually forms on arteries at the base of the brain. A berry aneurysm is the most common type of aneurysm.

  2. Fusiform aneurysm-This type of aneurysm causes bulging on all sides of the artery.

  3. Mycotic aneurysm-This type of aneurysm is caused by an infection. When an infection affects the arteries in the brain, it can weaken the artery wall. This can cause an aneurysm to form.


Fig. 2- types of brain aneurysms



Symptoms-


Unruptured aneurysm:

Most cerebral aneurysms do not show symptoms until they either become very large or rupture. Small unchanging aneurysms generally will not produce symptoms. 

A larger aneurysm that is steadily growing may press on tissues and nerves causing:

  • pain above and behind the eye

  • numbness

  • weakness

  • paralysis on one side of the face

  • a dilated pupil in the eye

  • vision changes or double vision.

Ruptured aneurysm:

When an aneurysm ruptures (bursts), one always experiences a sudden and extremely severe headache and may also develop:

  • double vision

  • nausea

  • vomiting

  • stiff neck

  • sensitivity to light

  • seizures

  • loss of consciousness (this may happen briefly or may be prolonged)

  • cardiac arrest.

Leaking aneurysm:

Sometimes an aneurysm may leak a small amount of blood into the brain (called a sentinel bleed). Sentinel or warning headaches may result from an aneurysm that suffers a tiny leak, days or weeks prior to a significant rupture. However, only a minority of individuals have a sentinel headache prior to rupture. 



Causes-


Brain aneurysms are caused by thinning artery walls. Aneurysms often form at forks or branches in arteries because those areas of the vessels are weaker. Although aneurysms can appear anywhere in the brain, they're most common in arteries at the base of the brain.



Risk factors-


Several factors can contribute to weakness in an artery wall. These factors may increase the risk of a brain aneurysm or aneurysm rupture. Some of these risk factors develop over time. But some conditions present at birth can increase the risk of developing a brain aneurysm.

Risk factors include-


  1. Older age

  2. High blood pressure

  3. Drugs, alcohol, smoking

  4. Inherited connective tissue disorders- such as Ehlers-Danlos syndrome. These disorders weaken blood vessels.

  5. Polycystic kidney disease- This inherited disorder results in fluid-filled sacs in the kidneys. It also may increase blood pressure.

  6. A narrow aorta, known as coarctation of the aorta- The aorta is the large blood vessel that delivers oxygen-rich blood from the heart to the body.

  7. Brain arteriovenous malformation, known as AVM- In this condition, arteries and veins in the brain are tangled. This affects blood flow.

  8. A family history of brain aneurysm

  9. Head injury

  10. Blood infections


Latest updates on cerebral aneurysms-


Scientists have long known about the link between cerebral and aortic aneurysm (the aorta is the body's main artery). However, they still do not fully understand the relationship between the two types of aneurysm.


Recent genome-wide association studies (GWAS) provide molecular evidence for shared biological function and activities (pathophysiology) of these aneurysms.  A specific site on chromosome 9p21 has been identified as increasing the risk for both cerebral and aortic aneurysms. This GWAS data, along with linkage data to other susceptible locations for genes or DNA sequences, indicate that individuals and families harboring one type of aneurysm may be at especially increased risk of the other.




REFERENCES-

bottom of page