Cerebral Aneurysm - Symptoms, Causes and Treatment

The cerebral aneurysm is a balloon-shaped protrusion that arises in one or more cerebral arteries due to a weakening of the vessel wall. The aneurysm has a much weaker wall than the healthy artery and, therefore, presents a high risk of rupture and may cause severe cerebral hemorrhages.

Cerebral aneurysms
Cerebral aneurysms

What is a cerebral aneurysm?

The arteries of our body are blood vessels with a strong muscular wall, able to withstand the pressure with which blood passes through them. If for any reason an artery point becomes weaker, it will no longer be able to withstand blood pressure, giving way slowly, forming a dilated area, like a bag or balloon. Hence the name saccular aneurysm.

Prevalence of cerebral aneurysm

It is estimated that up to 5% of the population has at least one brain aneurysm. 20% of these have two or more aneurysms at the same time. Aneurysms are more common in women and in people over 50. The rate of intracranial hemorrhage due to rupture of a cerebral aneurysm, however, is only 10 per 100,000 people. Therefore, it can be concluded that although the cerebral aneurysm is not a rare situation, most of them do not break. In fact, most aneurysms do not cause symptoms and the patient does not even suspect that they have them.

The problem is that the rupture of an aneurysm, although uncommon, is a dramatic event. 15% of patients die before reaching the hospital and 50% die even after being rescued. And even when the patient survives a brain hemorrhage, 50% are left with neurological sequelae.

Risk factors

Aneurysms arise from a weakness in the artery wall. The patient is not usually born with an aneurysm, he develops it throughout life. Generally, more than one factor acting concomitantly is required for an aneurysm to be formed. Among the most common risk factors are:
  • Smoking
  • Hypertension
  • Congenital abnormalities of the artery wall
  • Infective endocarditis
  • Family history of cerebral aneurysms
  • Age over 40 years
  • Presence of an arteriovenous malformation (AVM)
  • Drug use, especially cocaine
  • Excess alcohol
  • Brain tumors
  • Traumatic brain injury

Some genetic diseases are associated with an increased risk of developing brain aneurysms. Patients who have any of the following diseases have a much greater chance of having aneurysms than the general population:
  • Polycystic kidneys
  • Fibromuscular dysplasia
  • Osler-Weber-Rendu syndrome
  • Coarctation of the aorta
  • Moyamoya syndrome
  • Marfan syndrome
  • Ehlers-Danlos syndrome
  • Elastic pseudoxanthoma
  • Alpha 1-antitrypsin deficiency
  • Systemic lupus erythematosus
  • Sickle cell anemia
  • Neurofibromatosis type 1
  • Tuberous sclerosis

Some of the above diseases are rare, others are relatively common. Special attention should be given to polycystic kidney disease, which is a common disorder that affects 1 in 400 people and increases the risk of brain aneurysms by up to 7 times.

Symptoms of cerebral aneurysm

Most brain aneurysms are small and do not cause any signs or symptoms. Many are accidentally discovered during imaging tests, such as computed tomography or magnetic resonance imaging of the skull, ordered for any other reason.

Although it is usually asymptomatic, depending on location and size, the aneurysm can compress some important brain areas, causing symptoms. The most common are headaches, blurred vision, pupil changes, tingling, numbness or paralysis on one side of the face.

However, the most common situation is that the aneurysm remains silent, causing symptoms only at the time of rupture.

The rupture of a cerebral aneurysm causes a hemorrhagic stroke, which is a very serious medical emergency, with high mortality. When an aneurysm ruptures it usually causes the so-called subarachnoid hemorrhage, which is caused by bleeding into the subarachnoid space, the site of the meninges where the cerebrospinal fluid circulates. This type of bleeding is typical of ruptured aneurysms.

When blood escapes into the subarachnoid space, the patient experiences sudden symptoms. Medical help should be sought immediately if the patient suddenly exhibits one or more of the following symptoms:
  • The worst headache of your life
  • Loss of consciousness
  • Convulsive crisis
  • Stiff neck
  • Vomiting in a jet
  • Blurred or double vision
  • Sudden pain above or behind the eye, with difficulty seeing
  • Difficulty walking or sudden sudden dizziness
  • Weakness and numbness on one side of the body

Risk of ruptured aneurysm

The risk of a ruptured brain aneurysm is directly related to its size and speed of growth. Low-risk aneurysms are those with less than 5 to 7 millimeters (0.5 to 0.7 centimeters) in diameter and without growth over several months. The greater the aneurysm, the weaker the wall is and the greater the chance of it continuing to grow until it ruptures.

In addition to size and speed of growth, another important factor in the risk of rupture is the location of the aneurysm within the brain. Aneurysms of the posterior circulation, involving the arteries of the vertebrobasilar system or posterior communicants, presented the highest rupture rates.

Studies show that aneurysms larger than 2.5 cm, located in the posterior arteries of the brain, present a risk of bleeding above 50% over a 5-year period.

The two most commonly used tests to diagnose and follow a cerebral aneurysm are nuclear magnetic resonance angiography and computerized angiography of the skull


The decision to treat an unbroken brain aneurysm depends on the risk of rupture that it presents in the short/medium term. Small aneurysms at sites with low bleeding rates may only be observed.

These low-risk aneurysms can be monitored annually with MRI scans or CT scans for three years in a row. If the aneurysm remains stable, the examinations can be spaced every 2 to 5 years. If it is possible to detect that the aneurysm arose recently (as in the case of the patient having a recent tomography without evidence of aneurysms), the first examinations should be done at intervals of 6 months, since new aneurysms are those with higher risk of growth.

Patients on conservative treatment should be instructed to avoid smoking, excessive alcohol consumption, stimulant medications, illicit drugs, and excessive physical exertion.

In the case of large aneurysms with a high risk of rupture, or in ruptured aneurysms, the treatment is surgical, aiming at interrupting blood flow to the aneurysm site, preserving the passage of blood through the artery. In the case of a ruptured aneurysm, surgery is obviously urgent.

Embolization of the aneurysm is a less invasive method than surgery and has gained popularity in recent years. The process is similar to a catheterization. The surgeon inserts a catheter into an artery, usually in the groin, which is pushed through your body into the aneurysm. Upon reaching the aneurysm, a malleable platinum wire is implanted therein, disrupting blood flow and causing thrombosis of the aneurysm.

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