Cerebral aneurysm

GENERAL ASPECTS

What is it?

An aneurysm is an abnormal widening or dilation of the wall of a cerebral artery. It is estimated to affect between 3 and 5 percent of the general population.

Types:

They are classified according to their shape:

• Saccular aneurysm: it is the most common type (90% of aneurysms) and has the shape of a cherry.
• Fusiform aneurysm: the artery dilates globally like a spindle.
• Dissecting aneurysm: blood enters a small tear in the wall of the arteries separating its layers and bulging its contour.

Causes and risk factors

Most cerebral aneurysms are caused by a congenital abnormality of the arterial wall and, very rarely, a specific cause is identified. They are more common in people with certain genetic diseases such as connective tissue disorders and polycystic kidney disease, as well as certain circulatory disorders such as arteriovenous malformations.

In addition, factors such as high blood pressure, tobacco use, alcohol abuse and drug use (e.g. cocaine) increase the risk of developing a cerebral aneurysm.

Symptoms and diagnosis

Most aneurysms, especially the smaller ones, do not produce symptoms and are usually diagnosed accidentally when performing an imaging study (CT or MRI) for another reason, although it is confirmed with imaging tests (CT and cranial CT angiography, MRI and cerebral MRI angiography and/or cerebral arteriography) and sometimes it is convenient to perform a lumbar puncture.

Symptoms appear when the aneurysm ruptures and blood leaks into the space surrounding the brain (subarachnoid space), and it presents with what is known as ‘thunderclap headache’, a very intense and sudden onset headache that the patient usually describes as “the worst headache of his life”.

This pain may be accompanied by nausea, vomiting, neck pain and even loss of consciousness. A ruptured aneurysm is a medical emergency, so these symptoms should be reported to the emergency room.

The risk of rupture of each aneurysm is variable and depends on its shape, size, location and whether or not there is a history of bleeding due to the same cause. On other occasions they can produce symptoms by increasing in size and compressing structures of the nervous system.

Treatments

All ruptured cerebral aneurysms should be treated when the patient’s medical conditions allow it. The goal is to prevent re rupture, since 30% bleed again during the first month after the initial hemorrhage.

There are two types of treatment, surgery and endovascular embolization. In surgery, a craniotomy is performed and the aneurysm is closed by placing a clip at its base; while in endovascular embolization the aneurysm is accessed through a catheterization and the aneurysm is closed by introducing springs called coils. The choice of technique will depend on the anatomical characteristics of the aneurysm (size, location, morphology).

The decision to treat an unruptured aneurysm will depend on multiple factors such as the size and growth of the aneurysm in serial imaging studies over time, its location, the history of a subarachnoid hemorrhage due to rupture of another aneurysm, age, previous diseases and family history of aneurysms.