Nelson ASPESI, MD. Professor of Neurology and Neurosurgery, Rio Grande do Sul State University (UFRGS).

Marcelo FERREIRA, MD, Neurology.

Alternative names:

Subarachnoid hemorrhage, brain hemorrhage

What is it?

Brain aneurysm is an abnormal dilatation of a brain artery that may lead to its rupture at a weakened and dilated site.

A comparison of how an aneurysm looks like is the dilatation or irregularity of a tire chamber. Irregularities are formed on the tire chamber surface and in one of these sites a rupture occurs, with loss of air under pressure. In individuals with brain aneurysm, this irregularity in the brain artery ruptures, with leakage of blood into a space in the brain called “subarachnoid space”.

The initial rupture of a brain aneurysm leads nearly one-third of patients to die. Some patients have two or more episodes of brain aneurysm hemorrhage. In each one of these hemorrhage episodes, the risk of death builds up.

How does it develop?

The rupture of an aneurysm may occur anytime in a lifetime, but it’s more frequent between the forth and fifth decades of life.

Many people are born with brain aneurysms, the so-called congenital aneurysms, which may enlarge and rupture in the course of life.

There are risk factors such as being a close relative to someone who already suffered from aneurysm, especially siblings.

Other risk factors are: arterial hypertension, dyslipidemia (change in cholesterol and triglycerides), collagen diseases, diabetes mellitus (sugar in the blood), and smoking.

What does one experience?

The most common symptom is severe thunderclap headache accompanied by vomiting, convulsions and decreased consciousness. Some patients develop palpebral ptosis (sudden drooping of the upper eyelid) accompanied with headache. Others experience progressive vision loss arising from the compression of the optic nerve by the aneurysm.

Over the hours, headache may evolve into a significant pain in the nucha and lead to nucha rigidity, which is common in meningitis, or pain in the back and legs. This occurs because the blood runs from the head down to the column and “irritates” the nerve roots, eliciting backache.

Patients whose brain aneurysm is not ruptured may have symptoms of repeat cerebral ischemia, as there may be formation of small clots within the aneurysmal sac, causing the release of these to the bloodstream and occluding small arteries.

How does the doctor diagnose it?

It’s hard for the doctor to diagnose the condition in patients with non-ruptured aneurysm. Non-ruptured aneurysms don’t cause headache. Sometimes they present as minor cerebral ischemia or drooping of the upper eyelids. An experienced specialist should ask for a digital angiography of the brain or magnetic resonance angiography. Only in very large aneurysms a diagnosis can be achieved by computerized tomography of the brain.

The diagnosis of a suspicion is made through patient history when the aneurysm is ruptured. The patient often arrives in the hospital in coma. The doctor should ask for a computerized tomography (CT) of the brain demonstrating blood in the subarachnoid space or cerebral hematoma (clot inside the brain).

If the CT is normal and the patient presents nucha rigidity, the doctors proceeds to a lumbar puncture to see if there’s blood in the fluid bathing the brain and the spinal cord called “liquor cerebrospinalis”. In patients with brain aneurysm hemorrhage, the liquor cerebrospinalis– which is colorless like water – is reddened by the blood from hemorrhage.

How is it treated?

The treatment of non-ruptured aneurysm must be entertained, as the annual risk for aneurysm rupture is of 1.25%, that is, the patient can choose the right time for their treatment with their physician.

As regards ruptured aneurysms, these present as a medical emergency and have to be treated as soon as possible, as long as the patient’s clinical and neurological conditions allow it.

There are two treatment modalities: cerebrovascular microsurgery, which consists of placing a metal clip at the aneurysm, and intravascular treatment, which places a metal material into the aneurysmal sac. The microsurgical technique is already well established, with low mortality and sequelae. The intravascular treatment still poses technical difficulties by materials that aren’t suitable as of yet. This may be a solution in the near future.