What percentage of people survive brain aneurysms?
Only 7% of patients treated for a brain aneurysm suffer long-term sequelae
The most exhaustive study ever carried out on the short- and long-term prognosis for this pathology
The journal Neurology has just published the most complete and exhaustive study to date on the survival rate and sequelae of patients who suffer a ruptured brain aneurysm, a disease known as subarachnoid haemorrhage. The work was carried out by doctors at Hospital del Mar (from the Neurology, Neurosurgery, Intensive Medicine, Interventional Neuroradiology, Radiology and Anaesthesia and Resuscitation services) and researchers from the Hospital del Mar Medical Research Institute (IMIM). The results show that the strategy implemented in Catalonia to cover emergency care for this condition produces results comparable to those of the most advanced centres in the world.
The data analysed corresponds to 311 patients with aneurysmal subarachnoid haemorrhage treated at Hospital del Mar over the last 12 years. The short-term mortality rate is between 8.7% (one week after treatment, during the hospitalisation period), and 18.4% (after three months). One year after the vascular event, this figure reaches 22.9% and, five years later, 29%. Only 7% of the patients who survived after five years presented disabling sequelae. According to several studies, deaths from this pathology around the world are between 11% and 27.5% in hospital and over 30% after three months.
From left to right: Dr. Jaume Roquer, Dr. Gloria Villalba and Dr. Leopoldo Guimaraens. Source: Hospital del Mar.
Two types of approach
Treating subarachnoid haemorrhage is complex and requires the participation of a multidisciplinary and highly trained team. As Dr. Jaume Roquer, head of the Neurology Service and Neurovascular Research Group at the IMIM and lead author of the study, explains, «Teamwork between professionals who are highly trained in their field and specialists in the treatment of this pathology allows us to obtain very good results.» The study also analysed the results obtained according to the different approaches taken.
One of the critical aspects for successfully treating a brain aneurysm is its rapid diagnosis and treatment. This is why, when a patient arrives at the hospital, specialists in Interventional Neuroradiology locate the point where the lesion has occurred and repair it, on the spot, if possible. Other patients are treated by the Neurosurgery teams.
This difference improves the results of the endovascular treatment, since endovascular access allows the ruptured aneurysm to be repaired quickly. Consequently, 43.8% of these patients require mechanical ventilation, compared to 65.2% who require neurosurgical treatment. In addition, their stay in the hospital is two days shorter and the sequelae are milder.
Along these lines, Dr. Gerard Conesa, head of the Neurosurgery Service at Hospital del Mar, and Dr. Gloria Villalba, a consultant in the same service, emphasise that «Patients destined for surgical treatment at our centre are complex cases, either because of the shape of the aneurysm or because it is accompanied by a haematoma that is causing a very serious neurological state, and the haematoma and aneurysm have to be operated on at the same time. It is therefore understandable that the results of endovascular treatment in the hospital are better.» Dr. Leopoldo Guimaraens, head of the centre’s Therapeutic Neuroangiography Service, confirms that «In the patients we treat, the endovascular approach to intracranial aneurysms has a better prognosis than the surgical approach. The most important aspect is that our centre has very high quality services for treating this difficult pathology.»
The hospital on-call system
Subarachnoid haemorrhage is a relatively rare but very serious and highly complex pathology, which mainly affects people with an average age of 53. A patient’s progress is dependent on them receiving urgent care during the first few hours, and on carrying out an exhaustive medical follow-up over the first few days, to prevent, identify and treat the serious complications that these patients often present. Only certain hospitals are adequately prepared to treat these people. In Catalonia, there is an on-call system, whereby there is always one specialist treatment centre ready to receive cases. This comprises 5 hospitals, one of which is Hospital del Mar. Dr. Roquer affirms that «The Catalan system guarantees that all patients have access to emergency treatment. The data from our study show that the model is successful and that it really works.»
Short- and long-term outcome of patients with aneurysmal subarachnoid hemorrhage. Jaume Roquer, Elisa Cuadrado-Godia, Leopoldo Guimaraens, Gerardo Conesa, Ana Rodríguez-Campello, Jaume Capellades, María P. García-Arnillas, Juan L. Fernández-Candil, Carla Avellaneda-Gómez, Eva Giralt-Steinhauer, Jordi Jiménez-Conde, Carolina Soriano-Tárraga, Gloria Villalba-Martínez, Rosa M. Vivanco-Hidalgo, Elio Vivas, Angel Ois Neurology Sep 2020, 95 (13) e1819-e1829; DOI: 10.1212/WNL.0000000000010618
Overview — Brain aneurysm
As blood passes through the weakened blood vessel, the blood pressure causes a small area to bulge outwards like a balloon.
Aneurysms can develop in any blood vessel in the body, but the 2 most common places are:
- the artery that transports blood away from the heart to the rest of the body (the abdominal aorta)
- the brain
This topic is about brain aneurysms.
There’s a separate topic about abdominal aortic aneurysm.
About brain aneurysms
The medical term for an aneurysm that develops inside the brain is an intracranial or cerebral aneurysm.
Most brain aneurysms only cause noticeable symptoms if they burst (rupture).
This leads to an extremely serious condition known as a subarachnoid haemorrhage, where bleeding caused by the ruptured aneurysm can cause extensive brain damage and symptoms.
Symptoms of a burst brain aneurysm include:
- a sudden agonising headache – it’s been described as a «thunderclap headache», similar to a sudden hit on the head, resulting in a blinding pain unlike anything experienced before
- a stiff neck
- sickness and vomiting
- pain on looking at light
A ruptured brain aneurysm is a medical emergency.
If you think someone has had a brain haemorrhage, call 999 immediately and ask for an ambulance.
How brain aneurysms are treated
If a brain aneurysm is detected before it ruptures, treatment may be recommended to prevent it rupturing in future.
Most aneurysms do not rupture, so treatment is only carried out if the risk of a rupture is particularly high.
Factors that affect whether treatment is recommended include your age, the size and position of the aneurysm, your family medical history, and any other health conditions you have.
If treatment is recommended, this usually involves either filling the aneurysm with tiny metal coils (coiling) or an open operation to seal it shut with a tiny metal clip (surgical clipping).
The same techniques used to prevent ruptures are also used to treat brain aneurysms that have already ruptured.
If your risk of a rupture is low, you’ll have regular check-ups to monitor your aneurysm.
You may also be given medicine to reduce your blood pressure and advice about ways you can reduce your chances of a rupture, such as stopping smoking if you smoke.
Why brain aneurysms develop
Exactly what causes the wall of affected blood vessels to weaken is still unclear, although risk factors have been identified.
- high blood pressure
- a family history of brain aneurysms
In some cases, an aneurysm may develop because there was a weakness in the walls of the blood vessels at birth.
It’s difficult to estimate exactly how many people are affected by brain aneurysms because they usually cause no symptoms and pass undetected.
Some experts believe it could be as high as 1 in 20 people, while others think the figure is much lower at around 1 in 100 people.
The number of aneurysms that actually rupture is much smaller. Only around 1 in 15,000 people have a ruptured brain aneurysm in England each year.
Brain aneurysms can develop in anyone at any age, but are more common in people over the age of 40.
Women tend to be affected more commonly than men.
Preventing brain aneurysms
The best way to prevent getting an aneurysm, or reduce the risk of an aneurysm growing bigger and possibly rupturing, is to avoid activities that could damage your blood vessels.
Things to avoid include:
- eating a high-fat diet
- not controlling high blood pressure
- being overweight or obese
Page last reviewed: 11 April 2022
Next review due: 11 April 2025
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A brain aneurysm is a bulge or ballooning out of a blood vessel in the brain, most often resembling a berry (they are also termed berry aneurysms or cerebral aneurysms). Unfortunately, the walls of the aneurysm are not as stable as normal blood vessel walls. Consequently, brain aneurysms under certain conditions may rupture and allow blood to leak into surrounding tissues.
- There are two main types of brain aneurysms: saccular and fusiform aneurysms.
- Symptoms develop rapidly when an aneurysm ruptures.
- Ruptured aneurysms are medical emergencies; patients with suspected ruptured aneurysms should be seen immediately in emergency departments that have neurosurgeons on call (usually hospitals that handle major trauma have neurosurgeons on call).
What Are the Different Kinds of Brain Aneurysms?
There are two main types of brain aneurysms — saccular (berry) aneurysms and fusiform aneurysms. The most common type of aneurysm is saccular. Saccular or berry aneurysms look like a sack and are usually formed at the bifurcation or “Y” formation when a larger vessel splits into two vessels. These types of aneurysms are often found at the branches of larger arteries at the base of brain but may be found in other areas of the brain, too.
The second type, a fusiform aneurysm, is less common than a saccular aneurysm and is more stable and seldom ruptures. Fusiform aneurysms occur at the junction of the “Y” formation where a blood vessel branches and extends into both smaller vessels and also into the single larger vessel. Fusiform aneurysms don’t develop any stems like saccular aneurysms.
What Causes a Brain Aneurysm?
The development of brain aneurysms is considered a controversial topic. Currently, most researchers think that a combination of factors, both genetic and environmental, lead to the development of brain aneurysms. For example, some aneurysms may have a strong genetic component that is inherited (for example, individuals with polycystic kidney disease and arteriovenous malformations are more likely to develop aneurysms). However, environmental pressures such as hypertension are also associated with brain aneurysm development. In addition, some aneurysms are associated with environmental factors like infections or trauma.
Who Is at Risk for a Brain Aneurysm?
There are a number of medical conditions that increase risk for brain aneurysms. Individuals with the following conditions are at higher risk — polycystic kidney disease, fibromuscular dysplasia, arteriovenous malformations, lupus, sickle cell anemia, bacterial endocarditis, fungal infections, hypertension, cancers, cigarette smoking, alcohol use, illicit drug use, head trauma, and syndromes that involve connective or elastic tissue problems (for example, collagen disorders). Women are more likely to develop brain aneurysms than men (the ratio is 3 to 2). This list represents many people who are at higher risk for brain aneurysms, but it does not include every possible risk factor.
What Are the Signs and Symptoms of a Brain Aneurysm?
Most brain aneurysms do not cause any signs or symptoms and are discovered during tests for another condition. Symptoms develop rapidly when an aneurysm ruptures, and in some cases symptoms can be caused by pressure from an unruptured anuerysm. The signs and symptoms of a brain aneurysm are variable and occasionally relate to the area of the brain that is affected. However, the most common symptom of a ruptured brain aneurysm is headache and is characterized by the patient describing the headache as “the worst headache of my life.” However, some patients don’t report headache as a symptom. The following is a list of possible symptoms that are seen in patients with a brain aneurysm:
- visual defects
- facial pain
- focal neurological complaints
- passing out or fainting
- confusion or mental impairment
- nausea and/or vomiting
- cardiac dysrhythmias
- neck pain or stiffness
- trouble breathing
- dilated pupils
- stroke-like symptoms (loss of speech, loss of sense of smell, paralysis of muscles on one side of the body, or other movement defects)
How Do Doctors Diagnose a Brain Aneurysm?
In most instances, the diagnosis of a brain aneurysm is made by CT scan and/or MRI imaging studies of the brain. These tests help identify and localize the brain aneurysm. Other tests such as a cerebral angiogram and/or a cerebrospinal fluid analysis may also be used to help determine the diagnosis. In addition, transcranial Doppler ultrasonography and single-photon emission computed tomography (SPECT) may be used to examine blood flow within the brain. Laboratory tests that are almost always ordered are a complete blood cell count (CBC), prothrombin time (PT), activated partial thromboplastin time (a PTT), serum chemistries, liver function tests, and arterial blood gases. These tests help determine if the patient is anemic and/or prone to bleeding and help determine if the patient’s blood is getting appropriate oxygenation.
What Is the Treatment for a Brain Aneurysm?
Treatment for unruptured intracranial aneurysms is very controversial. Some investigators suggest that aneurysms less than 10 mm be left alone while those larger than that should be considered for treatment in patients less than 50 years old. The controversy lies in the surgical mortality and morbidity of surgically treated aneurysms. The mortality (death) rate is 1.7% and the morbidity (development of complications) is 6.7%. Many investigators suggest that aneurysms larger than 10 mm that are not associated with symptoms should be considered for treatment, especially in patients with coexisting medical conditions. Surgical treatment (clipping, in which the surgeon places a clip at the base of the aneurysm) is less likely in patients who have poor health or other serious medical conditions. Endovascular therapy or coiling (in which a small thin platinum wire is coiled into the aneurysm by a catheter in the blood vessel) is another surgical technique that can result in obliteration of the aneurysm. The goal of treatment for unruptured intracranial aneurysms is to prevent bleeding into the brain.
Ongoing bleeding of a brain aneurysm usually requires consultation with a neurosurgeon, interventional radiologist, and/or a neurologist. These individuals decide if surgery or interventional therapies such as coiling will be of benefit to the patient. For example, the neurosurgeon may decide to suction blood out of the area if it’s not too large and hasn’t caused catastrophic brain damage. Bleeding from a brain aneurysm is a medical emergency. Medical treatments for brain aneurysms that have bled are designed to reduce and/or alleviate symptoms. Nimodipine is used to prevent or relieve abnormal spasms of the arteries within the brain. Anti-epileptic drugs like phenytoin are used to treat and prevent seizures. Antihypertensive medications like labetalol can help reduce pressure on the blood vessel walls in the brain to lessen the chance of bleeding.
What Is the Survival Rate and Prognosis for a Brain Aneurysm?
Researchers estimate that about 6 million people in United States have an unruptured brain aneurysm, and about 10% to 15% of these people will have more than one brain aneurysm. Someone with an unruptured brain aneurysm has about a 1% chance of the aneurysm rupturing per year. Patients with “giant” aneurysms (1 inch or greater in diameter) have a much higher risk of rupture. The survival rate for those with a ruptured brain aneurysm is about 60% (40% die). For those who survive and recover, about 66% have some permanent neurological defect. In summary, patients with small brain aneurysms that do not rupture (about 80%) have a very good prognosis while those who suffer a rupture have a fair to poor prognosis.
Is It Possible to Prevent a Brain Aneurysm?
Most brain aneurysms cannot be prevented; however, certain types of lifestyle modification — such as avoiding illicit drugs and overuse of alcohol — may reduce the risk of a brain aneurysm. Some brain aneurysms may be treated with surgical techniques that reduce the risk of rupture.
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Brain Aneurysm Signs and Symptoms
Symptoms of a ruptured brain aneurysm often come on suddenly. If you have any of the following symptoms or notice them in someone you know, call or other emergency services right away:
- A sudden, severe headache that is different from past headaches.
- Neck pain.
- Nausea and vomiting.
- Sensitivity to light.
- Fainting or loss of consciousness.