Brain aneurysms are a serious health condition that can lead to severe morbidity or even death. The majority of brain aneurysms are small and do not result in any major problems, however, the rupturing of an aneurysm can be fatal. Approximately 1 in 50 people in the US have an unruptured brain aneurysm, and the majority of these people are unaware of the potential time bomb in their brain1.
This blog will discuss what a brain aneurysm is, what the symptoms are, what causes aneurysms, and the importance of early detection to allow treatment.
A brain aneurysm is a bulge or ballooning in a blood vessel wall caused by a weak or thin spot in that wall. Small aneurysms tend not to cause any problems. However, larger aneurysms can press on nerves and the surrounding tissue or can rupture, causing serious health problems2. Blood flowing through arteries is under high pressure; arteries have thick walls to cope with this3. The thinning of the vessel walls and loss of elastic fibers causes a weakness in the walls, resulting in the wall bulging in response to pressure and an aneurysm forming4. A rupture occurs when the blood vessel in the brain bursts, releasing blood into the space surrounding the brain. This is called a subarachnoid hemorrhage5. A ruptured aneurysm is life-threatening, with the possibility of causing a stroke, permanent nerve damage, or dangerous swelling and pressure on the brain6.
There are five main types of brain aneurysms:
Brain aneurysms can occur anywhere in the brain, but are most commonly found in the major arteries at the base of the skull2.
Unruptured brain aneurysms are relatively common; they are found in approximately 3-5 percent of the general population5. Approximately 6.8 million people in the US currently have an unruptured brain aneurysm1. Ruptured aneurysms have a lower prevalence but drastically worse effects. The annual rate of rupture is estimated at 8-10 in 100,000 people – so approximately 30,000 people per year in the US suffer a rupture1. Rupture depends on the size of the aneurysm and the location of the aneurysm5.
The prevalence of aneurysms differs depending on population demographics. Brain aneurysms are approximately 60 percent more common in women than men, increasing to twice as likely after menopause8. Age also affects aneurysm prevalence, with the highest prevalence in people between 35-60 years old1. Aneurysm prevalence can also depend on ethnicity, with African Americans and Hispanics showing a higher prevalence than Caucasians1,9.
Unruptured brain aneurysms are commonly asymptomatic, however, sentinel hemorrhages (a small amount of blood leaking from the brain aneurysm) or the expansion of the aneurysm to press on nerves or tissues can cause symptoms10. These symptoms will act as warning signs of a brain aneurysm and could be a sign of a brain aneurysm rupture before it happens.
Brain aneurysm symptoms before rupture can include2,10,11:
Ruptured brain aneurysm symptoms, on the other hand, will be more extreme. These can include2,10,11:
Medical attention should be sought immediately if a rapid-onset, severe headache is experienced, especially if in combination with any of the above-listed symptoms.
Although the genetics of brain aneurysms are not fully understood, certain associations have been found. The risk of developing a brain aneurysm is greater in an individual with 1 first-degree relative who has experienced an aneurysm, rising to 8 percent with 2 first-degree relatives with the condition12. Certain heritable diseases can also increase the risk of aneurysms, including polycystic kidney disease, Ehlers-Danlos type IV, fibromuscular dysplasia, and other diseases affecting connective tissue5.
Several lifestyle factors can increase the risk of developing aneurysms. Smoking is a well-established risk factor for both aneurysm formation and rupture13. Cigarette smoke and nicotine increase the blood vessel wall's sheer stress, thus increasing the likelihood of an aneurysm forming14. The risk of aneurysm rupture is significantly increased by smoking; increasing further with a longer duration and increased intensity of smoking15. Smokers are 3-6 times more at risk for aneurysm rupture than non-smokers, and this can be as high as 10 times for heavy smokers and female smokers16.
Smoking also increases the likelihood of developing multiple aneurysms17. High blood pressure significantly increases the risk of developing a brain aneurysm and the risk of rupture. When blood pressure is increased, the vessel walls experience increased sheer stress. Over time, this will weaken the vessel walls, leading to the formation of aneurysms and rupture18. High blood pressure also causes vascular inflammation, which in turn disrupts the vessel walls and increases the risk of aneurysm formation19. Illegal drug use can similarly influence the chances of developing an aneurysm. Cocaine causes blood vessel inflammation and high blood pressure, both of which contribute to aneurysm formation20.
There are several diagnostic methods and technologies that doctors use to check for brain aneurysms, the most common of which are brain imaging scans. Computed tomography (CT) scans use X-rays to create an image of the brain. Before scanning, a contrast dye can be injected into the bloodstream. The CT angiography scan will produce images of blood flow through the blood vessels in the brain and can, therefore, detect aneurysms2.
Magnetic resonance imaging (MRI) scans, such as those carried out by Ezra, can also be used to detect aneurysms. MRIs produce a highly detailed image of the brain – without using any ionizing radiation (such as X-rays). MR angiograms can be used to produce detailed images of the brain blood vessels, identifying the presence and location of aneurysms. Ezra’s Blueprint scan includes state-of-the-art angiogram technology to examine the arteries in the brain and neck. Cerebral angiograms are a further method of aneurysm detection. These involve the insertion of a catheter, which is guided to the blood vessels surrounding the brain, where a contrast dye is injected21. X-ray images are then produced to image the blood vessels.
These methods may be used if an aneurysm is suspected, if an individual has one or more of the risk factors associated with aneurysms or as part of preventive healthcare methods.
It is not possible to prevent brain aneurysms from forming. However, early detection of aneurysms can reduce the risk of rupture and, therefore, reduce the risk of serious complications. Brain aneurysms can kill you – the mortality rate for ruptured aneurysms can be as high as 50 percent, and even for those who survive, approximately 66 percent suffer permanent brain damage1. However, if detected early, treatments can be carried out to ‘clip’ an aneurysm, preventing blood from entering the aneurysm and therefore decreasing the risk of rupture22. Lifestyle changes can also be put in place to reduce the risk of further brain aneurysm formation and rupture, such as controlling blood pressure and quitting smoking.
Regular MRI or CT scans can identify aneurysms before rupture occurs, allowing early treatment and thus drastically reducing the risk of serious complications. Routine screenings are particularly advised for those with a family history of aneurysms23 but are also recommended for those interested in preventive healthcare.
Brain aneurysms can result in serious health complications or even death if left undiagnosed and untreated. Ruptured aneurysms produce classic symptoms, including a thunderclap headache. Unruptured aneurysms are often asymptomatic, but early detection using imaging techniques such as MRI or CT scans allows detection before rupture occurs. Although it is not possible to prevent brain aneurysms, lifestyle changes (such as quitting smoking and lowering blood pressure) can reduce the risk of developing brain aneurysms and reduce the risk of their rupture. Regular screenings are recommended as they can detect aneurysms before they rupture and allow treatment of the aneurysm.
If you want to be proactive about your health, why not book an Ezra full-body MRI? Our annual scan catches aneurysms and potential cancer earlier, leveraging AI through the screening process to make it more efficient, affordable, and faster.
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3. Physiology of Circulation | SEER Training. Accessed December 18, 2024. https://training.seer.cancer.gov/anatomy/cardiovascular/blood/physiology.html
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11. Symptoms of a Brain Aneurysm - The Niekro Aneurysm and AVM Foundation. July 15, 2014. Accessed December 18, 2024. https://niekrofoundation.org/understanding/symptoms-of-a-brain-aneurysm/
12. Chalouhi N, Chitale R, Jabbour P, et al. The case for family screening for intracranial aneurysms. Published online December 1, 2011. doi:10.3171/2011.9.FOCUS11210
13. Chalouhi N, Ali MS, Starke RM, et al. Cigarette Smoke and Inflammation: Role in Cerebral Aneurysm Formation and Rupture. Mediators Inflamm. 2012;2012:271582. doi:10.1155/2012/271582
14. Gerzanich V, Zhang F, West GA, Simard JM. Chronic Nicotine Alters NO Signaling of Ca2+ Channels in Cerebral Arterioles. Circ Res. 2001;88(3):359-365. doi:10.1161/01.RES.88.3.359
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16. Slettebø H, Karic T, Sorteberg A. Impact of smoking on course and outcome of aneurysmal subarachnoid hemorrhage. Acta Neurochir (Wien). 2020;162(12):3117-3128. doi:10.1007/s00701-020-04506-3
17. Juvela S. Risk Factors for Multiple Intracranial Aneurysms. Stroke. 2000;31(2):392-397. doi:10.1161/01.STR.31.2.392
18. Tada Y, Wada K, Shimada K, et al. Roles of hypertension in the rupture of intracranial aneurysms. Stroke J Cereb Circ. 2014;45(2):579-586. doi:10.1161/STROKEAHA.113.003072
19. Chalouhi N, Ali MS, Jabbour PM, et al. Biology of intracranial aneurysms: role of inflammation. J Cereb Blood Flow Metab. 2012;32(9):1659-1676. doi:10.1038/jcbfm.2012.84
20. Haddad YW, Korcari E, Polsinelli GN, Yuchuan D. The effect of cocaine and methamphetamine on saccular aneurysm formation and rupture: A literature review. Brain Hemorrhages. 2021;2(3):111-115. doi:10.1016/j.hest.2020.11.002
21. Cerebral Angiogram. Cleveland Clinic. Accessed December 18, 2024. https://my.clevelandclinic.org/health/diagnostics/13476-cerebral-angiogram
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23. Routine screening for individuals with a family history of aneurysm - Mayo Clinic. Accessed December 18, 2024. https://www.mayoclinic.org/medical-professionals/neurology-neurosurgery/news/routine-screening-for-individuals-with-a-family-history-of-aneurysm/mac-20531273
