An aneurysm occurs when a weak or thin part of an artery wall abnormally balloons or bulges. They can take years to develop and often remain small and asymptomatic1. Problems arise if an aneurysm expands quickly or ruptures. In the case of expansion, the aneurysm can grow to press on the surrounding tissue and nerves, causing pain, numbness, and – if located in the brain – double vision2. Expansion of the aneurysm causes further weakening of the artery wall; thus, as the aneurysm grows, the risk of rupture increases3. Aneurysm rupture leads to internal bleeding. Depending on the location of the aneurysm, this can have catastrophic consequences – potentially leading to death4.
This article will discuss the different types of aneurysms, their causes, how they are detected (including symptoms and warning signs), and how to prevent them.
Understanding Aneurysms: Types, Causes, Symptoms, Detection
What Are the Types of Aneurysms and Where Can They Happen?
Aneurysms can occur in any blood vessel but are most commonly found in arteries because they contain blood at a much higher pressure. Specific arteries are particularly at risk for developing aneurysms; these include:
- Cerebral aneurysm – occurs in blood vessels of the brain5.
- Thoracic aortic aneurysm – occurs in the aorta (the body’s largest blood vessel that transports blood from the heart), in the section that runs through the chest6.
- Abdominal aortic aneurysm – occurs in the section of the aorta that runs in the abdomen7.
- Popliteal artery aneurysm – occurs in the artery located behind the knee joint8.
The location of the aneurysm affects both the symptoms experienced (these will be localized to the area) and the severity of the effects of a rupture.
How Common Are Aneurysms?
Prevalence of Unruptured Aneurysms
The prevalence of aneurysms is dependent on the type. Abdominal aortic aneurysms (AAAs) are one of the most common, for which the average prevalence is approximately 2.82 percent. Prevalence increases with age – reaching 5.19 percent in males over 75 years old – and with lifestyle factors, such as smoking – reaching 9.98 percent in male smokers over 75 years old9. Brain aneurysms affect 3-6 percent of the population in the US10. Thoracic aortic aneurysms have a lower prevalence at 0.16 percent11.
However, this increases to 7.6 percent with a previous diagnosis of AAA12. A similar increase in prevalence among patients with AAAs is also seen with popliteal artery aneurysms – rising from 0.1-1 percent in the general population to approximately 20 percent13. Prevalence also differs depending on gender – with females more at risk for brain aneurysms14 but males more at risk for AAAs15 – and ethnicity16.
Prevalence of Ruptured Aneurysms
The prevalence of ruptured aneurysms is lower than that of unruptured aneurysms; however, the effects of rupture are much more serious. The risk of rupture depends on the size of the aneurysm, the location of the aneurysm, and lifestyle factors – such as smoking or high blood pressure. Approximately 8-10 in 100,000 people per year experience a ruptured brain aneurysm10, 5.6 in 100,000 people an abdominal aortic aneurysm, and 1.6 in 100,000 people a thoracic aortic aneurysm. Ruptured aneurysms are often life-threatening, depending on the location of the aneurysm. Mortality rates are particularly high for ruptured brain aneurysms (50 percent10), thoracic aortic aneurysms (97 percent17), and abdominal aortic aneurysms (81 percent18).
What Are the Causes of Aneurysms?
Degeneration of Blood Vessel Walls
Aneurysms are caused by the weakening of blood vessel walls. Therefore, factors that affect and cause the degeneration of these walls may cause aneurysms. As we age, we experience a deterioration in the strength and elasticity of our blood vessels, increasing susceptibility to aneurysm development19. Also, with age, a build-up of fatty plaques damages blood vessel walls and increases blood pressure (causing hypertension), both of which contribute further to increasing the risk of aneurysm20. In addition to causing an aneurysm, high blood pressure also increases the chances of an aneurysm bursting, as the elevated pressure puts more strain on the damaged blood vessel wall.
Genetic Factors
The risk of developing an aneurysm can be affected by genetic conditions. Conditions affecting connective tissue (a structural component of blood vessel walls) can increase the risk of developing aneurysms. For example, Vascular Ehlers-Danlos syndrome affects collagen metabolism, resulting in weak blood vessels and an increased risk of aneurysm development21. Several genetic conditions specifically affect the development of aortic aneurysms. Marfan Syndrome is a connective tissue disorder resulting in the progressive dilation of the aortic root, which can result in aortic aneurysm formation and rupture22. Accordingly, aneurysms can be hereditary but are not exclusively inherited conditions.
Injury or Trauma
Aneurysms can develop due to injury and trauma. This is most commonly seen in the brain, where head trauma can result in the formation of brain aneurysms23.
Infection
Certain infections can lead to the development of aneurysms. In rare and extreme cases, inflammation can cause damage to blood vessels or weaken blood vessels, contributing to the development of aneurysms24,25. Mycotic aneurysms are caused specifically by a bacterial or fungal infection occurring in and around blood vessel walls26.
What Are the Symptoms or Warning Signs of an Aneurysm?
Symptoms of Unruptured Aneurysms
Unruptured aneurysms are often asymptomatic. Symptoms may occur if the aneurysm is pressing on tissue or nerves, which can cause persistent, localized (but not severe) pain. If particularly large, it may present as a pulsating feeling27. These limited and fairly general signs and symptoms of aneurysms often do not provide clear early warning signs of the development of an aneurysm.
Symptoms of a Ruptured Aneurysm
The signs and symptoms of a ruptured aneurysm are much more obvious and will come on suddenly. They may include1,4:
- Sudden, severe pain in your head, chest, abdomen, or back
- Loss of consciousness
- Pulsating abdominal mass
- Swelling in the neck
- Lower extremities turning blue
- Difficulty swallowing
- Hoarseness
- Dizziness
- Vision changes
- Rapid heart rate
It is imperative to seek immediate medical care if you suspect that an aneurysm has ruptured.
How Are Aneurysms Diagnosed/Detected?
Medical imaging scans, such as MRI and CT scans, can be used to check for aneurysms. These scans, commonly combined with contrast dyes injected into the bloodstream, can image blood flow and, therefore, identify the location and size of any aneurysms3. Ezra carries out full-body MRI scans; their Blueprint scan includes angiogram technology to examine arteries for signs of aneurysms. Larger aneurysms may be identified using a physical examination where a pulsation in the area of the aneurysm can be felt3.
What Are the Risk Factors for Aneurysms, and Can We Prevent Them?
Although it is not possible to prevent an aneurysm, it can be possible to reduce the risk of developing an aneurysm and reduce the risk of the aneurysm rupturing. Certain risk factors, including age, gender, and a family history of aneurysms, cannot be adjusted; however, making certain lifestyle adjustments can help to stop an aneurysm from forming.
Lifestyle Risk Factors
The risk of developing aneurysms can be increased by certain lifestyle factors. Smoking increases the risk of aneurysms developing and rupturing due to cigarette smoke and nicotine, increasing blood vessel sheer stress28,29. Aneurysm rupture is 3-6 times more likely in smokers than non-smokers, increasing to 10 times more likely for heavy smokers and female smokers30. The risk of aneurysm development and rupture is also increased by high blood pressure due to increased sheer stress and vascular inflammation31,32. High blood pressure can be influenced by medical conditions and genetics, but lifestyle factors, such as an unhealthy diet, drinking too much alcohol, and experiencing high levels of stress, also contribute33. Excessive alcohol consumption has also been associated with an increased risk of aneurysm rupture34.
Medical Management
For those with high blood pressure, medication to lower blood pressure will help to reduce the risk of aneurysm development and rupturing35. On an aneurysm diagnosis, treatment may be required. Treatment involves ‘clipping’ the aneurysm to reduce blood flow to it and, therefore, remove the risk of rupture4. Regular screening for aneurysms is important as the early detection of an aneurysm and subsequent treatment can reduce the risk of catastrophic rupture. This is particularly important for those identified as at a higher risk of aneurysms36, but can also be carried out by those interested in preventive healthcare.
Summary: Understanding Aneurysms: Types, Causes, Symptoms, Detection
Aneurysms can have catastrophic consequences if left undiagnosed and untreated. It is not possible to prevent aneurysms, but the risk of developing an aneurysm and its rupturing can be decreased by lifestyle changes, such as quitting smoking and managing blood pressure. Early detection and treatment are essential to reducing the risk of rupture and improving long-term health outcomes.
If you want to be proactive about your health, why not book an Ezra full-body MRI? Our annual scan could catch aneurysms earlier, leveraging AI through the screening process to make it more efficient, affordable, and faster.
References
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