Aneurysms

What is an Aneurysm?

An aneurysm is a pathological local outpouching or bulge of a blood vessel, usually an artery. This weak point in the vessel wall can enlarge over time and, in the worst-case scenario, rupture, leading to life-threatening bleeding.

An aneurysm can lead to a hemorrhagic stroke if it bursts and causes bleeding. This bleeding can occur either directly into the brain tissue (intracerebral hemorrhage) or into the space between the meninges (subarachnoid hemorrhage).

The importance of early detection and treatment of an aneurysm is highlighted by a study showing that 50% of patients with a ruptured abdominal aortic aneurysm die before reaching the hospital. The overall mortality rate is even between 80-90%.

Aneurysm in MRI

An aneurysm can typically be visualized very well in an MRI, as MRI offers high resolution and excellent soft tissue representation. In particular, special sequences like Time-of-Flight (TOF) MRA can provide detailed images of aneurysms. This allows for precise visualization of both the size and shape of the aneurysm, as well as its location and any potential complications, such as thrombus formation or wall dissection. Therefore, MRI is a very important tool in the diagnosis and monitoring of aneurysms.

Aneurysm Symptoms

Often, aneurysms do not cause any symptoms and are discovered incidentally during routine examinations. The most common symptoms include sudden onset of headaches, vision disturbances, speech difficulties, coughing, or hoarseness. However, symptoms can vary based on the location and severity of the aneurysm.

• Cerebral Artery Aneurysms:
  • Sudden, severe headaches
  • Nausea and vomiting
  • Stiff neck
  • Vision disturbances
  • Loss of consciousness
• Extracranial Aneurysms (Carotid Artery):
  • Pulsating lump in the neck
  • Dizziness
  • Vision disturbances
  • Speech difficulties
  • Stroke symptoms
• Aortic Aneurysms:
  • Pain in the chest, back, or abdomen
  • Pulsating sensation in the abdomen
  • Coughing
  • Hoarseness
  • Shortness of breath

Types of Aneurysms

Aneurysms can occur in various parts of the body and are classified by their location and shape. The most common types are:

• Brain Aneurysm: A brain aneurysm occurs in the brain arteries and can lead to a subarachnoid hemorrhage if it ruptures, which is a life-threatening form of stroke. Adults aged 30 to 60 years are particularly affected, with women being more commonly affected than men.
• Neck Aneurysm: These aneurysms are located outside the skull (extracranial), typically in the carotid arteries. Aneurysms of the extracranial internal carotid artery (EICA), which is the internal carotid artery outside the skull, are rare and account for less than 1% of all arterial aneurysms. Despite their rarity, they are significant because they carry an increased risk of thromboembolic events in the brain, compression of cranial nerves, and rupture.
• Aortic Aneurysm: An aortic aneurysm occurs in the main artery (aorta), which is the largest artery in the body that originates from the heart and supplies blood to the body. Two main types of aortic aneurysms are distinguished:
  
  1) Chest Aneurysm: A chest aneurysm (thoracic aortic aneurysm) is an enlargement or bulging of a section of the aorta in the chest (thorax). Thoracic aortic aneurysms are rare, occurring in about 6-10 out of 100,000 people. Approximately 20% of thoracic aortic aneurysms can be attributed to a family history.
  
  2) Abdominal Aortic Aneurysm (AAA): An abdominal aortic aneurysm is a pathological dilation or bulging of the abdominal aorta. Abdominal aortic aneurysms affect up to 7% of individuals over 50 years old and are particularly common in older men who smoke. In most cases, these bulges remain small and grow slowly, posing little significant risk. However, in some cases, they can expand rapidly and rupture without warning. The resulting massive bleeding in the abdominal cavity is typically life-threatening.
• Aortectasia: Aortectasia is a slight dilation of the aorta up to 1.5 times the normal size, which does not meet the criteria for an aneurysm. An aneurysm is only considered when the diameter exceeds 1.5 times the normal size.

How Are Aneurysms Diagnosed?

The diagnosis of an aneurysm is typically made through imaging techniques such as ultrasound, CT angiography, or MRI angiography. Treatment depends on the size of the aneurysm and the individual patient's risk. Small aneurysms can be monitored regularly, while larger aneurysms often require surgery to reduce the risk of rupture.

• CT Angiography: Computed tomography (CT) angiography is the gold standard for assessing brain aneurysms (cerebral aneurysms), with a sensitivity and specificity of up to 100%. CT angiography is a rapid and cost-effective diagnostic technique with broad availability and high spatial resolution. However, angiography is an invasive method that involves the injection of contrast agents and subsequent X-ray imaging.
• Ultrasound Examination (Sonography): This non-invasive method allows for the detection of aneurysms in the abdominal area and other parts of the body. Studies show that emergency physicians can identify an abdominal aortic aneurysm with a sensitivity of 100% and specificity of up to 100%. Given the high mortality rate following a ruptured abdominal aneurysm of nearly 90%, rapid diagnosis and treatment play a crucial role. Another study demonstrated that an ultrasound examination at the accident scene could reduce the time to diagnosis from 111 minutes to 51 minutes.
• Magnetic Resonance Imaging (MRI): An MRI provides detailed images of the blood vessels and surrounding tissue. MRI examinations are generally very accurate in detecting unruptured brain aneurysms. In one study, 45 out of 57 brain aneurysms were detected through MRI scans. It was noted that MRI scans may be less effective in detecting aneurysms smaller than 4 mm. However, aneurysms of this size rupture less frequently and lead to bleeding. The risk of bleeding is higher for aneurysms larger than 7 mm.

What Does an MRI Show in Cases of Aneurysms?

Magnetic resonance imaging (MRI) is an important imaging technique for diagnosing aneurysms. It provides detailed images of blood vessels and allows doctors to assess the size, location, and shape of the aneurysm. The following parameters can be examined using MRI:

• Location: The MRI can display the exact position of the aneurysm in the brain, indicating whether it is located at an arterial bifurcation or at a curve. It can also show where the aneurysm is in relation to surrounding blood vessels and cranial nerves, and whether these structures are being compressed or displaced.
• Size and Shape: The size of the aneurysm (diameter of the bulge) and its shape can be precisely measured. This information is crucial for risk assessment and treatment planning.
• Brain Tissue: The MRI can reveal whether the aneurysm is exerting pressure on brain tissue or if there has already been a brain hemorrhage.
• Wall Changes: Inflammation or other changes in the aneurysm wall can be visualized using specific MRI sequences.
• Bleeding: If the aneurysm has already ruptured, the MRI can show the bleeding in the brain and any potential complications, such as circulatory disorders. Hemorrhages within brain tissue can also be detected on the MRI.

Aneurysm Causes & Risk Factors

An aneurysm can be congenital or acquired over a person's lifetime. However, the exact causes of aneurysms are often unknown. Nonetheless, several risk factors may increase the likelihood of developing an aneurysm:

• Age: The risk increases with age. A study found that two-thirds of all abdominal aortic aneurysms occurred in individuals over 75 years old.
• Gender: According to a study examining 682 treated intracranial aneurysms, the number of aneurysms in women was nearly three times higher than in men. Conversely, men are more frequently affected by abdominal aortic aneurysms (75% vs. 25%).
• Hypertension: High blood pressure puts strain on the arterial walls and can lead to weaknesses. A study indicated that lowering blood pressure significantly reduces the occurrence of ruptured aneurysms and the rupture rate.
• Smoking: Smoking is a significant risk factor for the development of abdominal aortic aneurysms (AAA). Studies show that smokers have a 3 to 12 times increased risk of developing an AAA. In a large-scale study, 75% of aneurysms measuring over 4 cm were attributed to smoking. A Swedish investigation found that 87% of affected men were current or former smokers. Additionally, smoking doubles the risk of rupture before age 65 compared to non-smokers.
• Atherosclerosis: Atherosclerosis leads to the formation of plaque in the arterial walls. This plaque can weaken the arterial walls and make them more susceptible to bulging. When the arterial wall is weakened by the plaque and blood pressure continues to exert force on it, the artery can expand and form an aneurysm.
• Heritability: Apart from familial occurrence (i.e., the clustering of intracranial aneurysms in a family), several inherited conditions are associated with the formation of intracranial aneurysms (IA). These include:
  • Autosomal dominant polycystic kidney disease (ADPKD)
  • Neurofibromatosis type I (NF1)
  • Multiple endocrine neoplasia type I (MEN1)
  • Hereditary hemorrhagic telangiectasia (HHT)
• Infections: Infections such as syphilis and tuberculosis can promote the formation of aneurysms by triggering an inflammatory response in the vessel wall. This inflammation damages the elastic fibers and muscle tissue, weakens the vessel wall, and makes it more susceptible to aneurysms.
• Injuries: Injuries that can lead to aneurysms typically involve direct or indirect damage to the arterial walls. These include:
  • Stab or gunshot wounds
  • Severe impacts or blows to the body, such as in car accidents or sports injuries
  • Surgical procedures
  • Catheter-based interventions
• Connective Tissue Disorders: Conditions affecting connective tissue, such as Marfan syndrome or Ehlers-Danlos syndrome (EDS), can weaken the arterial walls. Individuals with Marfan syndrome have an increased risk of aortic aneurysms, particularly in the ascending aorta (the part of the aorta closest to the heart). This is due to the weakened aortic wall being able to expand and bulge. Some forms of EDS, especially vascular EDS (vEDS), are associated with an increased risk of aneurysms and dissections in various blood vessels, including the aorta.

How is an Aneurysm Treated?

The treatment of an aneurysm is performed through endovascular therapy, also known as coiling, which aims to occlude the aneurysm. This typically involves accessing the body through the femoral artery, and less frequently through the arm artery. A microcatheter is used to insert platinum coils into the aneurysm to seal it off.

To enhance the closure and maintain long-term stability, bioactive coils coated with special materials may also be used.

In addition to occluding the aneurysm itself, neurosurgeons often place stents or so-called flow diverters into the affected brain vessel. These devices alter blood flow in such a way that the aneurysm is excluded from the bloodstream, preventing further expansion.

Another technique in neurosurgery is called clipping, where a vascular clip is used to close the aneurysm and clamp it at its base.

Conclusion

Aneurysms pose a significant health risk, as they can rupture in the worst case, leading to life-threatening bleeding.

The diagnosis of aneurysms is typically performed through imaging techniques such as ultrasound, CT angiography, or MRI angiography. The choice of method depends on the location and size of the aneurysm.

Treatment options include both minimally invasive procedures, such as coiling, where the aneurysm is sealed off with platinum coils, as well as surgical interventions like clipping, where the aneurysm is clamped with a clip.

Prevention and early detection of aneurysms are especially important, particularly for high-risk groups such as older adults, smokers, individuals with high blood pressure, or those with a family history of aneurysms. Regular medical examinations can help detect aneurysms early and minimize the risk of complications.

Schedule a scan now to assess your individual risk and identify potential aneurysms at an early stage.