An aneurysm is an outward bulging, likened to a bubble or balloon, caused by a localized, abnormal, weak spot on a

blood vessel The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away ...

wall. Aneurysms may be a result of a hereditary condition or an acquired disease. Aneurysms can also be a

nidus Nidus may refer to: * Nidus (nest), for insects or small animals * The characteristic lesion in osteoid osteoma * The centre of a bladder stone * The material around which an enterolith An enterolith is a mineral concretion or calculus formed ...

(starting point) for clot formation (

thrombosis Thrombosis (from Ancient Greek "clotting") is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel (a vein or an artery) is injured, the body uses platelets (t ...

) and

embolization Embolization refers to the passage and lodging of an embolus within the bloodstream. It may be of natural origin ( pathological), in which sense it is also called embolism, for example a pulmonary embolism; or it may be artificially indu ...

. As an aneurysm increases in size, the risk of rupture, which leads to uncontrolled bleeding, increases. Although they may occur in any blood vessel, particularly lethal examples include aneurysms of the

Circle of Willis The circle of Willis (also called Willis' circle, loop of Willis, cerebral arterial circle, and Willis polygon) is a circulatory anastomosis that supplies blood to the brain and surrounding structures in reptiles, birds and mammals, including huma ...

in the brain, aortic aneurysms affecting the thoracic

aorta The aorta ( ) is the main and largest artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries). The aorta distributes o ...

, and

abdominal aortic aneurysm Abdominal aortic aneurysm (AAA) is a localized enlargement of the abdominal aorta such that the diameter is greater than 3 cm or more than 50% larger than normal. They usually cause no symptoms, except during rupture. Occasionally, abdominal, ...

s. Aneurysms can arise in the heart itself following a

heart attack A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which ma ...

, including both ventricular and atrial septal aneurysms. There are congenital atrial septal aneurysms, a rare heart defect.

Etymology

The word is from

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

: ἀνεύρυσμα, aneurysma, "dilation", from ἀνευρύνειν, aneurynein, "to dilate".

Classification

Aneurysms are classified by type, morphology, or location.

True and false aneurysms

A true aneurysm is one that involves all three layers of the wall of an artery (

intima The tunica intima (New Latin "inner coat"), or intima for short, is the innermost tunica (layer) of an artery or vein. It is made up of one layer of endothelial cells and is supported by an internal elastic lamina. The endothelial cells are in ...

media Media may refer to: Communication * Media (communication), tools used to deliver information or data ** Advertising media, various media, content, buying and placement for advertising ** Broadcast media, communications delivered over mass e ...

and

adventitia The adventitia () is the outer layer of fibrous connective tissue surrounding an organ. The outer layer of connective tissue that surrounds an artery, or vein – the tunica externa, is also called the ''tunica adventitia''. To some degree, its ...

). True aneurysms include

atherosclerotic Atherosclerosis is a pattern of the disease arteriosclerosis in which the wall of the artery develops abnormalities, called lesions. These lesions may lead to narrowing due to the buildup of atheromatous plaque. At onset there are usually no ...

, syphilitic, and congenital aneurysms, as well as

ventricular aneurysm Ventricular aneurysms are one of the many complications that may occur after a heart attack. The word aneurysm refers to a bulge or 'pocketing' of the wall or lining of a vessel commonly occurring in the blood vessels at the base of the septum, o ...

s that follow transmural

myocardial infarction A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may ...

s (aneurysms that involve all layers of the attenuated wall of the heart are also considered true aneurysms). A false aneurysm, or

pseudoaneurysm A pseudoaneurysm, also known as a false aneurysm, is a locally contained hematoma outside an artery or heart due to damage to the vessel wall. The injury goes through all the three layers of the arterial wall causing a leak, which is contained b ...

, is a collection of blood leaking completely out of an artery or vein but confined next to the vessel by the surrounding tissue. This blood-filled cavity will eventually either thrombose (clot) enough to seal the leak or rupture out of the surrounding tissue. Pseudoaneurysms can be caused by

trauma Trauma most often refers to: * Major trauma, in physical medicine, severe physical injury caused by an external source * Psychological trauma, a type of damage to the psyche that occurs as a result of a severely distressing event *Traumatic i ...

that punctures the artery, such as knife and bullet wounds, as a result of

percutaneous {{More citations needed, date=January 2021 In surgery, a percutaneous procedurei.e. Granger et al., 2012 is any medical procedure or method where access to inner organs or other tissue is done via needle-puncture of the skin, rather than by using ...

surgical procedures such as coronary angiography or arterial grafting, or use of an artery for injection.

Morphology

Aneurysms can also be classified by their macroscopic shapes and sizes and are described as either saccular or fusiform. The shape of an aneurysm is not specific for a specific disease. The size of the base or neck is useful in determining the chance of for example

endovascular coiling Endovascular coiling is an endovascular treatment for intracranial aneurysms and bleeding throughout the body. The procedure reduces blood circulation to the aneurysm through the use of microsurgical detachable platinum wires, with the clinician i ...

. Saccular aneurysms, or "berry" aneurysms, are spherical in shape and involve only a portion of the vessel wall; they usually range from in diameter, and are often filled, either partially or fully, by a

thrombus A thrombus (plural thrombi), colloquially called a blood clot, is the final product of the blood coagulation step in hemostasis. There are two components to a thrombus: aggregated platelets and red blood cells that form a plug, and a mesh of ...

.Saccular aneurysms have a "neck" that connects the aneurysm to its main ("parent") artery, a larger, rounded area, called the dome. Fusiform aneurysms ("spindle-shaped" aneurysms) are variable in both their diameter and length; their diameters can extend up to . They often involve large portions of the ascending and transverse

aortic arch The aortic arch, arch of the aorta, or transverse aortic arch () is the part of the aorta between the ascending and descending aorta. The arch travels backward, so that it ultimately runs to the left of the trachea. Structure The aorta begins ...

, the abdominal aorta, or, less frequently, the iliac arteries.

Location

Aneurysms can also be classified by their location: Ultrasonography of a thrombosed great saphenous vein aneurysm

Arterial An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...

and

venous Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated ...

, with arterial being more common. * The

heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to t ...

, including

coronary artery aneurysm Coronary artery aneurysm is an abnormal dilatation of part of the coronary artery. This rare disorder occurs in about 0.3–4.9% of patients who undergo coronary angiography. Signs and symptoms Causes Acquired causes include atherosclerosis in a ...

s, aneurysm of sinus of Valsalva, and aneurysms following cardiac surgery. * The

, namely aortic aneurysms including

thoracic aortic aneurysm A thoracic aortic aneurysm is an aortic aneurysm that presents primarily in the thorax. A thoracic aortic aneurysm is the "ballooning" of the upper aspect of the aorta, above the diaphragm. Untreated or unrecognized they can be fatal due to dissec ...

s and

s. * The

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

, including

cerebral aneurysm An intracranial aneurysm, also known as a brain aneurysm, is a cerebrovascular disorder in which weakness in the wall of a cerebral artery or vein causes a localized dilation or ballooning of the blood vessel. Aneurysms in the posterior circula ...

s, berry aneurysms, and

Charcot–Bouchard aneurysm Charcot–Bouchard aneurysms are aneurysms of the brain vasculature which occur in small blood vessels (less than 300 micrometre diameter). Charcot–Bouchard aneurysms are most often located in the Anterolateral central arteries, lenticulostriate ...

s. * The legs, including the popliteal arteries. * The

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; blo ...

, including renal artery aneurysm and intraparenchymal aneurysms. *

Capillaries A capillary is a small blood vessel from 5 to 10 micrometres (μm) in diameter. Capillaries are composed of only the tunica intima, consisting of a thin wall of simple squamous endothelial cells. They are the smallest blood vessels in the body: ...

, specifically capillary aneurysms. * The Large vessels such as external and internal jugular veins

Cerebral aneurysms An intracranial aneurysm, also known as a brain aneurysm, is a cerebrovascular disorder in which weakness in the wall of a cerebral artery or vein causes a localized dilation or ballooning of the blood vessel. Aneurysms in the posterior circ ...

, also known as intracranial or brain aneurysms, occur most commonly in the

anterior cerebral artery The anterior cerebral artery (ACA) is one of a pair of cerebral arteries that supplies oxygenated blood to most midline portions of the frontal lobes and superior medial parietal lobes of the brain. The two anterior cerebral arteries arise from t ...

, which is part of the

circle of Willis The circle of Willis (also called Willis' circle, loop of Willis, cerebral arterial circle, and Willis polygon) is a circulatory anastomosis that supplies blood to the brain and surrounding structures in reptiles, birds and mammals, including huma ...

. This can cause severe strokes leading to death. The next most common sites of cerebral aneurysm occurrence are in the internal carotid artery.

Size

Abdominal aortic aneurysms are commonly divided according to their size and symptomatology. An aneurysm is usually defined as an outer aortic diameter over 3 cm (normal diameter of the

is around 2 cm), or more than 50% of normal diameter that of a healthy individual of the same sex and age. If the outer diameter exceeds 5.5 cm, the aneurysm is considered to be large. The

common iliac artery The common iliac artery is a large artery of the abdomen paired on each side. It originates from the aortic bifurcation at the level of the 4th lumbar vertebra. It ends in front of the sacroiliac joint, one on either side, and each bifurcate ...

is classified as:

Signs and symptoms

Aneurysm presentation may range from life-threatening complications of hypovolemic shock to being found incidentally on X-ray. Symptoms will differ by the site of the aneurysm and can include:

Cerebral aneurysm

Symptoms can occur when the aneurysm pushes on a structure in the brain. Symptoms will depend on whether an aneurysm has ruptured or not. There may be no symptoms present at all until the aneurysm ruptures. For an aneurysm that has not ruptured the following symptoms can occur: * Fatigue * Loss of perception *

Loss of balance A balance disorder is a disturbance that causes an individual to feel unsteady, for example when standing or walking. It may be accompanied by feelings of giddiness, or wooziness, or having a sensation of movement, spinning, or floating. Balance ...

* Speech problems * Double vision For a ruptured aneurysm, symptoms of a subarachnoid hemorrhage may present: * Severe headaches * Loss of vision * Double vision * Neck pain or stiffness * Pain above or behind the eyes

Abdominal aneurysm

Abdominal aortic aneurysm involves a regional dilation of the aorta and is diagnosed using

ultrasonography Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies fr ...

, computed tomography, or magnetic resonance imaging. A segment of the aorta that is found to be greater than 50% larger than that of a healthy individual of the same sex and age is considered aneurysmal. Abdominal aneurysms are usually asymptomatic but in rare cases can cause lower back pain or lower limb ischemia.

Renal (kidney) aneurysm

* Flank pain and tenderness * Hypertension * Haematuria * Signs of hypovolemic shock

Risk factors

Risk factors for an aneurysm include

diabetes Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ...

obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's ...

, hypertension,

tobacco use Tobacco smoking is the practice of burning tobacco and ingesting the resulting smoke. The smoke may be inhaled, as is done with cigarettes, or simply released from the mouth, as is generally done with pipes and cigars. The practice is believed ...

alcoholism Alcoholism is, broadly, any drinking of alcohol that results in significant mental or physical health problems. Because there is disagreement on the definition of the word ''alcoholism'', it is not a recognized diagnostic entity. Predomi ...

, high cholesterol,

copper deficiency Copper deficiency, or hypocupremia, is defined either as insufficient copper to meet the needs of the body, or as a serum copper level below the normal range. Symptoms may include fatigue, decreased red blood cells, early greying of the hair, an ...

, increasing age, and tertiary syphilis infection. Connective tissue disorders such as Loeys-Dietz syndrome, Marfan syndrome, and certain forms of Ehlers-Danlos syndrome are also associated with aneurysms. Aneurysms, dissections, and ruptures in individuals under 40 years of age are a major diagnostic criteria of the vascular form of Ehlers-Danlos syndrome (vEDS). Specific infective causes associated with aneurysm include: * Advanced syphilis infection resulting in

syphilitic aortitis Syphilitic aortitis is inflammation of the aorta associated with the tertiary stage of syphilis infection. SA begins as inflammation of the outermost layer of the blood vessel, including the blood vessels that supply the aorta itself with blood ...

and an aortic aneurysm *

Tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, i ...

, causing Rasmussen's aneurysms * Brain infections, causing infectious intracranial aneurysms A minority of aneurysms are associated with genetic factors. Examples include: * Berry aneurysms of the

anterior communicating artery In human anatomy, the anterior communicating artery is a blood vessel of the brain that connects the left and right anterior cerebral arteries. Anatomy The anterior communicating artery connects the two anterior cerebral arteries across the co ...

of the

, associated with

autosomal dominant polycystic kidney disease Autosomal dominant polycystic kidney disease (ADPKD) is one of the most common, life-threatening inherited human disorders and the most common hereditary kidney disease. It is associated with large interfamilial and intrafamilial variability, wh ...

* Familial thoracic aortic aneurysms * Cirsoid aneurysms, secondary to congenital arteriovenous malformations

Pathophysiology

Aneurysms form for a variety of interacting reasons. Multiple factors, including factors affecting a blood vessel wall and the blood through the vessel, contribute. The pressure of blood within the expanding aneurysm may also injure the blood vessels supplying the artery itself, further weakening the vessel wall. Without treatment, these aneurysms will ultimately progress and rupture. Infection. A

mycotic aneurysm An infected aneurysm is an aneurysm arising from bacterial infection of the arterial wall. It can be a common complication of the hematogenous spread of bacterial infection. William Osler first used the term "mycotic aneurysm" in 1885 to describe ...

is an aneurysm that results from an infectious process that involves the arterial wall. A person with a mycotic aneurysm has a bacterial infection in the wall of an artery, resulting in the formation of an aneurysm. One of the causes of mycotic aneurysms is

infective endocarditis Infective endocarditis is an infection of the inner surface of the heart, usually the valves. Signs and symptoms may include fever, small areas of bleeding into the skin, heart murmur, feeling tired, and low red blood cell count. Complications ...

. The most common locations include arteries in the abdomen, thigh, neck, and arm. A mycotic aneurysm can result in sepsis, or life-threatening bleeding if the aneurysm ruptures. Less than 3% of abdominal aortic aneurysms are mycotic aneurysms. Syphilis. The third stage of syphilis also manifests as aneurysm of the

, which is due to loss of the

vasa vasorum Vasa vasorum are small blood vessels that comprise a vascular network supplying the walls of large blood vessels, such as elastic arteries (e.g., the aorta) and large veins (e.g., the venae cavae). The name derives . Occasionally two differen ...

in the

tunica adventitia The tunica externa (New Latin "outer coat"), also known as the tunica adventitia (New Latin "additional coat"), is the outermost tunica (layer) of a blood vessel, surrounding the tunica media. It is mainly composed of collagen and, in arteries, i ...

. Copper deficiency. A minority of aneurysms are caused by

, which results in a decreased activity of the

lysyl oxidase Lysyl oxidase (LOX), also known as protein-lysine 6-oxidase, is an enzyme that, in humans, is encoded by the ''LOX'' gene. It catalyzes the conversion of lysine molecules into highly reactive aldehydes that form cross-links in extracellular matr ...

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

, affecting elastin, a key component in vessel walls. Copper deficiency results in vessel wall thinning, and thus has been noted as a cause of death in copper-deficient humans, chickens, and turkeys.

Mechanics

Aneurysmal blood vessels are prone to rupture under normal blood pressure and flow due to the special mechanical properties that make them weaker. To better understand this phenomenon, we can first look at healthy arterial vessels which exhibit a J-shaped stress-strain curve with high strength and high toughness (for a biomaterial ''in vivo''). Unlike crystalline materials whose linear elastic region follows Hooke's Law under uniaxial loading, many biomaterials exhibit a J-shaped stress-strain curve which is non-linear and concave up. The blood vessel can be under large strain, or the amount of stretch the blood vessel can undergo, for a range of low applied stress before fracture, as shown by the lower part of the curve. The area under the curve up to a given strain is much lower than that for the equivalent Hookean curve, which is correlated to toughness.

Toughness In materials science and metallurgy, toughness is the ability of a material to absorb energy and plastically deform without fracturing. Initially, for a given radius and pressure, stiffness of the material increases linearly. At a certain point, the stiffness of the arterial wall starts to decrease with increasing load. At higher strain values, the area under the curve increases, thus increasing the impact on the material that would promote crack propagation. The differences in the mechanical properties of the aneurysmal blood vessels and the healthy blood vessels stem from the compositional differences of the vessels. Compared to normal aortas, aneurysmal aortas have a much higher volume fraction of collagen and ground substance (54.8% vs. 95.6%) and a much lower volume fraction of elastin (22.7% vs. 2.4%) and smooth muscles (22.6% vs. 2.2%), which contribute to higher initial stiffness. It was also found that the ultimate tensile strength, or the strength to withstand rupture, of aneurysmal vessel wall is 50% lower than that of normal aortas. The wall strength of ruptured aneurysmal aortic wall was also found to be 54.2 N/cm², which is much lower than that of a repaired aorta wall, 82.3 N/cm². Due to the change in composition of the arterial wall, aneurysms overall have much lower strength to resist rupture. Predicting the risk of rupture is difficult due to the regional anisotropy the hardened blood vessels exhibit, meaning that the stress and strength values vary depending on the region and the direction of the vessel they are measured along.

Diagnosis

Ruptured 7mm left vertebral artery aneurysm

Diagnosis of a ruptured cerebral aneurysm is commonly made by finding signs of subarachnoid hemorrhage on a computed tomography (CT) scan. If the CT scan is negative but a ruptured aneurysm is still suspected based on clinical findings, a lumbar puncture can be performed to detect blood in the

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the ...

Computed tomography angiography Computed tomography angiography (also called CT angiography or CTA) is a computed tomography technique used for angiography—the visualization of arteries and veins—throughout the human body. Using contrast injected into the blood vessels, ...

(CTA) is an alternative to traditional angiography and can be performed without the need for arterial catheterization. This test combines a regular CT scan with a contrast dye injected into a vein. Once the dye is injected into a vein, it travels to the cerebral arteries, and images are created using a CT scan. These images show exactly how blood flows into the brain arteries.

Treatment

Historically, the treatment of arterial aneurysms has been limited to either surgical intervention or

watchful waiting Watchful waiting (also watch and wait or WAW) is an approach to a medical problem in which time is allowed to pass before medical intervention or therapy is used. During this time, repeated testing may be performed. Related terms include ''expe ...

in combination with control of blood pressure. At least, in the case of

(AAA), the decision does not come without significant risk and cost, hence, there is a great interest in identifying more advanced decision-making approaches that are not solely based on the

AAA AAA, Triple A, or Triple-A is a three-letter initialism or abbreviation which may refer to: Airports * Anaa Airport in French Polynesia (IATA airport code AAA) * Logan County Airport (Illinois) (FAA airport code AAA) Arts, entertainment, and me ...

diameter, but involve other geometrical and mechanical nuances such as local thickness and wall stress. In recent years, endovascular or minimally invasive techniques have been developed for many types of aneurysms. Aneurysm clips are used for surgical procedure i.e. clipping of aneurysms.

Intracranial

There are currently two treatment options for brain aneurysms: surgical clipping or endovascular coiling. There is currently debate in the medical literature about which treatment is most appropriate given particular situations. Surgical clipping was introduced by

Walter Dandy Walter Edward Dandy (April 6, 1886 – April 19, 1946) was an American neurosurgeon and scientist. He is considered one of the founding fathers of neurosurgery, along with Victor Horsley (1857–1916) and Harvey Cushing (1869–1939). Dandy is ...

of the

Johns Hopkins Hospital The Johns Hopkins Hospital (JHH) is the teaching hospital and biomedical research facility of the Johns Hopkins School of Medicine, located in Baltimore, Maryland, U.S. It was founded in 1889 using money from a bequest of over $7 million (1873 m ...

in 1937. It consists of a

craniotomy A craniotomy is a surgical operation in which a bone flap is temporarily removed from the skull to access the brain. Craniotomies are often critical operations, performed on patients who are suffering from brain lesions, such as tumors, blood clot ...

to expose the aneurysm and closing the base or neck of the aneurysm with a clip. The surgical technique has been modified and improved over the years.

Endovascular coiling Endovascular coiling is an endovascular treatment for intracranial aneurysms and bleeding throughout the body. The procedure reduces blood circulation to the aneurysm through the use of microsurgical detachable platinum wires, with the clinician i ...

was introduced by Italian neurosurgeon Guido Guglielmi at

UCLA The University of California, Los Angeles (UCLA) is a public land-grant research university in Los Angeles, California. UCLA's academic roots were established in 1881 as a teachers college then known as the southern branch of the California ...

in 1989. It consists of passing a catheter into the femoral artery in the groin, through the aorta, into the brain arteries, and finally into the aneurysm itself. Platinum coils initiate a clotting reaction within the aneurysm that, if successful, fills the aneurysm dome and prevents its rupture. A flow diverter can be used, but risks complications.

Aortic and peripheral

For aneurysms in the aorta, arms, legs, or head, the weakened section of the vessel may be replaced by a bypass graft that is sutured at the vascular stumps. Instead of sewing, the graft tube ends, made rigid and expandable by nitinol wireframe, can be easily inserted in its reduced diameter into the vascular stumps and then expanded up to the most appropriate diameter and permanently fixed there by external ligature. New devices were recently developed to substitute the external ligature by expandable ring allowing use in acute ascending aorta dissection, providing airtight (i.e. not dependent on the coagulation integrity), easy and quick anastomosis extended to the arch concavity Less invasive endovascular techniques allow covered metallic stent grafts to be inserted through the arteries of the leg and deployed across the aneurysm.

Renal

Renal aneurysms are very rare consisting of only 0.1–0.09% while rupture is even more rare. Conservative treatment with control of concomitant hypertension being the primary option with aneurysms smaller than 3 cm. If symptoms occur, or enlargement of the aneurysm, then endovascular or open repair should be considered. Pregnant women (due to high rupture risk of up to 80%) should be treated surgically.

Epidemiology

Incidence rates of cranial aneurysms are estimated at between 0.4% and 3.6%. Those without risk factors have expected prevalence of 2–3%. In adults, females are more likely to have aneurysms. They are most prevalent in people ages 35 – 60 but can occur in children as well. Aneurysms are rare in children with a reported prevalence of .5% to 4.6%. The most common incidence is among 50-year-olds, and there are typically no warning signs. Most aneurysms develop after the age of 40.

Pediatric aneurysms

Pediatric aneurysms have different incidences and features than adult aneurysms. Intracranial aneurysms are rare in childhood, with over 95% of all aneurysms occurring in adults.

Risk factors

Incidence rates are two to three times higher in males, while there are more large and giant aneurysms and fewer multiple aneurysms. Intracranial hemorrhages are 1.6 times more likely to be due to aneurysms than cerebral arteriovenous malformations in whites, but four times less in certain Asian populations. Most patients, particularly infants, present with subarachnoid hemorrhage and corresponding headaches or neurological deficits. The mortality rate for pediatric aneurysms is lower than in adults.

Modeling

Modeling of aneurysms consists of creating a 3D model that mimics a particular aneurysm. Using patient data for the blood velocity, and blood pressure, along with the geometry of the aneurysm, researchers can apply

computational fluid dynamics Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows. Computers are used to perform the calculations required to simulate ...

(CFD) to predict whether an aneurysm is benign or if it is at risk of complication. One risk is rupture. Analyzing the velocity and pressure profiles of the blood flow leads to obtaining the resulting wall shear stress on the vessel and aneurysm wall. The neck of the aneurysm is the most at risk due to the combination of a small wall thickness and high wall shear stress. When the wall shear stress reaches its limit, the aneurysm ruptures, leading to

intracranial hemorrhage Intracranial hemorrhage (ICH), also known as intracranial bleed, is hemorrhage, bleeding internal bleeding, within the Human skull, skull. Subtypes are intracerebral bleeds (intraventricular bleeds and intraparenchymal bleeds), subarachnoid bleed ...

. Conversely, another risk of aneurysms is the creation of clots. Aneurysms create a pocket which diverts blood flow. This diverted blood flow creates a vortex inside of the aneurysm. This vortex can lead to areas inside of the aneurysm where the blood flow is stagnant, which promotes formations of clots. Blood clots can dislodge from the aneurysm, which can then lead to an embolism when the clot gets stuck and disrupts blood flow. Model analysis allows these risky aneurysms to be identified and treated. In the past, aneurysms were modeled as rigid spheres with linear inlets and outlets. As technology advances, the ability to detect and analyze aneurysms becomes easier. Researchers are able to CT scan a patient's body to create a 3D computer model that possesses the correct geometry. Aneurysms can now be modeled with their distinctive "balloon" shape. Nowadays researchers are optimizing the parameters required to accurately model a patient's aneurysm that will lead to a successful intervention. Current modeling is not able to take into account all variables though. For example, blood is considered to be a

non-Newtonian fluid A non-Newtonian fluid is a fluid that does not follow Newton's law of viscosity, i.e., constant viscosity independent of stress. In non-Newtonian fluids, viscosity can change when under force to either more liquid or more solid. Ketchup, for ex ...

. Some researchers treat blood as a Newtonian fluid instead, as it sometimes has negligible effects to the analysis in large vessels. When analyzing small vessels though, such as those present in intracranial aneurysms. Similarly, sometimes it is difficult to model the varying wall thickness in small vessels, so researchers treat wall thickness as constant. Researchers make these assumptions to reduce computational time. Nonetheless, making erroneous assumptions could lead to a misdiagnosis that could put a patient's life at risk.

Notable cases

* U.S. President Joe Biden had two brain aneurysms in 1988. He recovered after successful surgeries to correct them. *

Lucille Ball Lucille Désirée Ball (August 6, 1911 – April 26, 1989) was an American actress, comedienne and producer. She was nominated for 13 Primetime Emmy Awards, winning five times, and was the recipient of several other accolades, such as the Golde ...

, who died from an aortic rupture in the abdominal area days after having undergone apparently successful

heart surgery Cardiac surgery, or cardiovascular surgery, is surgery on the heart or great vessels performed by cardiac surgeons. It is often used to treat complications of ischemic heart disease (for example, with coronary artery bypass grafting); to corr ...

for a dissecting aortic aneurysm *

Laura Branigan Laura Ann Branigan (July 3, 1952 – August 26, 2004) was an American singer, songwriter, and actress. Her signature song, the platinum-certified 1982 single "Gloria", stayed on the U.S. ''Billboard'' Hot 100 for 36 weeks, then a record for a ...

, who died of a cerebral aneurysm *

David Cone David Brian Cone (born January 2, 1963) is an American former Major League Baseball (MLB) pitcher, and current color commentator for the New York Yankees on the YES Network and WPIX as well as for ESPN on Sunday Night Baseball.Davie Cooper Davie is a surname and a form of the masculine given name David. It can refer to: Surname * Alan Davie (1920-2014), Scottish painter and musician * Alexander Edmund Batson Davie (1847-1889), Canadian politician and eighth Premier of British Col ...

, who died in 1995 following a subarachnoid hemorrhage whilst filming a football television series * John Olerud, had an aneurysm in 1989 and has worn a batting helmet on the field all of his career since then *

Albert Einstein Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theory ...

, who died from a repaired aortic aneurysm *

Thomas Mikal Ford Thomas Mikal Ford (September 5, 1964 – October 12, 2016) was an American actor and comedian. He was best known for his role as Thomas "Tommy" Strawn on the FOX sitcom ''Martin'', which originally aired from 1992 until 1997. He also had a recur ...

, who died from a ruptured aneurysm in his abdomen. He was 52. * Charles de Gaulle, who died from an aneurysm within his neck *

Richard Holbrooke Richard Charles Albert Holbrooke (April 24, 1941 – December 13, 2010) was an American diplomat and author. He was the only person to have held the position of Assistant Secretary of State for two different regions of the world (Asia from 1977 ...

, who died from a

Édith Piaf Édith Piaf (, , ; born Édith Giovanna Gassion, ; December 19, 1915– October 10, 1963) was a French singer, lyricist and actress. Noted as France's national chanteuse, she was one of the country's most widely known international stars. Pia ...

, who died from an aneurysm due to liver failure *

Stuart Sutcliffe Stuart Fergusson Victor Sutcliffe (23 June 1940 – 10 April 1962) was a Scottish painter and musician best known as the original bass guitarist of the English rock band the Beatles. Sutcliffe left the band to pursue his career as a paint ...

, who died from an aneurysm in his brain's right hemisphere *

John Ritter Johnathan Southworth Ritter (September 17, 1948 – September 11, 2003) was an American actor. Ritter was a son of the singing cowboy star Tex Ritter and the father of actors Jason and Tyler Ritter. He is known for playing Jack Tripper on the ...

, died in 2003 of a misdiagnosed thoracic aortic dissection (aortic aneurysm). * Isabel Granada, who died of a cerebral aneurysm * Geoffrey Thompson, who died of a brain aneurysm at his daughter's wedding, hosted at his theme park, Blackpool Pleasure Beach. *

Edwin Rosario Edwin "Chapo" Rosario Rivera (; March 15, 1963 – December 1, 1997) was a Puerto Rican professional boxer who competed from 1979 to 1997. He is a world champion in two weight classes, having held the WBC lightweight title from 1983 to 1984, ...

died of an aneurysm in 1997. * Joni Mitchell had a brain aneurysm in 2015, but survived. *

Grant Imahara Grant Masaru Imahara (October 23, 1970 – July 13, 2020) was an American electrical engineer, roboticist, and television host. He was best known for his work on the television series ''MythBusters'', on which he designed and built numerou ...

died from a brain aneurysm in July 2020. *

Dr. Dre Andre Romelle Young (born February 18, 1965), known professionally as Dr. Dre, is an American rapper and record producer. He is the founder and CEO of Aftermath Entertainment and Beats Electronics, and previously co-founded, co-owned, and ...

had a brain aneurysm in January 2021 * Chinese leader

Xi Jinping Xi Jinping ( ; ; ; born 15 June 1953) is a Chinese politician who has served as the general secretary of the Chinese Communist Party (CCP) and chairman of the Central Military Commission (CMC), and thus as the paramount leader of China, ...

reportedly had a cerebral aneurysm and is said to undergo Chinese traditional treatment. *

Jovit Baldivino Jovit Lasin Baldivino (October 16, 1993 – December 9, 2022) was a Filipino singer and actor. He was the first winner of the reality talent competition show ''Pilipinas Got Talent'' in 2010. Early life Jovit Baldivino came from a poor fami ...

died from a brain aneurysm in December 2022

References

External links

Brain aneurysm and percent packing calculator
{{Authority control Gross pathology Vascular diseases