Aneurysms what are they? Types, symptoms, causes
What are aneurysms?
Aneurysms are saclike structures formed by the bulging of the wall (tunica) of blood vessels. The wall is made up of three layers: an outer layer called the tunica externa, a middle layer called the tunica media, and an innermost layer called the tunica intima. Aneurysms may be saccular or fusiform, depending on their shape. Saccular aneurysms have a narrow neck at one end and a wide-mouthed "berry" at the other. Fusiform aneurysms are wide in all directions. The term "aneurysm" comes from two Greek words meaning "swelling out."
Where do they occur?
Aneurysms occur most frequently in arteries at the base of the brain (cerebral aneurysms) and in larger blood vessels, such as those leading from the heart. Aortic aneurysms, the most common type, may be found anywhere along the aorta but are more likely to develop near its branches that carry blood away from the heart—the coronary arteries that feed blood to your heart muscle and your renal arteries, which supply blood to your kidneys. Thoracic aortic aneurysms start just below your ribs.
Who is at risk for developing aneurysms?
Risk factors for aortic aneurysms include atherosclerosis (hardening of the arteries), polycystic kidney disease, bicuspid aortic valve, Down syndrome, Marfan syndrome (a disorder that affects connective tissue throughout the body), syphilis (a sexually transmitted infection that can cause degeneration of blood vessel walls), and trauma. Risk factors for brain aneurysms include sickle cell disease, vasculitis, or other diseases associated with poor circulation.
Types of aneurysms
This occurs when the artery dilates and widens in all directions. It often starts at a point where there is a weakness in the vessel wall, such as a berry aneurysm. This type of aneurysm can occur anywhere on the body's blood vessels, but it most commonly affects arteries near large muscle groups since they require greater blood pressure for circulation. In the brain, these aneurysms are typically located near branches from which other arteries arise—such as those that supply blood to lower parts of your face or one side of your head—which may lead to problems with facial movement or vision. In the leg, fusiform aneurysms usually form in and around the thighs and calves where muscles and blood flow are greater. These aneurysms may cause pain, swelling, or discomfort.
This type of aneurysm occurs when a weakened portion of the artery wall balloons out like a pouch (sac-like). Saccular aneurysms most often affect larger blood vessels such as those that carry blood from your heart to your lungs (pulmonary arteries), or those near your kidneys (renal arteries). High blood pressure is another risk factor for developing these types of aneurysms.
Saccular aortic aneurysm: The aorta is made up of many layers that work together to help control blood pressure as it leaves your heart. A weakness anywhere along these layers can lead to aneurysms, but those often start near places where arteries branch off from the aorta such as the kidneys or pelvis.
This type of aneurysm is caused by a tear in the inner wall of an artery that allows blood to separate the layers that make up the artery. In dissecting aneurysms, blood can leak into your tissue and create swelling. This condition can be life-threatening if not treated quickly because it reduces your heart's oxygen supply. Aneurysms near your brain are often considered more dangerous than those in other locations because bleeding from a ruptured brain aneurysm can lead to permanent damage or death if not treated right away. Risk factors for this type of aneurysm include atherosclerosis, polycystic kidney disease, trauma, cocaine use, and smoking.
Focal dissecting aneurysm
This type of aneurysm occurs in a single area and can be caused by trauma or atherosclerosis. An artery that is already weakened from a hardening of the arteries (atherosclerosis) may tear, allowing blood to separate the layers within the artery wall creating a focal dissecting aneurysm. The condition is most common in older adults but may affect people with sickle cell disease as well as those who smoke or have high cholesterol levels, atherosclerosis, hypertension (high blood pressure), diabetes mellitus, and obesity. Symptoms include weakness or numbness on one side of your body and can lead to severe complications if not treated right away.
Since dissecting aneurysms have a higher risk of early rupture, they typically must be treated immediately. In some cases, surgery to repair the artery may be necessary. If not treated right away, a dissecting aneurysm can cause permanent nerve damage or death.
Infection from bacteria can affect arteries anywhere in your body and create aneurysms that are called mycotic aneurysms. This type of condition is most common as a complication after a heart attack that weakens blood vessels. Infection from the bacteria streptococcus can weaken lining on the surface of heart valves leading to the formation of a mycotic aneurysm behind the valve.
Another common bacterium responsible for an aneurysm is pseudomonas, which can affect bones around your spinal column or lungs. If the infection enters a blood vessel in these areas, it can lead to the formation of mycotic aneurysms.
Symptoms of this type of aneurysm include fever and chills, chest pain, shortness of breath, sweating, or a skin rash. Treatment may involve antibiotics or surgery depending on the location of the affected arteries.
Saccular intracranial aneurysms (SCIAs)
What are the symptoms of aneurysms?
What causes aneurysms?
How are aneurysms treated?
What are the complications of aneurysms?
What are the outcomes of aneurysms?
What is the long-term outlook for people who have had aneurysms?
The overall prognosis after treatment for intracranial (brain) aneurysms is good, particularly if no serious underlying condition exists that could complicate recovery. If you've had more than one unruptured brain aneurysm, there's a chance that additional aneurysms will develop over time. If you've already had one or more unruptured brain aneurysms rupture, your risk of having another aneurysm increases to about 30 percent within 10 years. Your health care team may recommend regular follow-up care to monitor your condition.
Complications of brain aneurysms can include seizures, paralysis, and extreme personality changes (such as uncontrollable aggression). If you're older than 50, the risk of delayed neurologic complications is greater after surgery if you experience uncontrolled high blood pressure or other conditions that may affect recovery. The long-term outlook for people who have had abdominal aortic aneurysms repaired depends on several factors, including the size and location of the aneurysm before repair, whether there's any scar tissue remaining in the artery after repair and if you've also needed treatment for heart disease or another serious health problem.
The Mayo Clinic reports that about 25 percent of these die within 30 days of one type of surgery, called endovascular stent-graft repair. The five-year survival rate is about 90 percent. For patients with an untreated or ruptured thoracic aortic aneurysm, the prognosis is poor because 50 percent of these conditions are fatal within one month.
Aneurysms cause nearly 150,000 deaths worldwide each year and play a role in up to 10 percent of all strokes, according to the National Institutes of Health (NIH). Most people with brain aneurysms have no symptoms until they rupture; only half then survive, according to Johns Hopkins Medicine Brain Aneurysm Foundation. Most intracranial aneurysms are found incidentally when people are hospitalized for unrelated conditions.
Conventional wisdom suggests that aneurysms are caused by uncontrolled high blood pressure, but studies show that only a small number of cases are related to hypertension. So what does cause brain aneurysms? The NIH says that increased age is the most important risk factor for intracranial aneurysms, followed by smoking and heavy use of cocaine or amphetamines. Other risk factors include having a family history of brain aneurysms or genetic disorders such as polycystic kidney disease and sickle cell disease.