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.


aneurysms
aneurysm


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


Fusiform aneurysm

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.


Saccular aneurysm

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.


Dissecting aneurysm

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.


Mycotic aneurysms

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)

These are usually found when someone has had a head injury that causes bleeding into or around their brain. About three out of four people with SCAs don't remember having such an injury. Symptoms of SCIAs may include a bad headache that gets worse, vomiting, drowsiness, loss of consciousness, vision problems, trouble speaking or walking, numbness on one side of the body or face, and other neurological problems. Seizures are also possible. Symptoms depend on which area of the brain is affected by bleeding into or around it.

Severe SCIAs can lead to permanent brain damage, long-term disability, coma, and death. People with aneurysms should avoid activities that increase pressure inside their head such as lifting heavy objects, straining during bowel movements or urination, sneezing, coughing violently, straining while vomiting, having sex, etc.



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What are the symptoms of aneurysms?

Symptoms vary depending on where your aneurysm is located. Symptoms may be caused by bleeding into the space around the brain resulting in a subarachnoid hemorrhage or by rupture causing damage to the blood vessel wall and surrounding tissue resulting in a hemorrhagic stroke.

Subarachnoid hemorrhage symptoms include severe headache, stiff neck, vomiting, nausea, fever, or altered mental status. Hemorrhagic stroke symptoms include sudden severe headaches with no apparent cause because the bleeding has occurred between layers of tissue in the brain, loss of consciousness without warning signs, impaired speech or vision that suddenly develops within minutes to hours, pain above and behind one eye that builds over several hours and remains steady, sensitivity to light (photophobia) because increased pressure from the bleeding has closed off blood flow to parts of the eye. Symptoms may occur immediately after rupture develop slowly over days or weeks if the aneurysm has been present for many years without rupturing.

General symptoms are:

1. bleeding
2. increased heartbeats
3. pain
4. feeling dizzy 
5. lightheaded


What causes aneurysms?

Aneurysms occur when the wall of a blood vessel weakens and bulges out in a saclike fashion. One cause is atherosclerosis, which can weaken artery walls. Atherosclerosis occurs when fat, cholesterol, cellular waste products, and other substances form scar-like plaques that build up inside artery walls. If an aneurysm ruptures, it often causes bleeding in the subarachnoid space between layers of tissue in the brain or hemorrhage in one of several larger arteries leading from the heart. The following factors may increase your risk for developing aneurysms:

• Advanced age

• Alcohol abuse

• Cigarette smoking 

• Diabetes mellitus (sugar diabetes) 

• High blood pressure 

• High cholesterol


• Personal or family history of aneurysm, arterial dissection, and/or other connective tissue disorders such as Marfan syndrome and Ehlers-Danlos syndrome.



How are aneurysms treated?

Treatment for a ruptured brain aneurysm is directed at stopping the bleeding as quickly as possible (endovascular embolization), repairing the damaged artery if possible (coiling), and preventing future hemorrhage (cortical-subcortical bypass). Treatment for abdominal aortic aneurysms may involve open surgical repair, endovascular therapy, or watchful waiting. Treatment for thoracic aortic aneurysms includes watchful waiting unless the aneurysm is growing or causing symptoms.



What are the complications of aneurysms?

Aneurysms can enlarge or rupture, which may cause severe bleeding in your brain (subarachnoid hemorrhage) or forces that damage other body organs and tissues, including your heart, stomach, intestines, kidneys, and spine. Ruptures are more likely to occur if you have a tightness in your chest that doesn't go away or other symptoms such as difficulty breathing. The tear in the aorta is called a dissecting aneurysm. It may be fatal if not treated with surgery within 24 hours of its rupturing.



What are the outcomes of aneurysms?

The outcome varies depending on the type and location of your aneurysm, whether it's ruptured and what treatment you choose. With prompt diagnosis and appropriate treatment, you can expect a full recovery or significant improvement in symptoms. A complete neurological examination may be required to further assess nerve function and document any deficits that were present before surgery. People with severe brain injury from a ruptured aneurysm may remain in a coma or vegetative state requiring extensive support from family members and health care providers throughout their lives. Sudden cardiac arrest caused by severe rupture of a thoracic aortic aneurysm remains fatal in most cases. Prompt surgical repair of an abdominal aortic aneurysm can reduce the risk of death by about 50 percent.


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.


Facts 

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.