Blood to the brain is supplied by four major blood vessels that join together at the Circle of Willis at the base of the brain. Smaller branch arteries leave the circle to supply brain cells with oxygen and nutrients. Artery junction points may become weak, causing ballooning of the blood vessel wall that can form a small sac or aneurysm. Cerebral aneurysms are common, but most are asymptomatic and are found incidentally at autopsy. Aneurysms can leak or rupture causing symptoms from severe headache to stroke-like symptoms, or death. The health care practitioner needs to maintain a high incidence of suspicion to make the diagnosis, since many patients may have an initial small leak of blood causing symptoms before a catastrophic bleed occurs. Diagnosis of a brain aneurysm may require CT scans, lumbar puncture, or angiography. Treatment to repair the aneurysm may involve neurosurgery to put a clip across the weak blood vessel wall or clipping by interventional radiology.
The Circle of Willis is the junction of the four many arteries that supply the brain with nutrition (oxygen and glucose) two carotid arteries and two vertebral arteries. This loop of arteries is located at the base of the brain and sends out smaller branch arteries to all parts of the brain. The junctions where these arteries come together may develop weak spots. These weak spots can balloon out and fill with blood, creating the outpouchings of blood vessels known as aneurysms. These sac- like areas may leak or rupture, spilling blood into surrounding tissues.
The most common types of aneurysms involve the aorta, the large vessel that carries oxygen-containing blood away from the heart. In particular, aneurysms most commonly develop in the abdominal portion of the aorta and are designated abdominal aortic aneurysms. Abdominal aortic aneurysms are most common in men over the age of 60. Most aortic aneurysms are caused by atherosclerosis ("hardening of the arteries") since this condition can weaken the walls of the aorta and lead to thinning and widening of the affected areas. Another type of aneurysm is a brain aneurysm. Brain aneurysms are widened areas of arteries or veins within the brain itself. A special type of brain aneurysm is known as a berry aneurysm. Berry aneurysms are small, berry-shaped outpouchings of the main arteries that supply the brain and are particularly dangerous since they are susceptible to rupture, leading to often fatal bleeding within the brain. Brain aneurysms can occur at any age but are more common in adults.
high blood pressure atherosclerosis trauma heredity abnormal blood flow at the junction where arteries come together. smokingThere are other rare causes of aneurysms. Mycotic aneurysms are caused by infections of the artery wall Tumors and trauma can also cause aneurysms to form Drug abuse, especially cocaine, can cause the artery walls to inflame and weaken.
Brain aneurysms (aneurysms within arteries in the brain)are a common occurrence. At autopsy, incidentalasymptomatic aneurysms are found in more than 1% ofpeople. Most aneurysms remain small and never become anissue or are diagnosed. Some, however, may graduallybecome larger and exert pressure on surrounding braintissue and nerves and may be diagnosed because ofsymptoms such as: headache numbness weakness of one side of the face a dilated pupil or change in vision.The greater concern is a brain aneurysm that leaks orruptures, and potentially causes stroke or death. Bleeding leaks into one of the membranes that covers the brain and spinal canal and is known as a subarachnoid hemorrhage (sub= beneath + arachnoid=one of the brain coverings + hemorrhage=bleeding).
The headache associated with a leaking aneurysm is severe. Blood is very irritating to the brain and causes significant pain. Patients may describe the "worst headache of their life," The headache may be associated with nausea, vomiting, and change in vision. a subarachnoid hemorrhage also causes pain and stiffness of the neck seizures.
The diagnosis of brain aneurysm begins with a highindex of suspicion by the health carepractitioner. The history of the headache, an acuteonset of the worst headache of the patients life,associated with a stiff neck and an ill-appearingpatient on physical examination, typically lead thehealth care practitioner to order a CT (computerized tomography) scan of the head. This will show a subarachnoid hemorrhage in more than 90% of cases of ruptured aneurysm. In the few cases that are not recognized by CT, the health care practitioner may consider performing a lumbar puncture (LP, or spinal tap) to identify blood in the cerebrospinal fluid that runs in the subarachnoid space.
If the CT or the LP reveals the presence of blood, angiography is performed to identify where the aneurysm is located and to plan treatment. Angiography (angio=artery +graphy= picture) is a procedure in which a small flexible tube is threaded into one of the brains arteries, and dye is injected while pictures are taken. Newer technology allows angiography to be done in association with CT or magnetic resonance imaging (MRI). Magnetic resonance angiography (MRA). Similar to a CTA, MRA uses a magnetic field and pulses of radio wave energy to provide pictures of blood vessels inside the body. As with CTA and cerebral angiography, a dye is often used during MRA to make blood vessels show up more clearly.
Migraine headache, meningitis, tumor, and stroke all may cause neurologic symptoms. Based on the patients presentation, the healthcare practitioner will needto decide which tests andstudies to use to establish the correct diagnosis.
Surgical Clipping: A neurosurgeon can operate on the brain by cutting open the skull, identifying the damaged blood vessel and putting a clip across the aneurysm. This prevents blood from entering the aneurysm and causing further growth or blood leakage. Coil Embolization: A neurosurgeon or interventional radiologist can thread a tube through the arteries, as with an angiogram, identify the aneurysm, and fill it with coils of platinum wire or with latex. This prevents further blood from entering the aneurysm and resolves the problem. This procedure is less invasive and is believed to be safer than surgical clipping, although it may not be as effective at reducing the risk of a later rupture. It should be done in a large hospital where many such procedures are done.
Prior, during, and after surgery, attention is paid to protect the brain and its blood vessels from potential further damage. vitals signs are monitored frequently heart monitors are used to watch for abnormal heart rhythms. medications may be used to prevent blood vessel spasm, seizure, agitation, and pain.
Brain aneurysms are deadly. About 10% of patientswith a ruptured aneurysm die before receiving medical care. If untreated, another 50% will die within a month, with 25% of patients sustaining another bleeding episode within a week. Aside from the bleeding issues, there is significant risk of artery spasm leading to stroke.Survival rates are increased by early presentation to the hospital, early aneurysm repair, and control of potential blood vessel spasm with medications.