what is an Aneurysm?
An aneurysm is an abnormal outward bulging of the wall of a blood vessel, usually at a weakened section of an artery. They appear to result from a series of events, including stress on the arterial wall from blood pressure. As the blood pulsates against the arterial wall, abnormal blood flow develops which may lead to the development of an aneurysm, usually over a period of several years. An aneurysm may occur in any artery, but is often seen in arteries supplying the brain, which is more specifically called a cerebral aneurysm or an intracranial aneurysm.
Depending on the size and location of the brain aneurysm, they may rupture causing an intracranial hemorrhage or stroke. If the expansion of the aneurysm reaches a point where the wall becomes very thin, it ruptures and bleeds into the space around the brain. This event is called a subarachnoid hemorrhage. This catastrophic event requires immediate and urgent surgical and medical attention. After the first hemorrhage, almost half of patients die before they are able to seek treatment. If the aneurysm is not repaired in time and a second hemorrhage occurs, about 80 percent of patients die. Aneurysms can also cause symptoms by compressing nerves or brain tissue, resulting in pain, vision changes, paralysis or seizures.
symptoms of a cerebral Aneurysm?
Some studies estimate that almost 5% of the general population have an intracranial aneurysm. Many small cerebral aneurysms tend to be completely asymptomatic and patients are never aware of their existence. However, various neurological symptoms can arise when an aneurysm ruptures or when a larger unruptured aneurysm is pressing on the brain or the nerves arising from the brain. In the case of a cerebral aneurysm, the symptoms for an aneurysm that has ruptured and one that has not ruptured can be very different.
Symptoms for an aneurysm that has not ruptured. Any individual experiencing some or all of the following symptoms, regardless of age, should immediately contact a physician for evaluation:
– Dilated or asymmetric pupils
– Blurred or double vision
– Loss of perception
– Loss of balance
– Speech or language problems
Symptoms for a ruptured aneurysm (SAH). Seek medical attention immediately if you are experiencing some or all of these symptoms:
– Loss of consciousness
– Nausea, vomiting
– Sudden blurred or double vision
– Neck pain and/or stiffness
– Pain above and/or behind the eyes
– Sudden trouble walking or dizziness
– Sudden weakness or numbness
– Drooping eyelid
Two quick and safe ways to initially screen for aneurysms include MRI with MRA (Magnetic Resonance Imaging with Angiography) and CT with CTA (Computed Tomography with Angiography). Images that are obtained during these studies will reliably detect aneurysms as small as 2 or 3 mm. MRI is a special radiologic test that takes about half an hour and allows for excellent imaging of the brain and major arteries without using any radiation. In addition, MRA scans can often be done without contrast. CT scans take much less time and expose the patient to minimal levels of radiation. CTA images require the use of intravenous contrast. This is a very fast test that takes only a few minutes to perform and the quality and detail of the images of the blood vessels are excellent. Usually, CTA is reserved as a follow-up study to a MRA study if an aneurysm is detected and there is a need to collect more information on the aneurysm. This additional information allows for a more detailed conversation with the physician regarding the need for treatment and what types of treatment options are available.
*Special Note for MRI with MRA: It might take as long as 40 minutes for a patient to complete one of these studies, and patients who are claustrophobic frequently need to be sedated, as the confines of the machine induce a sense of claustrophobia.
Diagnosis of a ruptured cerebral aneurysm is commonly made by talking with the patient and performing these tests. If the imaging is negative but a ruptured aneurysm is still suspected, a lumbar puncture is performed to detect blood in the cerebrospinal fluid (CSF).
When an aneurysm is suspected, an arteriogram (angiogram) is generally recommended by our physician for diagnosis and treatment planning. An angiogram is a diagnostic study that determines the size and shape of blood vessels in the neck and brain, as well as the pattern of blood flow. A very thin, flexible tube called a catheter is introduced into an artery (usually at the top of the thigh) and then navigated through the blood vessels of the body to the arteries of the neck and eventually the brain. This is performed while using x-rays to see the position of the catheter as it is maneuvered. A liquid solution containing water and iodine salts (“contrast”) is injected so that x-ray images can be seen. This gives a detailed picture of the location, size and shape of the aneurysm or other vascular malformations. Based on this information, your physician will determine the plan and treatment of the findings. At this time, an angiogram is the test that most accurately shows the aneurysm and its relationship to the surrounding arteries and veins.
There are several options for managing unruptured intracranial aneurysms. The aneurysm can be treated via either an open surgical or endovascular approaches. An alternative is close observation in combination with control of risk factors, including smoking and blood pressure. Once an aneurysm has already ruptured, treatment of the aneurysm is recommended due to the possibility of re-rupture and the associated high mortality rates. They can be treated from outside the blood vessel, using open surgical techniques and placing a metal clip across the aneurysm, or from inside the blood vessel using endovascular techniques to fill the aneurysm with metal coils. Either should be performed as early as possible after hemorrhage to prevent rebleed of the aneurysm. The goal of either treatment is to seal off the aneurysm with either a clip or coils to prevent blood from filling the aneurysm.
Doctors consider several factors when deciding which treatment option is best for a particular patient. These include:
– Size of aneurysm
– Location of aneurysm
– Number of aneurysms
– Neurological condition of patient
– Other medical conditions
– Previous history of SAH or familial aneurysm
Aneurysm coiling: Aneurysm coiling is a minimally invasive procedure whereby metal coils are inserted within the aneurysm to induce clot formation to fill the aneurysm and prevent blood filling the aneurysm. Coiling is performed by neurosurgeons, neurologists, or neuroradiologists who are trained in endovascular techniques. This procedure is performed in an angiography suite and involves the assistance of an anesthesiologist. Endovascular treatment (embolization or coiling) is achieved with a catheter, similar to that used in the angiogram. The catheter is inserted into the femoral artery in the thigh and slowly maneuvered up to the blood vessels in the head under X-ray guidance to the site of the aneurysm.The goal of the procedure is to pack the aneurysm as completely as possible with material (coils) that will not allow blood to flow into the aneurysm. Materials used in this procedure are MRI-compatible coils made of platinum. Assisted techniques such as balloon remodeling and placement of small intracranial stents are also used for selected intracranial aneurysms.
Patients return for a follow-up angiogram at 6 months and one year after treatment to ensure the aneurysm remains completely occluded and has not enlarged. Overall, aneurysms need additional coils about 20% of the time.
Aneurysm clipping: The surgical approach (craniotomy for clipping of aneurysm) requires creating an opening in the skull through which allows the surgeon to place a metal clip across the neck of the aneurysm, preventing arterial blood from entering it. Clipping of aneurysms is performed by a neurosurgeon in an operating room and involves the assistance of an anesthesiologist.
Treatment of Vasospasm: Vasospasm is a condition in which the blood vessels spasm, leading to vasoconstriction. The blood from the initial hemorrhage irritates the muscle surrounding the arteries and causes them to constrict, which can impair blood flow to the brain and cause a stroke. Symptomatic vasospasm is a major contributor to post-operative stroke and death, especially after subarachnoid hemorrhage. Vasospasm typically appears 4 to 10 days after subarachnoid hemorrhage. For this procedure, the endovascular surgeon places a small micro catheter at the area of the spasm, and injects vasodilating medications to help open the blood vessels. Occasionally the spasm is so severe that angioplasty using a small balloon is needed to open the artery. The goal is to increase the blood flow to the brain and prevent stroke.
It is important to understand that the neither the open surgical or endovascular treatments repair the areas of the brain already injured by stroke or hemorrhage. The goal of these surgeries is to treat the aneurysm and prevent re-bleeding. Patients with SAH are in the hospital for several weeks to treat the vasospasm and other medical conditions associated with a hemorrhage.
risk factors & statistics
Risk factors shown to contribute to the formation and rupture of brain aneurysms include:
– Tobacco use
Other possible risk factors include:
– Drug use (particularly cocaine)
– High cholesterol and copper deficiency
– Age over 40
– Women are more likely than men to suffer from brain aneurysms, at a ratio of 3:2
– Other inherited disorders: Ehlers-Danlos Syndrome, Polycystic Kidney Disease, and Marfan Syndrome
– Presence of an AVM
Facts & Statistics
– 10-15% of patients diagnosed with a brain aneurysm will harbor more than one aneurysm.
– Ruptured brain aneurysms account for 3-5% of all new strokes.
– There are almost 500,000 deaths worldwide each year caused by brain aneurysms and half the victims are younger than 50.