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Uncontrollable risk factors include:
- • Age: People of all ages, including children, have strokes. But the older you are, the greater your risk of stroke.
- • Gender: Stroke is more common in men than in women.
- • Heredity and race: There is a greater risk of stroke if a parent, grandparent, sister or brother has had a stroke. Blacks have a much higher risk of death from a stroke than Caucasians do, partly because they are more prone to having high blood pressure, diabetes and obesity.
- • Prior stroke or heart attack: Those who have had a stroke are at much higher risk of having another one. Those who have had a heart attack are also at higher risk of having a stroke.
Carotid Stenosis
The carotid arteries supply oxygen-rich blood to the brain. Plaque forms when the internal carotid arteries become blocked by fat and cholesterol buildup. This process is called atherosclerosis. Severe blockage is called carotid stenosis. Carotid stenosis may cause a TIA.
Carotid stenosis is frequently asymptomatic. A doctor may detect it through an abnormal sound called a bruit (BROO'e) when listening to the carotid arteries with a stethoscope. Patients usually first undergo a thorough physical examination. This examination can reveal specific neurological, motor and sensory deficits that can provide clues about both the extent and location of the blockage. If the physician suspects stenosis, diagnostic tests such as Doppler ultrasound, carotid duplex or cerebral angiography will be recommended.
Medical Treatment
Treatment is determined by the extent of the narrowing and the condition of the patient. For many people with arteries narrowed less than 50 percent, medication is prescribed to help reduce the risk of ischemic stroke. These include antihypertensives to control high blood pressure, medications to reduce cholesterol levels, and anticoagulants to thin blood and prevent it from clotting.
Surgery
Carotid endarterectomy is a procedure in which the neurosurgeon makes an incision in the carotid artery and removes the plaque using a dissecting tool. Removing the plaque is accomplished by widening the passageway, which helps to restore normal blood flow. The artery will be repaired with sutures or a graft. The entire procedure usually takes about two hours. The patient may experience pain near the incision in the neck and some difficulty swallowing during the first few days after surgery. Most patients are able to go home after one or two days and return to work, usually within a month. Avoid driving and limit physical activities for a few weeks after surgery.
Carotid Angioplasty and Stenting
An alternative, new form of treatment, carotid angioplasty and stenting, shows some promise in patients who may be at too high risk to undergo surgery. Carotid stenting is a procedure in which a tiny, slender metal-mesh tube is fitted inside your carotid artery to increase the flow of blood blocked by plaques. The stent is inserted following a procedure called angioplasty, in which the doctor guides a balloon-tipped catheter into the blocked artery. The balloon is inflated and pressed against the plaque, flattening it and re-opening the artery. The stent acts as scaffolding to prevent the artery from collapsing or from closing up again after the procedure is completed.
Cerebral Aneurysms
A cerebral (or cranial) aneurysm is an area where a blood vessel in the brain weakens, resulting in a bulging or ballooning out of part of the vessel wall. Usually, aneurysms develop at the point where a blood vessel branches, because the "fork" is structurally more vulnerable. The disorder may result from congenital defects or from other conditions such as high blood pressure, atherosclerosis (the buildup of fatty deposits in the arteries) or head trauma.
Aneurysms occur in all age groups, but the incidence increases steadily for individuals age 25 and older, is most prevalent in people ages 50 to 60 and is about three times more prevalent in women. The outcome for patients treated before a ruptured aneurysm is much better than for those treated after, so the need for adequate evaluation of patients suspected of having a cerebral aneurysm is very important.
Unruptured cerebral aneurysms can be detected by noninvasive measures, including MRA and a carotid angiogram. A rupture can be detected by a CT scan or lumbar puncture. If these tests suggest the presence of an aneurysm, formal cerebral angiography may be performed.
People who suffer a ruptured brain aneurysm may have some or all of these warning signs: localized headache, nausea and vomiting, stiff neck, blurred or double vision, sensitivity to light (photophobia), or loss of sensation. Many people with unruptured brain aneurysms have no symptoms. Others might experience some or all of the following symptoms, which may be possible signs of an aneurysm: cranial nerve palsy, dilated pupils, double vision, pain above and behind eye and localized headache.
When cerebral aneurysms rupture, they usually cause bleeding in the brain, resulting in a subarachnoid hemorrhage. Blood can also leak into the cerebrospinal fluid (CSF) or areas surrounding the brain and cause an intracranial hematoma (a blood clot). Blood can irritate, damage or destroy nearby brain cells. This may cause problems with bodily functions or mental skills. In more serious cases, the bleeding may cause brain damage, paralysis or coma. Ruptured brain aneurysms are fatal in about 50 percent of cases.
Surgery
An operation to "clip" the aneurysm is performed by doing a craniotomy (opening the skull surgically), and isolating the aneurysm from the bloodstream using one or more clips, which allows it to deflate. Surgical repair of cerebral aneurysms is not possible if they are located in unreachable parts of the brain. Angiography is used to visualize closure of the aneurysm and preserve normal flow of blood in the brain.
A less invasive technique which does not require an operation, called endovascular therapy, uses micro catheters to deliver coils to the site of the enlarged blood vessel that occludes (closes up) the aneurysm from inside the blood vessel. A procedure called balloon assisted coiling uses a tiny balloon catheter to help hold the coil in place. A procedure called combination stent and coiling utilizes a small flexible cylindrical mesh tube that provides a scaffold for the coiling. Aneurysms may be treated with endovascular techniques when the risk of surgery is too high.
While the best method of securing the aneurysm should be made on an individual basis, in general, patients with a ruptured cerebral aneurysm should be treated as soon as possible. Surgical risks and outcomes depend on whether or not the aneurysm has ruptured, the size and location of the aneurysm and the patient’s age and overall health.
Postsurgical complications can include vasospasm and hydrocephalus. Vasospasm is a sudden constriction of a blood vessel that reduces the blood flow. Hydrocephalus is a condition in which excess cerebrospinal fluid (CSF) builds up within the ventricles (fluid-containing cavities) of the brain and may increase pressure within the head.
Vascular Malformations
The term vascular malformation refers to an abnormal connection of an artery, vein or both. These include malformations of normal veins or arteries leading directly to veins. Vascular malformations are formed as the blood vessels in the brain develop during pregnancy, but the direct cause is unknown.
Arteriovenous malformations (AVMs)
An AVM is a tangle of abnormal and poorly formed blood vessels (arteries and veins), with a higher rate of bleeding than normal vessels. AVMs can occur anywhere in the body, but brain AVMs present substantial risks when they bleed. Dural AVMs occur in the covering of the brain, and are an acquired disorder that may be triggered by an injury.
AVMs are usually diagnosed through a combination of MRI and angiography. AVMs can irritate the surrounding brain and cause seizures or headaches. Left untreated, AVMs can enlarge and rupture, causing intracerebral or subarachnoid hemorrhage and permanent brain damage. Every year, about four out of every 100 people with an AVM will experience a hemorrhage. Preventing the rupture of vascular malformations is one of the major reasons that early neurosurgical treatment is recommended for AVMs.
A treatment plan is devised to offer the lowest risk, yet highest chance of obliterating the lesion. The three types of treatment available include direct removal using microsurgical techniques, stereotactic radiosurgery and embolization using neuroendovascular techniques. Although microsurgical treatment affords the opportunity for immediate removal of the AVM, some AVMs may best be treated by a combination of therapies.
Stereotactic radiosurgery is a minimally invasive treatment that uses computer guidance to concentrate radiation to the malformed vessels of the brain. This radiation causes abnormal vessels to close off. Unfortunately, stereotactic radiosurgery is usually limited to lesions less than 3.5 cm in diameter and may take up to two years to completely obliterate the lesion.
Embolization uses neuroendovascular techniques to guide tiny catheters into the small cerebral vessels of the brain that feed the AVM. Once the catheter reaches the core of the AVM, liquid glue or particles can be injected to occlude portions of the AVM or its feeding arteries. Neuroendovascular therapy can make subsequent surgical removal of an AVM safer or can reduce the size of an AVM to a volume in which radiosurgery offers a higher efficacy.
Moyamoya disease
Moyamoya disease is a progressive disease of the carotid arteries and their major branches that can lead to irreversible blockage. The name comes from the Japanese word for a "puff of smoke" due to the appearance of the lesions that form. In fact, it affects people of Japanese origin far more commonly than the rest of the population. It is a disease that tends to affect children and adults in the third to fourth decades of life. Children with the disease may have strokes, TIAs, slowly progressive cognitive decline, seizures or involuntary movements of the extremities. Adults more commonly experience intracranial hemorrhages as a result of the disease.
There are several surgeries that have been developed for the condition, but currently the most favored are EDAS, EMS, STA-MCA and multiple burr holes.
The EDAS (encephaloduroarteriosynangiosis) procedure requires dissecting a scalp artery over a length of several inches and then making a small temporary opening in the skull directly beneath the artery. The artery is then sutured to the surface of the brain and the bone replaced.
In EMS (encephalomyosynangiosis) surgery, the temporalis muscle, which is in the temple region of the forehead, is dissected and through an opening in the skull, placed onto the surface of the brain.
Other operations include the STA-MCA (superficial temporal artery-middle cerebral artery), in which a scalp artery is directly sutured to a brain surface artery, and a procedure in which multiple small holes (burr holes) are placed in the skull to allow for growth of new vessels into the brain from the scalp.
Venous angiomas
Patients with venous angiomas may have headaches or seizures, although these symptoms may be unrelated to the angiomas. More commonly, these lesions are asymptomatic and are identified when patients are being evaluated for other conditions. They rarely bleed, so treatment is usually not necessary. They affect approximately 2 percent of the general population.
Vein of Galen malformation (VGM)
A far rarer malformation is the VGM, sometimes detected in prenatal testing, or through heart failure in infants. Occurring during embryonic development, a VGM is an abnormal connection between arteries and the deep draining veins of the brain. Under normal conditions, these arteries and veins are connected by capillaries that function to slow blood flow through the brain, allowing for the necessary exchange of oxygen and nutrients.
A VGM has a thicker wall than an AVM and is unlikely to rupture and bleed. However, because a VGM does not have capillaries, the blood may flow extremely fast, putting excessive strain on the heart, which may result in cardiac failure. It is very important that children suffering from this condition be evaluated and diagnosed by experts so that appropriate treatment measures are taken. Embolization is the method of choice for treating patients with VGMs.
Glossary
Aneurysm – An abnormal, balloon-like bulging of the wall of an artery.
Angiogram – A study which shows the blood vessels leading to and in the brain by injecting a dye or contrast substance through a catheter placed in the artery of the leg.
Angiography – Radiography of blood vessels using the injection of material opaque to X-rays, to better define the vessels.
Anticoagulant – Any medicine that keeps blood from clotting; a blood thinner.
Antihypertensive – Any medicine or other therapy that lowers blood pressure.
Arachnoid – Middle layer of membranes covering the brain and spinal cord.
Arteriovenous – Relating to both arteries and veins.
Artery – A blood vessel that carries blood away from the heart to the body.
Atherosclerosis – A disease process that leads to the buildup of fat and cholesterol, called plaque, inside blood vessels.
Brain attack – Another name for stroke.
Bruit – A sound made in the blood vessels resulting from turbulence, perhaps due to a buildup of plaque or damage to the vessels.
Carotid artery – A major artery on the right and left side of the neck supplying blood to the brain.
Cerebral embolism – A blood clot from one part of the body that is carried by the bloodstream to the brain, where it blocks an artery.
Cerebral hemorrhage – Bleeding within the brain resulting from a ruptured blood vessel, aneurysm or head injury.
Cerebral infarction – A stroke caused by interruption or blockage of blood flow to the brain; also called ischemic stroke.
Cerebral thrombosis – Formation of a blood clot in an artery that supplies blood to part of the brain.
Cerebrovascular – Pertaining to the brain and the blood vessels that supply it.
Cerebrovascular occlusion – The blocking or closing up of a blood vessel in the brain.
Endarterectomy – Removal of fatty or cholesterol plaques and calcified deposits from the internal wall of an artery.
Endovascular – Pertaining to a surgical procedure in which a catheter containing medications or miniature instruments is inserted through the skin into a blood vessel for the treatment of vascular disease.
Hydrocephalus – a condition in which excess cerebrospinal fluid (CSF) builds up within the ventricles (fluid-containing cavities) of the brain and may increase pressure within the head.
Ischemia – Inadequate circulation of blood generally due to a blockage of an artery.
Ischemic stroke – A stroke caused by interruption or blockage of blood flow to the brain.
Jugular veins – The veins that carry blood back from the head to the heart.
Plaque – A deposit of fatty (and other) substances in the inner lining of the artery wall, which usually leads to atherosclerosis.
Stent – A device made of expandable, metal mesh that is placed (by using a balloon catheter) at the site of a narrowing artery. The stent is then expanded and left in place to keep the artery open.
Subarachnoid hemorrhage – Blood in, or bleeding into, the space under the arachnoid membrane, most commonly from trauma or from rupture of an aneurysm.
Transient ischemic attack (TIA) – A temporary interruption of the blood supply to an area of the brain; also called a mini-stroke. It usually lasts only a few minutes and causes no permanent damage or disability.
Vasospasm – Spasm of blood vessels which decreases their diameter.