Cerebrovascular Accident (Stroke)

What is Cerebrovascular Accident ?

Also known as stroke, cerebrovascular accident (CVA) is a sudden impairment of cerebral circulation in one or more of the blood vessels supplying the brain. CVA interrupts or diminishes oxygen supply and commonly causes serious damage or necrosis in brain tissues. The sooner circulation returns to normal after CVA, the better chances are for complete recovery. About half of those who survive CVA remain permanently disabled and experience a recurrence within weeks, months, or years.

CVA is the third most common cause of death in the United States today and the most common cause of neurologic disability. It afflicts 500,000 persons each year; half of them die as a result. Although it mostly affects older adults, it can occur in people of any age and is most common in men, especially blacks.

CVAs are classified according to their course of progression. The least severe is the transient ischemic attack (TlA), which results from a temporary interruption of blood flow, most often in the carotid and vertebrobasilar arteries.

Causes of Cerebrovascular Accident

Stroke occurs when blood flow to a region of the brain is obstructed, causing brain tissue death. Ischemic stroke is usually caused by a blood clot in an artery that supplies blood to the brain. Introduction of a foreign substance into the bloodstream may also cause ischemic stroke. For example, an air embolism may occur in deep-sea divers who surface too quickly or may be introduced during intravenous injection.

Hemorrhagic stroke is caused by ruptured blood vessel (aneurysm), arteriovenous malformation (AVM, blood vessel defect), tumor, or traumatic brain injury.

Signs & Symptoms of Cerebrovascular Accident

Symptoms of stroke develop suddenly. Symptoms of a stroke depend on the area of the brain affected. The most common symptom is weakness or paralysis of one side of the body with partial or complete loss of voluntary movement or sensation in a leg or arm. There can be speech problems and weak face muscles, causing drooling. Numbness or tingling is very common. A stroke involving the base of the brain can affect balance, vision, swallowing, breathing and even unconsciousness. In cases of severe brain damage there may be deep coma, paralysis of one side of the body, and loss of speech, followed by death or permanent neurological disturbances after recovery.

Diagnostic Tests

Magnetic resonance imaging (MRI) and magnetic resonance angiography allow evaluation of the lesion's location and size without exposing the patient to radiation. MRI doesn't distinguish hemorrhage, tumor and infarction as well as computed tomography (IT scanning, but it provides superior images of the cerebellum and the brain stem.

CT scanning - This technique is usually the first test done when a patient comes to a hospital emergency room with stroke symptoms. The test uses low-dose X-rays to show an image of the brain and it can determine whether a stroke is caused by a blockage or a bleed, and the size and location of the stroke. The test is painless.

2-D echocardiogram evaluates the heart for dysfunction and provides information on etiology of a stroke.

Carotid Ultrasound - This test is conducted without entering the body and it evaluates the blood flow of the carotid arteries. Gel is used on the skin to send an ultrasound signal and a computer can calculate how fast the blood is traveling. This helps doctors determine how narrow an artery has become.

Angiogram involves injecting a contrast agent (dye) into the bloodstream and taking a series of x-rays of blood vessels. This test is used to identify the source and location of arterial blockage and to detect aneurysms and blood vessel defects.

Ophthalmoscopy may show signs of hypertension and atherosclerotic changes in the retinal arteries.

EEG may show reduced electrical activity in an area of cortical infarction. This test is especially useful when CT scan results are inconclusive. It can also differentiate seizure activity from CVA.

Oculoplethysmography indirectly measures ophthalmic blood flow and carotid artery blood flow.

Treatment

Treatment should include careful blood pressure management. Labetalol is the pressor of choice to regulate blood pressure. Blood pressure that is too low increases ischemia; blood pressure that is too high increases risk of hemorrhage. Tissue plasminogen activator may be used in emergency care of the patient within 3 hours of onset of the symptoms. Thrombolytic agents are a consideration if there is a sign of hemorrhage on CT, if there are no other contraindications, and if it is begun in a timely fashion.

Medical management of CVA commonly includes physical rehabilitation, dietary and drug regimens to help decrease risk factors, possibly surgery, and care measures to help the patient adapt to specific deficits, such as speech impairment and paralysis.

Depending on the cause and extent of the CVA, the patient may undergo a craniotomy to remove a hematoma, endarterectomy to remove atherosclerotic plaques from the inner arterial wall, or extracranialintracranial bypass to circumvent an artery that is blocked by occlusion or stenosis. Ventricular shunts may be necessary to drain cerebrospinal fluid.

Medications useful in CVA include:

• anticonvulsants, such as phenytoin or phenobarbital, to treat or prevent seizures
• stool softeners to avoid straining, which increases intracranial pressure (lCP)
• anticoagulants, such as heparin, warfarin, Plavix, and ticlopidine, to reduce the risk of thrombotic stroke
• analgesics such as codeine to relieve headache that may follow hemorrhagic CVA. Usually, aspirin is contraindicated in hemorrhagic CVA because it increases bleeding tendencies, but it may be useful in preventing TIAs.

Prevention Tips

• Quit smoking.
• Lose weight if you are overweight.
• Treat high blood pressure, diabetes, high cholesterol, and heart disease if present.
• Manage stress
• Avoid excessive alcohol
• Follow a low-fat diet.
• Exercise regularly.
• Wear protective helmets when engaging in contact sports, horseback riding, or riding bicycles.