Definition and Overview

Ischemic stroke occurs when an artery that carries oxygen and nutrients to the brain is blocked. There are two types of ischemic stroke: thrombotic and embolic. The former, which accounts for almost 50% of all strokes, occurs when cerebral arteries are blocked by blood clots that formed in the brain. Embolic stroke, on the other hand, is caused by blood clots that formed somewhere in the body (often from the heart), traveled through the bloodstream, and got stuck in cerebral arteries. The blood clot restricts the flow of blood to the brain. Without an adequate supply of oxygen and nutrients, the brain cells will eventually stop working. Unless blood flow to the brain is restored, the brain cells will start to die in a matter of minutes.

Ischemic stroke is the most common kind of stroke, accounting for approximately 88% of all stroke cases. The condition commonly affects people 60 years and older particularly those who have high blood pressure, diabetes, heart disease, and are smoking.

Every year, nearly 800,000 people in the United States suffer from stroke and about 130,000 of them die from it. It is the number five most common cause of death in the country and the leading cause of long-term disability.

Causes of Condition

Ischemic stroke occurs when the arteries that supply blood to the brain are blocked. This can be caused by:

  • Emboli or thrombus (blood clots)

  • Atherosclerosis - A condition where arteries are narrowed due to plaque buildup. When a huge amount of plaque collects in one spot, it is often enough to prevent the blood from flowing through. Atherosclerosis can develop in other arteries other than those leading to the brain. If it develops in coronary arteries, or those that supply blood to the heart, the condition can lead to a heart attack.

The major risk factors for an ischemic stroke are:

  • Age - The risk of stroke increases after age 55

  • Atrial fibrillation

  • Diabetes

  • Diet rich in cholesterol, sodium, sugar, or trans or saturated fats

  • High bad cholesterol or low good cholesterol levels

  • High blood pressure

  • History of transient ischemic attack (TIA) or a mini-stroke

  • Obesity or being overweight

  • Sedentary lifestyle

  • Smoking

Key Symptoms

An ischemic stroke causes a part of the brain to stop functioning, which leads to the sudden onset of the following signs and symptoms:

  • Numbness or weakness of one side of the body

  • Facial drooping or paralysis

  • Sudden mental confusion and trouble speaking or understanding

  • Loss of coordination or balance

  • Sudden vision problems

  • Sudden severe headaches

  • Trouble walking or falling without a cause

Who to See and Types of Treatments Available

It is crucial for patients showing signs and symptoms of ischemic stroke to receive emergency care. With this condition, every minute counts because the longer the brain is left without oxygen, the higher is the risk of life-changing complications or death.

To diagnose the condition and determine the best course of treatment, doctors usually order the following diagnostic tests:

  • Computed tomography (CT) and magnetic resonance imaging (MRI) scans - These imaging tests are used to view the brain, skull, and spinal cord to assess the condition and its severity. The tests can be used to diagnose not just ischemic stroke but also haemorrhagic stroke and other problems that affect the brain and brain stem.

  • Carotid Doppler - A test used to obtain detailed pictures of the carotid arteries in the neck to check if the blood flow in the artery is interrupted or blocked.

  • Transcranial Doppler - Measures the velocity of blood flow through the brain’s blood vessels using ultrasound waves.

  • Magnetic resonance angiogram (MRA) - A special type of MRI scan used to assess the condition of the blood vessels in the brain and neck.

  • Cerebral arteriogram - Performed by injecting a special dye into the blood vessels leading to the brain, which shows in x-ray images. This test produces more accurate results when compared to an MRA.

  • Neurologic tests, which may include electroencephalogram, lumbar puncture, a nerve conduction test, and brain biopsy.

Treatment

Doctors usually inject patients with tissue plasminogen activator (tPA) as soon as possible. For better outcomes, the drug, which is approved by the US FDA for the treatment of acute ischemic stroke, must be given within four hours after the symptoms first started. The drug works by dissolving the blood clot so normal blood flow to the brain is restored.

Once the patient is stable or the blood flow to the brain has normalised, doctors may perform a surgical procedure called carotid endarterectomy to remove fatty deposits in carotid arteries.

The procedure can be performed under general, regional, or local anaesthesia and it takes about one to two hours. It involves making a small cut on the skin directly above the blocked or narrowed carotid artery. The vascular surgeon then opens up the narrowed artery to remove the plaque that has built up inside it. Both the artery and the incision are then sutured closed.

Carotid endarterectomy offers the long-term benefit of reduced risk of developing a stroke. However, it comes with risks and possible complications, including postoperative bleeding, perioperative stroke, myocardial infarction, nerve injury, carotid stenosis, and infection, among others.

Although its mortality rate is slowly declining, stroke remains to be one of the leading causes of death across the globe and the leading cause of long-term disability. Around 60% of stroke survivors suffer from:

  • Physical problems, including difficulty walking

  • Cognitive problems

  • Depression

  • Communication problems

  • Emotional problems, such as anxiety, anger, and frustration

  • Visual problems

References:

  • Vascular and Interventional Radiology: The Requisites (2nd Edition), John A. Kaufman & Michael J. Lee, Publisher:Elsevier - Active as of 11/13/2014

  • Sims N.R.; Muyderman H. (2010). “Mitochondria, oxidative metabolism and cell death in stroke”. Biochimica et Biophysica Acta. 1802 (1): 80–91. PMID 19751827. doi:10.1016/j.bbadis.2009.09.003.

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