Stroke is an abrupt interruption of constant blood flow to the brain that causes loss of neurological function. The interruption of blood flow can be caused by a blockage, leading to the more common ischemic stroke, or by bleeding in the brain, leading to the more deadly hemorrhagic stroke. Ischemic stroke constitutes an estimated 87 percent of all stroke cases. Stroke often occurs with little or no warning, and the results can be devastating.

It is crucial that proper blood flow and oxygen be restored to the brain as soon as possible. Without oxygen and important nutrients, the affected brain cells are either damaged or die within a few minutes. Once brain cells die, they generally do not regenerate, and devastating damage may occur, sometimes resulting in physical, cognitive, and mental disabilities.

Ischemic Stroke

• Thrombotic (cerebral thrombosis) is the most common type of ischemic stroke. A blood clot forms inside a diseased or damaged artery in the brain resulting from atherosclerosis (cholesterol-containing deposits called plaque), blocking blood flow.
• Embolic (cerebral embolism) is caused when a clot or a small piece of plaque formed in one of the arteries leading to the brain or in the heart, is pushed through the bloodstream and lodges in narrower brain arteries. The blood supply is cut off from the brain due to the clogged vessel.

Transient ischemic attack (TIA)

This is a warning sign of a possible future stroke, and is treated as a neurological emergency. Common temporary symptoms include difficulty speaking or understanding others, loss or blurring of vision in one eye, and loss of strength or numbness in an arm or leg. Usually these symptoms resolve in less than 10 to 20 minutes, and almost always within one hour. Even if all the symptoms resolve, it is very important that anyone experiencing these symptoms call emergency room and immediately be evaluated by a qualified physician.

Hemorrhagic Stroke

• Subarachnoid Hemorrhage: bleeding that occurs in the space between the surface of them brain and the skull. A common cause of subarachnoid hemorrhagic stroke is a ruptured cerebral aneurysm, an area where a blood vessel in the brain weakens, resulting in a bulging or ballooning out of part of the vessel wall; or the rupture of an arteriovenous malformation, a tangle of abnormal and poorly formed blood vessels (arteries and veins), with an innate propensity to bleed.
• Intracerebral Hemorrhage: bleeding that occurs within the brain tissue. Many intracerebral hemorrhages are due to changes in the arteries caused by long-term hypertension. Other potential causes may be delineated through testing.

Risk Factors

Although they are more common in older adults, strokes can occur at any age. Understanding the factors that increase your risk of a stroke and recognizing the symptoms may help you prevent a stroke. Receiving early diagnosis and treatment may improve your chances for complete recovery.

Controllable or treatable risk factors for stroke include:

• Smoking: You can decrease your risk by quitting smoking.
• High blood pressure: Blood pressure of 140/90 mm Hg or higher is the most important risk factor for stroke.
• Carotid or other artery disease: The carotid arteries in your neck supply blood to your brain. A carotid artery narrowed by fatty deposits from atherosclerosis (plaque buildups in artery walls) may become blocked by a blood clot.
• History of TIAs: About 30 percent of strokes are preceded by one or more TIAs that can occur days, weeks or even months before a stroke.
• Diabetes: It is crucial to control your blood sugar levels, blood pressure, and cholesterol levels. Diabetes, especially when untreated, puts you at greater risk of stroke and has many other serious health implications.
• High blood cholesterol: A high level of total cholesterol in the blood (240 mg/dL or higher) is a major risk factor for heart disease, which raises your risk of stroke. Recent studies show that high levels of LDL (bad) cholesterol (greater than 100 mg/dL) and triglycerides(blood fats, 150 mg/dL or higher) increase the risk of stroke in people with previous coronary heart disease, ischemic stroke or TIAs. You can often improve your cholesterol levels by decreasing the salt and saturated fat in your diet.
• Physical inactivity and obesity: Being inactive, obese or both can increase your risk of high blood pressure, high blood cholesterol, diabetes, heart disease and stroke. Getting 30 minutes of moderate exercise, five days a week can help reduce your risk of stroke. Check with your doctor first before starting any exercise program if you have any health problems or have been inactive.
• Recent research shows evidence that people receiving hormone replacement therapy (HRT) have an overall 29 percent increased risk of stroke, in particular ischemic stroke.

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. However, women account for more than half of all stroke deaths. Women who are pregnant have a higher stroke risk.
• Heredity and race: You have a greater risk of stroke if a parent, grandparent, sister or brother has had a stroke.
• Prior stroke or heart attack: If you have had a stroke, you are at much higher risk of having another one. If you have had a heart attack, you are also at higher risk of having a stroke.

Stroke Symptoms

The range and severity of early stroke symptoms vary considerably, but they share the common characteristic of being sudden. Warning signs may include some or all of the following symptoms:

• Dizziness, nausea, or vomiting
• Unusually severe headache
• Confusion, disorientation or memory loss
• Numbness, weakness in an arm, leg or the face, especially on one side
• Abnormal or slurred speech
• Difficulty with comprehension
• Loss of vision or difficulty seeing
• Loss of balance, coordination, or the ability to walk
• It is especially important to note that many strokes may cause an utterly painless loss of neurological function, leading to potential hesitation to call 911 or visit an emergency room.

Stroke Effects

The effects of a stroke depend primarily on the location of the obstruction and the extent of brain tissue affected. One side of the brain controls the opposite side of the body, so a stroke affecting the right side will result in neurological complications on the left side of the body. A stroke on the right side may result in the following:

• Paralysis on the left side of the body
• Vision problems
• Quick, inquisitive or purposeless behavior
• Memory loss

A stroke on the left side may result in the following:

• Paralysis on the right side of the body
• Speech/language problems
• Slow, cautious behavior
• Memory loss

Stroke Treatment

Rehabilitation following a stroke may involve a number of medical specialists; but the early diagnosis of a stroke, its treatment or its prevention, can be undertaken by a neurosurgeon. Rapid and accurate diagnosis of the kind of stroke and the exact location of its damage is critical to successful treatment.

Ischemic Stroke Treatment

Ischemic stroke is treated by removing obstruction and restoring blood flow to the brain. The only FDA-approved medication for ischemic stroke is tissue plasminogen activator (tPA), which must be administered within a three-hour window from the onset of symptoms to work best. This medication carries a risk for increased intracranial hemorrhage and is not used for hemorrhagic stroke.

Medical Prevention

Medications used to help prevent stroke in high-risk patients (especially those who have experienced a previous TIA or ischemic stroke) fall into two major categories; anticoagulants and antiplatelet agents.

Anticoagulants thin the blood and prevent clotting. Heparin acts quickly and is given intravenously (through a vein) or subcutaneously (beneath the skin) while a patient is in the hospital. Slower-acting warfarin can be given orally and is used over a longer period. Because these drugs affect the blood’s ability to clot, they require close monitoring by a physician.

Antiplatelet drugs prevent platelet aggregation. Platelets are specialized cells in the blood that initiate a healing process. Large numbers of platelets clump together to form a clot, which can sometimes block an artery or break loose, travel through the bloodstream, and block a smaller artery. Antiplatelet drugs make platelets less sticky and less likely to form clots, reducing the risk of ischemic stroke in patients who have had TIA or prior ischemic stroke.

Preventive Surgical Procedures

Carotid Endarterectomy Surgery (Carotid Endarterectomy, CEA)

Carotid Angioplasty and Stenting

Hemorrhagic Stroke Treatment

Hemorrhagic stroke usually requires surgery to relieve intracranial (within the skull) pressure caused by bleeding. Surgical treatment for hemorrhagic stroke caused by an aneurysm or defective blood vessel can prevent additional strokes. Surgery may be performed to seal off the defective blood vessel and redirect blood flow to other vessels that supply blood to the same region of the brain.

The first 2 to 5 days after SAH represent the greatest threat of brain swelling; at which time special measures (both medical and surgical) are used to diminish the effect of swelling on intracranial pressure. Near the end of this initial period, the risk period for delayed cerebral vasospasm begins, and lasts the better part of the next 14 days. Intercurrent infections such as pneumonia are common, and hydrocephalus may develop.

Surgery/Clipping

Prior to surgery, the exact location of the subarachnoid hemorrhage or aneursym is identified through cerebral angiography images. An operation to “clip” the aneurysm is performed by doing a craniotomy (opening the skull surgically), and isolating the aneurysm from the normal bloodstream.

Endovascular (Neurointerventional) Treatment

Neurointerventional procedures for cerebral aneurysm share the advantages of no incision made in the skull, and an anesthesia time that is often dramatically shorter than for craniotomy and microsurgical clipping but has significantly more costly than clipping.

In endovascular microcoil embolization, the flexible, platinum coil is designed to conform to the shape of the aneurysm. Additional coils are advanced into the aneurysm to close the aneurysm from the inside. This prevents flow of blood into the aneurysm by causing a clot to form on the inside.

Stroke Rehabilitation

Recovery and rehabilitation are among the most important aspects of stroke treatment. As a rule, most strokes are associated with some recovery, the extent of which is variable. Rehabilitation includes physical therapy, speech therapy, and occupational therapy. This type of recovery is measured in months to years

• Physical therapy involves using exercise and other physical means (e.g., massage, heat) and may help patients regain the use of their arms and legs and prevent muscle stiffness in patients with permanent paralysis.
• Speech therapy may help patients regain the ability to speak.
• Occupational therapy may help patients regain independent function and relearn basic skills (e.g., getting dressed, preparing a meal, and bathing).

Conclusion

Modern treatments for ischemic and hemorrhagic stroke have reached an advanced state of development in the modern era of digital and device technology.