Westchester Sugery
Specializing in general and vascular surgery - minimally invasive, maximum results.
Specialty Orthopaedics

Strokes

What is a stroke?

Brain cell function requires a constant delivery of oxygen and glucose from the bloodstream. A stroke, or cerebrovascular accident (CVA), occurs when blood supply to part of the brain is disrupted, causing brain cells to die. Blood flow can be compromised by a variety of mechanisms.

Blockage of an artery

  • Narrowing of the small arteries within the brain can cause a lacunar stroke, (lacune means "empty space"). Blockage of a single arteriole can affect a tiny area of brain causing that tissue to die (infarct).
  • Hardening of the arteries (atherosclerosis) leading to the brain. There are four major blood vessels that supply the brain with blood. The anterior circulation of the brain that controls most motor activity, sensation, thought, speech, and emotion is supplied by the carotid arteries. The posterior circulation, which supplies the brainstem and the cerebellum, controlling the automatic parts of brain function and coordination, is supplied by the vertebrobasilar arteries.

If these arteries become narrow as a result of atherosclerosis, plaque or cholesterol, debris can break off and float downstream, clogging the blood supply to a part of the brain. As opposed to lacunar strokes, larger parts of the brain can lose blood supply, and this may produce more symptoms than a lacunar stroke.

  • Embolism to the brain from the heart. In some instances blood clots can form within the heart and the potential exists for them to break off and travel (embolize) to the arteries in the brain and cause a stroke.

Rupture of an artery (hemorrhage)

  • Cerebral hemorrhage (bleeding within the brain substance). The most common reason to have bleeding within the brain is uncontrolled high blood pressure. Other situations include aneurysms that leak or rupture or arteriovenous malformations (AVM) in which there is an abnormal collection of blood vessels that are fragile and can bleed.

What causes a stroke?

The blockage of an artery in the brain by a clot (thrombosis) is the most common cause of a stroke. The part of the brain that is supplied by the clotted blood vessel is then deprived of blood and oxygen. As a result of the deprived blood and oxygen, the cells of that part of the brain die and the part of the body that it controls stops working. Typically, a cholesterol plaque in a small blood vessel within the brain that has gradually caused blood vessel narrowing ruptures and starts the process of forming a small blood clot.

Risk factors for narrowed blood vessels in the brain are the same as those that cause narrowing blood vessels in the heart and heart attack (myocardial infarction). These risk factors include:

  • high blood pressure (hypertension)
  • high cholesterol
  • diabetes
  • smoking

Embolic stroke

Another type of stroke may occur when a blood clot or a piece of atherosclerotic plaque (cholesterol and calcium deposits on the wall of the inside of the heart or artery) breaks loose, travels through the bloodstream and lodges in an artery in the brain. When blood flow stops, brain cells do not receive the oxygen and glucose they require to function and a stroke occurs. This type of stroke is referred to as an embolic stroke. For example, a blood clot might originally form in the heart chamber as a result of an irregular heart rhythm, such as occurs in atrial fibrillation. Usually, these clots remain attached to the inner lining of the heart, but occasionally they can break off, travel through the blood stream, form a plug (embolism) in a brain artery, and cause a stroke. An embolism can also originate in a large artery (for example, the carotid artery, a major artery in the neck that supplies blood to the brain) and then travel downstream to clog a small artery within the brain.

Cerebral hemorrhage

A cerebral hemorrhage occurs when a blood vessel in the brain ruptures and bleeds into the surrounding brain tissue. A cerebral hemorrhage (bleeding in the brain) causes stroke symptoms by depriving blood and oxygen to parts of the brain in a variety of ways. Blood flow is lost to some cells. As well, blood is very irritating and can cause swelling of brain tissue (cerebral edema). Edema and the accumulation of blood from a cerebral hemorrhage increases pressure within the skull and causes further damage by squeezing the brain against the bony skull further decreasing blood flow to brain tissue and cells.

Subarachnoid hemorrhage

In a subarachnoid hemorrhage, blood accumulates in the space beneath the arachnoid membrane that lines the brain. The blood originates from an abnormal blood vessel that leaks or ruptures. Often this is from an aneurysm (an abnormal ballooning out of the wall of the vessel). Subarachnoid hemorrhages usually cause a sudden, severe headache, nausea, vomiting, light intolerance, and a stiff neck. If not recognized and treated, major neurological consequences, such as coma, and brain death may occur.

Vasculitis

Another rare cause of stroke is vasculitis, a condition in which the blood vessels become inflamed causing decreased blood flow to brain tissue.

Migraine headache

There appears to be a very slight increased occurrence of stroke in people with migraines headache. The mechanism for migraine or vascular headaches includes narrowing of the brain blood vessels. Some migraine headache episodes can even mimic stroke with loss of function of one side of the body or vision or speech problems. Usually, the symptoms resolve as the headache resolves.

What are the risk factors for stroke?

Overall, the most common risk factors for stroke are:

  • high blood pressure
  • high cholesterol
  • smoking
  • diabetes
  • increasing age

Heart rhythm disturbances like atrial fibrillation, patent foramen ovale, and heart valve disease can also be the cause.

When strokes occur in younger individuals (less than 50 years old), less common risk factors to be considered include illicit drugs, such as cocaine or amphetamines, ruptured aneurysms, and inherited (genetic) predispositions to abnormal blood clotting.

An example of a genetic predisposition to stroke occurs in a rare condition called homocystinuria, in which there are excessive levels of the chemical homocystine in the body. Scientists are trying to determine whether the non-hereditary occurrence of high levels of homocystine at any age can predispose to stroke.

What is a transient ischemic attack (TIA)?

A transient ischemic attack (TIA, mini-stroke) is a short-lived stroke that gets better and resolves. It is a short-lived episode (less than 24 hours) of temporary impairment if brain function that is caused by a loss of blood supply. A TIA causes a loss of function in the area of the body that is controlled by the portion of the brain affected. The loss of blood supply to the brain is most often caused by a clot that spontaneously forms in a blood vessel within the brain (thrombosis). However, it can also result from a clot that forms elsewhere in the body, dislodges from that location, and travels to lodge in an artery of the brain (emboli). A spasm and, rarely, a bleed are other causes of a TIA. Many people refer to a TIA as a "mini-stroke."

Some TIAs develop slowly, while others develop rapidly. By definition, all TIAs resolve within 24 hours. Strokes take longer to resolve than TIAs, and with strokes, complete function may never return and reflect a more permanent and serious problem. Although most TIAs often last only a few minutes, all TIAs should be evaluated with the same urgency as a stroke in an effort to prevent recurrences and/or strokes. TIAs can occur once, multiple times, or precede a permanent stroke. A transient ischemic attack should be considered an emergency because there is no guarantee that the situation will resolve and function will return.

A TIA from a clot in the blood vessel that supplies the retina of the eye can cause temporary visual loss (amaurosis fugax), which is often described as the sensation of a curtain coming down. A TIA that involves the carotid artery (the largest blood vessel supplying the brain) can produce problems with movement or sensation on one side of the body, which is the side opposite to the actual blockage. An affected patient may experience temporary double vision, dizziness (vertigo), loss of balance, one sided weakness or complete paralysis of the arm, leg, face, or one whole side of the body or be unable to speak or understand comma.

What is the impact of strokes?

In the United States, stroke is the third largest cause of death (behind heart disease and all forms of cancer). The cost of strokes is not just measured in the billions of dollars lost in work, hospitalization, and the care of survivors in nursing homes. The major cost or impact of a stroke is the loss of independence that occurs in 30% of the survivors. For some individuals, what was a self-sustaining and an enjoyable lifestyle prior to the stroke, many may lose most of their quality of life after a stroke. Family members and friends may have their lives altered as they find themselves in the new role as caregivers.

What are stroke symptoms?

When brain cells are deprived of oxygen, they cease to perform their usual tasks. The symptoms that follow a stroke depend on the area of the brain that has been affected and the amount of brain tissue damage.

Small strokes may not cause any symptoms, but can still damage brain tissue. These strokes that do not cause symptoms are referred to as silent strokes. According to The U.S. National Institute of Neurological Disorders and Stroke (NINDS), these are the five major signs of stroke:

  1. Sudden numbness or weakness of the face, arm or leg, especially on one side of the body. The loss of voluntary movement and/or sensation may be complete or partial. There may an associated tingling sensation in the affected area.
  2. Sudden confusion or trouble speaking or understanding. Sometimes weakness in the muscles of the face can cause drooling.
  3. Sudden trouble seeing in one or both eyes
  4. Sudden trouble walking, dizziness, loss of balance or coordination
  5. Sudden, severe headache with no known cause

What should be done if you suspect you or someone else is having a stroke?

If any of the symptoms mentioned above suddenly appear, immediate emergency medical attention should be sought. The first action should be to activate the emergency medical system in your area (call 911 if it is available). The goal is to get the stroke victim to a hospital as quickly as possible to confirm the diagnosis. An urgent medical decision is necessary in the emergency room to determine whether thrombolytic or clot busting drugs can potentially reverse the stroke situation. There is a very limited window of opportunity from the onset of symptoms to when this therapy can be used. If delays occur, the opportunity to intervene is lost.

The first priority is ensuring that the ambulance arrives as soon as possible since first responders, EMTs and paramedics may be able to help make the diagnosis and alert the hospital about the stoke victim's situation.

While waiting for the ambulance, the following first aid suggestions may be helpful:

  • The affected person should lie flat to promote an optimal blood flow to the brain.
  • If drowsiness, unresponsiveness, or nausea are present, the person should be placed in the rescue position on their side to prevent choking should vomiting occur.
  • Although aspirin plays a major role in stroke prevention (see below), once the symptoms of a stroke begin, it is generally recommended that additional aspirin not be taken until the patient receives medical attention. If stroke is of the bleeding type, aspirin could theoretically make matters worse. Moreover, patients with stroke may have swallowing difficulties and may choke on the pill.

Three commands, known as the Cincinnati Prehospital Stroke Scale (CPSS), may help to determine if the potential for stroke exists. Ask the patient to do the following:

  1. Smile: the face should move symmetrically
  2. Raise both arms: looking for weakness on one side of the body
  3. Speak a simple sentence

If a potential stroke victim cannot perform these tasks, 911 should be called to activate the emergency medical system.

What is the treatment of a stroke?

Tissue plasminogen activator (TPA)

There is opportunity to use alteplase (TPA) as a clot-buster drug to dissolve the blood clot that is causing the stroke. There is a narrow window of opportunity to use this drug. The earlier that it is given, the better the result and the less potential for the complication of bleeding into the brain.

Present American Heart Association guidelines recommend that if used, TPA must be given within 4 1/2 hours after the onset of symptoms. for patients who waken from sleep with symptoms of stroke, the clock starts when they were last seen in a normal state.

TPA is injected into a vein in the arm but, the time frame for its use may be extended to six hours if it is dripped directly into the blood vessel that is blocked requiring angiography, which is performed by an interventional radiologist. Not all hospitals have access to this technology.

TPA may reverse stroke symptoms in more than one-third of patients, but may also cause bleeding in 6% patients, potentially making the stroke worse.

For posterior circulation strokes that involve the vertebrobasilar system, the time frame for treatment with TPA may be extended even further to 18 hours.

Heparin and aspirin

Drugs to thin the blood (anticoagulation; for example, heparin) are also sometimes used in treating stroke patients in the hopes of improving the patient's recovery. It is unclear, however, whether the use of anticoagulation improves the outcome from the current stroke or simply helps to prevent subsequent strokes (see below). In certain patients, aspirin given after the onset of a stroke does have a small, but measurable effect on recovery. The treating doctor will determine the medications to be used based upon a patient's specific needs.

Managing other Medical Problems

Blood pressure will be tightly controlled often using intravenous medication to prevent stroke symptoms from progressing. This is true whether the stroke is ischemic or hemorrhagic.

Supplemental oxygen is often provided.

In patients with diabetes, the blood sugar (glucose) level is often elevated after a stroke. Controlling the glucose level in these patients may minimize the size of a stroke.

Patients who have suffered a transient ischemic attacks, the patient may be discharged with blood pressure and cholesterol medications even if the blood pressure and cholesterol levels are within acceptable levels. Smoking cessation is mandatory.

Rehabilitation

When a patient is no longer acutely ill after a stroke, the health care staff focuses on maximizing the individuals functional abilities. This is most often done in an inpatient rehabilitation hospital or in a special area of a general hospital. Rehabilitation can also take place at a nursing facility.

The rehabilitation process can include some or all of the following:

  1. speech therapy to relearn talking and swallowing;
  2. occupational therapy to regain as much function dexterity in the arms and hands as possible;
  3. physical therapy to improve strength and walking; and
  4. family education to orient them in caring for their loved one at home and the challenges they will face.

The goal is for the patient to resume as many, if not all, of their pre-stroke activities and functions. Since a stroke involves the permanent loss of brain cells, a total return to the patient's pre-stroke status is not necessarily a realistic goal in many cases. However, many stroke patients can return to vibrant independent lives.

Many times, home health providers can assess the home living situation and make recommendations to ease the transition home. Unfortunately, some stroke patients have such significant nursing needs that they cannot be met by relatives and friends and long-term nursing home care may be required.