Stroke

A stroke will occur the moment when a vessel / an artery that supplies blood to a certain brain area is destroyed and breaks down or is blocked by a blood clot. In a short period of time from the breakage/blockage, the nerve cells in that area will be affected and they are going to die completely in just a few hours. As the main result of this condition, that part of the body that is controlled by the affected brain area will suffer permanent damage.

 

Causes of Different Types of Stroke

Ischemic stroke

An ischemic stroke can be caused by a blood clot that will make the circulation of blood in a respective area impossible. This blood clot can form in a narrowed artery and can travel until it reaches into arteries that conduct the blood to the brain after it migrates from the heart or other regions of the human body. Blood clots usually occur as the main result of other types of affections that strongly affect the way blood flows through one’s body. These include:

  • Atherosclerosis (the artery walls get stiffer), which is mostly caused by a high blood pressure, diabetes or high cholesterol levels
  • Atrial fibrillation / cardiac arrhythmias
  • Heart diseases – mitral valve prolapse / stenosis
  • Endocarditis
  • Congenital heart defects
  • Vasculitis

Although this is quite rare, a low blood pressure can cause an ischemic stroke. Low blood pressure will eventually lead to a decreased blood flow, so it reaches the brain slower. This can be the result of narrowed / damaged arteries or a massive blood loss. Severe infections can also cause a low blood pressure, which is medically called hypotension. Some surgeries or procedures (e.g. endarterectomy / angioplasty) are performed on a patient in order to treat a carotid artery that’s been narrowed visibly, yet this can have a side effect: the formation of blood clots.

Hemorrhagic stroke

A hemorrhagic stroke can be caused by a bleeding located inside the brain which is medically called an intracerebral hemorrhage. The bleeding can also be located in a certain area around the brain, which represents a subarachnoid hemorrhage. A bleeding inside the brain is usually the result of an elevated blood pressure, that suffered changes over time. Bleeding in the area around the brain is mostly caused by aneurysms or a high blood pressure that was never treated properly. Other uncommon causes of the apparition of a hemorrhagic stroke include:

  • Blood vessels inflammation, caused by syphilis or tuberculosis
  • Blood coagulability disorders, including hemophilia
  • Injuries around the neck or the head that could have affected the blood vessels present in the region
  • Certain treatments used for cancer
  • Cerebral amyloid angiopathy

Transient Ischemic Attack (TIA)

The transient ischemic attack is not as dangerous as the other types of stroke mentioned above. TIA is described as a type of neurological dysfunction which is caused by a low blood flow (which is the cause of strokes as well). What’s new about TIA is that the symptoms that appear when a patient is encountering it disappear in approximately 24 hours. People often confuse TIA with SCIs (Silent Cerebral Infarct) and they should know that the main difference is that in the case of an infarct the symptoms would be immediate, while in the case of TIA the symptoms appear immediately. The signs of TIA are very similar to the ones of a stroke. Yet, they can be different from one person to another and depend on the side of the brain that is affected.

 

Stroke Risk Factors

There are two main types of stroke risk factors that a person needs to take into account: the first type includes the risk factors that can be somehow controlled by changing habits or treating for certain types of disorders, while the other type includes risk factors that cannot be influenced in any way. See below what each type refers to:

Controllable risk factors

  • Hypertension
  • Diabetes (1/4 people with diabetes suffer from deathly strokes since this affection increases the risk of encountering stroke)
  • High cholesterol (leading to heart muscle damage)
  • Coronary artery disease
  • Atrial fibrillation, endocarditis, cardiomyopathies
  • Smoking and passive smoking
  • Lack of physical activities
  • Obesity
  • Oral contraceptives
  • Alcohol
  • Drugs

Uncontrollable risk factors

  • The age of the patient (the risk of strokes increases with age and doubles each decade after reaching the age of 55)
  • Race (black and Hispanic people are exposed to a higher risk of encountering a stroke than other races)
  • Gender (strokes are more common in men than women)
  • Family history
  • A patient who previously experienced a stroke

 

Stroke Symptoms

As soon as a person notices the following symptoms, emergency medical check-ups are required. The symptoms of strokes have a sudden onset and include:

  • Numbness/weakness/paralysis in body areas such as the face, the arm or the leg on one single side of the body
  • Blurred vision, double vision, loss of vision (on one single eye or both of them)
  • Confusion
  • Dizziness
  • Loss of balance and coordination
  • Severe headaches

The aforementioned symptoms can differ from one person to another and they can also be different from one type of stroke to another. The symptoms of a stroke which was caused by a clot that has blocked a vessel usually appear somewhere around the chest area, on the side which is opposite to the brain area that was affected. For instance, the symptoms of a stroke which occurred somewhere around the right side of the brain will show symptoms on the left side of the body and so on. The symptoms of a stroke caused by bleeding may be similar to the ones caused by an ischemic stroke, but they can be distinguished by signs that are highly related to the blood pressure of a patient. When experiencing severe headaches, nausea, and vomiting, dizziness, convulsions, irritability etc., it is a hemorrhagic stroke. It is important to remember that stroke symptoms can progress in just a few minutes or the process can last a few days. Mild weakness can evolve in temporary paralysis. Ischemic strokes include the apparition of symptoms within seconds.

When it comes to TIA, the symptoms can be similar to the ones caused by many other affections. These symptoms include:

  • Migraines that are highly specific and last for a long time
  • Seizures
  • Issues related to glucose
  • Demyelinating disease

 

The Pathophysiological Mechanism of Strokes

When an ischemic stroke occurs, the right quantity of oxygen-rich blood no longer reaches the brain. When a hemorrhagic stroke occurs, there will be a bleeding inside the brain. After about 4 full minutes without oxygen-rich blood, the brain cells become damaged and they can actually be destroyed. Thus, the body will try to restore the normal parameters of the blood flow by expanding other blood vessels existent near the affected area. If the blockage was produced in a large blood vessel, then the body might be unable to supply the quantities of blood through other blood vessels present in the area. When blood intake cannot be restored to its initial state, permanent lesions occur.

When the brain cells are damaged or destroyed, the parts of a patient’s body which are controlled by the cells can no longer function. The loss of their functions can be either mild or severe (temporary or permanent). This usually depends on the location and the extent of the affected area. In addition, if the blood supply is quickly restored, the effects can be reversed. When symptoms of stroke appear, urgent medical attention is highly required. After having a stroke, a patient is exposed to life-threatening complications that need to be handled by specialists right away.

Stroke is the most common cause of physical disability among nervous system disorders. In people who survived a stroke, almost half of them are going to suffer further complications six months afterward. Treating the effects of stroke depends on the location affected and the ability of the patient to recover. Generally, the lower the damage to brain tissues, the lower the resulting disability, and the greater the chance of complete recovery. The greatest chance of recovery is encountered during the first months after a stroke occurred.

Recovering certain abilities, such as speech, can be done by slow progress. Approximately half of all people who develop a stroke will have a lengthy period of time that includes difficulty in speaking, understanding, and making decisions. They can also encounter behavioral disorders that affect their relationships with family members or friends. Long-term complications of a stroke such as depression or pneumonia may develop immediately or after a period of several months to a few years after apparition. Some long-term complications can be prevented with proper home treatment and by being monitoring by a doctor. Among those who encounter a stroke or a transient ischemic attack (TIA) for the very first time, almost 1/4 will have another stroke or TIA during the next year.

 

Stroke Treatment

Generalities

The faster the treatment is being administered, the better the recovery after stroke. The medical affections associated with stroke are dangerous and an appropriate rehabilitation program should be selected as soon as possible after the apparition of it. See below a list of different types of treatment for stroke:

Initial treatment scheme selection

The very first measurements that one should take for treating a stroke depend on what caused it in the first place. Before choosing one treatment scheme or another, a patient should have a CT scan performed or – if possible – an MRI to know for sure what type of stroke should be treated.  Another test can be performed to determine the localization of the clot/hemorrhage involved and to assess the extent of existent brain damage. While determining treatment options, specialists should closely track the blood pressure and the respiratory capacity of the patient and administer oxygen for the entire duration.

Ischemic stroke

In the case of an ischemic stroke, the emergency treatment depends on the location and the cause of clot formation. Stabilizing vital signs with the help of medicine and other methods is required immediately. If the stroke is diagnosed within the first three hours since the onset of the symptoms, t-PA administration could be the solution. However, this works only for an ischemic stroke and if the type of stroke that the patient has is not correctly established from the very beginning there is a high risk of losing the patient by administering tissue plasminogen activators. High blood pressure should not be treated immediately after the apparition of the stroke symptoms.

Hemorrhagic stroke

The initial treatment in case of a hemorrhagic stroke is quite difficult to determine. Efforts should be made in the direction of controlling the bleeding, lowering the intracranial pressure and stabilizing vital signs for the patient. There are several drugs that can be administered for treating a hemorrhagic stroke and their effects include controlling the blood pressure, decreasing the cerebral inflammation or calming convulsions. If a large amount of bleeding occurs, emergency surgery is recommended to remove the blood accumulated in the brain and reduce the intracranial pressure. Repairing an aneurysm include an endovascular embolization.

It is paramount to seek emergency medical intervention if there are any symptoms of stroke implied. If an ischemic stroke is caused by a blood clot, a tissue plasminogen activator (t-PA), which is a clot-dissolving drug, can be administered. This drug is highly recommended, but it is effective if administered within the first 3 hours of the onset of symptoms. If t-PA is administered during this time, there may be great chances of fast recovery. However, t-PA may be dangerous (potentially lethal) if administered to a patient with a hemorrhagic stroke (caused by a bleeding).

Since most strokes are caused by blood clots, clotting drugs are used to prevent subsequent ischemic stroke. These pills are usually administered after the initial treatment was established by a doctor. They are not recommended within the first 24 hours of t-PA administration. The two types of drugs used are:

  • a platelet antiaggregant, which implies that the smallest cells in the blood will form aggregates – Aspirin is the most commonly used platelet antiaggregant that is administered in order to prevent stroke. Studies have shown that aspirin taken within the first 48 hours of stroke apparition can reduce the chance of encountering another stroke and even prevent death. Persons who cannot take aspirin or those who have a transient ischemic stroke (TIA) or a stroke being treated with aspirin are sometimes advised to take other antiplatelet drugs such as ticlopidine. Aspirin is not recommended in the first 24 hours after t-PA administration.
  • anticoagulants that prevent the production of proteins necessary for normal blood clot formation – Administration of anticoagulants (mainly warfarin) is the best method to prevent heart attacks caused by atrial fibrillation, myocardial infarction, heart valvular heart disease and heart failure. They are not used as an emergency treatment in strokes.

In people with coronary artery disease, the treatment with cholesterol-lowering medicines called statins may slow the development of atherosclerosis in the carotid arteries and may also decrease the risk of developing a TIA or a stroke. Studies show an improvement of stroke risk of about 20% to 30% in people who are being administered statins.

Anticoagulants (warfarin and heparin) are often used instead of or in combination with a platelet antiaggregant such as aspirin or ticlopidine. Anticoagulants are recommended for people who are at risk of developing a stroke in case they suffer from:

  • abnormal heart rhythm, (heart arrhythmia, atrial fibrillation)
  • myocardial infarction, if a blood clot is present in the heart
  • heart failure
  • abnormal or artificial heart valves

In case of high blood pressure, medication may be recommended to reduce its effects. This medication scheme includes:

  • angiotensin-converting enzyme (IEC) inhibitors
  • angiotensin II receptor blockers
  • beta-blockers
  • diuretics
  • calcium blockers

 

AAOM Editor

Academic Association of Medicine is the go to resource for all health related issues. We are an independent body that seeks to offer general information on various health topics and unbiased reviews on health products.

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