Conditions: Stroke
Also known as cerebrovascular accident, stroke is when brain tissue dies due to lack of oxygen. This may be life-threatening.
What is a stroke or cerebrovascular accident?
A stroke is a medical condition in which poor blood flow to the brain causes cell death. There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functioning properly.
Due to the arrangement of the existing nerve fibers and that usually this failure of blood supply is in a specific area of the brain, certain functions of the body contralateral to the injury (relating to or denoting the side of the body opposite to that on which the condition occurs) may be affected in one way or another. One of the most frequent symptoms is contralateral paralysis, that means, if the right side of the brain is affected, the paralysis will affect the left side of the body and vice versa.
Why is stroke a problem?
A stroke can cause parts of the brain to become permanently nonfunctional. The extent of deficit may range from minor to incapacitating or fatal.
Embolic stroke. Image Source: Blausen Medical Communications, Inc., CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons
What causes a stroke?
There are two main types of stroke: ischemic, due to lack of blood flow, and hemorrhagic, due to bleeding. Both cause parts of the brain to stop functioning properly.
The main risk factor for stroke is high blood pressure. Other risk factors include high blood cholesterol, tobacco smoking, obesity, diabetes mellitus, a previous TIA, end-stage kidney disease, and atrial fibrillation. An ischemic stroke is typically caused by blockage of a blood vessel, though there are also less common causes. A hemorrhagic stroke is caused by either bleeding directly into the brain or into the space between the brain's membranes. Bleeding may occur due to a ruptured brain aneurysm.
HOw is stroke prevented?
Prevention includes decreasing risk factors, surgery to open up the arteries to the brain in those with problematic carotid narrowing, and use of blood “thinning” medication to lessen the blood’s ability to clot in people with an irregular heart rhythm called atrial fibrillation. Blood clot inhibitors (blood “thinners”) or cholesterol lowering medications (statins) may be recommended by physicians for prevention.
How is stroke identified?
Signs and symptoms of a stroke may include an inability to move or feel on one side of the body (including the face or limbs), problems understanding or speaking, dizziness, or loss of vision to one side. Signs and symptoms often appear soon after the stroke has occurred. If symptoms last less than one or two hours, the stroke is a transient ischemic attack (TIA), also called a mini-stroke. A hemorrhagic stroke may also be associated with a severe headache. The symptoms of a stroke can be permanent. Long-term complications may include pneumonia and loss of bladder control.
Diagnosis is typically based on a physical exam and supported by medical imaging such as a CT scan or MRI scan. A CT scan can rule out bleeding, but may not necessarily rule out ischemia, which early on typically does not show up on a CT scan. Other tests such as an electrocardiogram (ECG) and blood tests are done to determine risk factors and rule out other possible causes. Low blood sugar may cause similar symptoms.
How is stroke treated?
Generally, initial treatment for a new stroke is directed at attempting to restore normal blood flow to the brain to limit progression of injury. In the case of an ischemic stroke, removing the blockage within the affected artery may be helpful if performed within the first few hours. This may be done with drugs that break down the clot (thrombolysis) or by surgically removing the blockage (thrombectomy).
In the case of a hemorrhagic stroke, where bleeding into the brain tissue has occurred, treatment is directed at maintaining ideal blood pressure, oxygen delivery, and blood sugar levels. When bleeding has already occurred, anticoagulants and antithrombotics can make bleeding worse, so treatment usually involves restoring the blood’s ability to clot back to normal. Some hemorrhagic strokes may benefit from surgery.
Stroke rehabilitation is the process by which those with disabling strokes undergo treatment to help them return to normal life as much as possible by regaining and relearning the skills of everyday living. It also aims to help the survivor understand and adapt to difficulties, prevent secondary complications, and educate family members to play a supporting role.