What is a stroke?

A stroke, also called a cerebrovascular accident or a brain attack, happens when the blood flow to a part of the brain is interrupted. Without blood supply, the affected part of the brain does not receive enough oxygen and starts to die. Death of cells in an area of the brain can lead to a permanent or temporary loss of functions that area once controlled. The long-term effects of a stroke depend on how many cells die and in which area of the brain. Severe effects can include paralysis, loss of speech, or loss of bladder and bowel control. To limit the damage from a stroke, it is critical to get medical help as soon as possible by calling 911.

In the US, about 795,000 people have a stroke every year. Strokes are a leading cause of death, accounting for over 140,000 deaths a year. They are also a leading cause of disability.

Types of strokes

There are two main types of strokes.

1. Ischemic stroke

Ischemic strokes are the most common types of strokes. The cause of such strokes is a partial or complete blockage in the arteries that take the blood to the brain. The blockage can happen due to a blood clot or a build-up of other materials such as fat deposits, plaques (atherosclerosis), and other debris. 

Symptoms of an ischemic stroke include:

• Sudden weakness or numbness of the face, arm, or leg which may be more pronounced on one side of the body
• Sudden confusion
• Sudden difficulty with speech
• Sudden inability to understand speech
• Sudden inability to see with one or both eyes
• Sudden dizziness, loss of balance and coordination, or difficulty walking
• Sudden severe headache

Not all symptoms may be felt by everyone, and symptoms could come and go. Women may feel additional symptoms such as hiccups, nausea, chest pain, and shortness of breath.

2. Hemorrhagic stroke

Hemorrhagic strokes happen when a weakened blood vessel in the brain ruptures or leaks. The resulting bleeding in the brain (called a hemorrhage) compresses the surrounding brain tissue.

While hemorrhagic strokes constitute only 8-15% of all strokes, they are typically more serious and have worse outcomes. Early treatment is necessary as the hemorrhage can expand rapidly and cause neurological dysfunction.

There are two subtypes of hemorrhagic strokes.

1. Strokes due to intracerebral hemorrhage. These occur when there is bleeding in the brain parenchyma, the bulk of the brain that contains the gray and white matter.
2. Strokes due to subarachnoid hemorrhage. These occur when there is bleeding in the subarachnoid space. The subarachnoid space in the brain and spinal cord consists of the cerebrospinal fluid, major blood vessels, and cisterns.

Symptoms of hemorrhagic strokes include:

• Sudden and severe headache
• Sudden difficulty with communication including speaking, understanding spoken words, reading, and writing
• One-sided muscle weakness
• Facial palsy (muscle weakness on one side of the face)
• Vomiting
• Neck stiffness
• Increase in blood pressure
• Seizures
• Photophobia
• Coma, etc.

Specific symptoms can be indicative of the part of the brain that is impacted by the hemorrhage.

Transient ischemic attack

A transient ischemic attack (TIA) is a mini-stroke that only lasts a few minutes. It happens due to a small blockage in an artery to the brain but the brain quickly gets its blood supply back, resulting in no long-term adverse effects. However, a TIA is still a medical emergency requiring immediate medical intervention because it could portend a bigger stroke.  

Symptoms of TIA include:

• Numbness or weakness in the face, arm, or leg, especially on one side.
• Confusion, difficulty in talking or understanding speech.
• Trouble seeing in one or both eyes
• Loss of balance and coordination and trouble walking
• Dizziness