Introduction to stroke

What is a Stroke?

A stroke is a medical emergency caused by a sudden interruption in the blood flow to the brain, leading to cell death due to lack of oxygen. This is often due to a blood clot blocking a vessel (ischaemic stroke) or bleeding in or around the brain (hemorrhagic stroke). When oxygen supply is cut off, neurological functions become impaired, manifesting in a variety of symptoms. The majority of strokes occurring in those over 65 years old

Types of Stroke

There are two major categories of strokes:

1. Ischaemic Stroke: This is the most common type of stroke, accounting for about 87% of all cases. It is caused by a blood clot blocking a blood vessel in the brain, resulting in a lack of blood flow and oxygen to the brain tissue.

2. Hemorrhagic Stroke: This is less common but can be more serious. It is caused by bleeding directly into the brain or the space around the brain, typically due to a ruptured blood vessel or an abnormal vascular structure.

Symptoms

Symptoms of a stroke usually appear suddenly and may include:

• Weakness or numbness on one side of the body
• Drooping of one side of the face
• Difficulty in speaking or understanding
• Dizziness or loss of balance
• Loss of vision to one side
• Severe headache (typically in hemorrhagic stroke)

In some cases, the symptoms may be temporary, lasting a few minutes or persisting up to 24 hours. This is known as a transient ischaemic attack (TIA) or a “mini-stroke.” Even if symptoms resolve they should be treated urgently as they often serve as a warning for an impending full stroke.

Risk Factors

Key risk factors for stroke include high blood pressure, high blood cholesterol, smoking, obesity, diabetes mellitus, a previous TIA, end-stage kidney disease, and atrial fibrillation.

Diagnosis and Treatment

Stroke is diagnosed based on physical examination and medical imaging like CT scans or MRI scans. Other tests like ECG and blood tests help determine risk factors and rule out other causes.

Time is critical in stroke treatment. For ischaemic strokes, a medication that can break down the clot may be effective if given within the first few hours. Procedures may be necessary in certain instances to remove the obstructing blood clot, called mechanical thrombectomy.

Additionally, if the stroke leads to brain swelling surgery might be necessary to mitigate pressure on other parts of the brain.

Prevention

Prevention measures include managing risk factors, surgery for problematic carotid narrowing, and medication in certain cases.

Long-term Implications

Strokes can have permanent symptoms such as persistent weakness, inability to walk and speak normally, and impaired vision. Stroke rehabilitation is essential to help recover lost functions.