Overview 

Just like a heart attack happens when blood flow to the heart is blocked, a stroke occurs when blood flow to the brain is interrupted. This may be due to the narrowing or blockage of an artery (an ischaemic stroke) or the rupture of a blood vessel that supplies blood to the brain (a hemorrhagic stroke). Strokes can damage several parts of the brain, leading to various symptoms such as problems with movement, speech, vision, loss of coordination, or other functions depending on which part of the brain is affected. 

Patients who experience symptoms of stroke should immediately be transferred and assessed at a hospital for accurate diagnosis and treatment. To help you understand and recognise the symptoms of strokes, this article will discuss the symptoms, causes, diagnosis, and treatment of ischaemic stroke.

What is an ischaemic stroke?

An ischaemic stroke occurs when a blood clot in an artery reduces blood flow to or within the brain.¹ Ischaemic strokes are the most common type of stroke, accounting for 85% of all stroke cases. Hemorrhagic strokes account for the remaining 15% of stroke cases. 

Ischaemic strokes can be divided into two main subtypes:

• Thrombotic strokes: caused by a blood clot forming inside one of the blood vessels in the brain, reducing blood flow to the affected area of the brain.¹
• Embolic stroke: caused by a blood clot or plaque debris originating elsewhere in the body, such as the heart or neck arteries. The clot or debris breaks away from its original blood vessel and travels through the bloodstream until it becomes stuck in a smaller artery in the brain, blocking it and reducing blood flow to the brain.¹

Causes of ischaemic strokes

Your risk of an ischaemic stroke can be affected by various risk factors. The risk factors of an ischaemic stroke can be divided into modifiable and non-modifiable factors.²

Non-modifiable risk factors

Non-modifiable risk factors are characteristics that you cannot change or control. These inherent traits contribute to your risk of certain health conditions, regardless of your lifestyle.²

Non-modifiable risk factors include:

• Age 
• Gender 
• Family history 
• Race 
• Certain pre-existing or genetic medical conditions

Modifiable risk factors

Modifiable risk factors are aspects of your lifestyle or health that can be changed or controlled.  This means you can reduce your risk of certain health conditions, including an ischaemic stroke by making healthy lifestyle changes.²

Modifiable risk factors can include:

• Blood pressure 
• Cholesterol levels
• Smoking  
• Weight 
• Exercising 
• Diet

Symptoms 

The main symptoms of stroke can be remembered with the acronym FAST:³

• Face - the face may have drooped on one side, and the person may be unable to smile
• Arms - the person is unable to lift or move their arms due to weakness or numbness
• Speech - the person’s speech may be slurred or unable to talk
• Time - if you notice the signs of someone having a stroke, it's time to dial 999 immediately

While most stroke symptoms can be identified using FAST, they can vary depending on the affected part of the brain.

Other possible symptoms of an ischaemic stroke include:

• Dizziness 
• Paralysis of one side of the body
• Difficulty swallowing 
• Confusion 
• A sudden loss or blurred vision 
• Problems with balance or coordination 
• Difficulty understanding what others are saying

Diagnosis 

When a patient arrives at a hospital with stroke symptoms, the doctor will want to exclude other conditions such as migraine, seizures, and brain tumours.⁴  

Diagnosis of an ischaemic stroke is based on the symptoms presented, symptom onset and duration, medical history, if any medication has been taken, and neurological function -  including muscle strength, coordination, and cognitive abilities.

Physical and imaging tests are then conducted to confirm the diagnosis if stroke is suspected.

Imaging tests

• Computed tomography (CT) scan: a CT scan is a basic imaging technique that is fast and effective.  A CT scan uses both X-ray and computer technology to create cross-sectional images of the brain. It can detect signs of bleeding or blockage in the blood vessels, helping to discern between ischaemic and hemorrhagic stroke. CT scans are often the first choice due to their quick results.⁵
• Magnetic resonance imaging (MRI) scan: an MRI scan is another imaging technique that uses magnetic fields and radio waves to produce detailed images of the brain compared to a CT scan.  It can detect a lack of blood flow or tissue damage, and identify stroke causes such as clots or arterial blockages.⁵ 

Blood tests

While no singular blood test can diagnose a stroke, it can be used to help the doctor exclude other conditions and determine appropriate treatment.  

Some blood tests include:

• Complete blood count (CBC): measures the level of platelets in the blood.  Platelets are cells that help your blood clot to stop bleeding.  High platelet levels (known as thrombocytosis) may suggest an increased risk of clot formation, which may lead to an ischaemic stroke.^6,7
• Blood clotting tests: blood clotting tests such as prothrombin time (PT) and partial thromboplastin time (PTT) can measure how quickly the blood clots.  If the blood clots too quickly  (known as hypercoagulability) may indicate an ischaemic stroke.⁸
• Blood sugar levels: high glucose levels (hyperglycemia) are associated with diabetes and poorer clinical outcomes in stroke patients.⁹
• Cholesterol levels: high levels of “bad cholesterol” (low-density lipoprotein) in the blood have been associated with an increased risk of an ischaemic stroke.¹⁰

Heart tests

A doctor may use heart tests to find problems that may have caused an ischaemic stroke.

These heart tests can include:

• Carotid ultrasound: a carotid ultrasound scan uses sound waves to produce an image of the carotid arteries in the neck.  It can detect any blockages or narrowing that could have led to an ischaemic stroke by affecting blood flow to the brain.¹¹
• Electrocardiogram (ECG): an ECG monitors the electrical activity of the heart and identifies irregular heart rhythms such as atrial fibrillation, which is a known risk factor for stroke.¹² 
• Echocardiogram: an echocardiogram is a type of ultrasound scan that can create an image of the heart’s structure and function.  This scan can reveal information about blood flow patterns and if there are blood clots present or abnormal heart rhythms.¹³ 

Treatment 

Initial treatment to break up or remove the blood clot

The primary treatment for an ischemic stroke is to dissolve or remove the blood clot, restoring blood flow to the brain to minimise damage and complications. 

The two main treatments used to break up or remove blood clots are^1,5:

• Thrombolysis 
• Thrombectomy 

Thrombolysis (clot-busting medication)

The first-choice treatment for an ischemic stroke is alteplase, a clot-dissolving medication that is administered intravenously (i.e. through a needle in your arm). It is a type of drug called a tissue plasminogen activator (tPA) and works best when given within 3 to 4.5 hours after the onset of stroke symptoms. However, a doctor must confirm the diagnosis of ischaemic stroke before giving this medication.^1,5

Thrombectomy (clot removal)

In cases where thrombolysis is not suitable or cannot be used (e.g., a patient arriving at the hospital 4.5 hours after symptom onset), thrombectomy may be performed as an alternative procedure. During thrombectomy, a specialised device, such as a catheter or stent, is inserted into an artery (usually in the groin area). The doctor then guides the device through the blood vessels to the site of the blood clot in the brain. Using the device, the clot is physically removed or broken up, allowing blood flow to be restored to the affected area of the brain.^1,5

Treatments to reduce future ischaemic strokes

Medications

Antiplatelets 

Antiplatelet agents such as clopidogrel, dipyridamole, and low-dose aspirin work by preventing the abnormal formation of platelets in the blood.  These medications can help blood flow through narrowed or damaged blood vessels preventing blood cells called platelets from sticking together and forming clots in the blood vessels.^5,14

Anticoagulants 

Anticoagulant medications (also known as blood thinners) may be offered to some patients with pre-existing heart conditions such as atrial fibrillation. These medications change specific proteins in the blood that are involved in clotting, making it difficult for blood clots to form quickly.  Examples of these anticoagulant medications include warfarin, apixaban, and edoxaban.^5,15  

Managing health conditions 

Blood pressure

Having hypertension (high blood pressure) is associated with an increased risk for an ischaemic stroke.  It is recommended for patients to control their blood pressure to prevent future strokes.  Patients with hypertension may be offered beta-blockers, alpha-blockers, or calcium channel blockers.  Patients are also advised to make lifestyle changes such as eating a low-sodium diet, exercising regularly, and reducing stress levels.^5,16 

Cholesterol levels 

High cholesterol levels contribute to the buildup of plaque in the arteries and increase the risk for future ischaemic strokes. As such, high-risk patients may be offered statin medications to lower the level of low-density lipoprotein (LDL) cholesterol in their blood. Statins work by blocking an enzyme that plays a part in the production of cholesterol in the liver. Lifestyle changes, such as eating a heart-healthy diet, exercising regularly, and maintaining a healthy weight can also help manage cholesterol levels.^5,17

Managing diabetes 

Those with diabetes are at increased risk of stroke due to factors such as high blood sugar levels and associated cardiovascular complications. Diabetes can be managed through blood sugar monitoring, and making lifestyle changes is important for lowering the risk of future strokes.^5,18

Summary 

Ischaemic strokes occur when a blood clot in an artery reduces blood flow leading to or within the brain.  Doctors will diagnose an ischaemic stroke by assessing your symptoms, medical history, and overall neurological function. However, doctors will also use brain imaging, blood, and heart tests to help diagnose an ischaemic stroke. Treatment of ischaemic strokes involves thrombolysis (within 3-4.5 hours) or thrombectomy.  Preventive measures for reducing your risk of future ischaemic strokes include managing risk factors like blood, pressure, cholesterol, diabetes, and lifestyle changes.