Stroke is a leading cause of disability and death worldwide. Rapid and accurate diagnosis is crucial for effective treatment and improved outcomes. CT (Computed Tomography) scans play a mission critical role in the diagnosis and effective management of a stroke, offering critical information that guides treatment decisions.
The Different Types of Strokes and Initial Diagnosis
There are two main types of strokes, being able to tell them apart with the help of CT scans gives your doctors valuable insights into the best ways to treat each case.
- Ischemic Stroke: This type of stroke is caused by a blockage of blood flow to the brain, normally this blockage occurs in local blood vessels which supply the brain with oxygen. Even if blood flow is not totally blocked, a partial block in blood vessels can still cause a stroke, this is due to the lack of oxygen and other essential nutrients reaching the brain.
- Haemorrhagic Stroke: This type of stroke occurs when blood vessels in the brain either rupture or begin to leak, leading to bleeding. This type of stroke is particularly dangerous as bleeding in the brain can increases the pressure on brain leading to potential damage.
Importance of CT scans in Stroke Diagnosis
Differentiation of Stroke Types: The beauty of CT scans is that they can quickly and effectively identify a stroke and very importantly differentiate between the two different kinds of strokes mentioned above, which is crucial as treatments for these types differ significantly. This allows your doctors to make informed decisions on the best way to move forward when treating a stroke.
- Speed and Accessibility: CT scans are widely available and can be performed quickly, which is essential in the acute setting of stroke where every minute counts.
- Detection of Acute Haemorrhage: CT scans are highly effective in detecting bleeding in the brain, making them the preferred initial imaging modality for suspected haemorrhagic stroke.
CT Angiography (CTA) and Perfusion CT (CTP)
- CT Angiography (CTA): This imaging technique involves the injection of contrast material to visualise blood vessels. It helps in identifying the location and extent of vessel occlusion in ischemic stroke.
- Perfusion CT (CTP): CTP assesses blood flow in the brain. It helps determine the penumbra (the area of the brain at risk of damage but still salvageable) and the infarct core (the area of irreversible damage).
Benefits of CT scans in Stroke Management
- Rapid Assessment: Enables quick decision-making regarding the use of thrombolytic therapy (e.g., tPA) for ischemic stroke or surgical intervention for haemorrhagic stroke.
- Treatment Planning: Provides detailed images that help in planning interventions such as thrombectomy (mechanical removal of a blood clot).
- Monitoring and Follow-Up: CT scans are used to monitor the effectiveness of treatment and detect any complications, such as haemorrhagic transformation in ischemic stroke patients.
Challenges and Limitations
- Radiation Exposure: Repeated CT scans expose patients to radiation, which is a concern, especially in younger patients. The radiation dose received from a CT scan largely depends on three primary factors including the duration of the CT scan, The particular tissue receiving a CT scan, and the CT scanning device itself.
While exposure to radiation is concerning, most agree that the benefits of CT scans far out way the potential negatives. Additionally strokes are far less common in young patients with the majority of strokes affecting those 65 and older.
- Contrast Reactions: The use of contrast material in CTA and CTP can cause allergic reactions in some patients.
- Limited Detail: While CT scans are excellent for detecting acute haemorrhage, they are less sensitive than MRI for detecting early ischemic changes.
Advancements in CT Technology
- Low-Dose CT: Newer CT technologies aim to reduce radiation exposure without compromising image quality.
- Artificial Intelligence: AI is being integrated to enhance the speed and accuracy of stroke diagnosis by automatically detecting abnormalities such as blocked blood vessels.
CT scans are indispensable in the diagnosis and management of stroke, offering rapid, reliable, and accessible imaging that is crucial for timely intervention. Continued advancements in CT technology and techniques promise to further enhance stroke care, improving outcomes for patients worldwide.
Factors That Place Patients at Higher Risk of Stroke
Strokes in South Africa are very high due to a number of ever-increasing risk factors like fast foods, obesity, smoking, lack of exercise and HIV & AIDS.
1. HIV & AIDS
As South Africa has a high prevalence of HIV & AIDS this risk factor needs to be addressed first and foremost. The main reason HIV increases your risk of stroke is due to the inflammatory response, in people who live with the HIV virus. This typically leads to an ischaemic stroke in patients, though this is most likely to happen to patients in the advanced stages of AIDS who also have secondary opportunistic infections.
Additionally, there are also cases of patients who develop what’s known as immune reconstruction inflammatory syndrome or IRIS for short. This can happen to patients who react to the anti-HIV medication itself and who also have a low CD4 count. The reason inflammation is so dangerous in these cases is that the blood in the arteries themselves can become blocked due to the inflammation in the patient’s body. This is why we see ischaemic strokes being more common in those with HIV and AIDS.
2. Obesity
In short, the main issues with obesity and stroke risk are the known problems that come with obesity, such as the multitude of cardiovascular diseases. inflammation as well as high blood pressure are common causes of stroke in obese patients, with high blood pressure being one of the most well-known risk factors for strokes.
Diseases commonly related to obesity such as diabetes are also known to increase the risk of stroke in those affected by diabetes. These risks can be compounded by an unhealthy lifestyle, in this case, we are referring to the regular consumption of fast foods combined with an inactive lifestyle.
3. Smoking
The Problem with smoking is the way it affects the cholesterol in our bodies, smoking reduces the amount of HDL cholesterol which is known as a good type of cholesterol in a person’s body, while also increasing the amount of LDL cholesterol commonly known as a harmful type of cholesterol within the body.
The chemicals in tobacco are also known to make blood more prone to clotting which can potentially cause a ischaemic stroke if the blood vessels leading to the brain were to become clotted and blocked. Finally, nicotine itself is well known to lower the contraction of oxygen in the blood, which can be dangerous in those with blood oxygen levels that are already down from a pre-existing condition.
Real World Stroke & Treatment
Joe is an overweight 60-year-old gent, who suffers from high blood pressure, is a known diabetic and has smoked for most of his life.
He has recently complained of headaches causing dizziness and confusion and on the odd occasion has noticed that his speech is slurred. He collapsed at home at 07h30am and was rushed the ER within an hour for emergency treatment.
Diagnosis Via CT Scan
The ER staff were fast and immediately suspected a stroke or cerebrovascular accident (CVA) and ordered a non-contrasted CT scan of Joe’s head at 08h15am. Fortunately for Joe – the CT scan showed no actual visible ruptured bleed on the brain (haemorrhagic stroke) and they went on to do a brain angiogram (a repeat scan, with contrast this time)
Based on the imaging of the scan, the doctors were able to identify an ischaemic stroke, which showed the arteries that were blocked (clotted) in Joe’s brain, preventing blood from reaching parts of his brain- explaining his symptoms.
Treatment
The stroke team were able to apply Thrombolytic therapy immediately, through a drip in Joe’s arm over the next 48 hours. These drugs known as tissue plasminogen activators (TPAs), assisted in dissolving Joe’s brain clots.
Recovery & Follow-up Scans
Joe’s physical condition showed improvement and his follow-up scan some days later revealed that the occlusion had almost dissolved. Within 5 days, Joe was discharged to home care. Whilst the quick thinking of his family and ER team saved him this time- Joe will still need to take responsibility for his health, correct his lifestyle and ensure he attends regular follow-ups.
Timing is Everything
When dealing with a suspected stroke person- the first 4.5 hours from the time of collapse are the most critical for the correct stroke diagnosis and the use of thrombolytic therapy.