Q1. How can ischaemic stroke be treated?
In ischaemic stroke, blood supply to the brain is abruptly compromised by blockage of blood vessel. As a result, about 2 millions brain cells die in every minute. Therefore, the blocked blood vessels must be opened up as quickly as possible to restore normal brain perfusion.
Two types of reperfusion therapy are currently available: the first is Intravenous Thrombolysis, in which intravenous medication is given to dissolve blood clots and restore blood flow. The other is Intra-arterial (IA) Thrombectomy: A small catheter is introduced into the femoral artery in groin area. Under X-ray guidance, it is then navigated to the blocked neck or brain artery to remove the blood clots. This modality can allow a longer time window for treatment. Two methods are used for blood clot removal: Aspiration Thrombectomy and Mechanical Thrombectomy. In Aspiration Thrombectomy, an aspiration catheter is directed to engage the blood clot, suction is then applied to aspirate it. In Mechanical Thrombectomy, a stent-retriever is navigated to the clot though microcatheter. The stent is deployed to grasp the clot, which can then be retrieved when the stent-retriever is withdrawn. Both methods showed comparable successful rates.
Q2. Is IA Thrombectomy applicable to all patients? Are there any restrictions?
Time is the biggest limitation for both intravenous Thrombolysis and IA Thrombectomy. More and more brain cells die and the volume of infarct (dead brain tissue) increases with time. This infarct tissue will become fragile and easily bleeds after reperfusion. Therefore, the risk of cerebral haemorrhage after reopening of blocked vessels increases with time. Studies have shown that risk of bleeding complication after thrombolysis become significant when it is performed after 3 to 4.5 hours from stroke onset. IA Thrombectomy has a longer treatment time window. It can be safely performed within 8 hours from onset.
Q3. What can be done if it has already been 8 hours after onset?
In view of the risk of bleeding complication, patients might not be eligible for IA Thrombectomy if the time from symptom onset to treatment exceeds 8 hours. For patients who wake up with a stroke, the time of onset is often difficult to estimate. For example, if a patient wakes up with a stroke at 8:00 am, the onset time could be 5:00 am or the time he first fell asleep, like around 12:00 pm or 1:00 am. This can make a difference in the treatment decision. Thanks to the medical breakthrough in MRI and AI software, we can now instantly distinguish the irreversibly damaged brain issues from those which are just deprived of blood supply but salvageable. By IA Thrombectomy, normal function can be restored to patients with a high percentage of salvageable brain tissues. More patients can now benefit from AI technology. For some patients, the treatment time window can now be extended to 16, even 24 hours.
Q4. Are there any other ways to prevent a stroke besides managing the “3-highs”?
To prevent a stroke, you need to manage the 3-highs (blood pressure, sugar and cholesterol) and beware of any warning signs of a mini stroke. Transient Ischaemic Attacks (TIA) share similar symptoms with strokes, such as problem in speech or articulation, numbness or weakness on one side of the body, dimmed vision or blurred central vision in one eye. As warning signs, these symptoms should not be ignored despite their short duration. The risk of stroke in future can be very high if they are not treated in time. Sometime, it can be due to severe narrowing of arteries in the neck or inside the brain. If medication alone is not effective, stent angioplasty may be considered. Similar to coronary angioplasty, a stent is introduced to the narrowed segment of the artery. A balloon is inflated to open up the narrowing, and the stent is left behind to maintain its patency. Blood supply to the brain is then improved and stroke can be prevented.
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