What is a stroke?
There are a variety of types of stroke. The most common type of stroke is an acute ischemic stroke where a blood vessel in the brain is blocked by a blood clot. The brain tissue is then deprived of oxygen delivery and goes on to be irreversibly damaged if the artery is not opened up again. A large vessel occlusion (LVO) is when a large arterial branch is blocked and a significant territory of the brain compromised. A lacunar infarct is a type of stroke in which a very small vessel is blocked in the base of the brain. A hemorrhagic stroke is a general term for a ruptured blood vessel in the brain. This type of stroke is less common than ischemic stroke and is discussed elsewhere on our website related to individual types of pathology.
What are the symptoms of a stroke?
Stroke symptoms depend on the location of the blood vessel that is blocked. Most classically, with blockage of one of the main arteries that predominantly supplies the majority of either hemisphere (middle cerebral artery (MCA)), patients present with paralysis and loss of sensation on the opposite side of the body. Depending on the side and extent of the blockage, this may additionally variably impact understanding/production of speech, vision and a variety of other functions.
How is a stroke diagnosed?
Stroke onset tends to be sudden. Therefore, the initial diagnosis begins with recognition of a new problem by the patient or family members with rapid activation of emergency medical services. A rapid neurological examination helps further triage care, followed by emergent transportation and a CT scan. The CT scan allows us to identify if a large stroke has already become established, or if it is of a hemorrhagic variety. This is critical to determine the type of further management. A CTA is typically also performed (CT angiography), which involves the injection of IV contrast to depict the blood vessels in detail. This allows us to determine whether an LVO is present. CTP (CT perfusion) is a type of supplementary imaging utilized in patients who present in an extended time frame from when they were last seen normal. This helps to characterize how small or large of a stroke has already occurred, predicting the degree to which a patient will benefit from a procedure. Lastly, an MRI scan is often performed after initial management as the most accurate modality to characterize the size of a stroke. Given the time it takes to perform an MRI scan, it is only seldom used in the initial patient assessment.
How is stroke treated?
The main treatments for stroke are medical and interventional. The initial medical treatment for stroke is a clot-busting medication (thrombolytic) known as tPA, which is administered intravenously for patients that meet strict criteria. If a CT scan reveals bleeding in the brain or a large established stroke, tPA cannot be given due to bleeding risks. Regardless of whether or not tPA is administered, the current standard of care for an LVO is known as mechanical thrombectomy. This procedure involves minimally invasive access through the femoral artery in the leg (or occasionally the arteries of the arm) followed by navigation of a device that removes the clot to the blocked blood vessel.