A stroke occurs when the blood supply to a part of the brain is interrupted. This prevents brain tissue from receiving the oxygen and nutrients it needs. Brain cells can die within minutes without this supply, highlighting the time-sensitive nature of stroke.
What is an Ischemic Stroke?
An ischemic stroke occurs when a blood clot obstructs an artery supplying blood to the brain. This blockage deprives brain tissue of oxygen and nutrients, leading to cell damage. Ischemic strokes are the most common type, accounting for approximately 87% of all cases.
These blockages form in two primary ways. A thrombotic stroke happens when a blood clot develops within a brain artery, often in vessels damaged by fatty deposits. An embolic stroke occurs when a clot forms elsewhere, travels through the bloodstream, and lodges in a narrower brain artery.
What is a Hemorrhagic Stroke?
A hemorrhagic stroke results from a ruptured blood vessel in the brain, causing blood to leak into surrounding brain tissue or spaces. This bleeding directly damages brain cells and creates pressure that harms brain tissue. Hemorrhagic strokes are less common, making up about 13% to 15% of all incidents.
This type of stroke is categorized into two main forms. An intracerebral hemorrhage involves bleeding within the brain tissue itself. A subarachnoid hemorrhage occurs when bleeding happens in the space between the brain and its surrounding membranes.
How Do They Differ?
The main distinction between ischemic and hemorrhagic strokes lies in their underlying mechanism. Ischemic strokes involve a blockage that cuts off blood flow, like a clogged pipe. Hemorrhagic strokes involve a burst blood vessel that causes bleeding, similar to a pipe bursting.
Many stroke symptoms can overlap, such as sudden weakness, difficulty speaking, or vision problems. However, some symptoms may offer clues to the type. Hemorrhagic strokes often present with a sudden, severe headache. Seizures are also more frequently associated with hemorrhagic strokes.
Which Type is More Dangerous?
Hemorrhagic strokes carry a higher risk of mortality and more severe long-term disability. The immediate fatality rate for hemorrhagic stroke is greater than for ischemic stroke. For instance, the 30-day death rate for hemorrhagic stroke can be as high as 50%, whereas for ischemic stroke, it is around 10% to 15%.
This increased danger stems from several factors. Bleeding in a hemorrhagic stroke directly damages brain tissue and can lead to a rapid increase in pressure within the skull. This pressure can further compromise brain function and blood flow. Additionally, blood outside of vessels can irritate brain tissue and lead to vasospasm, where blood vessels constrict, potentially causing further damage.
What Happens After a Stroke?
A stroke is a medical emergency requiring immediate attention. Calling emergency services promptly is important, as early treatment can significantly reduce brain damage and improve outcomes. Medical professionals use brain imaging, such as a CT scan, to quickly determine whether the stroke is ischemic or hemorrhagic, which guides treatment decisions.
Treatment for an ischemic stroke often involves medications to dissolve the blood clot or procedures to remove it. For a hemorrhagic stroke, the focus is on controlling bleeding and managing pressure within the brain, sometimes requiring surgery. Following emergency treatment, rehabilitation is a key part of recovery, often beginning soon after the stroke to help individuals regain lost abilities and adapt to any lasting effects.