Types of Stroke
Stroke occurs when the brain is deprived of oxygen and essential nutrients, killing the brain cells in the immediate vicinity.
This can happen one of two ways:
Ischemic Stroke - vessel in the brain clogs
Hemorrhagic Stroke - A vessel in the brain ruptures
More than 80 percent of all strokes are due to ischemic cerebral infarction, where brain tissue is injured because the blood supply is lost. The other nearly 20 percent of strokes are due to bleeding into the brain because a blood vessel ruptures (commonly known as a hemorrhage).
Cerebrovascular disease (disease of the blood vessels delivering blood to the brain) can be caused by one of several processes that involve the blood vessels of the brain:
- Disease of the blood vessel, such as atherosclerosis, lipohyalinosis, inflammation, amyloid deposition, arterial dissection, developmental malformation, aneurysmal dilation or venous thrombosis
- A clot (embolus) from the heart or large vessels in the chest breaks off and lodges in a vessel inside the upper part of the skull
- Low pressure/flow of blood to the brain or sluggish flow due to increased blood viscosity (thickness)
Understanding why a stroke occurred helps doctors treat patients for an ischemic stroke. Usually, doctors suspect a cause when the patient first arrives and follow up with tests to confirm the cause of the stroke.
Because there isn't a single cause of stroke, there isn't a single treatment. Each stroke is unique, and treatment is tailored to the needs of the individual patient.
Hemorrhagic stroke occurs in only 17% of stroke cases, but is the more deadly type of stroke. This type of stroke takes place when a weakened blood vessel ruptures, causing bleeding in the immediate area. The blood compresses the brain tissue, which damages the brain cells.
Typically, there are two types of weakened blood vessels that cause hemorrhagic stroke, aneurysms and arteriovenous malformations (AVMs). Aneurysms occur when there is a bulging of a blood vessel caused by disease or weakening blood vessel wall. AVMs are a collection of abnormally created blood vessels. If any of the vessels rupture, severe bleeding will occur.
Transient Ischemic Attack (TIA)
Transient Ischemic Attack, also known as a TIA, can be caused by a temporary disturbance of blood supply to an area of the brain. Previously referred to as a “mini-stroke," during TIA the victim experiences the same symptoms of stroke, but the attack often resolves itself through natural methods.
TIAs can cause temporary or permanent neurological symptoms. TIAs often last only a few minutes and can reoccur with varying frequency. The attacks can reoccur as little as several times per year, once per week or even several times per day.
Symptoms usually include hand, arm, leg, face, tongue or cheek numbness or weakness. Language, visual or cognitive difficulty may also by symptoms of a TIA depending on the part of the brain involved.
When a TIA is cause by a stenotic lesion that obstructs blood flow to the vessels in the back of the brain, the recurrent symptoms are different than those described above. Since there are many closely packed neuronal structures in the brainstem this can cause a feeling of dizziness in the patient that may or may not include spinning or vertigo. Patients may feel as if the room is tilting or the floor is coming up at them.
Other symptoms may include numbness of one side of the body or face, slurred or difficult to understand speech and double vision.
There may also be leg and arm weakness or numbness on both sides of the body and a feeling of low energy or a sense of impending doom.
Ischemia occurring in the basilar artery may have many of the symptoms mentioned above in addition to overwhelming drowsiness, vertical double vision, eyelid drooping and the inability to look up.
TIAs are strong indicators of a future stroke. If you experience a TIA, learn about preventive measures against stroke. Our outpatient stroke clinic provides a full medical workup and evaluation for recovering stroke patients and those at high risk.