Neurological Diseases (General)

Stroke

A stroke is in many ways analogous to a heart attack of the brain. When the brain does not receive a sufficient amount of blood, neurons are deprived of the nutrients and oxygen they need to survive. Two major types of stroke exist: the ischemic stroke and the hemorrhagic stroke. In an ischemic stroke, blood is blocked from getting to the brain. This usually happens because of fatty deposits in arteries (atherosclerosis) or a blood clot (emboli). A hemorrhagic stroke occurs when a blood vessel in the brain bursts and bleeds. It is often caused by an aneurysm—a thin and/or weak area of an artery. A milder form of stroke, a transient ischemic attack (TIA), occurs when less blood than normal gets to the brain but there is never complete occlusion. The duration of a TIA is usually short and the symptoms can range from nonexistent to remarkably similar to a complete stroke. The signs of stroke are usually sudden in onset and include numbness or weakness of the face, arm, or leg (mainly on one side of the body); trouble seeing in one or both eyes; trouble walking, dizziness, or loss of balance; confusion or trouble talking or understanding speech; or a bad headache with no known cause.

A stroke is usually diagnosed by a physician who conducts a complete neurological exam and, when available, employs multiple imagines modalities. Computed tomography (CT) and magnetic resonance imaging (MRI) scans are the most common techniques used for suspected stroke victims. A CT scan is helpful in distinguishing between an ischemic and hemorrhagic stroke. A Doppler ultrasound can detect blood flow problems and is the least invasive imaging modality.

The effects of a stroke vary depending on what part of the brain is involved. A stroke in the right hemisphere can cause problems judging distances, behavior changes, and short-term memory loss. A stroke in the left hemisphere can cause speech and language problems, and memory impairment. A stroke in the cerebellum will affect balance and coordination. Strokes in the brain stem can be particularly devastating, causing paralysis, loss of various sensations (i.e., pain, temperature, vibration), and even death.

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