Stroke Basics

511792433.jpg

A stroke is brain damage that results from diminished blood supply to the brain. Generally, a stroke occurs when one of the blood vessels that delivers blood to the brain becomes blocked or leaks.

Stroke Symptoms 

A stroke causes symptoms that correspond to the area in the brain that suffers from diminished blood supply. A stroke can cause any of the following symptoms:

  • Weakness of one side of the body
  • Numbness, tingling or unusual sensations 
  • Trouble walking
  • Coordination problems 
  • Vision loss or decrease in vision
  • Blurred vision or double vision 
  • Slurred speech 
  • Trouble communicating 
  • Trouble understanding words
  • Face asymmetry
  • Droopy eyelid
  • Dizziness
  • Headache
  • Confusion

How the Brain Determines Stroke Symptoms

The brain is an important body organ that has many interacting regions that work to control a variety of functions- from thinking, to vision, to movement, to coordination, to sensation, to vital functions such as breathing and sustaining life. These regions work together in a coordinated, sophisticated fashion.

Proper brain function requires blood supply for the delivery of nutrients and oxygen. Blood is delivered to the brain through a group of blood vessels that travel to and through the brain. The blood vessels include the carotid arteries, the cerebral arteries, and the vertebral arteries.

Each blood vessel divides into smaller blood vessels that deliver blood to a specific region in the brain. Any decrease in blood supply to a portion of the brain results in impairment of the brain functions that are normally controlled by that area of the brain. A stroke can occur if a large or small blood vessel is blocked or bleeding, preventing proper delivery of nutrients and oxygen to the destination in the brain.

Depending on the blood vessel affected by a stroke and the part of the brain that is impaired, the initial symptoms and long-term effects may differ.

How a Stroke Happens

The blood that travels to the brain through arteries carries oxygen and nutrients that allow the brain to function and survive. When blood supply to an area of the brain is diminished, even temporarily, the brain tissue may suffers from ischemia- a lack of the oxygen and nutrients it needs to function. If ischemia lasts longer than a few minutes, the affected brain tissue may become severely damaged and cease to function- which is a stroke.

TIA and Silent Stroke

The effects of diminished blood supply may last for only a short time if the ischemia is brief and quickly restored. A brief period of ischemia may result in a transient ischemic attack (TIA).

When ischemia occurs in a small region of the brain that controls functions that are also controlled elsewhere in the brain, a silent stroke, or an unnoticeable stroke, may result.

Causes Of a Stroke

The blood supply to the brain can be interrupted due to blockage, bleeding or low blood flow.

Infarct: Blockage can be caused by blood clot that develops within the blood vessel (infarct) or a blood clot that arrived from another location and lodged in the blood vessel (thrombus.)

Hemorrhage: A bleeding blood vessel in the brain can result from a rupture of a defective blood vessel or from extreme blood pressure instability. In rare instances, a severe infection or an air bubble can block a blood vessel, causing a stroke. When a blood vessel breaks and bleeds, the brain is harmed by ischemia due to interruption of blood flow. However, when bleeding or hemorrhage occurs, irritation from the blood near the brain tissue also causes pain and neurological symptoms, in addition to the stroke symptoms caused by ischemia.

What To Do In Case Of a Stroke

Recognition of stroke symptoms is important.

Diagnosis may require medical specialists. Prompt diagnosis is necessary because treatment for stroke requires careful, high level, decision making. The most effective treatments for stroke are most successful when administered promptly.

Stroke Treatment

Treatment of stroke consists of methods that allow reestablishment of blood supply to the ischemic brain tissue and stabilization of health and vital functions to allow for optimal recovery. Reestablishment of blood supply is tricky- in some instances, in can result in bleeding. In the initial stage of a stroke, the ischemic tissue is prone to bleeding, so extreme care must be taken with re-establishment of blood flow.

A Word From Verywell

Long-term effects of a stroke vary tremendously, but most people recover and experience some improvement. Recovery includes physical rehabilitation and supportive care.

Prevention of recurrent strokes and addressing underlying risk factors is a critical component of stroke recovery. If you have experienced a stroke or a TIA, that is a sign that that you may be at risk of having another stroke. Identification of stroke risk factors is important because most stroke risk factors can be managed to reduce the risk of stroke.

Further reading:

Ischemic Stroke: Advances in Diagnosis and Management, Cassella CR, Jagoda A, Emerg Med Clin North Am. 2017 Nov;35(4):911-930. doi: 10.1016/j.emc.2017.07.007.