What is Stroke?

Stroke occurs when a clogged or burst artery interrupts blood flow to the brain. This interruption of blood flow deprives the brain of needed oxygen and causes the affected brain cells to die. When brain cells die, function of the body parts they control is impaired or lost.

What are the types of stroke?
Stroke can be caused either by a clot obstructing the flow of blood to the brain (ischemic stroke) or by a blood vessel rupturing and preventing blood flow to the brain (hemorrhagic stroke).

Ischemic Stroke (Clots)
Ischemic stroke accounts for about 87 percent of all cases. Ischemic strokes occur as a result of an obstruction within a blood vessel supplying blood to the brain. The underlying condition for this type of obstruction is the development of fatty deposits lining the vessel walls. This condition is called atherosclerosis.

These fatty deposits can cause two types of obstruction:

• Cerebral thrombosis refers to a thrombus (blood clot) that develops at the clogged part of the vessel.
• Cerebral embolism refers generally to a blood clot that forms at another location in the circulatory system, usually the heart and large arteries of the upper chest and neck. A portion of the blood clot breaks loose, enters the bloodstream and travels through the brain’s blood vessels until it reaches vessels too small to let it pass. A second important cause of embolism is an irregular heartbeat, known as atrial fibrillation. It creates conditions where clots can form in the heart, dislodge and travel to the brain.

Hemorrhagic (Bleeds)
Hemorrhagic stroke accounts for about 13 percent of stroke cases. It results from a weakened vessel that ruptures and bleeds into the surrounding brain. The blood accumulates and compresses the surrounding brain tissue. The two types of hemorrhagic strokes are intracerebral hemorrhage or subarachnoid hemorrhage.

Intracerebral refers to blood escaping from blood vessels into deep tissue. Subarachnoid refers to blood escaping from blood vessels on the surface of the brain into the limited area called the subarachnoid space.

The two types of weakened blood vessels that may cause hemorrhagic stroke are aneurysms and arteriovenous malformations (AVMs).

Aneurysm is a ballooning of a weakened region of a blood vessel. If left untreated, the aneurysm continues to weaken until it ruptures and bleeds into the brain.

Arteriovenous malformation (AVM) is a cluster of abnormally formed blood vessels. Any one of these vessels can rupture, also causing bleeding into the brain.

What are the effects of stroke?
The brain is an extremely complex organ that controls various body functions. If a stroke occurs and blood flow can’t reach the region that controls a particular body function, that part of the body won’t work as it should.

If the stroke occurs toward the back of the brain, for instance, it’s likely that some disability involving vision will result. The effects of a stroke depend primarily on the location of the obstruction and the extent of brain tissue affected. However, because one side of the brain controls the opposite side of the body, a stroke affecting the right side of the brain will result in neurological complications on the side of the left side of the body and vice versa.

Right Brain
If the stroke occurs in the brain’s right side, the left side of the body (and the left side of the face) will be affected, which could produce any or all of the following:

• Paralysis on the left side of 
the body
• Vision problems
• Acting without thinking 
of consequences
• Memory loss

Left Brain
If the stroke occurs in the left side of the brain, the right side of the body (and the right side of the face) will be affected, producing some or all of the following:

• Paralysis on the right side of 
the body
• Speech/language problems
• Slow, cautious behavioral style
• Memory loss

Brain Stem
When stroke occurs in the brain stem, depending on the severity of the injury, it can affect both sides of the body and may leave someone in a ‘locked-in’ state. When a locked-in state occurs, the patient is generally unable to speak or achieve any movement below the neck.

Statistics on Stroke
In the United States:

• In 2018, one in every six deaths from cardiovascular disease was due to stroke
• About 795,000 Americans each year suffer a stroke
• About 185,0000 strokes, nearly one in four, are recurrent stroke
• On average, a stroke occurs every 40 seconds
• Stroke kills about 140,000 people a year. That’s about 1 of every 20 deaths. It’s the number five cause of death behind diseases of the heart, cancer, accidents and chronic lower respiratory diseases.
• The risk of having a first stroke is nearly twice as high for people of color as for Caucasians, with African-Americans having the highest rate of death due to stroke
• Between 2014 and 2015, there was nearly $46 billion in stroke-related medical costs in the United States
• Stroke risk increases with age, but strokes can, and do, occur at any age.

In Minnesota:

• From 2012-2016, the stroke death rate was 26 percent higher in both African-Americans and Asians compared to whites. The lowest stroke death rates are in Hispanic men and women.
• In 2017, approximately 2.4 percent of adults in Minnesota reported ever having had a stroke in their lifetime – over 100,000 people
• More than five percent of all deaths in Minnesota are due to stroke, making it the sixth-leading cause of death in the state
• In 2016, Minnesotans experienced more than 11,000 hospitalizations for acute stroke events
• In 2017, Minnesota was ranked 11th lowest for overall stroke mortality in the United States.

Information courtesy of the Centers for Disease Control and Prevention and the Minnesota Department of Health