Understanding the Different Types of Strokes and Why They Occur

May 24, 2021

Approximately 700,000 Americans suffer a stroke each year. It is the fifth major cause of death in the United States. The good news is that stroke is treatable and preventable.

Every minute spent without adequate blood supply; 2 million brain cells die. A stroke is similar to a heart attack, except the blood flow to the brain, rather than the heart, is interrupted, explains David Roshal, DO, DABPN, neurologist and medical director of stroke services at Jefferson Health – New Jersey.

Strokes are also called cerebrovascular accidents (CVAs) or "brain attacks,” adds Dr. Roshal.

The gold standard mnemonic to help recognize stroke symptoms is B.E. F.A.S.T, which stands for Balance, Eyes, Face, Arm, Speech and Time (to call 911 and get immediate medical attention).  

Types of Stroke:

Ischemic strokes occur when a blood clot ("thrombus") or fatty plaque (composed of fat deposits/cholesterol) blocks blood flow to an area of the brain, says Dr. Roshal, causing death of the associated neurons/brain cells. “Fatty plaques often line the interior artery walls of people with a cardiovascular disease, called arteriosclerosis (or ‘hardening of the arteries’).”

Common modifiable risk factors for arteriosclerosis — and thus stroke — include high blood pressure, high cholesterol, smoking, diabetes, and obesity.

“These plaques narrow the arterial space in blood vessels, resulting in blood clots that reduce the amount of blood (and therefore oxygen) able to pass through,” continues Dr. Roshal. “Clots can also detach and float downstream (they are then referred to as emboli), block blood flow to other areas, and cause subsequent damage. Some 25 percent of ischemic strokes are cardioembolic, which result from blood clots that form in the heart due to an abnormal heart rhythm, such as atrial fibrillation or atrial flutter.”

Studies show approximately 85 percent of strokes are ischemic events. Arterial blood vessels can become blocked on a permanent or temporary basis; stroke generally results from a more permanent blockage.

Transient, temporary blockages are called Transient Ischemic Attacks (TIAs), which alter physical and/or mental function for less than 24 hours, but do not create lasting damage, explains Dr. Roshal. “Because symptoms are short-lived, a TIA is sometimes referred to as a ‘warning’ stroke. Those who experience TIAs are at greater risk for having serious strokes in the near future (next 90 days).”

The blockage that causes an ischemic stroke can be opened with “clot buster medicine,” says Dr. Roshal, and/or a neurosurgical procedure using a catheter or narrow tube to mechanically remove the clot. These interventions are very time-sensitive — “time is brain” — and outcomes are highly dependent on early treatment. Rehabilitation is also critical for increasing the chances of recovery. The key to preventing an ischemic stroke is to adequately treat the underlying modifiable risk factors, listed above.

Hemorrhagic strokes occur when a cerebral artery ruptures and spills blood into brain tissue, explains Dr. Roshal. This spilled blood collects inside the brain, exerting pressure and causing damage to delicate brain tissue. In addition, the ruptured vessels can’t perform their typical job of feeding blood to specific areas of the brain.

“Between being starved for oxygen and nutrients, and being squeezed by the pressure of spilled blood, the brain ends up being severely injured or destroyed,” said Dr. Roshal.

Studies show around 15 percent of strokes are hemorrhagic. High blood pressure is the leading cause of hemorrhagic stroke, which can be prevented with close monitoring of blood pressure and treatment when it gets too high. 

An acute, or sudden, brain bleed is usually treated in the neurosurgical ICU, says Dr. Roshal, by rapidly lowering blood pressure, as well as reversing the effects of any strong blood thinners (e.g., Coumadin) that the patient may be taking. “In some cases, a neurosurgeon may need to place a catheter into the brain, and/or remove part of the skull to drain the blood and relieve the pressure on the brain.”

Unfortunately, outcomes after a hemorrhagic stroke tend to not be as good as after an ischemic stroke.

Life After Stroke:

Though strokes can be fatal, many people survive them and even fully recover. In some cases, stroke survivors will experience a range of limitations. For example, someone might lose the ability to comprehend language, speak, walk, or control parts of their body.

Generally, the right side of the brain controls the left side of the body, and the left side of the brain controls the right side of the body, explains Dr. Roshal. “Due to ‘neuroplasticity,’ healthy areas of the brain are sometimes able to compensate for abilities lost to stroke. This is why we see people experience partial recovery, and some, even full recovery of pre-stroke abilities, especially with the help of post-stroke rehabilitation.”

Remember, stroke can be treatable and, most importantly, preventable. TIME IS BRAIN!

To learn more about stroke and Neuroscience services offered at Jefferson Health in New Jersey, click HERE.