Brain Primer

Stroke

  • Published28 Aug 2023
  • Author Gail Zyla
  • Source BrainFacts/SfN
Nurse helping older woman
iStock.com via Edwin Tan

Like the rest of your body, your brain requires a steady flow of oxygen and glucose-rich blood for it to function. When the blood flow to one area is interrupted or blocked, brain cells can start to die within minutes.

Each year, nearly 800,000 people in the United States suffer a stroke — an interruption in blood flow to the brain due to a ruptured blood vessel or a blood clot. Of these, about 600,000 are first-time strokes. Strokes are a leading cause of long-term disability in the United States, costing about *$56.5 billion each year, including the costs of health care services and medicines to treat stroke, and missed days of work.

Risk factors for stroke include older age, high blood pressure, atrial fibrillation, heart disease, high cholesterol, diabetes, physical inactivity, obesity, smoking, and drinking too much alcohol. Controlling these factors by maintaining a healthful weight, exercising, avoiding excessive alcohol intake, and taking medications for stroke-related physical problems can reduce the risk of having a stroke. There is also a genetic risk for stroke, especially evident if there is a parental history of stroke. To date, several candidate genes have been suggested, but increased stroke risk is most likely due to multiple genetic factors. There are also well-defined genetic risks of stroke such a sickle cell disease.

There are various types of strokes. Ischemic strokes occur when a blood vessel supplying blood to the brain clots. These account for 87% of all strokes. These strokes can occur due to a buildup of cholesterol in the blood vessel wall or a detachment of a clot from the carotid arteries (major blood vessels that provide your brain's blood supply) or the heart, lodging itself into a blood vessel in your brain. A transient ischemic attack (TIA) is a temporary blockage of blood flow to the brain, which usually gets dislodged or dissolves on its own with symptoms that usually last up to a day or less. This “warning stroke” signals a possible full-blown stroke ahead. Hemorrhagic strokes occur when a weakened blood vessel ruptures and bleeds into the brain. All these causes of strokes are serious medical conditions that require emergency care as quickly as possible to prevent further brain damage or death.

The acronym B.E.F.A.S.T. can be used to help people identify and act on the early warning signs of a stroke. B.E.F.A.S.T. stands for:

  1. Balance (a sudden loss of balance or coordination, or onset of dizziness)
  2. Eyes (a sudden difficulty seeing out of one or both eyes)
  3. Face (asymmetry or numbness in the face)
  4. Arms (weakness or numbness in the arms)
  5. Speech (slurred or garbled speech)
  6. Time (call emergency services if any of the above signs are present)

Until recently, treatments for a stroke did not go far beyond physical or speech therapy. Today, however, clot-dissolving medications known as thrombolytics are a standard treatment. Tissue plasminogen activator (tPA), a clot-dissolving drug approved by the FDA in 1996, helps to break down blood clots and open blocked blood vessels. tPA can restore circulation before oxygen and glucose loss causes permanent brain damage; given within three hours of a stroke, its use often limits brain damage. Tenecteplase (TNK), another thrombolytic not FDA approved for stroke treatment, has been used in clinical trials to test its effectiveness as an alternative thrombolytic. Anticoagulant drugs given to patients with stroke risk factors help by reducing the likelihood of clots forming in the heart or arteries and traveling to the brain, causing a stroke. In addition, major advances in surgery has shown success in opening clogged arteries, and treatments targeting heart problems like atrial fibrillation can help prevent strokes.

Strokes have a range of long-term outcomes: paralysis, weakness, numbness, pain, mental health conditions, and trouble with speech, cognition, emotions, and motor skills. Rehabilitation efforts following strokes can include engaging in physical therapy, speech therapy, occupational therapy, and connecting with support groups.

Research is underway to find new methods for preventing and treating strokes. Some drugs have been shown to be effective at preventing damage to the nervous system, including nerve cell death following a stroke. Another promising research area is the use of neural stem cells to improve recovery after a stroke. Preliminary research suggests that injection of stem cells helps promote recovery, even when given several days after a stroke. Administering growth-stimulating substances along with the stem cells might enhance the benefits of stem cell transplant.


Adapted from the 8th edition of Brain Facts by Gail Zyla.

*This number has been updated to reflect the latest estimates for stroke’s cost of illness in the United States.

CONTENT PROVIDED BY

BrainFacts/SfN

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