An AVC, or Cerebrovascular Accident, is the medical term for what is commonly known as a stroke, representing a sudden and serious event affecting the blood supply to the brain. This event occurs when a part of the brain is deprived of oxygen and nutrients, leading to the rapid death of brain cells. Because brain tissue begins to die within minutes, an AVC is an absolute medical emergency requiring immediate attention.
Understanding the Two Main Types
The two main types of AVC are Ischemic and Hemorrhagic. An Ischemic AVC is the most frequent type, accounting for approximately 85% of all cases, and occurs due to a blockage in a blood vessel supplying the brain. This blockage usually involves a blood clot. The clot may form directly within a brain artery (thrombotic stroke) or travel from another part of the body before lodging in a smaller cerebral vessel (embolic stroke). This blockage results in ischemia, causing cellular damage and infarction due to a lack of blood flow and oxygen.
The less common form is a Hemorrhagic AVC, which results from a blood vessel in the brain rupturing or leaking. This rupture causes blood to spill into the surrounding brain tissue, creating pressure from the pooling blood (hematoma) and depriving the area beyond the rupture of blood flow. Hemorrhagic strokes are frequently caused by high blood pressure, which weakens arterial walls over time. The resulting increase in intracranial pressure can lead to widespread brain injury.
Identifying Warning Signs and Symptoms
Recognizing the sudden onset of symptoms is crucial, as the speed of treatment directly impacts the extent of brain damage. The acronym F.A.S.T. is used to quickly identify the most common signs.
- F stands for Face drooping, where one side of the face may be numb or droop, making the smile appear uneven.
- A represents Arm weakness, meaning the person cannot raise one arm fully or keep it elevated.
- S refers to Speech difficulty, which can manifest as slurred speech or trouble understanding simple conversations.
- T stands for Time to call emergency services immediately, even if the symptoms appear to go away.
Other sudden symptoms can include a severe headache with no known cause, loss of balance, or sudden vision problems. The phrase “time is brain” emphasizes that millions of neurons can die every minute an AVC remains untreated.
Common Causes and Risk Factors
Many underlying health conditions increase the probability of an AVC by damaging blood vessels over time. High blood pressure (hypertension) is the leading risk factor for both ischemic and hemorrhagic strokes, as it stresses and weakens artery walls. Diabetes and high cholesterol contribute to atherosclerosis, the buildup of fatty plaques inside the arteries that narrows them and promotes clot formation. Individuals with atrial fibrillation, an irregular heart rhythm, are also at an elevated risk because the condition allows clots to form in the heart and travel to the brain.
Controllable lifestyle factors include smoking, which thickens the blood and promotes plaque buildup, and excessive alcohol consumption, which raises blood pressure. Obesity and a lack of physical activity also contribute to related risk factors like hypertension and diabetes. Uncontrollable risk factors include increasing age and a family history of AVC or cardiovascular disease. A prior stroke or transient ischemic attack (TIA) also indicates a much higher risk of a future AVC.
Immediate Medical Response and Treatment
Upon arrival at the hospital, the immediate priority is a rapid diagnosis to determine the type of AVC. Emergency medical teams use imaging tests, such as a computed tomography (CT) scan or magnetic resonance imaging (MRI), to confirm if the stroke is ischemic or hemorrhagic. This differentiation is essential because the treatments for the two types are opposed. For an ischemic AVC, the goal is to quickly restore blood flow by dissolving or removing the clot.
The most common intervention is the administration of a clot-busting drug, tissue plasminogen activator (tPA), which must be given within a narrow window, typically within four and a half hours of symptom onset. For large vessel blockages, doctors may perform a mechanical thrombectomy, where a specialized device physically extracts the clot. Conversely, treatment for a hemorrhagic AVC focuses on controlling the bleeding and reducing pressure on the brain. This often involves strict blood pressure management and, sometimes, surgical intervention to clip the ruptured vessel or drain the accumulated blood. Following the acute phase, rehabilitation is initiated to help the patient regain lost function.