A cerebrovascular accident (CVA), commonly called a stroke, occurs when blood flow to part of the brain is interrupted or when a blood vessel in the brain ruptures. Brain cells in the affected area begin dying within minutes, making stroke the third leading cause of death and disability worldwide. In 2021, there were roughly 11.9 million new strokes globally, and the lifetime risk has increased by 50% over the past two decades. One in four adults is now predicted to experience a stroke in their lifetime.
Ischemic vs. Hemorrhagic Stroke
There are two main types of CVA, and knowing the difference matters because they require opposite treatments.
Ischemic stroke is the more common type. It happens when a blood clot or buildup of fatty deposits blocks an artery supplying the brain. Without blood flow, the affected brain tissue loses its energy supply. Cells burn through their remaining fuel, toxic levels of calcium flood in, and a chain reaction of damage follows: cell membranes break down, swelling develops, and destructive molecules called free radicals tear through proteins and DNA. This cascade ultimately kills neurons through a mix of rapid cell death and slower, programmed self-destruction. The area of brain tissue that dies is called an infarct.
Hemorrhagic stroke is less common but more deadly. It occurs when a blood vessel in the brain ruptures, spilling blood into the surrounding tissue or into the space around the brain. The most frequent causes are uncontrolled high blood pressure, blood-thinning medications, a condition where abnormal proteins weaken blood vessel walls, and malformed blood vessels. The bleeding itself damages brain cells, and the pooling blood creates pressure that injures even more tissue nearby.
Warning Signs: The BE FAST Method
Recognizing a stroke quickly is the single most important factor in survival and recovery. The expanded BE FAST acronym covers the key signs:
- Balance: Sudden loss of balance or coordination
- Eyes: Vision changes, including loss of sight in one or both eyes, or sudden double vision
- Face: Drooping on one side of the face
- Arms: Weakness or numbness in one arm or leg
- Speech: Slurred words, difficulty speaking, or trouble understanding others
- Time: Call emergency services immediately
Symptoms typically appear on one side of the body because each half of the brain controls the opposite side. A stroke in the left hemisphere, for instance, usually causes right-sided weakness and may affect language. These signs can appear suddenly and without pain, which is partly why people sometimes wait too long to call for help.
Transient Ischemic Attack
A transient ischemic attack (TIA) produces the same symptoms as a full stroke but lasts only minutes, typically under an hour, and causes no permanent brain damage. It happens when blood flow to the brain is briefly interrupted and then restored on its own. A TIA is a medical emergency, not a minor event. It signals that a full stroke may follow in the days or weeks ahead, making it a critical window for diagnosis and prevention.
Major Risk Factors
A large international study across 22 countries found that 10 modifiable risk factors explain about 90% of all stroke risk. High blood pressure stands far above the rest: it accounts for roughly 54% of strokes in the population. That makes blood pressure management the single most impactful thing you can do to lower your risk.
The other well-established risk factors include diabetes, high cholesterol, smoking, physical inactivity, poor diet, obesity, excessive alcohol use, heart conditions like atrial fibrillation, and high stress or depression. Non-modifiable risk factors include age, sex, and race, with stroke risk roughly doubling each decade after age 55.
How a Stroke Is Diagnosed
When you arrive at the hospital with suspected stroke symptoms, the first imaging test is almost always a non-contrast CT scan of the head. It’s fast and widely available, and its primary job is to determine whether you’re having a hemorrhagic stroke, since bleeding shows up clearly on CT. This distinction is critical because the treatments for ischemic and hemorrhagic stroke are fundamentally different.
CT is less sensitive at detecting early ischemic changes, though experienced radiologists can spot subtle signs like blurring of the boundary between gray and white matter or a bright spot indicating a clot in a major artery. MRI is more sensitive and more specific for ischemic stroke, particularly for small areas of damage and strokes in the back of the brain, where CT has limitations. MRI also does a better job distinguishing true strokes from conditions that mimic stroke symptoms. The trade-off is that MRI takes longer and isn’t available in every emergency department. In practice, most acute stroke evaluations start with CT, with MRI used for follow-up or more complex cases.
Acute Treatment
For ischemic stroke, the primary goal is restoring blood flow as quickly as possible. The standard clot-dissolving medication can be given intravenously to eligible patients within 3 hours of when they were last known to be normal. A slightly broader window of up to 4.5 hours applies for a more selective group of patients. Every minute matters: the faster treatment begins, the more brain tissue is saved.
For strokes caused by a large clot in a major brain artery, a procedure called mechanical thrombectomy may be performed. A catheter is threaded through a blood vessel, typically from the groin, up to the blocked artery in the brain, where the clot is physically removed. This procedure is most effective within the first 6 hours, but recent evidence shows it can still work up to 24 hours after symptom onset in selected patients with confirmed large vessel blockages.
Hemorrhagic strokes are treated differently. The priority is controlling bleeding, managing blood pressure, and reducing pressure inside the skull. Surgery may be needed to drain pooled blood or repair a ruptured blood vessel.
Recovery and Rehabilitation
Rehabilitation typically begins within 24 hours of the stroke being treated. In the hospital, therapy sessions may happen up to six times per day in the initial period, covering physical, occupational, and speech therapy depending on the deficits. This early work helps clinicians assess the extent of the damage while jumpstarting the brain’s recovery process.
The first three months after a stroke represent the most critical recovery window. This is when the brain is most actively reorganizing itself, forming new neural pathways to compensate for damaged areas. During this period, some patients experience spontaneous recovery, where a skill or ability that appeared lost suddenly returns as the brain finds alternative routes to perform the task. Most patients complete an inpatient rehabilitation program or make significant progress in outpatient therapy during this time.
By the six-month mark, the pace of improvement slows considerably and most patients reach a relatively stable baseline. That doesn’t mean recovery stops entirely. Gains are still possible after six months, but they come more slowly and require sustained effort. The type and severity of lasting effects vary enormously depending on which brain region was affected, how much tissue was damaged, and how quickly treatment was received. Some people recover nearly fully; others live with long-term challenges in movement, speech, memory, or emotional regulation.