A cerebral infarction is an area of dead brain tissue caused by a blocked blood supply. It’s the medical term for what most people know as an ischemic stroke, which accounts for roughly 87% of all strokes. In 2021, nearly 70 million people worldwide were living with the effects of ischemic stroke, with about 92 new cases per 100,000 people each year.
How a Cerebral Infarction Happens
Your brain depends on a constant flow of blood to deliver oxygen and glucose. Normal brain tissue receives more than 17 milliliters of blood per 100 grams of tissue every minute. When a clot or other blockage cuts off an artery feeding the brain, blood flow drops rapidly. If flow falls below about 10 mL per 100 grams per minute, brain cells in that zone begin to die within minutes. This region of irreversible damage is the infarct core.
Surrounding the core is a ring of tissue called the ischemic penumbra, where blood flow is reduced (roughly 10 to 17 mL per 100 grams per minute) but cells are still alive and potentially salvageable. The penumbra is the target of emergency treatment. Without restored blood flow, the penumbra gradually converts into dead tissue over the following hours, expanding the final size of the infarction.
What Causes the Blockage
The standard classification system identifies five subtypes of cerebral infarction based on the underlying cause:
- Large-artery atherosclerosis: Fatty plaque builds up in a major artery supplying the brain, eventually narrowing it enough to block flow or send a chunk of plaque downstream.
- Cardioembolism: A blood clot forms in the heart, often due to an irregular heartbeat like atrial fibrillation, and travels to the brain.
- Small-vessel occlusion: Tiny arteries deep inside the brain become blocked, producing small infarctions called lacunar strokes. These tend to be less than 20 mm in diameter and occur in deep brain structures where small branches split off from the brain’s major arteries at sharp angles.
- Other determined causes: Less common conditions like blood-clotting disorders, artery dissections, or inflammatory diseases.
- Undetermined cause: No single cause can be identified despite thorough testing, or multiple causes are present.
Major Risk Factors
The INTERSTROKE study, which examined over 13,000 first-ever stroke cases across 32 countries, found that ten modifiable risk factors collectively accounted for about 91% of all strokes. High blood pressure alone was responsible for nearly 48% of the population risk, making it by far the single largest contributor. Physical inactivity and abnormal blood lipid levels each contributed about 36%. Poor diet accounted for roughly 23%.
Non-modifiable risk factors include age (risk roughly doubles each decade after 55), male sex, and family history of stroke. Diabetes, smoking, heavy alcohol use, and obesity round out the list of well-established contributors. Because so many of the major risk factors are treatable or preventable, the majority of cerebral infarctions are theoretically avoidable.
Symptoms by Location
The symptoms of a cerebral infarction depend entirely on which artery is blocked and what part of the brain it supplies. The middle cerebral artery is the most commonly affected vessel. Blockages here typically cause weakness or paralysis on one side of the body, difficulty speaking or understanding language, and neglect of one side of the visual field.
When the anterior cerebral artery is blocked, leg weakness is often more prominent than arm weakness, and personality or behavioral changes can occur because this artery supplies the frontal lobe. Posterior cerebral artery infarctions primarily affect vision. A blockage on one side can wipe out half the visual field in both eyes, while bilateral blockages can cause complete cortical blindness. Damage in this territory can also impair the ability to read, perceive colors, or form new memories if structures involved in memory processing are affected.
Lacunar infarctions in the deep brain typically produce isolated symptoms: pure weakness on one side, pure numbness on one side, or a combination of clumsiness and weakness in a hand and leg.
How It’s Diagnosed
A non-contrast CT scan of the head is usually the first imaging test performed in the emergency room because it’s fast and widely available. Its primary job is to rule out bleeding in the brain, which requires completely different treatment. However, CT is not great at detecting the infarction itself in the early hours. In one comparison study, CT identified large territory involvement only 14 to 43% of the time.
MRI with diffusion-weighted imaging is far more sensitive, detecting the same large infarctions 57 to 86% of the time. Diffusion-weighted MRI can reveal dead or dying brain tissue within minutes of the blockage. Advanced perfusion imaging, which maps blood flow in real time, can also distinguish the salvageable penumbra from the infarct core and help determine whether a patient is still a candidate for treatment even hours after symptoms began.
Emergency Treatment Windows
The central goal of acute treatment is reopening the blocked artery before the penumbra dies. Intravenous clot-dissolving medication has traditionally been given within 4.5 hours of symptom onset. Updated guidelines now extend this window for carefully selected patients. If someone wakes up with stroke symptoms or has an unknown time of onset, MRI can determine whether enough brain tissue is still salvageable to justify treatment. In some cases, clot-dissolving therapy can be considered up to 9 hours from the midpoint of sleep, and in select patients with favorable imaging, up to 24 hours from when they were last known to be well.
For blockages in large arteries, a procedure called mechanical thrombectomy can physically retrieve the clot using a catheter threaded through the blood vessels. This approach has dramatically improved outcomes for the most severe strokes and is also guided by advanced imaging to identify patients who will benefit.
Complications After the Infarction
Even after initial treatment, the brain continues to respond to the injury in ways that can worsen the situation. Swelling (cerebral edema) develops as damaged cells absorb excess fluid. In large infarctions, this swelling can become life-threatening by compressing surrounding healthy brain tissue, typically peaking two to five days after the stroke.
Hemorrhagic transformation is another concern, where blood leaks into the area of dead tissue. This is more likely in larger infarctions and in patients who received clot-dissolving medication, though the overall benefit of treatment still outweighs this risk in appropriately selected patients. Research has linked both complications to impaired autoregulation, the brain’s normal ability to maintain stable blood flow despite changes in blood pressure.
Long-Term Prevention
After a cerebral infarction, the priority shifts to preventing a second one. Antiplatelet medications reduce the tendency of blood to form new clots. Standard options include low-dose aspirin (80 to 325 mg daily) or an alternative antiplatelet drug at 75 mg daily. For people whose stroke was caused by a heart-related clot, blood thinners that target the clotting cascade are used instead.
High-intensity cholesterol-lowering medication is a cornerstone of secondary prevention, particularly for strokes related to atherosclerosis. Aggressive blood pressure management is equally important given that hypertension drives nearly half of all stroke risk. Lifestyle changes, including regular physical activity, a diet rich in fruits, vegetables, and whole grains, smoking cessation, and moderate alcohol intake, address several of the top risk factors simultaneously. Because these modifiable factors account for over 90% of stroke risk at a population level, sustained changes in daily habits are as important as any medication.