There are three main types of stroke: ischemic stroke, hemorrhagic stroke, and transient ischemic attack (TIA). Ischemic strokes, caused by blocked blood vessels, account for roughly 87% of all strokes. Hemorrhagic strokes are caused by bleeding in or around the brain. TIAs, sometimes called mini-strokes, involve a temporary blockage that resolves on its own. Within these three categories, there are several important subtypes worth understanding.
Ischemic Stroke
An ischemic stroke happens when a blood clot or buildup of fatty deposits blocks an artery supplying blood to the brain. Without blood flow, brain cells in the affected area begin to die within minutes. This is by far the most common type, and it breaks down into two main subtypes based on where the clot forms.
A thrombotic ischemic stroke occurs when a clot develops directly inside an artery in the brain. This typically happens in arteries that have already narrowed over time from plaque buildup. An embolic ischemic stroke, on the other hand, involves a clot that forms somewhere else in the body, often the heart or a large artery in the neck, and then travels through the bloodstream until it lodges in a smaller brain artery. The distinction matters because the underlying cause shapes long-term treatment and prevention strategies.
About one in three ischemic strokes (roughly 35%) are classified as cryptogenic, meaning doctors can’t pinpoint a definitive cause even after thorough testing. That translates to more than 240,000 strokes per year in the U.S. alone. In many of these cases, an undetected heart rhythm abnormality or other hidden condition may be responsible, and identifying the cause becomes a priority to prevent a second stroke.
Hemorrhagic Stroke
A hemorrhagic stroke occurs when a blood vessel in or near the brain ruptures and blood spills into surrounding tissue. This bleeding damages brain cells both directly and by increasing pressure inside the skull. Though less common than ischemic strokes, hemorrhagic strokes tend to be more deadly.
There are two subtypes, classified by where the bleeding occurs.
Intracerebral Hemorrhage
This is the more common form of hemorrhagic stroke. Bleeding happens directly inside brain tissue, usually because chronic high blood pressure has weakened a small artery to the point of rupture. Over years, uncontrolled blood pressure gradually damages vessel walls, making them fragile and prone to breaking open.
Subarachnoid Hemorrhage
In this type, bleeding occurs in the space between the brain and the thin membranes that cover it. The most frequent cause is a ruptured aneurysm, a balloon-like weak spot on an artery wall. Some people are born with aneurysms; others develop them later due to high blood pressure or hardening of the arteries. A less common cause is an arteriovenous malformation (AVM), a tangled cluster of abnormal blood vessels that can rupture. AVMs are present from birth, and their exact cause is unknown, though they can sometimes be genetic.
Transient Ischemic Attack (TIA)
A TIA works the same way as an ischemic stroke, with a clot temporarily blocking blood flow to part of the brain, but it resolves on its own. Symptoms are identical to a full stroke: sudden numbness, confusion, trouble speaking, or vision changes. The key difference is that TIA symptoms disappear within 24 hours, and most clear up in just minutes. A TIA also leaves no permanent damage visible on brain imaging, while an ischemic stroke does.
Despite being temporary, a TIA is a serious warning sign. Having one often means a full stroke could follow in the near future. It signals that something in your vascular system, whether a narrowed artery, a clotting problem, or a heart rhythm issue, is creating conditions for a stroke. Treating those underlying causes after a TIA is one of the most effective ways to prevent a major stroke.
Silent Strokes
Not all strokes produce noticeable symptoms. Silent cerebral infarctions are small strokes that occur without any obvious neurological signs. They’re typically discovered by accident, when a brain scan is performed for another reason and reveals evidence of past damage from a blocked blood vessel. Because there are no symptoms at the time, most people have no idea they’ve had one.
Silent strokes are far from harmless, though. Each one destroys a small area of brain tissue, and over time, repeated silent strokes can contribute to problems with memory, thinking, and movement. The risk factors are the same ones that drive other stroke types: high blood pressure, diabetes, smoking, and aging.
Cerebral Venous Sinus Thrombosis
Most strokes involve arteries, but a rare form called cerebral venous sinus thrombosis (CVST) involves a clot forming in the brain’s veins. These veins normally drain blood away from the brain, and when they’re blocked, blood backs up and can leak into brain tissue. CVST affects about 5 people per million each year.
Symptoms can look different from a typical stroke. Headache, blurred vision, seizures, and fainting are common, and the onset is sometimes more gradual. Risk factors include pregnancy and the early postpartum period, blood clotting disorders, cancer, obesity, and inflammatory conditions like Crohn’s disease or lupus. In children and newborns, sickle cell anemia, infections, dehydration, and heart defects can play a role.
Strokes in Children and Newborns
Strokes aren’t limited to adults. Pediatric strokes fall into two broad categories based on timing. Perinatal strokes occur between 28 weeks of pregnancy and 28 days after birth. Childhood strokes occur from 28 days of age through 18 years.
Perinatal strokes sometimes present immediately, with seizures or other signs in the first days of life. Others aren’t discovered until months or years later, when a child shows developmental delays and brain imaging reveals an old area of damage. About 80% of perinatal strokes are ischemic, caused by a blocked artery. Risk factors include complications during delivery, infections, blood clotting disorders in the mother or infant, and heart defects.
In older children, the causes differ significantly from adult strokes. Atherosclerosis, the gradual fatty plaque buildup that drives most adult strokes, is rarely a factor. Instead, sickle cell disease is a major cause, increasing stroke risk more than 200-fold, particularly in Black children. Heart abnormalities, infections, and clotting disorders also play significant roles.
How Doctors Tell Stroke Types Apart
Distinguishing between stroke types is the first and most urgent step in treatment, because the approach for a blocked artery is fundamentally different from the approach for a bleeding vessel. Brain imaging is used in every suspected stroke case to make this determination. A CT scan can quickly identify bleeding in the brain, which is critical in the first minutes of emergency care. MRI is more sensitive for detecting early ischemic strokes, pinpointing the exact location of damage, and ruling out conditions that mimic stroke symptoms. In emergency settings, doctors rely on specific MRI sequences to confirm there’s no hemorrhage before administering clot-dissolving treatment for an ischemic stroke.