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HEART Insight:
doi: 10.1097/01.HEARTI.0000319862.79578.e3
Features: Related Risk

Stroke And Seizure

Lippert, Joan

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They're Different, Yet Similar In Surprising Ways

People often describe a seizure as “convulsions,” and stroke as sudden paralysis of an arm or leg or suddenly having trouble talking, but these short descriptions don't tell the whole story. Sometimes a seizure looks just like a stroke — and vice versa. It's important to know which is which to limit long-term effects and brain damage.

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As Mission Control for all the systems in your body, your brain needs a steady blood supply. It's also a circuit board that requires a consistent electrical current.

A seizure happens when a brief, strong surge of electrical activity affects part or all of the brain. Nerve cells in your brain conduct the electricity. Cells that are chemically or physically unstable may become too active, conduct too much electricity and activate nearby nerves. Imagine a firecracker going off in a fireworks faactory: First, there's a small explosion, then a few nearby firecrackers explode, then an ever-spreading wave of activity races through the entire factory.

A stroke interferes with the brain's blood supply in one of two ways: When a blood vessel that carries oxygen and nutrients to the brain is either blocked by a clot (ischemic) or bursts (hemorrhagic). In both types of stroke, the surrounding area of the brain can't get the blood and oxygen it needs, and it starts to die within two to three minutes.

A transient ischemic attack (TIA) is a transient (meaning short-lived) type of ischemic stroke, in which a blood clot blocks a blood vessel. But while the symptoms of a TIA and a full-blown ischemic stroke are the same, the TIA lasts just a few minutes. With amyloid angiopathy, a type of hemorrhagic stroke, protein deposits in the brain can create blockages or cause slow bleeding, and the resulting damage to brain tissue is progressive and may cause seizures and dementia over time. TIA and amyloid angiopathy are the opposite of each other in one respect—the first is a “fast” stroke, and the second is a “slow” stroke.

Sometimes it's difficult to tell strokes and seizures apart. We usually think of strokes as symptoms of “absence” — “you can't move, you can't see, you can't speak,” says Joseph Broderick, M.D., Chairman of the Department of Neurology, University of Cincinnati College of Medicine in Ohio. Seizures are the opposite in that something is happening — shaking, muscle spasms, convulsions. But “some seizures are much more subtle and don't include convulsions or spasms,” says Robert J. Adams, M.S., M.D., Director of the Medical University of South Carolina Stroke Center in Columbia.

A lay person can easily confuse symptoms of stroke and TIA — also known as a “warning stroke” or “mini-stroke” — with seizures (see box above).

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▪ Sudden numbness or weakness of the face, arm or leg, especially on one side of the body

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▪ Sudden confusion, trouble speaking or understanding

▪ Sudden trouble seeing in one or both eyes

▪ Sudden trouble walking, dizziness, loss of balance or coordination

▪ Sudden, severe headache with no known cause

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▪ Convulsions, muscle spasms or loss of consciousness — sometimes

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▪ Temporary post-seizure confusion and/or trouble speaking or understanding speech (aphasia)

▪ Blank staring, lip smacking or jerking movements of arms and legs

▪ Breathing stoaps temporarily, followed by sighing; incontinence

▪ Strange sensations, emotions or behavior

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While a stroke isn't a seizure, the two are connected. In an unfair twist of medical fate, seizure can sometimes follow stroke — as Steve Park found out.

In 1992, Steve had brain surgery to correct a life-threatening blood vessel deformity known as an arteriovenous malformation (AVM). While on the operating table for the delicate operation, he had a stroke when a blood vessel began to bleed, a risk that he, his wife of 13 years and the medical team had been well aware of. The stroke injured the speech center on the left side of Steve's brain, and he developed aphasia, which made if difficult for him to find the right words when trying to say something.

After Steve's operation, his doctor prescribed several medications, including an anticonvulsant, to prevent seizure. Six seizure-free months later, Steve's doctor thought he could be weaned off the anticonvulsant, but “a year later, he had his first seizure,” says his wife and one-woman support system, Charlie (short for Charlene). He's had more since then. Charlie is accustomed to Steve's seizures and usually helps him into bed after he has one.

What happened in Steve's brain that caused his seizures? “After a stroke, the brain can heal, but there's still scarring,” explains Broderick, which creates abnormal nerve connections that disrupt the smooth flow of the brain's electrical current, causing seizures. According to the Seizures After Stroke Study (SASS), conducted by the University of Toronto in Ontario, Canada, 2.5 percent of stroke patients go on to develop epilepsy, which is defined as more than one seizure separated by at least 24 hours.

Seizure is more common after hemorrhagic (bleeding into the brain) stroke, which is the type of stroke Steve had, says Broderick. In the first 24 hours after onset of stroke symptoms (see box below), roughly eight percent of patients who have had a hemorrhagic stroke will have a seizure, as compared to three percent who have had an ischemic stroke.

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The danger comes when strokes are mistaken for seizures. With strokes, time is of the essence! Millions of brain cells die each minute a stroke goes untreated, so all strokes should be treated as serious medical emergencies. In particular, to limit brain injury during an ischemic stroke, “a clot-busting drug must be administered within three hours of the onset of stroke symptoms,” says Broderick. Only three to five percent of people who experience a stroke reach the hospital in time to receive this treatment.

In contrast, seizures that last a few minutes — which is true of most — generally cause no permanent damage, says Christine O'Dell, R.N., M.S.N., medical advisor, the Epilepsy Institute at Montefiore Medical Center in The Bronx. They're harmful only when they last longer than about an hour, which can exacerbate the brain injury of a previous stroke by damaging the neurons in the brain, or if the person having the seizure hits the floor or falls onto something hot, like a radiator.

So how can you tell if it's a stroke or a seizure? You can't — so leave it to the professionals! If you or a loved one are having symptoms and aren't sure what they mean, “don't drive to the hospital — call 9-1-1 immediately,” urges Broderick. In the ambulance, emergency medical technicians will gather information about what happened, stabilize breathing and circulation and check blood sugar (low blood sugar can mimic stroke).

Once at the hospital, Emergency Room staff will check neurologic signs and the patient will move quickly to a computed tomography (CT or CAT) scan or magnetic resonance imaging (MRI) to distinguish between seizure, ischemic stroke or hemorrhagic stroke. In the next day or two, an electroencephalogram (EEG) can diagnose seizure if that's what's going on, says O'Dell.

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Though some stroke risk factors can't be changed — heredity, advancing age, male gender, pregnancy — you can modify others related to your lifestyle or environment. Among them are high blood pressure (the most controllable risk factor for stroke), smoking, diabetes, heart and artery disorders, high cholesterol, physical inactivity and obesity, says Adams. A person who's had one or more TIAs is almost 10 times more likely to have a stroke than someone who hasn't. So take the hint!

And the risk of stroke for someone who has already had one is many times that of a person who has not. For ischemic stroke, antiplatelet agents, such as aspirin, and anticoagulants, such as warfarin, interfere with the blood's ability to clot. Other treatments involve removing blockages from the carotid artery.

For hemorrhagic stroke, surgical treatment is often recommended either to place a metal clip at the base of an aneurysm (bulging vessel) or to remove an AVM. Other less invasive procedures involve a catheter introduced through a major artery in the leg or arm and guided to the aneurysm or AVM, where it deposits an agent such as a coil to prevent rupture.

Stroke patients should avoid triggers, such as fatigue and low sodium, which reduce the seizure threshold, says Adams. Anti-seizure medication may be prescribed after the first or second seizure, or preventively, depending on the type and location of the stroke damage.

“If one medication doesn't work or stops working, we usually try a second one,” says O'Dell. “If that doesn't work, we go on to a third. If that doesn't work, then we add a second medication or a third.” If there's still no response, it may be time to consider surgery or a vagus nerve stimulator (VNS), a pacemaker-like device that normalizes electrical impulses in the brain, she says.

If one treatment doesn't help, it's worthwhile to keep working with your doctor to find one that does because in most states people with epilepsy must be seizure-free for six months before they can get behind the wheel of a car, notes Adams. Steve knows just how important it is to be self-sufficient. “The big thing for me has always been to work,” he says. His job? Helping other stroke survivors find employment.

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▪ Stroke is the No. 3 cause of death in the United States, behind diseases of the heart and cancer.

▪ Eight out of 10 strokes are ischemic, caused by a blockage of a blood vessel in the brain.

▪ About 780,000 Americans have a stroke each year.

▪ About 9 percent of people who have strokes will also have one seizure; 2.5 percent will develop epilepsy (more than one seizure).

▪ In the year after a hemorrhagic (bleeding) stroke, chances of seizure are about 20 percent.

▪ In the year after an ischemic stroke, chances of seizure are about 14 percent.

© 2008 American Heart Association, Inc.