A seizure after a stroke can be scary and unexpected. You may wonder why it happened, whether it could happen again, and what it means for recovery.

Poststroke seizures (PSS) affect only a small number of stroke survivors, but some people are more likely to have them than others. Seizures can happen soon after a stroke or weeks, months, or even years later.

This article explains why seizures can happen after a stroke, who may be at greater risk, what poststroke epilepsy (PSE) means, and how these seizures are treated. You’ll also learn what to do if you see someone having a seizure.

Causes of Poststroke Seizures

When a person is first diagnosed with epileptic seizures and is over the age of 65, the cause of their seizures is unknown 50 percent of the time. For those whose cause of epilepsy is known, however, stroke is among the leading causes.

Stroke is one of the most common causes of seizures in people over 60 years of age.

Diseases involving blood flow in the brain, including stroke, account for 30 percent to 50 percent of newly diagnosed epilepsy cases among older adults.

There are several risk factors for PSS.

Hemorrhagic Stroke

Stroke occurs when a blood clot blocks blood flow to the brain (ischemic stroke) or when a blood vessel in the brain ruptures (hemorrhagic stroke), causing a brain bleed.

While both types of strokes can lead to seizures, hemorrhagic strokes carry a greater risk of PSS. In one study, people who had a hemorrhagic stroke were at almost two times greater risk of PSS.

The risk of seizure after a stroke is greatest with hemorrhagic strokes that occur in the cerebral cortex (the outermost part of the brain that is responsible for language, memory, motor function, and other higher cognitive functions).

Brain Injury

Seizures that occur after a stroke may be caused by damage to the brain and scar tissue from the stroke. The scar tissue can interfere with electrical signals that tell the body what to do. Brain injuries with cortical involvement, hemorrhage, larger or more severe strokes, and early seizures may be more likely to lead to PSS.

Treating Poststroke Seizures

Falls, sudden muscle jerks, confusion, and loss of consciousness can sometimes be signs of PSS or PSE. Knowing the signs of a seizure can help a person get the right care sooner.

Treatment depends partly on when the seizure happens after a stroke. Early seizures may only need treatment for a short time. Late seizures are more likely to happen again and may need longer-term treatment.

People with PSE usually need ongoing care from a neurologist. Treatment is similar to the care used for other types of epilepsy.

Anti-Seizure Medication

PSE can usually be controlled with anti-seizure medication (formerly referred to as antiepileptic drugs). These medicines control seizures but don’t necessarily prevent epilepsy from developing. Routine preventive anti-seizure medication is not generally recommended for stroke survivors who have never had a seizure.

It’s important to take medication as prescribed to keep seizures under control. Let your doctor know about all medications you may be taking, as there are potentially dangerous drug interactions between medications used for stroke (such as blood thinners) and anti-seizure medications.

Vagus Nerve Stimulation

Vagus nerve stimulation (VNS) is a treatment used mainly for people with drug-resistant epilepsy. A small VNS device is placed under the skin in the chest. A thin wire connects the device to the vagus nerve in the neck.

The device sends mild electrical signals through the vagus nerve to the brain. These signals may help reduce how often seizures happen.

Basic Seizure First Aid

It may be helpful to know the basics of seizure first aid if you recognize that someone is having a PSS. Most seizures do not require emergency health services and end naturally within a few minutes.

If the person is unresponsive, turn them onto their side, make sure their breathing is not blocked, and stay with them until they recover. The golden rule for providing seizure first aid is to prevent harm or injury until the seizure is over and the person regains consciousness or awareness.

If a person is having a seizure, remember these tips:

• Help the person to a horizontal position so they don’t fall.
• Put a pillow under the person’s head.
• Move sharp or hard objects out of the way during convulsions.
• Keep an eye on the time to see how long the person’s seizure symptoms last.
• Don’t try to restrain the person’s movements.
• Don’t put anything in the person’s mouth.

Seek immediate medical help in any of the following situations:

• The seizure lasts longer than five minutes.
• They have repeated seizures without regaining consciousness in between.
• This is their first known seizure.
• They’re having trouble breathing.
• There’s a serious injury.
• They’re pregnant.
• They’re immersed in water during the seizure.

These symptoms could indicate a life-threatening condition called status epilepticus (defined as a seizure that lasts longer than five minutes or repeated seizures without regaining consciousness).

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