Not every person who has a stroke will have a seizure. Only a fraction of people who have a stroke have a post-stroke seizure (PSS), some of whom go on to develop post-stroke epilepsy (PSE). PSE is diagnosed when a person has additional stroke-related seizures after their first seizure event.
Around 795,000 people in the United States per year will have a stroke. An estimated 4 percent to 10 percent of stroke survivors experience early onset PSS, defined as a seizure that occurs within the first 24 hours to two weeks after a stroke. Late-onset PSS is a stroke-related seizure that occurs more than two weeks after a stroke. The more time that passes after a person has a stroke, the lower their risk of having a first PSS event. However, the likelihood of developing epilepsy is greater if an initial PSS occurs later.
PSE is usually defined by having at least one early onset PSS event followed by at least one late-onset PSS event.
When a person is first diagnosed with epileptic seizures as an adult, 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 accounts for almost half of newly diagnosed, adult-onset epilepsy cases. It’s also one of the most common causes of seizures in people older than 60 years.
There are several risk factors for PSS.
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 had a hemorrhagic stroke were at almost two times greater risk of PSS. The risk of stroke after a seizure is greatest with hemorrhagic strokes that occur in the cerebral cortex (the outermost part of the brain, which is responsible for language, memory, motor function, and other functions).
Seizures that occur after a stroke may be caused by damage to the brain and scar tissue from the stroke. This scar tissue disrupts proper transmission of electrical signals that control the body. Brain injury caused by very severe strokes, multiple strokes, or strokes that occur in younger people may be more likely to lead to PSS.
Adults who have a history of epilepsy are at significantly higher risk of having a stroke than people without a history of the seizure disorder. Twenty-three percent of adults aged 65 years or older with a history of epilepsy reported having a stroke, compared to only about 5 percent of older adults who didn’t have a history of epilepsy.
The abnormal electrical activity caused by stroke-related scar tissue can trigger different types of seizures. The seizure type usually depends on where in the brain the electrical abnormalities or seizure begin, whether the abnormal electrical activity spreads to other parts of the brain, and the parts of the brain affected. PSS usually starts in the part of the brain where the stroke occured and spreads to involve the other parts of the brain and sometimes the entire brain.
Types of PSS can include partial seizures (focal seizures) with or without awareness. Focal seizures usually affect one side of the brain. Focal seizures can become generalized seizures (also called focal-to-bilateral or tonic-clonic seizures). Symptoms of tonic-clonic seizures include convulsions characterized by stiffening and jerking of the body and often a loss of consciousness. Generalized seizures, caused by electrical pulses on both sides of the brain, are the most common type of PSS.
Many people may not recognize that falls, confusion, and loss of consciousness may be signs of PSS or PSE. Knowing the signs and symptoms of a seizure is an important way to get the right treatment as soon as possible.
In general, PSE can and should be managed by a neurologist much like other types of seizures and epilepsies. PSE can usually be controlled with antiepileptic drugs (AEDs). 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 AEDs.
Another option is vagus nerve stimulation. Like a pacemaker for your brain, a vagus nerve stimulator (VNS) is a battery-operated device surgically attached to the vagus nerve in the neck, which carries information to and from the brain. A VNS sends out mild electrical impulses to regulate and stimulate the nerves in the brain, which may reduce the risk of a person having a seizure.
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 of the seizure’s onset. 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:
If a person has a seizure that lasts longer than five minutes, or has three seizures in a row without regaining consciousness between them, seek immediate medical help. These symptoms could be a life-threatening condition called status epilepticus.
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