Understanding The Link Between Ischemic Strokes And Seizures

Ischaemic stroke occurs when blood vessels leading to the brain are blocked, interrupting blood flow to the brain. Haemorrhagic stroke, on the other hand, is when an artery in the brain bursts, causing blood to spill into the surrounding tissue. Both types of stroke can lead to a loss of blood supply in parts of the brain. After a stroke, some survivors may experience seizures, which are abnormal brain activity that may cause uncontrollable shaking movements, loss of consciousness, and confusion. Seizures can occur within the first few days or weeks after a stroke, and the risk lessens over time. While a single seizure is not usually fatal, people with epilepsy are at a higher risk of death.

Post-stroke seizures and epilepsy

Overview

Post-stroke seizures are most likely to occur within the first few days following a stroke, but they can also happen years later. Stroke is the most common cause of seizures in older people, and the risk of having a seizure reduces over time after a stroke.

Risk Factors

You are more likely to have a seizure if you have had a severe stroke, a haemorrhagic stroke (bleed on the brain), or a stroke in the cerebral cortex (the large outer layer of the brain responsible for vital functions like movement, thinking, vision, and emotion).

Diagnosis and Treatment

If you have a seizure after a stroke, it does not necessarily mean you have epilepsy or will develop it. However, some people will have repeated seizures and be diagnosed with epilepsy. If you have a seizure, you must stop driving and notify the relevant authorities and your insurance company.

To diagnose epilepsy, a specialist (usually a neurologist) will ask you questions about what happened and may request further tests, especially if the seizure did not involve convulsions. Electroencephalogram (EEG) and magnetic resonance imaging (MRI) scans can help identify unusual brain activity and problems inside the brain that might cause epilepsy.

Anti-epileptic drugs (AEDs) are typically used to treat epilepsy, and medication can usually reduce seizures, allowing people to lead a normal life. The choice of medication depends on the type and frequency of seizures, other stroke effects, and other medications being taken.

First Aid for Seizures

If you see someone having a seizure, it is important to protect them from injury, place them on their side to prevent choking and vomiting, loosen any tight clothing around their neck, and remove any sharp objects nearby. Do not restrict their movement unless they are at risk of hurting themselves, and do not put anything in their mouth. Stay with them until the seizure ends.

Outlook

People with post-stroke seizures tend to have longer hospital stays and a higher risk of disability, complications, and death. They are also more likely to have long-term disability, develop dementia, and have an increased mortality rate compared to those who do not have post-stroke seizures.

Risk factors for post-stroke seizures

Seizures are a known complication of ischaemic stroke. While they are not exclusive to severe strokes, seizures are indicative of a more severe stroke. The risk of a post-stroke seizure is highest in the first few weeks following a stroke, especially within the first 24 hours.

• Stroke type: People who have had a haemorrhagic stroke are more likely to have seizures than those who have had an ischaemic stroke.
• Stroke severity: The more severe the stroke, the higher the risk of a seizure.
• Stroke location: Strokes that occur in the cerebral cortex, the large outer layer of the brain, carry a higher risk of seizure.
• Age: Stroke incidence increases with age, and age is an independent risk factor for stroke.
• Sex: Men have a higher risk of post-stroke seizures than women.
• Previous epilepsy: People with a history of epilepsy are more likely to experience post-stroke seizures.
• Embolic stroke: Embolic strokes are a recognised risk factor for early post-stroke seizures.
• Middle cerebral artery aneurysm: The presence of a middle cerebral aneurysm increases the risk of post-stroke seizures.
• Intraparenchymal haematoma: The presence of an intraparenchymal haematoma increases the risk of post-stroke seizures.
• Structural brain lesions: Structural brain lesions are associated with a higher risk of post-stroke seizures and a higher recurrence rate.
• EEG abnormalities: EEG abnormalities are associated with a higher risk of post-stroke seizures and a higher recurrence rate.
• Partial-type seizures: Partial-type seizures are associated with a higher risk of post-stroke seizures and a higher recurrence rate.

Pathophysiology of post-stroke epilepsy

Post-stroke epilepsy (PSE) is a form of epilepsy that occurs after a haemorrhagic or ischemic stroke without a previous history of epilepsy. PSE is not accompanied by brain structural abnormalities or metabolic disorders of other causes. Stroke is the most common cause of epilepsy in patients over 65 years old and is the most frequent cause of secondary epilepsy in the elderly. The incidence of PSE is rising with the extension of life expectancy.

Pathophysiology

The pathophysiology of PSE differs between early- and late-onset seizures. Late seizures are often due to long-lasting structural brain changes, while early seizures often develop from electrophysiological abnormalities caused by cellular hypoxia and ischemia due to decreased blood supply post-stroke and during reperfusion therapy.

Early Onset Seizures

The stroke-induced acute ischemia and hypoxia can reduce the stability of nerve cell membranes and cause metabolic disorders of neurons. This can lead to a subsequent sodium pump failure, increased Na+ influx, and depolarisation of the membrane potential. When the membrane's potential depolarisation reaches a certain degree, calcium channels will be activated, and Ca2+ will rapidly flow in, leading to an increase in intracellular Ca2+

Treatment of post-stroke seizures

Seizures after a stroke, or post-stroke seizures, are most likely to occur within the first few days following a stroke, but they can also occur much later—even years after the stroke. People who have had a stroke are at an increased risk of having a seizure, and this risk is even higher in the case of severe strokes or haemorrhagic strokes (bleeds on the brain).

If you have a seizure after a stroke, it does not necessarily mean that you have epilepsy. However, if you experience repeated seizures, you may be diagnosed with epilepsy. The chances of this happening depend on where in the brain the stroke occurred and the size of the stroke.

If you have a seizure, you should notify a doctor immediately. They will ask about the circumstances surrounding the seizure and may consider prescribing antiseizure medications to prevent future seizures. According to the European Stroke Organisation, antiseizure medications are not advised after a first post-stroke seizure. However, if you experience a second seizure, your risk of further seizures increases, and experts agree that treatment with antiseizure medications should be started. Newer antiseizure medications, such as lamotrigine and gabapentin, may be more effective than older ones.

If you are at risk of having a seizure, it is recommended that you avoid activities that could put you or others in danger, such as swimming or cooking. It is also important to educate your friends and family about seizures so that they can help keep you safe if you have one.

Post-stroke seizures are typically managed and treated in the same way as other types of seizures and epilepsy. Anti-epileptic drugs (AEDs) are usually the first line of treatment and can help reduce seizures, allowing individuals to lead a normal life. The choice of medication depends on the type of seizures, the frequency of attacks, and other factors such as swallowing problems or other medications being taken. Surgery may be an option if anti-epileptic drugs are ineffective and if the epilepsy is due to a physical cause in the brain, such as scarring or stroke damage.

Impact of post-stroke seizures on stroke outcome

Seizures are a known complication of ischaemic stroke. Post-stroke seizures are most common in the first few days after a stroke, but they can occur at any time. They are indicative of a more severe stroke.

Post-stroke seizures are focal, meaning they start in a specific region of the brain—the area affected by the stroke. They may then generalise, spreading to both sides of the brain. Generalised seizures involve a loss of consciousness, while other symptoms include changes to perception, loss of muscle control, and loss of bladder control.

Post-stroke seizures are associated with worse outcomes. A 2023 review found that people who experience seizures after a stroke are more likely to have long-term disabilities, develop dementia, and die. They also tend to have longer hospital stays.

To prevent future seizures, treatments include antiseizure medications such as lamotrigine and gabapentin. However, the European Stroke Organisation advises against their use after a first post-stroke seizure.

Frequently asked questions