Post Stroke Seizures and Epilepsy: Is There A Higher Risk of Having a Seizure After Strokes?
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A stroke seizure can happen well after the original event, surprising survivors who thought the worst was behind them. Many families do not see one coming, and it can be deeply unsettling for everyone involved. A seizure after a stroke draws on damage already done, and the survivor on the other side of it is the survivor from before.
The Link Between Stroke And Seizure Activity
Seizures are a known complication of stroke, particularly in the first weeks of recovery and in the years that follow. After a stroke, the brain has been injured, and that injury can disturb the electrical signals nerve cells use to communicate. A stroke seizure is the result of those disturbed signals firing in a way they should not.
The risk is not the same for every type of stroke. Haemorrhagic strokes, where a blood vessel bleeds into the brain, carry a higher seizure risk than ischaemic strokes, where a clot blocks blood flow. Strokes that injure the outer surface of the brain, are also more likely to trigger seizures than those deeper inside.
How A Stroke Triggers Seizures In The Brain
A stroke seizure happens when the injured part of the brain disrupts normal nerve activity. The cause of a poststroke seizure depends on whether it happens early or late after the stroke.
Early seizures, which occur within seven days of the stroke, are driven by the acute injury itself. When brain tissue is starved of oxygen or surrounded by bleeding chemicals flood the area. Nearby nerve cells are overstimulated by those chemicals and fire abnormally. Salt and blood sugar levels in the brain are thrown off, which adds to the instability.
Late seizures have a different cause. As the brain heals, scar tissue and a kind of nerve cell scarring called gliosis form around the damaged area. That scarred tissue can become a focal point where abnormal electrical activity develops. The brain is also rewired during recovery, and some of those new connections fire in ways that trigger seizures. Late seizures carry a much higher chance of returning.
Stroke Risk Factors
A stroke seizure cannot occur without a stroke, so the factors that drive stroke risk also determine who later faces the chance of seizure activity. Some sit within personal control and others do not.
Uncontrolled high blood pressure tops the modifiable list; it damages artery walls over time and feeds into both clot-driven and bleed-driven strokes. Diabetes roughly doubles that risk by accelerating artery damage. Smoking, high cholesterol, obesity, low physical activity, and heavy drinking each add weight on top.
Age sits at the top of the factors outside personal control; stroke risk roughly doubles each decade after 55. Men face a higher chance of stroke at younger ages than women, though women carry a higher lifetime risk because they live longer. A close family history of stroke at younger ages raises personal risk.
A previous stroke or transient ischaemic attack (TIA), sometimes called a mini-stroke, is the single strongest predictor of a future event. The first 90 days after a TIA carry the highest risk of a full stroke, which is why a TIA is a medical emergency in its own right.
What A Post Stroke Seizure Looks Like
A stroke seizure can look very different depending on which part of the brain is firing abnormally and how widely the activity spreads. Two broad types appear after stroke: focal and generalised.
Focal seizures start in one area of the brain instead of both. Twitching of one arm or leg, sudden numbness on one side, brief loss of speech, or odd sensations such as a strange taste or smell can all signal a focal seizure. The person may stay aware of what is happening, or they may seem dazed and unresponsive while the seizure runs its course.
Generalised seizures involve both sides of the brain at once. The most familiar form is the tonic-clonic seizure, where the body stiffens, the person falls, and rhythmic jerking follows. The eyes may roll back, breathing can sound noisy, and the person will be unconscious during the event.
First Aid For Someone Having A Stroke Seizure
When someone has a stroke seizure, your first job is to keep them safe from injury while their body sorts itself out. The seizure cannot be stopped so your focus is on protection.
Move any sharp or hard objects away from the person and place something soft under their head. Loosen anything tight around their neck. Do not try to hold them still or restrain their movements, and do not put anything in their mouth; the idea that they might swallow their tongue if you don’t is a myth.
If possible, time the seizure. A seizure that ends within two minutes can be left to run its course; one lasting longer needs urgent help. Once the convulsions stop, gently roll the person onto their side into the recovery position, with their head tilted slightly back to keep the airway clear. If there is vomit, fluid, or food in their mouth, roll them onto their side immediately, even before the jerking has fully stopped.
Triple zero (000) is required in any of these situations:
- The seizure lasts longer than five minutes
- A second seizure follows the first
- The person does not wake up within five minutes
- Breathing does not return to normal
- The person is injured, pregnant, in water, or has diabetes
- This is their first seizure since the stroke
- You are unsure or worried
Stay with the person until they are fully alert. Confusion, tiredness, and patchy memory of the event are normal in the minutes after a seizure. Speak calmly, explain what happened, and keep them still if they’ve been injured.
When Post-Stroke Seizures Develop Into Epilepsy
A stroke seizure does not always mean epilepsy. The diagnosis and management of post-stroke epilepsy depend on timing and the chance of recurrence rather than on a single event. The risk rises further with several factors. Larger strokes, strokes affecting the cerebral cortex, and more severe strokes are linked to a higher chance of seizure recurrence.
Reduce The Risk Of Seizures After A Stroke
A stroke seizure ends in minutes, but the recovery already in place endures past it. A stroke seizure asks for calm, judgment, and protection from harm. A nationally recognised first aid course is where that preparation happens. Your readiness is what stands between someone’s worst moment and a steady hand.
FAQs
What is an Ischemic Stroke?
An ischemic stroke happens when a blood clot blocks an artery supplying part of the brain, cutting off oxygen and nutrients to the tissue downstream. Around four out of five strokes are ischemic, and they fall into two camps: thrombotic strokes, where a clot forms in a brain artery itself, and embolic strokes, where a clot forms elsewhere in the body and travels to the brain.
What is a Haemorrhagic Stroke?
A haemorrhagic stroke occurs when a weakened blood vessel in or around the brain ruptures, causing bleeding that damages nearby tissue and raises pressure inside the skull. Two main forms exist: intracerebral haemorrhage, where bleeding happens within the brain itself, and subarachnoid haemorrhage, where bleeding happens in the space between the brain and the membranes covering it. Causes include uncontrolled high blood pressure, ruptured aneurysms, and abnormal tangles of blood vessels called arteriovenous malformations.
How Many Stroke Survivors Develop Epilepsy?
The risk of post-stroke epilepsy climbs with time, sitting at around 2 to 5% within the first five years after an ischaemic stroke and reaching close to 12.5% after a decade.
