A stroke and a seizure can occur together, with the stroke often triggering the seizure. The brain injury caused by a stroke immediately destabilizes surrounding tissue, leading to abnormal electrical activity. This co-occurrence is a significant complication requiring specialized medical attention. This article explores the distinct nature of strokes and seizures, the timelines in which they co-occur, and how clinicians identify and treat these combined events.
Understanding Strokes and Seizures
A stroke and a seizure are fundamentally different events, though both involve the brain. A stroke is a vascular event caused by a problem with the brain’s blood supply. This interruption of blood flow, whether from a blockage (ischemic) or a burst vessel (hemorrhagic), deprives brain cells of oxygen and nutrients, causing tissue injury and cell death.
A seizure, by contrast, is an electrical event defined by an abnormal, uncontrolled surge of electrical activity within the brain. Neurons begin to fire in an uncoordinated and excessive manner. This electrical storm can manifest as convulsions, loss of consciousness, or temporary changes in sensation and awareness.
Seizures Occurring During the Acute Stroke Phase
The injury caused by a stroke can directly provoke a seizure because the damaged brain tissue becomes electrically unstable. These immediate reactions are classified as acute symptomatic seizures, meaning they occur within the first seven days following the stroke. The toxic environment created by the stroke, including hypoxia and metabolic dysfunction, triggers this early electrical instability.
Acute symptomatic seizures are more likely to occur after hemorrhagic strokes or strokes that affect the cerebral cortex. The presence of blood in the brain, common in hemorrhagic strokes, is particularly irritating to neurons and increases the risk of early seizure activity. The seizure risk is highest in the first 24 hours after the event and gradually decreases over the following week.
Developing Epilepsy After a Stroke
A stroke can also lead to a long-term neurological condition known as post-stroke epilepsy (PSE). This is defined by the occurrence of unprovoked seizures that happen more than seven days after the initial stroke. The brain tissue that survives the stroke can undergo epileptogenesis, where the injury site becomes a chronic focus of hyperexcitability.
The resulting scar tissue disrupts normal electrical signaling within the neural network. Risk factors for developing PSE include having a severe stroke, a stroke that involved the cortex, or having experienced an acute symptomatic seizure within the first week. For those who develop PSE, the first remote seizure most often occurs within the first two years following the stroke.
Identifying and Treating Co-occurring Events
The symptoms of a stroke and a seizure can sometimes be difficult to distinguish in the emergency setting, as both can cause sudden confusion or motor deficits. A seizure might cause temporary weakness that mimics stroke paralysis, while a stroke can cause movements similar to a focal seizure. Clinicians use diagnostic tools to confirm the nature of the event and the extent of the damage.
Brain imaging, such as CT or MRI scans, is used to visualize the stroke and confirm the area of vascular injury. An electroencephalogram (EEG) is employed to record the brain’s electrical activity and characterize the electrical disturbance.
Treatment involves addressing the underlying stroke, often with time-sensitive interventions, while also using anti-epileptic drugs (AEDs) to control seizure activity. Acute seizures are managed with a short course of AEDs, whereas post-stroke epilepsy requires long-term medication to prevent recurrence.