Can seizures injure the brain?
Brain damage happens when nerve cells (neurons) in the brain are damaged or destroyed. Depending on the part of the brain that’s impacted, damage can lead to a variety of different physical, cognitive, and emotional symptoms.
Most types of seizures last only a short amount of time and do not lead to damage to neurons. However, experiencing a prolonged seizure can cause injury.
These types of seizures are called status epilepticus. Permanent neurological damage can happen after about 30 minutes of status epilepticus due to prolonged abnormal electrical activity in the affected area of the brain.
Status epilepticus is a medical emergency. It’s a good rule of thumb to treat any seizure that lasts over 5 minutes as status epilepticus and call 911 or your local emergency number.
While most seizures do not cause damage to the brain, some may lead to changes that may impact brain structure or cognitive functions. Below, we’ll look at some of the research into this topic.
What does the research say?
Much of the research into the effect of seizures on the brain centers on focal, or localized, seizures, particularly those affecting the temporal lobe. In fact, temporal lobe epilepsy is the most common type of focal epilepsy in adults.
Individuals with temporal lobe epilepsy often have problems with memory and other cognitive functions. Additionally, in about one-third of people with temporal lobe epilepsy, seizures do not resolve after starting antiseizure medications.
Below, we’ll touch on some of the research into seizures and the brain, much of it focusing on temporal lobe epilepsy. Then, in the next section, we’ll cover some of the ongoing questions related to this topic.
Markers of brain injury
A 2017 study looked for markers of brain injury in individuals with a specific type of focal epilepsy. To do this, they analyzed post-surgical tissue samples from 20 people with frequent seizures that were resistant to treatment with antiseizure medications.
Researchers found that although markers of injury were found in the area where the seizures occurred, they were not observed in adjacent areas. They say that this argues against the theory that recurrent seizures cause damage to healthy brain tissue.
A 2018 study investigated structural changes in the brains of people with epilepsy. To accomplish this, pooled data from 24 different research centers around the world was used.
MRI brain scans of 2,149 individuals with different types of epilepsy were compared to those of 1,727 healthy individuals. Researchers found shared reductions in gray matter across different types of epilepsy.
They also observed structural changes that were specific to certain types of epilepsy. An example of this is the reduced volume of the hippocampus, the area associated with memory, in people with temporal lobe epilepsy.
However, the researchers note that there are some limitations to their study:
- They cannot be sure if these structural changes were present from the onset of a person’s epilepsy or if they’re directly caused by the seizures.
- They cannot separate out other factors that may contribute to structural changes, such as seizure frequency, severity, or the effects of antiseizure medications.
- The different research centers in the study may have used different scanning protocols when performing the MRI scans, which may have affected the analysis.
A 2017 meta-analysis assessed 42 articles on temporal lobe epilepsy that was resistant to treatment with antiseizure medications. The researchers found that:
- The reviewed studies suggested a progressive loss of neurons or connections between neurons (brain atrophy) in this type of epilepsy.
- However, many studies have not directly demonstrated that this is due to the seizures.
- Larger, more long-term studies are needed to determine if the observed brain atrophy is due to natural aging or to epilepsy disease progression.
Seizures and memory networks
A 2016 study in rats looked at how seizure-like activity impacted memory consolidation. Memory function can be affected in some types of epilepsy, including temporal lobe epilepsy.
Memory consolidation normally happens during sleep and involves small ripples of activity in the hippocampus, the area of the brain concerned with memory.
These ripples can be followed by activity in the prefrontal cortex, an area involved in higher-level cognitive functions.
In people with temporal lobe epilepsy, short bursts of electrical activity called IEDs can happen between seizures. The researchers wanted to see if these abnormal bursts of electrical activity impacted memory in rats. They found that:
- Stimulating IEDs in rats led to impaired memory in a maze-solving activity.
- The effect on memory increased with the amount of IEDs that a rat experienced.
- IEDs beginning in the hippocampus were followed by electrical activity in the prefrontal cortex. This happened while the rats were both asleep and awake.
- A similar pattern of activity was seen when observing 4 individuals with epilepsy and IEDs.
The researchers believe that IEDs can disrupt normal signaling for memory consolidation. In short, IEDs from the hippocampus may impact how the prefrontal cortex responds to signaling from this area, potentially affecting memory.
A 2020 study used a modeling program to estimate brain age in 104 individuals with temporal lobe epilepsy and 151 healthy individuals. Some notable points from this study are:
- Structural brain age. When the modeling program analyzed MRI scans from study participants, it found that the brains of individuals with temporal lobe epilepsy appeared an average of 6.6 years older.
- Functional brain age. Participants did seven types of cognitive test, which were then correlated with their actual age and estimated brain age. This analysis found that the brains of individuals with temporal lobe epilepsy were on average 8.3 years older.
- Correlations. Increased brain age was lightly, but not significantly, associated with complex partial seizure frequency and the amount of antiseizure medications taken.
In summary, researchers found that modeling showed that the brains of people with temporal lobe epilepsy were both structurally and functionally older than their actual chronological age.
However, the researchers note that the exact cause of this observation remains unknown. Future studies are needed to investigate this.
What are seizures?
A seizure happens when neurons in the brain send many signals all at once. Most seizures do not last very long. Some may have no noticeable symptoms, while others can lead to loss of consciousness or uncontrolled muscle twitching.
Epilepsy is when an individual has recurring, unprovoked seizures. According to the National Institute of Neurological Disorders and Stroke, about 2.3 million adults in the United States have epilepsy.
After reviewing your medical history and performing a physical examination, your doctor can use several tests to diagnose epilepsy. These can include an electroencephalogram (EEG), MRI scan, and blood tests.
Epilepsy is most commonly treated with medications that can prevent seizures. Other potential treatment options include surgery, vagus nerve stimulation, and changes in diet.
Ongoing questions about seizures and the brain
From what research tells us, it’s apparent that there can be structural and cognitive differences in people with certain types of epilepsy. However, many questions still remain.
Now let’s discuss some of the ongoing questions and limitations associated with this research.
What came first?
Injury to the brain can cause epilepsy to develop in some individuals. This can happen due to things like traumatic brain injury, stroke, or inflammation in the brain.
Because of this, researchers are grappling with a “chicken and egg” question:
Additional factors that can impact observations are:
- the natural process of aging
- the presence of other health conditions
- the use of antiseizure medications
In many cases, it can be very hard for researchers to separate what may be directly causing a finding from what’s not causing it.
Does type of epilepsy play a role?
There are many different types of seizures, all with different characteristics. According to the National Institute of Neurological Disorders and Stroke, doctors have identified over 30 different types of seizures.
As such, research findings may not translate across different seizure types. For example, what’s true for someone with temporal lobe epilepsy may not be true for an individual with a different type of epilepsy.
The effectiveness of medications may also play a role. For example, someone whose seizures can be managed using antiseizure medications may not experience the same effects as an individual with epilepsy who’s body is resistant to medications.
Differences in study design
Each study that investigates seizures and the brain has a different design. Different researchers may use different methods to address a question. They may also interpret their results differently from another group.
Sample size is also important. For example, a study with only a small number of people may not be representative of what’s happening in larger groups.
Some studies may also assess participants at only a single point in time. This is much different than following the course of someone’s epilepsy over many years.
Most types of seizures do not cause damage to the brain. However, having a prolonged, uncontrolled seizure can cause harm. Because of this, treat any seizure lasting over 5 minutes as a medical emergency.
Overall, it’s hard to tell if changes in the brain are present prior to the onset of seizures or if they’re due to damage caused by the seizures themselves. Additional research is needed to answer this question as well as many others.
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