What is Temporal Seizure?
Epilepsy is a long-term, disabling condition that affects around seventy million people worldwide. Most cases of epilepsy are found in a part of the brain called the temporal lobe.
Temporal lobe epilepsy can further be separated into two types based on where the epilepsy originates in the brain:
* Mesial Temporal Lobe Epilepsy (MTLE): This type occurs in the innermost part of the temporal lobe, including the hippocampus, parahippocampal gyrus, and amygdala. These are parts of the brain that play a big role in memory and emotions. MTLE is the most common form of temporal lobe seizures and often occurs due to a disease process known as hippocampal sclerosis (HS), which is a hardening of the hippocampus.
* Lateral Temporal Lobe Epilepsy (LTLE): This type is also known as neocortical temporal lobe seizures. These seizures are very rare and are usually caused by genetic or acquired changes to the structure of the brain.
Epilepsy can significantly diminish a person’s quality of life, reduce lifespan, and cause considerable economic strain for the individual and society.
What Causes Temporal Seizure?
Temporal lobe seizures can be caused by many things, including:
1. Hippocampal sclerosis
2. Infections
3. Tumors
4. Traumatic brain injury
5. Abnormal blood vessels
6. Genetic factors
7. Unknown causes
One prevalent type of epilepsy, known as mesial temporal lobe epilepsy (MTLE), is often a result of a condition called hippocampal sclerosis (HS). This condition was first recognized in the late 19th century and involves harmful changes in nerve cells.
Seizures can occur due to overstimulation from neurotransmitters, such as glutamate, or a lack of inhibitory neurotransmitters like gamma-aminobutyric acid (GABA). The hippocampus part of the brain is usually the focus of these seizures.
The extent of HS can predict surgical outcomes after seizures, with severe HS indicating a more favorable prognosis. A scale has been developed by physicians to grade HS from 0 (no HS) to 4 (severe HS), which helps provide a semi-quantitative measure of the condition.
The International League Against Epilepsy (ILAE) has also classified HS into three types based on their severity and a fourth subtype characterized only by gliosis (brain tissue scarring):
1. HS ILAE type 1 – notable for significant nerve cell loss and gliosis, mainly in CA1 and CA4 regions of the hippocampus. This type has links to a history of injuries triggering seizures in children. It’s also associated with a better prognosis after surgery.
2. HS ILAE type 2 – characterized by more pronounced cell loss and gliosis in CA1 regions of the hippocampus. It’s less studied and may predict a less favorable outcome after surgery.
3. HS ILAE type 3 – marked by more pronounced cell loss and gliosis in CA4 regions of the hippocampus. Like type 2, less research is available on this type, and it may also suggest a less favorable surgical outcome.
4. No-HS – characterized by gliosis only and often indicates a less favorable prognosis.
While some children who have febrile seizures (seizures caused by fever) may develop epilepsy, there is not conclusive evidence linking a history of febrile seizures to the development of temporal lobe epilepsy. However, there is a recognized association between specific brain lesions seen on medical imaging, such as mesial temporal lobe sclerosis, and the development of temporal lobe epilepsy in pediatric populations.
Risk Factors and Frequency for Temporal Seizure
Temporal lobe epilepsy is typically diagnosed in the first 20 years of life. It affects both males and females equally, although women may experience seizures related to their menstrual cycle. It’s been difficult to estimate how often epilepsy happens due to different definitions and diagnosis methods used over the years. The effectiveness of diagnosis techniques, like electroencephalography (EEG) and imaging scans, often depends on the skills of the diagnostician and access to these tools. Consequently, there is limited research on exactly how often this type of epilepsy occurs.
However, it is clear that a high occurrence rate of a particular type of temporal lobe seizure often leads to surgical referrals. This suggests that the affected region often responds poorly to regular epilepsy treatments. Focal epilepsy, where seizures start in just one part of the brain, accounts for about 60% of all epilepsy cases. The majority of these cases originate in the temporal lobe. Between 48 to 56 percent of the cases happen on both sides of the brain.
- Temporal lobe epilepsy is usually diagnosed early in life.
- It does not favor any gender, but women may experience seizures during menstrual cycles.
- Diagnosis is often challenging due to the different definitions and techniques used.
- The occurrence rate for a particular type of temporal lobe epilepsy often leads to surgery.
- About 60% of all epilepsy cases are focal, and most start in the temporal lobe.
- Bilateral cases, where both sides of the brain are affected, make up 48 to 56 percent of these.
- When seizures persist for over a year despite the use of two or more epilepsy medications, surgery may be considered.
Signs and Symptoms of Temporal Seizure
Temporal lobe epilepsy is a condition where seizures start in the temporal lobes of the brain. These seizures can be of different types: they can be focal seizures where the person is aware, seizures where the person becomes less aware, or seizures that start in the temporal lobe but spread to both sides of the brain, often resulting in what are known as bilateral tonic-clonic seizures. Chronic memory problems are commonly seen in people with this condition.
Symptoms of temporal lobe epilepsy can include:
- Focal aware seizures, also called “auras.” During these seizures, people can have different types of unusual sensations, such as smells, tastes, and feelings in the stomach. They might also feel like they’ve experienced something before (“deja vu”) or for the first time (“jamais vu”). A person might also feel scared or anxious.
- Focal impaired awareness seizures. In this case, what starts as a focal aware seizure might lead to a loss of consciousness. When this happens, the person might stare blankly, have enlarged pupils, and exhibit automatic movements such as facial twitching or stiff body posture.
- Seizures that start in one area of the brain and spread to involve both halves, often shown as bilateral tonic-clonic convulsions (a type of seizure that involves the whole body).
After the seizures mentioned in the second and third bullet points, a person might feel confused or have trouble talking or remembering things.
Between seizures, the symptoms aren’t very specific. Sometimes, people might show changes in their speech patterns or changes in their facial expressions when they are emotionally excited.
Testing for Temporal Seizure
If your doctor thinks you might have temporal lobe epilepsy, they will likely use neuroimaging and an electroencephalogram (EEG) to confirm the diagnosis. An EEG is a test that measures the brain’s electrical activity. This can be helpful in finding where the seizure is starting in the brain.
Although seizures can be rare and brief events in those with epilepsy, regular EEG testing might be able to provide essential information between seizures. It may even reveal the exact area of the brain that’s causing the seizure, which is extremely helpful for treating the condition.
An EEG during a seizure might show a rhythmic wave pattern. This is typically seen in the area of the brain experiencing the seizure. However, determining whether the seizure is coming from the right or left side of the brain can be difficult using only an EEG.
It’s possible that your first EEG might appear normal, in which case, your doctor might suggest other tests, like sleep-deprived EEGs or video EEG monitoring. They might also place electrodes directly onto the brain to get more detailed readings.
Neuroimaging scans, like CT scans or MRI scans, are vital for finding any physical abnormalities in the brain that might be causing the seizures. CT scans are often used initially but have some limitations. For example, they might not be able to detect smaller changes in the brain that could be causing seizures. MRI scans provide a much more detailed image of the brain and are the preferred method in most cases.
In people with temporal lobe epilepsy who don’t respond well to medication, an MRI is also helpful in planning for surgery. It can reveal changes in the size of the brain’s structures and whether there’s an abnormal level of water in the brain tissue, both of which might be signs of epilepsy. It’s important to note that reading MRI images and diagnosing epilepsy requires specialist expertise and experience.
Other types of scans, like functional imaging positron emission tomography (PET) scans, magnetic resonance spectroscopy (MRS), and single-photon emission computed tomography (SPECT) scans, might also be used in certain situations. For example, if the MRI doesn’t clearly show where the seizures are starting, a PET or SPECT scan can show the areas of the brain that are working differently than expected.
Before epilepsy surgery, it’s essential to pinpoint precisely where the seizures are starting in the brain, while sparing the unaffected areas of the brain. This helps improve the success of the surgery. EEG and neuroimaging play a big role in achieving this goal.
One traditional method of discovering the parts of the brain responsible for memory and language before surgery is the WADA test. This test involves injecting a drug into the carotid artery that temporarily affects one side of the brain, allowing doctors to see the other side’s vital functions. More recently, functional MRI (fMRI) has been used to achieve the same goals in a less invasive manner.
Treatment Options for Temporal Seizure
If you have been diagnosed with epilepsy, reducing the number of seizures you experience is important because it can help prevent negative effects on your thinking and memory skills. It’s also essential to consider that having epilepsy, and managing it, can greatly impact your quality of life.
For people diagnosed with a type of epilepsy known as temporal lobe epilepsy, doctors usually start treatment with medication, specifically a group of drugs known as anti-epileptic drugs (AEDs). There are many types of these drugs available, both older versions like phenytoin and newer ones like levetiracetam. They are equally effective, but people often experience more side effects with the older drugs. Pregnant women or women who may become pregnant should be aware that AEDs can be harmful to the developing baby, especially if taken during the first trimester of pregnancy.
About a third of people with temporal lobe epilepsy do not see improvement from AEDs alone. For these individuals, doctors might then consider surgery as an option, which could lead to fewer or no seizures in up to 80 percent of people. Surgery seems to be more effective than medication alone in controlling seizures, particularly for those with difficult-to-control epilepsy. In fact, early surgical intervention may lead to improved quality of life and better thinking and memory skills, among other benefits.
The two most common types of surgery for temporal lobe epilepsy include the removal of the front part of the temporal lobe (anterior temporal lobectomy) or the removal of specific inner structures of the temporal lobe (selective amygdalohippocampectomy). Both methods have been shown to result in significant improvements in stopping seizures compared to medication alone. The specifics of these surgeries may vary based on which techniques a surgeon uses.
There other more specific surgical methods that could also help in preserving the brain’s functionality. Some examples include using radiation or laser therapy to target specific regions of the brain, which could be useful when the area causing seizures is hard to reach or if traditional surgery is too risky. There are also other treatment options for those who cannot have surgery. For example, nerve stimulation therapies like vagus nerve stimulation (VNS) or responsive neurostimulation (RNS) are sometimes used. Additionally, some people might find a special high-fat, low-carb diet known as the ketogenic diet helpful in reducing the frequency of seizures.
What else can Temporal Seizure be?
Doctors consider a variety of conditions when diagnosing temporal lobe epilepsy. These include:
- Other types of epilepsy that start in a specific part of the brain (like the frontal or parietal lobe)
- Migraines
- Mental health disorders (like panic disorders and psychotic disorders)
- Seizures that aren’t caused by epilepsy (nonepileptic seizures)
- Syncope (fainting)
What to expect with Temporal Seizure
Most people with epilepsy can successfully control their seizures with one or a combination of anti-epileptic drugs (AEDs). However, temporal lobe epilepsy often proves resistant to these medicines. Roughly 75% of patients with medial temporal lobe epilepsy (MTLE) don’t see significant improvement with medication treatment. Interestingly, approximately 75% of these patients experience freedom from seizures following surgical intervention.
For those who don’t respond to AEDs, surgery on the temporal lobe has demonstrated to improve quality of life, decrease death rate, and lower overall healthcare costs when the procedure is successful.
Possible Complications When Diagnosed with Temporal Seizure
: The risk of losing brain functions permanently increases with the duration and frequency of epilepsy. This greatly affects a person’s quality of life and social interaction. Furthermore, it can lead to a range of mental health issues including depression, anxiety, and memory problems.
Medicine used to treat epilepsy, also known as AEDs, can cause negative side effects such as liver damage, birth defects, and skin reactions. In addition, there can be complications during surgical treatments.
A sudden death in an epileptic patient without any known causes is referred to as SUDEP. It has a yearly incidence of around 0.1 percent among people with epilepsy and is the leading cause of death among people who can’t control their seizures. The cause is thought to mostly come down to disorders of the heart’s automatic workings or issues with the respiratory system.
Epilepsy Side Effects:
- Permanent neurocognitive decline
- Reductions in quality of life or social interaction
- Depression, anxiety, memory problems
- Negative side effects of AEDs such as liver damage, birth defects
- Skin reactions from AEDs
- Potential surgical complications
- Sudden unexplained death (SUDEP)
- Potential heart or respiratory dysfunction
Preventing Temporal Seizure
Patients should be informed about the possible complications that can occur with epilepsy. They should also learn about the benefits and risks of all available treatment options. In some states, people who have epilepsy are required to report their condition to the Department of Motor Vehicles. This is because seizures, or “ictal events”, can make it risky for them to drive and potentially lead to accidents.