November is National Epilepsy Awareness Month

November is National Epilepsy Awareness Month

Friday, November 25, 2022

What is epilepsy?

The human brain is organized by lobes (frontal, temporal, parietal, and occipital) which contain various networks that carry out different functions (language, sensation, movement, vision, emotion, planning etc…). These lobes and networks do no exist in isolation, rather, they are all interconnected and communicate with one another using electrical impulses.

The growing understanding of epilepsy over the years has resulted in changes to the definition and classification of this brain disorder. In 2014, the International League Against Epilepsy (ILAE) set forth an updated practical definition. Epilepsy is defined as:

1. Two unprovoked seizures occurring more than 24 hours apart.
2. One unprovoked seizure and a probability of further seizures greater than 60% over 10 years.
3. A diagnosis of an epilepsy syndrome.

With that, it is important to define a seizure. A seizure is a transient sign or symptom due to abnormal excessive and synchronous neuronal activity in the brain. At the risk of oversimplifying this complex disease, epilepsy is a disorder of the brain’s electrical activity, and the symptom of this disorder is the seizure.

 Epilepsy classification.

Epilepsy is classified either by seizure type or by the underlying etiology. One common misconception is that a seizure can only be a convulsive event where a patient violently shakes. In reality, the seizure can be a number of signs or symptoms depending on where in the brain it is originating. Seizures can be a visual hallucination, a staring event, a sensory disturbance (such as tingling), a muscle twitch, a sudden collapse to the ground, a stiffening of one or more limbs, a laughter, or autonomic dysfunction (such as sudden blood pressure changes).

Seizure type largely refers to the onset of the seizure in the brain. If the seizure arises from one particular region in the brain, this is called focal. And if the seizure engages bilateral brain networks at onset, this is referred to as generalized. Therefore, if a patient only has focal seizures, then they have focal epilepsy. If they have only generalized seizures, then they have generalized epilepsy. And if they have a combination of the two, then they’re said to have combined generalized and focal epilepsy. Of note, a focal seizure can spread to neighboring brain regions and eventually become generalized which is referred to as secondary generalization.

The other classification method for epilepsy employs an understanding of the underlying cause. With that, there are six categories epilepsy can fall under:

1. Structural: this is an epilepsy that is driven by an abnormality in the brain’s structure which can be a developmental abnormality or an acquired abnormality such as a tumor, stroke, hemorrhage, or infection. These abnormalities are more often than not detected on brain MRI.
2. Genetic: this type of epilepsy results when an aberrant gene known to cause epilepsy is present or a genetic predisposition which is often the result of multiple genes present.
3. Infectious: this is the most common worldwide cause of epilepsy though it is most prevalent in developing nations. This is diagnosed when seizures are the core symptom of an infectious syndrome such cerebral malaria, Zika infection, HIV, and certain parasitic infections like neurocysticercosis.
4. Metabolic: this type of epilepsy is driven by an abnormal metabolic process in the body, such as poor metabolism of a certain chemical or glucose transport deficiency. Identifying and treating these metabolic derangements can sometimes prevent developmental decline and in some instances be curative.
5. Immune: this epilepsy results from an inflammatory condition in the brain referred to as autoimmune encephalitis. As the immune system incorrectly attacks the brain, seizures can occur in a recurrent fashion.
6. Unknown: this is a category used for patients who undergo an exhaustive evaluation after a first unprovoked seizure and no cause is found. This occurs in up to 50% of newly diagnosed patients.

Diagnosis of epilepsy.

To this day, epilepsy for the most part remains a clinical diagnosis. If a patient of the right age group develops typical recurrent and stereotyped events that are brief and self-resolving, they have epilepsy once mimics have been excluded. Epilepsy is bimodal and typically occurring in the first few years of life or with increasing rate after the fifth decade of life. The etiology varies by age as well. Childhood epilepsies are often generalized and genetic whereas adult epilepsies are often focal and structural. Exception exist in both age groups. Neurologists often employ several diagnostic tools at their disposal to not only confirm the diagnosis epilepsy, but better classify and treat the patient.

MRI imaging of the brain has become a cornerstone in the evaluation of the patient with epilepsy, especially focal epilepsy. The main purpose of imaging is to evaluate the structure of the brain for any abnormality that could be resulting in the epilepsy and present a surgical target. Examples include scarring (mesial temporal sclerosis), tumor, stroke, hemorrhage, vascular malformation, and congenital malformation to name a few.

Electroencephalogram (EEG) is another tool often used in the evaluation of an epilepsy patient. This test uses electrodes placed on the scalp to record and map the electrical activity of the brain in an effort to identify the region of abnormal activity which can aid in classification and treatment.

Epilepsy monitoring units are a growing service and tool in the evaluation of epilepsy. A patient is electively admitted to the hospital where an EEG study is conducted continuously for five days typically during which time the patient’s medications are often held and provoking/activating procedures are performed. This can be done for various reason including but not limited to confirming a diagnosis of epilepsy, confirming a diagnosis of non-epileptic seizures (“stress seizure”), evaluating response to treatment, titrating medications, and evaluating a patient for epilepsy surgery. This technology is slowly getting perfected on the outpatient side as well where patients can now be monitored in their home environment using ambulatory EEG. 

Treatment of epilepsy. 

The successful treatment of epilepsy is a joint endeavor where the patient contribution is just as crucial as the Neurologist. Treatment begins with proper patient education. One big question that arises is can or should the patient be allowed to drive. State laws vary when it comes to driving with epilepsy but all require a certain period of seizure freedom before operating a vehicle again. This can be as little as three months or as long as a year. Another important education relating to epilepsy is Sudden Unexplained Death in Epilepsy (SUDEP). Patients with epilepsy can sadly expire following a seizure which is currently an exploding area of research attempting to explain this phenomenon. Observations made so far suggest patients with generalized epilepsy are more likely to suffer from SUDEP than focal epilepsy. Additionally, uncontrolled convulsive seizures significantly increase the risk of SUDEP.

 Lifestyle modifications are another cornerstone in treating epilepsy. This is mainly aimed at reducing the risk of a seizure occurring. Examples of lifestyle modification includes avoiding known triggers, getting adequate sleep, adhering to medications, avoiding stressful situations, and avoiding or consuming alcohol in moderation. Other lifestyle modifications are aimed at ensuring patient safety. These include not driving as discussed above, not bathing alone, not swimming unattended, avoiding heights/ladders, not cooking alone, and avoiding use of heavy machinery.

The mainstay treatment of epilepsy is the use of antiseizure medications. It is important to stress these medications suppress seizures but do not modify or cure the underlying disease, the epilepsy. Antiseizure medications (ASM) is an ever-evolving field with advent of newer and more effective medicines on a regular basis. ASM are classified as broad spectrum (having multiple mechanisms of action in the brain) or narrow spectrum (having a single mechanism of action). Narrow spectrum ASM are used only for focal epilepsy whereas broad spectrum ASM are used for both focal and generalized epilepsy. If seizure freedom is not achieved with a single ASM, the likelihood of that occurring decreases with additional agents. In fact, based on one observational study, about 87% of patients treated with a single ASM achieve seizure freedom at one year. Adding a second ASM offers an additional 11.6% likelihood of seizure freedom. A third ASM adds 4.4% chance of seizure freedom, and any added medication after that 2.2%.

This paves the way to epilepsy surgery, a treatment reserved for drug resistant epilepsy, or medically intractable epilepsy. The latter is defined as unremitting seizures despite taking at least two medications at optimal doses, whether together or separately. Should a patient get diagnosed with intractable epilepsy, they undergo Phase I and Phase II monitoring in an epilepsy unit. During this extensive evaluation, their seizure focus is accurately mapped and tests are done to determine the effects of removing said focus. If the tests indicate the loss of this brain portion does not negatively impact the patient, then they are cleared to undergo surgery. Otherwise, they are not deemed a surgical candidate. There are now several surgical techniques in treating intractable epilepsy including Vagus Nerve Stimulation (VNS), Anterior Temporal Lobectomy (ATL), Laser Interstitial Thermal Ablation (LITT), Deep Brain stimulation (DBS), Stereotactic radiosurgery, and Responsive Neurostimulation (RNS).

Dr. Oliver Achi, Neurologist, Medical Director of Neurology Services, Iberia Medical Center 

Appointments with Dr. Achi:  337.374.7242