What Is Epilepsy?
Illustration by Mira Norian for Health
Medically reviewed by Nicholas R. Metrus, MD
Epilepsy is a seizure disorder that affects part of or the entire brain and can have very noticeable symptoms. Symptoms vary based on the seizure type.
Abnormal patterns of electrical activity in the brain cause epilepsy. The exact cause of epilepsy is unknown in most cases. Stroke, brain trauma, inflammation, and genetics can lead to epilepsy. High blood pressure and previous head injury have also been shown to increase the risk.
About 50 million people around the world have epilepsy. Many people manage epilepsy with treatments. Read on to learn about epilepsy, including types, symptoms, treatments, and more.
Related: What Is a Concussion?
Types of Epilepsy
The International League Against Epilepsy (ILAE) developed diagnostic criteria for epilepsy in 2017. The criteria combine different symptoms and features of epilepsy, leading to a specific diagnosis. Seizures are typically broadly classified into different groups: focal, generalized, and unknown onset. These groups are categorized based on where the seizure occurred in the brain.
Sometimes, seizures occur with no known underlying cause. Others occur as a result of something that can be detected, such as a brain tumor or stroke.
Focal Onset
A focal onset seizure starts in one part of the brain, only affecting that one side. These are further divided into two subtypes: focal awareness seizures and focal impaired awareness.
A person with focal aware does not lose awareness during the seizure. There may be motor or non-motor symptoms. A person with focal impaired awareness, in contrast, loses some awareness. The symptoms may also be motor or non-motor.
Different ways of classifying the seizure include:
Impaired awareness seizure: This seizure results in a noticeable change in your level of awareness. You may have involuntary repetitive movements, or automatisms.
Motor seizure: This causes jerking, stiffening, or twitching of muscles and sometimes repetitive movements.
Non-motor seizures: These seizures may cause strange sensations or a feeling of déjà vu (the feeling that you’ve had this exact experience before). You will remain alert to these changes.
Generalized Onset
A generalized onset seizure affects both sides of the brain. There are many ways of describing seizures of this type, including:
Absence seizure: A person loses consciousness and stares into space.
Atonic seizure: Your body goes limp. These seizures may also cause you to fall, make your head nod, or cause your eyelids to droop.
Bilateral tonic-clonic (grand mal) seizures: These seizures start from one region but spread and affect the entire brain. This leads to the stiffening and twitching of muscles.
Myoclonic seizure: These seizures involve brief jerking muscle spasms.
Tonic seizure: These seizures cause the stiffening of muscles.
Tonic-clonic seizure: Your muscles stiffen and then twitch and jerk.
Unknown Onset
Healthcare providers are sometimes not able to determine the type of epilepsy. People have unknown onset if a healthcare provider cannot narrow down the type.
luaeva / Getty Images
Epilepsy Symptoms
Epilepsy symptoms are based on the type and parts of the brain affected. Some people will have both focal and generalized types of seizures. This typically occurs with epilepsy caused by genetic factors.
Prodromal
More than 20% of people with epilepsy have prodromal symptoms. These symptoms can occur days before the onset of the seizure itself.
Prodromal symptoms include:
A "funny feeling"
Confusion
Headache
Irritability
Focal Onset
Focal onset seizures affect only one specific part of the brain. The symptoms of these seizures depend on their location.
Symptoms generally include:
A smell, taste, or feeling that isn't real (e.g., the smell of burnt toast when there is no toast nearby)
Auditory or visual hallucinations
Intense déjà vu
Movements in one body part
Repetitive behaviors (e.g., frequent blinking, twitching, or mouth movements)
Unexplained feelings of joy, anger, sadness, or nausea
Zoning out of consciousness into a dreamlike state
Generalized Onset
Generalized onset seizures affect both sides of the brain. Subtypes include distinctive symptoms:
Absence seizures: These cause impaired awareness, staring into space, and repetitive behaviors or muscle twitching.
Atonic seizures: These seizures make your muscles go limp, which causes falls.
Clonic seizures: These seizures cause repetitive jerking movements on both sides of your body.
Myoclonic seizures: You may have twitching movements in your upper body, arms, or legs.
Tonic seizures: Your muscles become stiff, and you may fall down or struggle to stay afloat if you are swimming.
Tonic-clonic seizures: Symptoms of this subtype include body stiffening, followed by repetitive jerking of the limbs. You may lose consciousness.
What Causes Epilepsy?
Nerve cells (neurons) normally communicate through electrical signals and neurotransmitters. Neurotransmitters are chemicals that send messages throughout your body. Gamma-aminobutyric acid (GABA) and glutamate are neurotransmitters.
Glutamate causes neurons to fire, while GABA tells neurons to stop. The signals from these neurotransmitters are not balanced in people with epilepsy. This imbalance can cause the neurons to misfire. Abnormal electrical activity is a telltale sign of seizures.
The underlying cause of epilepsy is unclear in most cases. Possible causes include:
Genetics: Multiple genetic factors affect electrical signaling in the brain. Inheriting these factors may lead to epilepsy.
Inflammation due to infection: Immune cells normally make antibodies to destroy germs. This response damages healthy cells.
Traumatic brain injury (TBI) or stroke: Repetitive trauma or strokes damage the brain. The brain can make a mistake that leads to epilepsy as it recovers by rewiring itself. The immune response to this injury may also lead to further damage.
Tumors: Seizures that occur with brain tumors are caused by a combination of where the tumor is located, genetics, and irritation of the surrounding brain.
Risk Factors
Multiple factors contribute to epilepsy risk. Risk factors include:
Age: Epilepsy is most common in early childhood and after the age of 85.
Geography: Rates of epilepsy are about three times higher in low- and middle-income countries than in high-income countries. This discrepancy may result from differences in access to healthcare.
Hypertension: This is high blood pressure. Hypertension damages blood vessels and puts you at risk of stroke, which can lead to epilepsy.
Medications: Many drug classes increase the risk of epilepsy. These include antidepressants, stimulants, and antihistamines, among others.
Prior brain injury: Head trauma contributes to the risk of epilepsy later in life. These injuries may make the brain more prone to seizure activity.
Sex: Rates of epilepsy are slightly higher in people assigned female at birth than in people assigned male at birth.
How Is Epilepsy Diagnosed?
A neurologist will start by collecting your medical history and performing a physical exam to help diagnose epilepsy. This healthcare provider specializes in treating disorders of the brain and spinal cord.
Neurologists may screen for and rule out other health conditions. A first-time seizure, for example, does not mean a person has epilepsy. A neurologist may check for triggers, such as hemorrhage, high blood pressure, and stress. A high fever can cause seizures, called febrile seizures, in infants and young children.
Tests that help diagnose epilepsy include:
Blood tests: These can spot signs of inflammation, infections, and other problems that lead to seizures. Low levels of sodium or high blood sugar, for example, can cause seizures.
Computer tomography (CT) scan: This imaging test combines multiple X-ray images of the brain. A CT scan can identify tumors or cysts that cause seizures.
Electroencephalography (EEG): This non-invasive exam involves placing electrodes on your scalp to measure brain activity. Spikes and sharp waves in the recording of one region suggest it's prone to seizures. Abnormalities in many regions of the brain suggest generalized onset.
Genetic tests: Testing for epilepsy-associated genes helps diagnose genetic forms. These genes alter the brain's electrical activity, making neurons misfire.
Magnetic resonance imaging (MRI): This imaging test uses a magnetic field and radio waves to get a detailed image of the brain. An MRI detects lesions that may signal focal onset or other structural irregularities. Functional MRIs (fMRIs) measure changes in blood flow to the brain.
Magnetoencephalography (MEG): This non-invasive test measures magnetic signals from brain cells. A MEG helps localize focal onset by identifying the border between healthy and seizure-prone areas.
Positron emission tomography (PET): This measures the brain's metabolic activity. Areas prone to seizures show low metabolic function. Metabolic function increases during a seizure.
Single-photon emission computed tomography (SPECT): This measures changes in blood flow during seizure activity. A neurologist will inject a blood flow tracer within 30 seconds of a seizure. This tool highlights the regions of the brain affected.
Wada test: A neurologist will inject a drug into one of the carotid arteries, leading to a five-minute paralysis of one side of the brain. Carotid arteries are the vessels that provide blood to the brain. A neurologist can test memory and language in the non-paralyzed side of the brain. A Wada test also verifies the source of a seizure before surgery.
Treatments for Epilepsy
Treatments for epilepsy include medications, surgery, brain stimulation, and diet changes. The goal of treatment is to reduce the severity and number of seizures. Some people even go into full remission.
Focal Onset Medications
Anti-seizure drugs alter the balance of excitatory and inhibitory signals in the brain. This prevents abnormal electrical activity. Epilepsy is treatment-resistant if a person does not respond to the first two drugs.
Anti-seizure drugs prescribed for focal onset include:
Keppra (levetiracetam)
Lamictal (lamotrigine)
Tegretol or Curatil (carbamazepine)
Trileptal (oxcarbazepine)
Vimpat (lacosamide)
Generalized Onset Medications
Anti-seizure drugs that treat the generalized onset type depend on the subtype of seizure. A healthcare provider may prescribe the following for tonic-clonic seizures:
Depakene or Depakote (valproate)
Keppra
Lamictal
Topamax (topiramate)
Zonegran (zonisamide)
Depakene, Depakote, Keppra, and Zonegran also treat myoclonic seizures. Lamictal and Zarontin (ethosuximide) help alleviate absence seizures.
These anti-seizure drugs share many side effects, including drowsiness, dizziness, and loss of balance. These drugs rarely lead to a hypersensitivity reaction, impaired cognition, or weight changes. Valproate may increase the risk of birth defects for pregnant people.
Surgery
Surgery may be an option for treatment-resistant epilepsy. There are different procedures, including:
Corpus callosotomy: Cutting the connective fibers between the left and right side of the brain to prevent seizures from spreading
Hemispherectomy: Removing one half of the brain as a last resort procedure
Lobectomy or laminectomy: Removal of a small part of the brain causing seizures
Multiple subpial transection: Making multiple cuts in the brain to prevent further spreading of a seizure
Thermal ablation: Using lasers to destroy parts of the brain that cause seizures
Surgeons use brain imaging to localize seizures. They may also accidentally damage healthy parts of the brain. Damage can lead to cognitive impairment, personality changes, and physical disability.
Brain Stimulation
Some people are not good candidates for surgery, such as those with multiple regions of the brain causing seizures. There are two types of brain stimulation devices available that can help these people.
Deep brain stimulation uses a pacemaker to continuously stimulate the brain to prevent seizures. Responsive neurostimulation uses a pacemaker to stimulate the brain only when seizures are about to occur.
Brain stimulation may cause headaches, pain at the implant site, and a burning or prickling sensation. Rarely does brain stimulation lead to hemorrhage or infection.
Ketogenic Diet
Some evidence suggests that a strict, high-fat, low-carb diet treats epilepsy. This diet is known as the ketogenic, or "keto," diet. More research is needed to know how effective or safe the keto diet is.
It's always best to consult a healthcare provider before making any changes to your diet. They can advise you based on your individual needs and ensure your diet does not conflict with your treatment plan.
How To Prevent Epilepsy
There are limited ways to prevent epilepsy since researchers are not sure what causes many types. Here are some ways you may lower your risk:
Follow vaccination schedules: Early childhood infections or diseases can lead to epilepsy.
Lower risk of stroke and heart disease: These health concerns may cause epilepsy. Managing your blood pressure and cholesterol with medications and lifestyle changes can reduce your risk.
Prepare food safely: Cysticercosis is a parasitic infection that can lead to epilepsy. Proper food safety practices prevent the infection from spreading.
Reduce the risk of head trauma: Wearing helmets and avoiding high-impact sports can prevent brain damage.
Related Conditions
At least one-third of people with epilepsy have issues with cognition, anxiety, or depression. Children experience stigma due to their seizures. Stigma can lead to bullying, loneliness, or depression. Many of these issues are treatable through therapy, medications, and support from loved ones.
Epilepsy has been linked to a rare disorder called sudden unexpected death in epilepsy (SUDEP). Researchers are not sure what causes SUDEP. Some evidence suggests that SUDEP involves problems with the heart and lungs.
Related: What Is Tardive Dyskinesia (TD)?
Living With Epilepsy
Epilepsy is a treatable neurological condition. Seizures may reduce your mobility at first. Many states have laws preventing people from driving unless they've been seizure-free for a certain period of time.
Medications and surgery can help most people get their seizure symptoms under control. Many people go years without seizures after discontinuing drug treatment. Keep in mind, however, that it's important to never go off seizure medication on your own if you are diagnosed with epilepsy.
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