Epilepsy Fast Facts

Epilepsy is a chronic disorder, the hallmark of which is recurrent, unprovoked seizures. A person is diagnosed with epilepsy if they have two unprovoked seizures (or one unprovoked seizure with the likelihood of more) that were not caused by some known and reversible medical condition like alcohol withdrawal or extremely low blood sugar.

The seizures in epilepsy may be related to a brain injury or a family tendency, but often the cause is entirely unknown. The word “epilepsy” does not indicate anything about the cause of the person’s seizures or their severity.

Many people with epilepsy have more than one type of seizure and may have other symptoms of neurological problems. Sometimes EEG (electroencephalogram) testing, clinical history, family history, and outlook are similar among a group of people with epilepsy. In these situations, their condition can be defined as specific epilepsy syndrome.

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Epilepsy strikes about 1% of the population by age 20, and 3% by age 75. Approximately 150,000 new cases of epilepsy are diagnosed in the U.S. each year.

What is Epilepsy?

Usually, the brain and body are a symphony of electrical activity. Brain cells constantly send out electrical signals that travel along the nerves to the rest of the body. Seizures result from an abnormal electrical discharge in the brain.

Seizures come on suddenly and strike the brain like an electrical storm. Nerve cells, or neurons, fire wildly. A seizure occurs when a surge of electricity overloads parts of the brain’s circuitry and causes unwanted changes in movement, behavior, or feeling.

Epilepsy is characterized by a wide range of seizure types and varies from person to person. Having a single seizure may not mean someone has epilepsy. Epilepsy is diagnosed when someone has two unprovoked seizures not caused by a medical condition, such as alcohol withdrawal or extremely low blood sugar.

Epilepsy can cause periods of unusual behavior and strange sensations. Seizures can also disrupt “eloquent” regions of the brain involving essential functions such as speech, movement, and awareness.

Types of Seizures

Focal (partial) seizures are caused by abnormal activity in just one area of the brain. There are two types of focal seizures:

  • Focal seizures without loss of consciousness may change a person’s emotions or make things look, smell, feel, taste, or sound different. They may also cause involuntary jerking of the body, tingling, and dizziness.
  • Focal seizures with impaired awareness involve a change or loss of consciousness or awareness. During a complex partial seizure, a person may stare into space and not respond normally to their surroundings.

Seizures that involve all areas of the brain are called generalized seizures. There are six types:

  • Absence seizures. Previously known as petit mal seizures, they usually happen in children. Seizures vary in frequency and duration from a few seconds to several minutes. Absence seizures may look like short attention blackouts or daydreaming. A child may seem momentarily confused or unaware of his or her surroundings. Absence seizures last up to 20 seconds and can occur very often (up to hundreds of times a day). Medications can help control symptoms.
  • Tonic seizures cause muscle stiffening, usually in the back, arms, and legs.
  • Atonic seizures cause a loss of muscle control, which may cause someone to fall suddenly.
  • Clonic seizures are characterized by repeated or rhythmic jerking muscle movements, especially in the neck, face, and arms.
  • Myoclonic seizures are usually characterized as sudden, brief jerks or twitches of the arms and legs.
  • Tonic-clonic seizures were previously known as grand mal seizures. They are the most dramatic type of epileptic seizure. Tonic-clonic seizures can cause loss of consciousness, body stiffening and shaking, loss of bladder control, or tongue-biting.

Phases of a seizure

The active part of a seizure is called the “ictal” state. The “postictal” state afterward is the period before normal consciousness returns. During that time, there is typically a period of recovery. It usually lasts about three to 15 minutes (but may go on for hours).

The postictal state is often characterized by confusion, fatigue, headache, and abnormal behavior. People may not remember what happened during a seizure and immediately after.

What Causes Epilepsy?

Epilepsy is caused by unusual nerve cell activity in the brain. Seizures are the result of excessive and abnormal activity by neurons in the brain’s cerebral cortex.

Epilepsy most often strikes the brain’s temporal lobe (beneath the temples). Seizures generally have no immediate cause.

Epilepsy is not “contagious.” A person can’t “catch it” from someone else. About half the cases occur for no known reason. In the other half, epilepsy may be caused by any of the following:

  • Genetics. Epilepsy sometimes runs in families. Specific genes may make someone more sensitive to environmental conditions that can lead to seizures.
  • Head injury can cause epilepsy. Seizures may go away after the acute injury calms down. Seizures can also occur later on, driven by scarring in the brain after an injury. This is known as “post-traumatic epilepsy.”
  • Brain disorders. Conditions like a brain tumor, stroke, or dementia can cause epilepsy. Stroke is a common cause of epilepsy in those over age 55.
  • Infectious Diseases. Meningitis, AIDS, and viral encephalitis (an infection of the brain) can cause epilepsy. Even after the infection is treated, the condition can leave scars on the brain that cause seizures.
  • Prenatal conditions. Before birth, brain damage can develop from an infection, poor nutrition, or oxygen deficiency. This damage can cause epilepsy.
  • Developmental health conditions. Developmental disorders, such as autism spectrum disorder, can cause epilepsy.
  • Childhood seizures. High fevers in children are associated with seizures. Usually, children with seizures caused by high fevers don’t develop epilepsy. The risk increases if a child has a prolonged seizure, another nervous system condition, or a family history of epilepsy.

Related conditions

Learning disabilities are common in people with epilepsy, especially children. Certain disorders — including depression, anxiety, obsessive-compulsive disorder (OCD), and migraine — occur more often in people with epilepsy.

Attention deficit hyperactivity disorder (ADHD) affects three to five times more children with epilepsy than those without the condition.

About a third of people with epilepsy are accidentally injured each year as a result of the disorder.

Is Epilepsy Hereditary?

Genetic factors influence whether someone will develop epilepsy. The disorder doesn’t result from a single gene. It can happen to anyone, at any age.

If a close relative, such as a parent or sibling, has epilepsy, an individual may be at higher risk for epilepsy than someone with no family history. The chance of passing epilepsy down through generations is low.

If a parent has epilepsy, there is a 9%–12% chance that the child will also have epilepsy. Although most siblings of a child with epilepsy do not develop the disorder, brothers and sisters have a higher risk of epilepsy. If one twin has idiopathic epilepsy, meaning it arises for no reason, the identical twin is also likely to develop the disorder.

Two members of the same family may both develop epilepsy, but the effects in each may be very different.

Some epilepsy syndromes are known to have a genetic basis, but the specific gene or genes that cause them have not been identified.

How Is Epilepsy Detected?

Epilepsy is diagnosed when someone has two unprovoked seizures (or one unprovoked seizure with the likelihood of more). What accounts for the severity and timing of seizure activity?

Seizures may be related to a brain injury or family history, but often the cause is entirely unknown. Brainwave activity offers subtle clues to the origin of a seizure.

  • Many people with epilepsy have more than one type of seizure. The earlier someone is diagnosed, the sooner the relief from the seizures.
  • Anyone who has had a seizure — or suspects they might have had one — should see a doctor.
  • A primary care provider will refer someone suspected of having a seizure to a neurologist, a doctor with special training in disorders of the brain, including epilepsy.
  • Many people with epilepsy show symptoms of other neurological problems.
  • When someone is diagnosed with epilepsy, it can be helpful to know what triggered the seizure. Researchers are seeking ways to predict seizures before they occur.
  • Earlier detection of seizures might help: very early detection of a seizure’s onset may allow therapeutic or warning devices to be triggered before the start of disabling clinical symptoms. 

How Is Epilepsy Diagnosed?

Diagnostic testing for epilepsy begins with an EEG (electroencephalogram). The doctor will also ask about any family history of epilepsy.

Diagnosing epilepsy can be like putting the pieces of a puzzle together. It can include information from many specialists and types of tests. Several other medical issues — fainting, hyperventilation, migraines, narcolepsy, and panic attacks — may seem like epilepsy.

Someone who has epilepsy may want to bring along someone who saw the seizure. The doctor will want to hear about the seizure, but also what happened before or afterward. Having someone else there can be helpful.

To diagnose epilepsy, the doctor will go over the symptoms and medical history. The doctor may order tests to figure out why someone is having seizures, such as:

  • A neurological exam. A doctor tests a person’s behavior, motor skills, and mental capabilities to determine if they have epilepsy.
  • Blood tests. A specialist may take a blood sample to check for signs of infections, genetic conditions, or other conditions that might cause seizures.
  • Electroencephalogram (EEG) is the most common test used to diagnose epilepsy. During this test, doctors attach electrodes to a person’s scalp, which records the brain’s electrical activity. If someone has epilepsy, it’s common to have changes in the regular brain wave pattern, even while not having a seizure.
  • The doctor may monitor a patient on video while conducting an EEG to record any seizures they experience, either awake or asleep. The EEG can help determine the type of seizures.
  • Computerized tomography (CT) scan. A CT scan uses X-rays to reveal if anything else in the brain — such as tumors or bleeding — may be causing seizures.
  • Magnetic resonance imaging (MRI). An MRI uses powerful magnets and radio waves to create a detailed view of the brain. Like a CT scan, MRI can also show if any brain abnormalities could be causing seizures.
  • Positron emission tomography (PET). During a PET scan, the doctor injects a small amount of low-dose radioactive material into the vein. This material helps doctors observe active areas in the brain for anything abnormal.
  • Single-photon emission computerized tomography (SPECT). This test is typically used to pinpoint the location where seizures arise in the brain. A small amount of low-dose radioactive material is injected into a vein. SPECT creates a 3D map of the brain’s blood flow.

How Is Epilepsy Treated?

Doctors usually treat epilepsy with medication. Seizures are controllable by medicines in about 70% of cases. If drugs don’t stop the seizures, the doctor may propose surgery or another type of treatment. Dietary changes are often tried for childhood epilepsy.

The U.S. Food and Drug Administration (FDA) has approved several prescription drugs to treat epilepsy.


Most people with epilepsy can become seizure-free by taking a single anti-seizure medication. Others may be able to decrease the frequency and intensity of their seizures by combining medicines.

Starting anti-seizure medication therapy reduces the risk of another seizure. The doctor will schedule ongoing follow-up appointments to evaluate how the medications are working.

Finding the proper medication and dosage can be complicated. The doctor will consider a patient’s age and overall health, how often seizures occur,  and other factors when prescribing a medication. Some people with epilepsy may be able to go off medications if they have gone two or more years without seizures — with their doctor’s advice and support.

Anti-seizure medications may have side effects, such as:

  • Fatigue
  • Dizziness
  • Weight gain
  • Loss of bone density
  • Skin Rashes
  • Loss of coordination
  • Speech problems
  • Memory and thinking problems

More severe, but rare, side-effects include:

  • Depression
  • Suicidal thoughts and behaviors
  • Severe rash
  • Inflammation of specific organs, including the liver

Epilepsy surgery

If medications don’t control seizures, surgery may help. During epilepsy surgery, a surgeon removes the area of the brain where seizures begin.

Doctors usually perform surgery when tests show that seizures originate in a small, well-defined area of the brain that doesn’t interfere with crucial functions such as speech, language, motor function, vision, or hearing.

Although many people still need medication to help prevent seizures after successful surgery, they may be of a lower dose.

Other therapies

In addition to medications and surgery, additional therapies offer options for epilepsy:

  • Ketogenic diet. Some children with epilepsy can reduce seizures by following a strict diet high in fats and low in carbohydrates. The “ketogenic” diet allows the body to use fat, rather than carbohydrates, for energy. After a few years, some children may be able to stop the ketogenic diet and remain seizure-free.

A ketogenic diet must be strictly monitored and prescribed by a doctor. A registered dietitian (RD) can help families manage their diet. Side-effects of a ketogenic diet include dehydration, constipation, slowed growth due to nutritional deficiencies, and kidney stones. These side-effects are rare if the diet is medically supervised.

  • Vagus nerve stimulation can often reduce seizures by 20-40%. The doctor implants a device called a vagus nerve stimulator underneath the skin of the chest. It’s similar to a heart pacemaker. Wires from the stimulator are connected to the vagus nerve in the neck. The battery-powered device sends bursts of electrical energy through the vagus nerve to the brain. Potential side-effects from vagus nerve stimulation include throat pain, hoarse voice, shortness of breath, or coughing. After vagus nerve stimulation, people often still need to take anti-seizure medication, though they may be able to lower the dose.
  • Deep brain stimulation. Surgeons implant electrodes into a specific part of the brain, typically the thalamus. Like vagus nerve stimulation, the electrodes are connected to a generator implanted in the chest or skull. The device sends electrical pulses to the brain, which may reduce seizures. Deep brain stimulation may help relieve symptoms. People may need to take anti-seizure medication, though they may be able to lower the dose.
  • Avoidance therapy. Some people experience seizures as a reaction to specific stimuli, like certain sounds or flashing lights. Avoidance therapy focuses on minimizing or eliminating triggers. For example, those who are sensitive to light may benefit from using a small television, avoiding video games, or wearing dark glasses. Avoidance does not replace medicine.
  • Exercise. Exercise has been proposed as potentially helpful in preventing seizures.
  • Therapy animals. Some dogs, often referred to as seizure dogs, may help during or after a seizure. It is not clear whether dogs can predict seizures before they occur.

How Does Epilepsy Progress?

Medication is usually tried first to control seizures. Sometimes epilepsy is managed with surgery or other therapies. As epilepsy progresses, people exhibit a wide variety of symptoms, including sensations of déjà vu, twitching on one side of the body, acting confused, or having difficulty speaking. Some people just stare blankly for a few seconds. Others may twitch their arms and legs or fall.

The percentage of people with treatment-resistant epilepsy has not decreased despite introducing a dozen new FDA-approved antiepileptic medications since 1993. Recurrent seizures are believed to cause progressive brain injury, resulting in loss of cognitive ability and “kindling” further seizures in the brain’s affected region.

Epilepsy research is ongoing at medical centers around the world. Scientists are investigating new therapies to halt the progression of epilepsy. Experimental treatments include:

  • Responsive neurostimulation. Researchers are working on developing pacemaker-like devices that help prevent seizures. They analyze the brain’s activity to spot episodes before they happen and deliver an electrical charge or drug to stop the seizure.
  • Continuous stimulation of the seizure onset zone (subthreshold stimulation). Bringing constant stimulation to one area of the brain may improve some people’s quality of life with seizures.
  • Minimally invasive surgery. New minimally invasive surgical techniques, such as MRI-guided laser ablation, may reduce seizures with fewer risks than traditional brain surgery.
  • Stereotactic laser ablation or stereotactic radiosurgery. If surgery is considered too risky, a laser or radiation beam can target a specific area in the brain. Destroying a small area may reduce abnormal activity in the part of the brain where seizures begin.
  • External nerve stimulation. The device is designed to reduce seizures by stimulating specific nerves. Unlike vagus nerve stimulation, this device is worn externally, so no surgery to implant is required.
  • Genetic testing. Researchers are trying to identify genes that influence or cause epilepsy. Someday, doctors may be able to prevent the disorder or predict which treatments will be most beneficial to people with specific types of epilepsy.

How Is Epilepsy Prevented?

In most cases, epilepsy can’t be prevented.  However, once a diagnosis of epilepsy is determined, it can be managed.

Changes in diet have been shown to improve seizures in children. Some people may need treatment for the rest of their lives to control seizures. Sometimes, seizures go away. Many children with epilepsy stop having seizures as they get older: more than 50% of children outgrow epilepsy.

Twenty years after an epilepsy diagnosis, 75% will have been seizure-free for at least five years — although some may still need to take daily medication. Epilepsy is considered to be resolved for people who have remained seizure-free for the past ten years, with no seizure medications for the past five years.

Epilepsy Caregiver Tips

The most important thing you can do for a loved one with epilepsy is to be supportive. Epilepsy is a common condition. Some seizures rarely cause problems.

Overall, the chance of injury is higher for people with uncontrolled seizures. Bruises, cuts, burns, and falls are all common injuries. Less common concerns include breathing problems, drowning (due to a seizure while swimming or bathing), car accidents (many states restrict driver’s licenses for those with epilepsy), and pregnancy complications.

Rolling someone with an active tonic-clonic seizure onto their side helps prevent fluids from getting into the lungs. Putting fingers, a bite block, or tongue depressor in the mouth is not recommended.  

It’s essential to help a loved one with epilepsy keep track of how often seizures occur. It’s especially crucial when trying a new treatment, like a new medication or a different dosage.

Caregivers should also be aware of the rare, but life-threatening complications of epilepsy, including:

  • Status epilepticus, a state of continuous seizure activity lasting more than five minutes. People with status epilepticus have an increased risk of permanent brain damage and death.
  • Sudden unexpected death in epilepsy (SUDEP). People with epilepsy also have a small risk of sudden unexpected death. The risk is very low (about 1% of people with epilepsy), and the cause is unknown. People whose seizures aren’t controlled by medications or who have frequent tonic-clonic seizures have a higher risk of SUDEP.

Many people with epilepsy also suffer from other brain and mental health-related issues, a condition called co-morbidity. Here are a few of the disorders commonly associated with epilepsy:

Epilepsy Brain Science

Epilepsy causes recurring, spontaneous seizures. Scientists study seizures by measuring brain waves and analyzing patterns of electrical activity in the brain.

  • Seizures describe a period of abnormal, synchronized neuronal firing. The manifestation of the seizure depends on the brain region where the excitable neurons are located.
  • Many possible mechanisms underlie epilepsy, including genetics, previous injury, and environment.
  • Scientific studies have determined numerous genetic mutations that may contribute to epilepsy. These mutations promote a state of hyperexcitability in specific brain regions.
  • Researchers are working on responsive neurostimulation. The pacemaker-like devices help prevent seizures by analyzing the brain’s activity. They spot seizures before they happen and deliver an electrical charge or drug to stop the seizure.
  • Continuous stimulation of a particular area of the brain may improve some people’s quality of life with seizures. One promising technique is the constant stimulation of the seizure onset zone (subthreshold stimulation).
  • Personalized medicine and targeted therapies are accelerating the pace of research. Gene therapy is being studied in some types of epilepsy. Breakthroughs continue to bring hope to people with brain disorders.

Pregnant women with epilepsy taking antiepileptic medication can help researchers learn how drugs affect unborn children by participating in the Antiepileptic Drug Pregnancy Registry.

Epilepsy Research

Title: Auditory Stimulation Effects on Sleep and Memory in Patients With Epilepsy

Stage: Recruiting

Principal Investigator:  Dara Manoach, PhD

Massachusetts General Hospital

Boston, MA

The investigators will test the hypotheses that coordinated brain rhythms during nonrapid eye movement sleep are associated with memory consolidation and can be enhanced with auditory stimulation (playing precisely timed brief bursts of quiet noise) to improve memory. The investigators will measure differences in sleep and memory performance in epilepsy inpatients with implanted hippocampal electrodes and continuous full scalp EEG monitoring under three overnight sleep conditions: a baseline night; a memory night during which sleep-dependent memory consolidation is assessed with the finger tapping motor sequence task (MST) with training before sleep and testing the following morning; and a stimulation night during which participants train on the MST, have precisely timed auditory stimulation during the sleep that follows, and are tested on the MST in the morning.

Title: Ketogenic Diet for New-Onset Absence Epilepsy

Stage: Recruiting

Principal Investigator:  Eric H. Kossoff, MD

Johns Hopkins University

Baltimore, MD

The ketogenic diet is a medical therapy for epilepsy used nearly predominantly for refractory epilepsy (after 2-3 drugs have been tried and failed). However, there is both published evidence for first-line use (infantile spasms, Glut1 deficiency syndrome) and also anecdotal experience (families choosing to change the child’s (or the family’s own) diet rather than use anticonvulsant medications). Childhood absence epilepsy (refractory) has been previously published as being responsive to ketogenic diet therapy by the investigators’ group. This is a small, prospective, 3-month trial to assess if using a modified Atkins diet is a feasible and effective option for new-onset childhood absence epilepsy. The investigators will compare to a group of children in which the parents have declined and chose to start anticonvulsant medications.

Title: Imaging of Neuro-Inflammation and the Risk for Post-Traumatic Epilepsy

Stage: Recruiting

Contact:  Ryan M. Martin, MD

University of California, Davis

Sacramento, CA

This study plans to evaluate the time course of inflammation in the brain after a moderate to severe traumatic brain injury using positron emission tomography (PET) brain imaging. Patients will undergo PET scans of the brain at two weeks and two months after injury to measure neuroinflammation. The results of the PET scans will be analyzed and correlated with the risk of post-traumatic epilepsy.  

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