Epilepsy is a chronic neurological disorder in which the normal chemical and electrical activities between nerve cells in the brain (neurons) become disturbed. This disturbance causes the neurons to fire abnormally, resulting in seizures.

In a seizure, many neurons fire at the same time, much faster than usual — up to 500 times a second.
According to the U.S. Centers for Disease Control and Prevention (CDC), in 2015 about 3 million adults and 470,000 children and adolescents had “active” epilepsy nationally. This means they’re being treated for the condition, or they have had a seizure in the past year.

Generalized Seizures

In generalized seizures, the abnormal neuronal activity spreads across both halves (“hemispheres”) of the brain. Generalized seizures have both motor (movement) and nonmotor (absence) symptoms.

People having a generalized seizure are generally not aware of their surroundings, so observers should try to be alert to the person’s safety.

Some types of generalized seizures include:

  • Absence seizures Previously known as “petit mal” seizures, absence seizures are more common in children. This type of seizure may last only seconds and is sometimes confused with daydreaming. The person is usually unresponsive, but people having an “atypical” absence seizure may be able to respond a little.
  • Atonic seizures These are also known as “drop attacks” or “drop seizures.” The person’s normal resting muscle tension (called “tone”) goes limp. If the person is sitting, they may suddenly slump over. If they are standing, they may drop like a rag doll to the ground.
  • Myoclonic seizures These seizures are sudden body “jolts” or increases in muscle tone that make it seem as if the person has been jolted with electricity. A myoclonic seizure is similar to the sudden jerks people often experience as they are falling asleep, but these latter “sleep myoclonic” jerks are harmless, while myoclonic seizures aren’t. A subtype of myoclonic seizures, infantile spasms, typically begin in children between 3 and 12 months old and may persist for several years. They typically consist of a sudden jerk followed by stiffening. This particularly severe form of epilepsy can have lasting effects on a child.
  • Tonic seizures In this kind of seizure, the person’s muscle tone suddenly stiffens and they lose consciousness. They may also fall to the ground, but they fall in a rigid manner, more like a tree trunk than a rag doll.
  • Clonic seizures This type of seizure causes a person’s muscles to spasm and jerk; the muscles in the elbows, legs, and neck flex and relax in rapid succession. The jerking motion slows down as the seizure subsides and finally stops altogether.
  • Tonic-clonic seizures Previously known as “grand mal” seizures, these are the kind of convulsions that people often associate with epilepsy. The person becomes rigid, as with a tonic seizure, and then muscle jerking (known as “clonus”) begins.

If you see a person having an apparent seizure of any kind, do what you can to ensure the person’s safety, and make note of the time. Tonic-clonic seizures lasting more than 5 minutes are considered to be a medical emergency, and you should call 911 if you observe one.

People having a tonic-clonic seizure may lose control of their bladder or bowels, and they will feel exhausted and sore after the seizure (known as the “postictal” period).

Focal Seizures

About 60 percent of people with epilepsy have focal seizures. Focal seizures originate in one part of the brain and stay in just one hemisphere of the brain.
Focal epilepsies are also known as “localization-related” epilepsies; they were previously referred to as “partial” epilepsies.

Many focal epilepsies have an “aura,” or warning symptoms of an upcoming seizure. The person experiencing the aura is conscious.

Focal seizure symptoms are subdivided into motor (movement), sensory, autonomic, and psychic.

A focal seizure with motor symptoms typically causes jerking movements of a foot, the face, an arm, or another part of the body, while a focal seizure with sensory symptoms affects a person’s hearing or sense of smell or may cause them to experience hallucinations.

A focal seizure with autonomic symptoms affects the part of the brain responsible for involuntary functions, causing changes in blood pressure, heart rate, or bowel or bladder function. Finally, focal seizures can strike the parts of the brain that trigger emotions or memories, causing feelings of fear, anxiety, or déjà vu (the feeling that something has been experienced before).

Because focal seizures only involve part of the brain, symptoms are often not as extensive as generalized seizures. Focal symptoms often involve only one side of the body instead of both.

Focal seizures are further classified by level of awareness: aware, impaired awareness, or unknown awareness.

The types of focal seizures, by level of awareness, are:
  • Focal aware seizure (previously called “simple partial”) During a focal aware seizure, the person is awake, and they will be able to recall the seizure afterward. They may be “frozen” and unable to respond, or they may be able to tell you what is happening. These seizures may last from a few seconds to a couple of minutes, and the person will usually be able to resume normal activity afterward, although a focal aware seizure may sometimes be a sign that a more severe seizure is still to come.
  • Focal impaired awareness seizure (previously called “complex partial”) During this kind of seizure, there may be slightly impaired awareness, or awareness may be severely impaired. The person having the seizure may perform activities that seem purposeful, but it’s as if there’s “nobody home.” The actions can be fairly simple, like lip-smacking, or they may be complex actions, like walking, removing clothing, thrusting the pelvis, or bicycling the legs. They may seem like they are daydreaming, but they can’t be startled out of it, unlike a person who is daydreaming.

Some seizures start as a focal impaired awareness seizure and then progress to a generalized tonic-clonic seizure.

Remember, any tonic-clonic seizure lasting over five minutes should prompt a call to 911.

Combined and Unknown Seizure Types

Generalized and focal seizures Some epilepsies include both focal and generalized seizures, particularly some of the syndromes of early childhood, such as Dravet syndrome and Lennox-Gastaut syndrome. Some seizures begin as a focal seizure and then spread to both sides of the brain to become a generalized tonic-clonic seizure, a characteristic that used to be called “secondarily generalized seizures,” but is now called “focal onset bilateral tonic-clonic seizures.”

Learn More About Dravet Syndrome

Unknown onset seizures This term is used to describe epilepsies that seem like generalized seizures even though they’re actually caused by a focal lesion of the brain. This seizure classification is also used for people who seem to have had a generalized seizure but whose diagnostic tests are inconclusive or unavailable.

Learn More About Signs and Symptoms of Epilepsy

Types of Epilepsy

Epilepsies are often grouped by a complex set of characteristics that mark a type as a known “syndrome.” They are also sometimes described by their symptoms or by the part of the brain affected.

Examples of Some Epilepsy Syndromes

Hundreds of different epilepsy syndromes have been identified.Some epilepsies can co-occur with or lead to developmental delays. Other epilepsies have no effect on cognitive development.

Here are some of the most common epilepsy syndromes:

  • Childhood absence epilepsy (CAE) People with this epilepsy syndrome have staring spells that last 10 to 20 seconds and then end abruptly. This was previously called “petit mal” epilepsy and is most common in children. CAE often responds to medical treatment and disappears by adolescence.
  • Juvenile absence epilepsy (JAE) JAE is different from childhood absence epilepsy (CAE). The seizures tend to last longer, and the person may have this epilepsy for the rest of their life. About 80 percent of people with JAE will also have tonic-clonic seizures. JAE will often respond to treatment, but that treatment tends to be lifelong.
  • Juvenile myoclonic epilepsy (JME) Usually seizures take place within an hour of awakening. People with JME can have absence seizures, myoclonic (muscle-jerking) seizures, and generalized tonic-clonic seizures. Common triggers include sleep deprivation and stress, or exhaustion after excessive alcohol intake.
  • Childhood epilepsy with centrotemporal spikes, previously known as benign rolandic epilepsy This is a focal seizure type that appears in children ages 3 to 12 years. Half of the face may begin to twitch, and numbness of the face or tongue can occur. These seizures usually occur at night, often during sleep. For most children, seizures cease by age 13, although they can continue to age 18.
  • Reflex epilepsies With reflex epilepsy syndromes, a certain stimulus can trigger a generalized tonic-clonic (grand mal) seizure. The most common reflex epilepsy syndrome is photosensitive epilepsy, where flashing lights can trigger a seizure. This can make it a problem to watch TV, play video games, or even observe light through the trees. Other reflex epilepsy triggers can be auditory, like a song or church bells. Some people have tactile triggers, such as a hot bath or toothbrushing. The best way to prevent a seizure is to avoid the trigger, but that is not always possible.
  • Sleep-related epilepsy syndromes Some epilepsies relate directly to sleep or to immediate arousal from sleep. Examples include sleep-related hypermotor epilepsy (SHE; previously known as nocturnal frontal lobe epilepsy) and nocturnal temporal lobe epilepsy (NTLE). As with childhood epilepsy with centrotemporal spikes, sleep-related epilepsy syndromes are sometimes not caught unless someone has a seizure with motor symptoms in their sleep.

Characteristics of Epilepsies Based Upon Brain Region

Because different parts of the brain perform different functions, seizure activities in different areas can have distinct symptoms.

Here are some examples of epilepsy syndromes characterized by the regions of the brain that are affected:

  • Temporal lobe epilepsy (TLE) TLE often has an aura of déjà vu, fear, or an unusual smell or taste. TLE often begins in childhood or in the teen years. A TLE seizure can look like a staring spell, or the person may engage in pointless repetitive behaviors, called automatisms. Some common automatisms include picking at clothing, smacking the lips, eye blinking, and unusual head movements. TLE is associated with damage to the hippocampus, called hippocampal sclerosis (HS). Damage to the hippocampus can also interfere with learning and memory.
  • Frontal lobe epilepsy This often affects movement. A person who has frontal lobe epilepsy may have muscle weakness and abnormal movements, like twisting, waving the arms and legs, or grimacing during seizures. The person may be startled and even scream. There is often some loss of awareness, and some frontal lobe seizures happen when the person is asleep.
  • Neocortical epilepsy This type of epilepsy can be generalized or focal. The cortex is the outer layer of the brain, and seizure symptoms can vary from unusual sensations to visual hallucinations, emotional changes, or convulsions.
  • Occipital lobe epilepsy This is uncommon but can develop because of tumors or brain malformations, and is one of the benign focal epilepsies of childhood. It sometimes causes convulsions on both sides of the body, and visual changes can occur both before and after the seizure.
  • Hypothalamic seizures This rare type of epilepsy begins in childhood and is caused by a noncancerous tumor of the hypothalamus, a region at the base of the brain. Hypothalamic hamartoma is often difficult to diagnose, as the seizures can seem like laughing (“gelastic” seizures) or crying (“dacrystic” seizure).

How Is Epilepsy Diagnosed?

A variety of tests are used to look for evidence of epilepsy and to rule out other possible causes of seizures.

One of the main tools used in the diagnosis of epilepsy is the electroencephalogram, or EEG. An EEG records the brain’s electrical activity and can reveal the abnormal electrical brain activity that causes epilepsy.

Sometimes brain imaging is done using MRI or computed tomography (CT) to look for structural abnormalities in the brain that may be causing seizures.

A person’s medical history also provides important clues to the underlying cause of seizures.

Learn More About Diagnosing Epilepsy

Prognosis of Epilepsy

Epilepsy is a potentially life-threatening condition, and it carries a risk of premature death if it’s not properly diagnosed and treated.

Children and young adults diagnosed with the condition — roughly half of all cases of epilepsy are diagnosed in people age 25 years or younger — aren’t likely to see any reduction in their life expectancy from epilepsy, particularly if they’re on a medication that effectively controls their seizures.

Older adults who develop epilepsy are more likely to die from the condition or one of its complications, but many go on to live otherwise healthy lives.

Treatment and Medication Options for Epilepsy