Juvenile myoclonic epilepsy (JME) is a type of epilepsy that usually begins in the teenage years and causes seizures in otherwise healthy young people. With medicine and support, most people with JME can control their seizures well. Seizures may decrease in frequency as the person gets older but lifelong treatment is usually needed to prevent relapse.

JME is a type of epilepsy syndrome (a group of conditions that cause repeated seizures). JME starts most often between ages 12 and 18 but can occur any time between ages 6 and 36. The condition is also called Janz syndrome or impulsive petit mal. It is one of the most common generalized epilepsy syndromes, which means it affects both sides of the brain at once.

People with JME experience up to three different types of seizures that usually happen soon after waking up in the morning or after missing sleep. These types include:

• Myoclonic jerks, which are sudden, brief muscle twitches, usually in the arms, that do not cause loss of awareness. These are present in most people with the condition.
• Generalized tonic-clonic seizures, which involve stiffening and shaking of the whole body, often with temporary loss of consciousness. They occur in most people with JME.
• Absence seizures, which are short episodes of staring or loss of awareness. These occur in about 20% to 40% of people with JME, usually starting before the other types of seizures. Absence seizures can be so mild they go unnoticed.

JME affects both males and females and accounts for about 5% to 10% of all epilepsy cases. For many people with the condition, seizures become less frequent as they grow older. However, the condition is lifelong and requires ongoing treatment to control seizures and prevent relapse.

Researchers do not fully understand what causes JME. Genetic factors appear to play a major role in many cases.

JME is a genetic generalized epilepsy, meaning it is linked to changes in genes that affect how brain cells communicate. Multiple genes have been linked to JME, including several that are involved in brain signaling and development. JME runs in families, and about half of people with the condition have a close relative with epilepsy or seizures. However, not everyone who carries the gene changes will develop JME. In addition, about half of people with JME have no family history of seizures.

In most JME cases, routine brain scans such as magnetic resonance imaging (MRI) appear normal, but advanced tests sometimes show subtle changes in brain structure or function. Environmental factors such as sleep deprivation, stress, or flashing lights can trigger seizures in people with JME, but these do not cause the condition itself.

The main risk factors for JME include age, family history, and certain triggers that increase the risk for seizures.

Risk factors for JME include:

• Having a close family member with epilepsy or seizures
• Age between 12 and 18 years (when the condition most often appears)
• Personal or family history of absence seizures in childhood, which can sometimes develop into JME

Symptoms of JME include different types of seizures, which can range from mild to severe.

Symptoms include:

• Myoclonic jerks, which are sudden, brief muscle twitches, usually in both arms, often within an hour of waking up
• Dropping objects or feeling clumsy due to subtle myoclonic jerks in the fingers
• Generalized tonic-clonic seizures, which are episodes of full-body stiffening and shaking, often with loss of consciousness
• Absence seizures, which are short periods of staring or unresponsiveness, sometimes lasting less than 10 seconds
• Seizures triggered by lack of sleep, stress, alcohol, or flashing lights
• In rare cases, clusters of myoclonic jerks that do not stop easily (myoclonic status epilepticus), especially after missing sleep or medicine
• Mood changes, anxiety, or depression, which may accompany JME

Contact a doctor promptly if seizures last longer than usual, occur back-to-back without recovery, or if there is a first-time seizure or injury or trouble breathing during a seizure.

To diagnose JME, a doctor typically reviews the person’s medical history, performs a physical exam, and orders several medical tests.

The doctor will ask about symptoms and types of seizures, including when they began, triggers, and family history. They may also ask for descriptions of seizure events from parents, teachers, or others who have witnessed them. Usually, a physical and neurological exam doesn’t reveal anything concerning, though it helps rule out other causes of the symptoms.

The following tests are used to diagnose JME:

• Electroencephalogram (EEG), which records the brain’s electrical activity and looks for patterns typically seen in JME
• Sleep-deprived or overnight EEG, which increases the chance of finding abnormal brain activity and may be done if the routine EEG is normal
• Video EEG monitoring, which records both the EEG and a video of the person during seizures, helping to confirm the diagnosis and rule out other conditions
• MRI scan, a brain scan that may sometimes be used to rule out other causes
• Other tests, such as blood tests, to rule out metabolic or toxic causes if needed

A diagnosis of JME requires both myoclonic seizures and EEG findings typical of JME. Other seizure types or findings may suggest a different diagnosis.

Treatment for JME focuses on controlling seizures and avoiding triggers. Most people with the condition respond well to the right medicine, but some people may require more than one medicine (combination therapy) to control the different types of seizures that can occur.

Main treatment options include:

• Valproic acid (also called valproate), a broad-spectrum anti-seizure medicine (meaning it treats many seizure types), can control most seizure types seen in JME. This is usually the first-choice medication but may carry risks for developing fetuses.
• Levetiracetam is a medicine that works well for myoclonic and generalized seizures. It is often used if valproic acid is not suitable.
• Lamotrigine, another medication, is sometimes used, especially for women of childbearing age. It can sometimes make myoclonic jerks worse.
• Topiramate or zonisamide, both broad-spectrum medicines, may be used if other treatments are not tolerated or effective.
• Clonazepam or clobazam may be added to help control myoclonic jerks, usually as part of combination therapy.
• Vagus nerve stimulation (VNS), a device that delivers mild electrical signals to the vagus nerve, which then transmits the signals to the brain, is sometimes used when seizures do not respond to medicine.
• Lifestyle changes to avoid triggers such as sleep deprivation, alcohol, missed medicine doses, and flashing lights can help reduce seizures.

Some medicines can make seizures worse in people with JME. These include carbamazepine, phenytoin, oxcarbazepine, gabapentin, pregabalin, tiagabine, vigabatrin, and phenobarbital.

If pregnancy is possible, discuss medication choices with a doctor, as some medicines can harm a developing fetus.

Complications of JME include:

• Injury from falls or accidents during seizures, especially generalized tonic-clonic seizures
• Status epilepticus, or prolonged or repeated seizures without recovery, a medical emergency
• Myoclonic status epilepticus, which are clusters of myoclonic jerks that do not stop easily, and usually occur after missing sleep or medicine
• Nonconvulsive status epilepticus, which involves prolonged confusion or unresponsiveness, and is rare but serious
• Mood disorders such as depression, anxiety, or personality changes, which are more common in people with JME
• Problems with attention, planning, or memory, sometimes related to seizures or medicine side effects
• Social challenges, such as limits on driving, swimming alone, or certain types of jobs
• Sudden unexpected death in epilepsy (SUDEP), a rare but serious risk in all epilepsy types

The following require emergency medical care:

• A seizure lasts longer than five minutes
• Repeated seizures without recovery
• Trouble breathing or injury during a seizure
• First-time seizure

The outlook for people with JME is generally positive with proper treatment. Seizures tend to improve after age 40. Some people may experience challenges with mood, memory, or social situations, but support and education can help manage these issues.

Most people achieve good seizure control with medicine. About one in four people with JME can eventually stop medicine and remain seizure-free. However, stopping medicine leads to a high risk of seizures returning. Most people with the condition need lifelong treatment to prevent relapses. Regular follow-up with a doctor and attention to triggers are important for the best outcomes.

“Our team at Yale Medicine provides a tailored approach to every child or young adult with juvenile myoclonic epilepsy and specifically helps transition patients to the right adult epilepsy provider,” says Vinita Knight, MD, a Yale Medicine pediatric neurologist.