What Is Juvenile Myoclonic Epilepsy?

Juvenile myoclonic epilepsy (JME) affects about 10% of people with epilepsy. Several types of seizures occur with JME. The seizures generally begin during late childhood or early adolescence.

Seizures can usually be prevented with medication, although sometimes the seizures are not adequately controlled with anti-epilepsy drugs (AEDs). The prognosis of the condition is variable—some people with JME need to continue to take AEDs throughout life, but some no longer need medication during adulthood.

This article describes the symptoms, causes, diagnosis, and treatment of juvenile myoclonic epilepsy. It also provides information about what you can expect if you or your child is diagnosed with this type of epilepsy. JME is also called juvenile myoclonic epilepsy of Janz or Janz syndrome.

Juvenile Myoclonic Epilepsy Symptoms

Seizures are the primary symptoms of JME. Children who may have been otherwise healthy can begin experiencing the symptoms of JME between ages 12 and 25.

In JME, the seizures are typically triggered by stress and a lack of sleep. Some people with JME have photosensitive epilepsy, which means that the seizures are triggered by rapidly flashing lights. Additionally, alcohol, drugs, and severe illness can also trigger seizures.

The three seizure types occur in JME are:

• Myoclonic seizures: A myoclonic seizure in JME typically occurs within a few hours of waking up from sleep. These episodes involve involuntary jerking motions, usually of the arms, with or without a decreased level of awareness.
• Generalized tonic-clonic seizures: This type of seizure involves involuntary shaking and jerking of both sides of the body, with unawareness of what is happening. A person may pass out or sleep for minutes or longer after a generalized tonic-clonic seizure. This seizure type may result in physical injuries.
• Absence seizures: The episodes are often described as staring spells. Absence seizures include staring into space without interacting or responding. Less often, they involve involuntary face, hand, or mouth movements. Absence seizures typically last for less than 10 seconds at a time, and people can’t remember having them.

The severity and seizure pattern in JME varies, and people may have one or more of these seizure types. 

Associated Conditions 

People with JME have a higher-than-average risk of learning problems and motor deficits (impaired movement).

JME is associated with a higher risk of cluster B personality disorders, which include borderline personality disorder, antisocial personality disorder, histrionic personality disorder, and narcissistic personality disorder. Personality disorders are long-term patterns of behavior and inner experiences that differ significantly from what is expected.

The sibling of a person with JME also has a higher-than-average risk of learning problems.

Causes 

Seizures are caused by spontaneous, abnormal electrical activity in the brain. It’s believed that JME is caused by structural changes in the brain that occur during early brain development. 

The condition can occur without any family history of epilepsy. But about half of people who have JME have relatives with epilepsy.

The genes that have been identified in association with JME are variations of GABRA1, GABRD, EFHC1, BRD2, CASR, and ICK, with complex inheritance patterns. These genes are associated with brain development.

Diagnosis 

Epilepsy is diagnosed based on symptoms, physical examination, electroencephalogram (EEG) (a test that records electrical activity in the brain), and brain imaging tests. 

Different epilepsy syndromes, such as JME, have certain characteristics. While not everyone with JME has exactly the same experiences, the age of onset and the descriptions of the episodes may suggest that a person has this epilepsy syndrome.

For most people who have JME, a physical examination, including a neurological examination, is expected to be normal.

Brain imaging is normal in this condition as well. Some subtle changes can be detected on brain magnetic resonance imaging (MRI) or positron-emission tomography (PET) scans, but the presence or absence of such changes doesn’t rule in or rule out JME.

An EEG may show a pattern that is described as a 3 Hertz spike and wave pattern that is primary noted in the occipital cortex, which is the posterior (back) area of the brain.

Treatment

For most people, JME is treated with AED medication, which must be taken on a daily basis to prevent seizures from occurring. The AED most commonly associated with the improvement of JME is Depakote (valproate). However, valproate does not always fully control seizures. 

Valproate is known to be potentially unsafe during pregnancy. People who might become pregnant may switch to an AED that is safe during pregnancy, ideally before becoming pregnant.

Other AEDs used for preventing JME seizures include Lamictal (lamotrigine), Keppra (levetiracetam), Zonegran (zonisamide), and Topamax (topiramate). If the seizures aren't well controlled, one or more of these AEDs can be added to valproate or used instead of valproate.

Some people may have treatment-resistant epilepsy, which means that the seizures are not adequately controlled with tolerable doses of AED treatment. In these situations, epilepsy surgery might be considered a potential option.

Surgical procedures used for treating epilepsy include the implantation of electrical devices or surgically placed lesions in the brain that can help prevent the electrical brain activity that causes seizures. 

Prognosis 

The outcome of JME is variable. For many people, the symptoms of JME stop during their 40s. In these instances, adults can discontinue AED treatment under the supervision of a physician. However, some people with JME may continue having seizures and need lifelong AED treatment. 

It is not possible to predict with certainty whether a child or teenager will continue to need lifelong treatment or whether they will have an improvement in their seizures when they reach adulthood. In general, having continued seizures due to JME is associated with more severe and frequent seizures during childhood and adolescence.

Coping 

Living with epilepsy as a young person can be challenging. It’s important to take medication as directed and learn the potential side effects. Discuss any side effects with your healthcare provider because some AED side effects can be serious. 

It can be difficult to gauge how well the AED medication is working. Keeping a diary to track your seizures can help monitor whether the seizures are improving. 

Avoiding triggers is a key factor in preventing seizures. Lifestyle measures you need to pay attention to include: 

• Don’t drink alcohol.
• Get enough sleep. 
• Learn how to recognize your stress so you can slow down.
• Learn about stress management techniques.

Talk to a healthcare provider about whether it’s safe for you to drive, and be prepared to adopt safer ways of getting around if there is any risk that you could have a seizure while you are driving. 

Summary 

Juvenile myoclonic epilepsy (JME) is an epilepsy syndrome that begins during adolescence. It is characterized by three different types of seizures, which include myoclonic seizures, absence seizures, and generalized tonic-clonic seizures.

The condition can be treated with anti-seizure medication, and treatment is effective for most people. Several different medications are available for treating JME, but some anti-seizure medications can actually worsen this type of epilepsy.

Many people outgrow JME by the time they reach mid-adulthood, but some may need treatment for the rest of their lives.

A Word From Verywell

Epilepsy is a serious medical condition, but it is manageable with medication. You may need to make some lifestyle changes if you have JME. In particular, get enough rest, manage stress, and avoid alcohol.

Certain activities, such as driving or operating dangerous equipment, require careful consideration and a discussion with your healthcare provider about whether they are safe for you. Most people are able to live long, healthy, and productive lives after being diagnosed with JME.