Authors: Dorottya B. Kacsoh, University of Central Florida College of Medicine
Alison L. Christy, MD, PhD, Providence Pediatric Neurology at St. Vincent Medical Center—Portland, Oregon
Reviewed: February 2023 

SUMMARY

Juvenile myoclonic epilepsy (JME) is a common, readily controlled form of epilepsy. Epilepsy is a condition characterized by a tendency to have seizures.  

JME makes up about 8–10% of epilepsy cases in adults and adolescents. About half of cases are due to unknown causes. The other half are due to genetic causes. 

JME usually presents between the ages of twelve and eighteen in otherwise healthy children. Males and females are equally affected. JME does not cause intellectual or physical disability.  

JME is also known as Janz syndrome.

Disorder Overview

DESCRIPTION

JME involves three different seizure types:

Myoclonic jerks are the first sign of JME. They may be subtle. So, they can easily be missed. A few months later, generalized seizures typically begin.  

Absence seizures are present in over one third of individuals. It is not necessary to have all three seizure types to have JME.  

A seizure lasting longer than five minutes is not likely to end on its own. So, rescue medicine may be given at that time. However, seizures are unlikely to cause brain damage unless they last longer than thirty minutes. 

A relatively rare complication of seizures in JME is status epilepticus. Status epilepticus occurs when either a seizure does not stop on its own after five minutes or at least two seizures occur without a return to normal.  

It is imperative to seek treatment if your child develops status epilepticus. There is an increased risk of death and disability.  

There is a low risk of death associated with JME. Sudden unexpected death in epilepsy (SUDEP) is a rare complication of epilepsy. It is unknown why SUDEP occurs. To learn more about SUDEP visit this webpage on the CNF website.  

SIGNS AND SYMPTOMS

Children will have typical growth and development. Seizures begin during adolescence. Myoclonic jerks are the first sign. These are followed shortly by GTCS.  

Seizures are typically provoked by:  

• Sleep deprivation  
• Excessive alcohol consumption

Some seizures can be triggered by flashing lights. Stress may also be a contributing factor.

After seizures begin, children will not develop any intellectual or physical disabilities. Besides having seizures, they are otherwise healthy.

CAUSES

In about half of cases, the cause of JME is unknown. It is thought that JME runs in families. However, many people have no family members with epilepsy. Mutations in CACNB4, EFHC1, and GABRA1 genes are associated with JME.

LABORATORY INVESTIGATIONS

JME is diagnosed by obtaining a thorough history and an electroencephalogram (EEG).  

An EEG is a test that measures the electrical activity of the brain. Electrodes are taped to a person’s scalp.  EEGs are abnormal during seizures, but they may also be abnormal between seizures. JME has a characteristic pattern between seizures.  

Imaging studies are unnecessary in the diagnosis of JME. If an MRI is obtained, it will be normal in most cases.  

No lab work or genetic testing is needed to make a diagnosis.

TREATMENT AND THERAPIES

Most cases of JME are readily controlled with daily medications. Many people will stop having seizures with a single medication. Sometimes, more than one will be necessary. Discuss medication options with the child’s provider. It is also important to discuss medications that can make seizures worse. They should be avoided. 

Seizures that last longer than five minutes are more likely to progress to status epilepticus. So, a rescue therapy should be used for seizures lasting longer than five minutes. Discuss seizure rescue therapy options with the child’s provider. There are multiple rescue therapy options to choose from.  

Vagus nerve stimulation (VNS) is an alternative to medication. VNS involves surgically inserting a device under the skin. This device sends electrical pulses to the brain. These control seizures before they start. VNS is reserved for those who fail treatment with multiple medications.  

The ketogenic diet is used in cases of epilepsy that do not respond to medical treatment. Because seizures are typically well controlled in JME, the ketogenic diet is rarely used. 

OUTLOOK

JME does not affect growth and development or academic performance. Children can participate in most regular activities. Teachers should be made aware of their diagnosis.  

JME is a lifelong condition. Symptoms typically lessen by the fourth decade of life. Individuals will require lifelong treatment with daily medication.  

The prognosis for JME is excellent. Most people will go on to live independently. With appropriate management, individuals may remain completely seizure-free.

RELATED DISORDERS

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Research 

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Before participating in a study, you are encouraged to talk to your health care provider and learn about the  risks and potential benefits. 

For more information about participation in clinical trials, check out our education hub on the topic here.  

Information for research and clinical trials specific to Juvenile Myoclonic Epilepsy can be found on the Pediatric Epilepsy Surgery Alliance website.  

The information in the CNF Child Neurology Disorder Directory is not intended to provide diagnosis, treatment, or medical advice and should not be considered a substitute for advice from a healthcare professional. Content provided is for informational purposes only.  CNF is not responsible for actions taken based on the information included on this webpage. Please consult with a physician or other healthcare professional regarding any medical or health related diagnosis or treatment options. 

About VNS Therapy [Internet]. Livanova; 2023 [cited 2023 Jan 15]. Available from: https://www.livanova.com/epilepsy-vnstherapy/en-us. 

Panayiotopoulos CP. A clinical guide to epileptic syndromes and their treatment: Based on the new ILAE Diagnostic scheme. Oxfordshire, UK: Bladon Medical Pub.; 2002.   

Amrutkar C, Riel-Romero RM. Juvenile Myoclonic Epilepsy. [Updated 2022 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537109/.

Gidal B, Detyniecki K. Rescue therapies for seizure clusters: Pharmacology and target of treatments. Epilepsia. 2022 Sep;63 Suppl 1(Suppl 1):S34-S44. https://doi.org/10.1111/epi.17341. PMID: 35999174; PMCID: PMC9543841.