Juvenile myoclonic epilepsy (JME) is a type of epilepsy that usually begins during adolescence. Myoclonic seizures are the hallmark of JME. They are often the first sign of the condition. Most children with JME also have generalized tonic-clonic seizures. A small percentage, around 20%, also have absence seizures. These types of seizures are described below.
JME is a common type of epilepsy. Females are more likely to be affected by JME. There is no cure for JME. Seizure medications usually work well to control seizures.
Juvenile Myoclonic Epilepsy Causes
The exact cause of JME is unknown. Experts think there is a genetic link. Some children with JME have a family history of seizures or epilepsy. Before developing JME, some children may have fever-related seizures or childhood absence epilepsy (CAE).
Juvenile Myoclonic Epilepsy Symptoms
The main symptom of JME is having myoclonic seizures that occur any time. These are more likely when a person wakes up, either in the morning or from a nap. These seizures involve sudden, quick, small jerks of the arms and shoulder and, less often, the legs. These movements may be limited to the hands. The person may throw or drop something from their hands.
Myoclonic seizures can occur in clusters, affecting one or both sides of the body. These seizures can be a warning sign that a generalized tonic-clonic seizure is about to occur. In a generalized tonic-clonic seizure, the jerking spreads throughout the entire body.
Some children with JME also have absence seizures. These can be very subtle and even go unnoticed. During these seizures, the person will “space out,” staring and becoming unresponsive for short periods of time. No twitching or convulsing occurs during absence seizures.
Certain factors can make seizures more likely in people with JME. Avoiding these triggers can help reduce seizures. For people with JME, these triggers can include:
- Inconsistent sleep patterns, being tired
- Drinking alcoholic beverages or large amounts of caffeine
- Flickering lights, such as strobe lights, video games or light reflecting off ocean waves or snow
Other Conditions Associated with Juvenile Myoclonic Epilepsy
The most concerning part of juvenile myoclonic epilepsy is the chance for a condition known as “myoclonic status epilepticus.” While uncommon, when this occurs, the person has multiple myoclonic seizures that last for more than five minutes. Patients can significantly reduce their risk for this condition by following a regular sleep schedule and taking their seizure medications as prescribed.
Juvenile Myoclonic Epilepsy Diagnosis
If your child is having myoclonic seizures and absence and/or generalized tonic-clonic seizures, the doctor may suspect JME. If your child’s doctor suspects JME, they will recommend an electroencephalogram (EEG) to record brain waves.
Your child may be asked to look at flashing lights during the EEG. This could trigger a myoclonic seizure. A specific pattern of spikes and waves on the EEG indicates JME. Sometimes a longer EEG may be needed to decide if certain movements are myoclonic seizures.
Juvenile Myoclonic Epilepsy Treatment
People with juvenile myoclonic epilepsy may not outgrow it. It may be a lifelong disease. People with JME may stay on seizure medication for the rest of their lives. However, seizure medication is usually very effective. It allows most people with JME to go without seizures for years. People who have multiple seizure types may need multiple types of seizure medication to have control of their seizures.
Juvenile Myoclonic Epilepsy Prognosis
Most people with JME can achieve total or almost total seizure control with the help of seizure medication. This is particularly true for those who have mostly myoclonic seizures and only a few tonic-clonic seizures.