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Juvenile myoclonic epilepsy (JME)

This is a common epilepsy syndrome that begins anywhere between the ages of 8 and 26 years; but it usually starts between the ages of 12 and 16. It is more common in girls than boy

Other names for juvenile myoclonic epilepsy (JME)

  • Janz syndrome


People who have JME have 3 types of seizures: myoclonic, tonic-clonic and absence seizures.

Myoclonic seizures cause sudden jerks of the muscles, either in the arms, legs, face or whole body. These seizures usually happen soon after waking up and sometimes when getting dressed or having breakfast. They may also happen in the evening or when the person is tired.

Two thirds of people with JME also have tonic-clonic seizures. They usually happen in the morning, within an hour or two of waking up. These are more likely to occur if the person with JME has been to bed late the night before, or has woken up earlier than usual.

About one third to one half of children and young people with JME also have absence seizures. These can happen at any time of the day, but are most likely in the morning.

Photosensitivity means that the myoclonic or tonic-clonic seizures are triggered by flickering or flashing light at certain frequencies. It affects around 4 out of 10 people with JME. Photosensitivity will usually show on the electroencephalogram (EEG) if you have JME. Specific advice will be given about photosensitivity.

Epilepsy Action has more information about photosensitive epilepsy and different types of seizure.


It is important that the doctor making a diagnosis has a full account of what happens during the seizures. This is especially important if the person with JME has myoclonic or ‘jerk’ seizures, which can be easily missed.

The EEG is usually abnormal, and shows epileptic discharges coming from both sides of the brain at the same time. These are called generalised discharges. Some people may be photosensitive.


The seizures in JME are usually fully controlled with epilepsy medicines, particularly sodium valproate (Epilim). Sometimes lamotrigine (Lamictal) may be taken. Other medicines, including levetiracetam (Keppra) and clonazepam (Rivotril), may also be helpful.

There may be research studies open that are relevant to this epilepsy syndrome. Your child’s doctor will be able to discuss this with you.

Information about treatments for children can be found on the Medicines for Children website.


Around 8 out of every 10 people with JME need to take epilepsy medicines for the rest of their lives. If the medicine is stopped, it is common for seizures to return.

Living with juvenile myoclonic epilepsy

People with JME are likely to have seizures if they don’t get enough sleep. Drinking alcohol can also be a trigger for seizures.

Epilepsy Action has more information about alcohol and epilepsy and sleep and epilepsy.


Helpline: 0808 808 3555
Website: cafamily.org.uk
Email: info@cafamily.org.uk

What is a syndrome?

A syndrome is a group of signs and symptoms that, added together, suggest a particular medical condition. In epilepsy, examples of these signs and symptoms would be things like the age at which seizures begin, the type of seizures, whether the child is male or female and whether they have physical or learning disabilities, or both. The results of an electroencephalogram (EEG) are also used to help identify epilepsy syndromes.

If you would like to know more about an epilepsy syndrome, please speak to your doctor. If you would like to know more about epilepsy in general, please contact Epilepsy Action.


Epilepsy Action would like to thank Drs Richard Appleton and Rachel Kneen (at Alder Hey Children’s Hospital, Liverpool) and Stewart Macleod (at Yorkhill Children’s Hospital, Glasgow), consultants who specialise in children’s epilepsy, who have updated this fact sheet.


This information is exempt under the terms of Epilepsy Action's information quality standards.

  • Updated June 2016
    To be reviewed June 2019

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