Juvenile Myoclonic Epilepsy (JME)

24th May 2021

Juvenile Myoclonic Epilepsy (JME) is a relatively common syndrome that can occur between the ages of 6 and 26, although the majority of cases fall within the smaller timescale of 12 to 16 years. JME presents more commonly in females than males and has also been known as Janz Syndrome. 


JME often presents with three distinct types of seizures, known as myoclonic, tonic-clonic and absence. 

Myoclonic seizures, for which the syndrome is named, are characterised by a sudden and brief jerking motion in the limbs, face, or in some cases, the entire body. Myoclonic seizures most commonly occur in the mornings soon after waking or later in the evening when the person is becoming tired. All people with JME will experience these types of seizures. 

Tonic-clonic seizures also most commonly occur at moments when the person is most tired. A tonic-clonic seizure is where the person loses consciousness and the muscles stiffen and begin to jerk. Tonic-clonic seizures will usually last for 1 to 3 minutes, but in some cases can last longer. Around two thirds of people with JME will have tonic-clonic seizures. 

Absence seizures are more subtle and involve a brief lapse in consciousness. A person having an absence seizure may appear as though they are just staring blankly into space before they return to consciousness. Absence seizures affect approximately 50% of people with JME. 

Click here to learn more about the different seizure types. 

In addition, a large number (around 4 in 5) people with JME will be photosensitive, which means that their seizures can be triggered by flashing or flickering lights.


In order to make a diagnosis, a healthcare professional will need a full account of the seizures. Particularly the myoclonic seizures which can often be overlooked as many people who experience them don’t realise they are a seizure and just put the jerks down to being tired. 

An electroencephalogram (EEG) test will usually show as abnormal for JME, showing discharges from both sides of the brain at the same time. These discharges are known as a generalised spike and wave or a polyspike and slow wave discharges. An EEG will also show evidence of photosensitivity in the 4 out of 5 people affected. 


Anti-seizure medications are usually effective at fully controlling JME. Sodium valproate is particularly effective when used with this particular syndrome, however, this particular medication needs to be used very carefully with women of childbearing age as it can be harmful to unborn babies. If sodium valproate is prescribed, a pregnancy prevention programme must be adhered to. Lamotrigine is also potentially effective, as well as levetiracetam, clobazam, topiramate and zonisamide. 


Approximately 8 out of 10 people who have JME will need to take anti-seizure medications for the duration of their life to effectively manage seizures. However, once under control people with JME will be able to lead relatively normal lives. A number of people with JME could experience mild attention and learning difficulties, usually during their teenage years. 

National Epilepsy Training can help 
For more information on Juvenile Myoclonic Epilepsy (JME), please call us on 01706 373075 or email admin@nationalepilepsytraining.co.uk.