Myoclonic seizures

What are myoclonic seizures?

Myoclonic seizures have a generalised onset. This means both sides of the brain are affected from the start.

You say it like ‘my-oh-KLON-ik’.

Myoclonic seizures are sudden, short jerks that can affect part of, or all of your body. Seizures can affect your upper body, legs, arms, or another part. They are usually too short to affect your consciousness. This means that you will stay awake and aware when they happen.

The jerking can be very mild, like a twitch, or it can be very forceful. If the jerk is very strong you may throw something you’re holding, or fall over.

Myoclonic seizures can happen when you are awake or when you are asleep. Research suggests that overall, they are more likely to happen when you are awake.

Who gets myoclonic seizures?

Myoclonic seizures can happen in many different types of epilepsy. They are often a feature of some childhood epilepsy syndromes, but not always.

Examples of childhood syndromes with myoclonic seizures include:

• Juvenile myoclonic epilepsy (JME)
• Epilepsy with myoclonic-atonic seizures (Doose syndrome)
• Myoclonic epilepsy in infancy
• Lennox-Gastaut syndrome
• Epilepsy with myoclonic absences

Adults and older adults can also sometimes develop myoclonic seizures. For example, after a stroke or another type of illness or injury.

How long do myoclonic seizures last?

Myoclonic seizures last for less than a second. Some people have them in clusters of several seizures over a short period of time.

What happens after a myoclonic seizure?

After a single myoclonic seizure you can usually get back to what you were doing straight away. Myoclonic seizures are very brief, but can be very frustrating. They can cause injuries or accidents, like spilling food and drink.

Some people may feel confused or tired after a seizure. Or, if you are having more than one myoclonic seizure in row (called a ‘cluster’), you may want to lie down or rest somewhere until they have passed.

If this is your first myoclonic seizure

You may not need immediate medical help the first time you have a myoclonic seizure, unless you injure yourself. But you should make an urgent appointment to see your GP who can decide if any tests or a referral to a specialist are needed. We have more information on our diagnosis page.

“I was diagnosed with myoclonic epilepsy last year after experiencing daily shock-like sensations through my body, followed by confusion.

 

“I didn’t realise these were seizures, so the diagnosis came as a huge shock. It was a scary and isolating time. Especially when I was made to feel by others that my epilepsy wasn’t valid as I did not have tonic-clonic seizures that are on the TV and in films. Thankfully, my seizures are now controlled with medication.”

Myoclonic seizure first aid

This short video at the top of the page explains what to do if someone has a myoclonic seizure.

How to help

• Myoclonic seizures happen very quickly. There is not much others can do during the seizure
• People usually recover straight away and can continue what they were doing
• Someone may need help if they injure themselves during the seizure. For example, if they cut or scald themselves
• Offer to help if anything needs clearing up after the seizure
• Ask the person what they need. They may need more help or space to rest and recover, especially if they are having a cluster of myoclonic seizures

Can myoclonic seizures become an emergency?

In very rare cases, myoclonic seizures can happen one after another for a long time. Or, they can turn into prolonged tonic-clonic seizures. This is called status epilepticus, and it is a medical emergency.

It is status epilepticus if:

• Someone has myoclonic seizures clustering for over 30 minutes, or
• They have a continuing tonic-clonic seizure for longer than 5 minutes

Call an ambulance if this happens, or if you are worried.

“Go and sit or lie somewhere safe like a bed or the floor and wait until it’s definitely passed. Make someone aware of what’s happening so they’re on standby should the situation escalate.”

This page is printable and can be downloaded. We also have accessibility tools available at the top of the page. These tools can also translate this page into different languages.

Thank you to our expert reviewers and health information volunteers, for contributing to and reviewing this content. Thank you also to everyone who shared their experiences for the quotes used on this page.

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