What Are Myoclonic Seizures?

Reviewed by: HU Medical Review Board | Last reviewed: March 2022

Myoclonic seizures are a type of seizure that causes sudden muscle contractions or spasms. "Myo" means muscle and "clonic" refers to the jerking motion of the muscles during a seizure. The jerking usually occurs in the arms, legs, or face.1

Myoclonic seizures can be very brief. Some people may not even realize they have had one.1

Myoclonic seizures are usually caused by epilepsy, a condition that causes seizures.
Some forms of epilepsy that include myoclonic seizures are:1

Myoclonic seizure symptoms

During a myoclonic seizure, your muscles will suddenly tighten up. That tightening also happens when you get shocked by electricity. These are like the jolts that occur before you fall asleep. But myoclonic seizures come in bursts, unlike the brief jerking that occasionally occurs before sleep.1

If you have a myoclonic seizure, you will probably remain awake and aware of your surroundings. You might even overlook a brief myoclonic seizure. The jerking movements can also look like:1

  • A spasm
  • A tic
  • Clumsiness

Epilepsies that include myoclonic seizures

Juvenile myoclonic epilepsy (JME)

JME is a type of epilepsy that most often starts around puberty. People with JME have recurrent, brief seizures. During these seizures, muscles in their arms and legs jerk or twitch. The seizures can occur whether they are awake or asleep.1,2

JME can sometimes be difficult to diagnose. That is because it can look like other types of seizures. Also, symptoms can vary from person to person. On the plus side:1,2

  • JME is a fairly common type of epilepsy
  • Treatments for JME can help control seizures

Progressive myoclonic epilepsies (PME)

PME is the name for a group of rare epilepsies. These epilepsies typically start in childhood or early adulthood. PME often leads to progressive worsening of mental function and physical abilities. Treatment does not succeed for very long. The symptoms of PME get worse and worse over time.1,3

Lennox-Gastaut syndrome (LGS)

LGS is a rare, severe type of epilepsy that usually starts in childhood. LGS causes multiple types of seizures:1,4-6

  • Tonic-clonic (grand mal) seizures
  • Atonic seizures (drop attacks)
  • Myoclonic seizures

A person with LGS will usually have myoclonic seizures in their:1,4-6

  • Neck
  • Shoulders
  • Upper arms
  • Face

LGS can be tough to control. And there is no cure. But treatments are available. If you have LGS, treatment can help reduce the number of seizures you have and improve your quality of life.1,4-6

Myoclonic atonic epilepsy (MAE)

MAE is the newer term for a rare epilepsy syndrome, also known as Doose syndrome. It usually affects children under 10 years old. Most commonly, the child with MAE will have generalized tonic-clonic seizures. But they can also have myoclonic seizures and absence seizures.1,7

There is no known cause for MAE. But scientists believe it is caused by a genetic defect. Treatment usually includes dietary changes and medications to control seizures.1,7

Diagnosing myoclonic seizures

Myoclonic seizures are usually easy to diagnose with a complete physical exam and EEG (electroencephalogram). The doctor will:1

  • Focus the exam on your brain and nerves (a neurological exam)
  • Ask about your symptoms and past medical history
  • Order some tests, including the EEG

An EEG is a painless test that records the brain's electrical activity. An EEG can help diagnose seizures and epilepsy. It can also help determine the type of seizure a person has. An EEG can be done:8,9

  • In a hospital
  • At home
  • In a doctor's office

Treating myoclonic seizures

Myoclonic seizures are treated similarly to other forms of seizure and epilepsy. Treatment can include:1

Expert care at epilepsy treatment centers is essential. Talk to your doctor or your child’s doctor about which treatment is best.1

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