Atonic seizures

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Read about the causes and symptoms of atonic seizures, or drop seizures, and how they are treated.

Key points

  • Atonic seizures are a type of generalized seizure and usually last less than 15 seconds.
  • The seizure often causes a child to go limp, which can make them fall down. For this reason, they are often known as "drop attacks".
  • Because these seizures can come on suddenly, it can be difficult to protect your child in time.
  • If your child has these seizures often, they may need to wear a helmet to protect against injury from a fall.

Atonic seizures are a type of generalized seizure and are more common in children than adults. They involve a sudden loss of muscle tone, making a child go limp and fall to the ground. They are often present in children who also have other seizure types, such as tonic or myoclonic seizures.

What are other terms for atonic seizures?

Other terms for atonic seizures include:

  • astatic seizure
  • drop seizure
  • drop attack.

How can you tell if your child has atonic seizures?

Atonic Seizures

Possible signs and symptoms of an atonic seizure include:

  • sudden loss of muscle tone
  • going limp and falling straight to the ground
  • remaining conscious or briefly losing consciousness
  • drooping eyelids or nodding head
  • jerking.

The seizure usually lasts less than 15 seconds, but some may last several minutes. The child quickly becomes conscious and alert again after the seizure.

When we stand or sit, many of our muscles are slightly contracted, working to keep us upright. When a child has an atonic seizure, the muscles in their body lose their tone and go limp, and the child falls straight to the ground. It may be hard to recognize an atonic seizure if a child is sitting or lying down, as the seizure will not cause them to fall.

An atonic seizure may begin with one or more myoclonic jerks. There are several different seizure types that may cause a child to fall, including tonic seizures; with atonic seizures, however, the child falls straight to the ground, and is not pushed forward or backward by muscle contractions as with tonic seizures.

In babies, who cannot stand up, atonic seizures most often appear as a head drop.

How many other children have atonic seizures?

Atonic seizures are rare, although they are seen more often in children than in adults. Approximately 1 per cent to 3 per cent of children with epilepsy have atonic seizures.

What causes atonic seizures?

Researchers do not really understand the causes of atonic seizures yet. They are seen in various kinds of symptomatic epilepsy and rarely in idiopathic epilepsy.

How are atonic seizures treated?

Atonic seizures are treated with anti-epileptic drugs, although they do not always respond well to them. They may also be treated with the ketogenic diet, vagus nerve stimulation or a type of surgical procedure called a corpus callosotomy.

What should I do when my child has an atonic seizure?

These seizures are often known as “drop attacks” because they can cause your child to fall down suddenly if they are standing when the seizure begins. It can be difficult or impossible to intervene in time. If your child often has seizures of this type, they may need to wear a helmet to protect their head from injury.

No specific intervention is needed for one of these seizures, unless your child was injured in falling.

What is the outlook for a child with atonic seizures?

The outlook depends largely on the diagnosis. Some epilepsy syndromes will go away when the child gets older. In other cases, the child may need to keep taking anti-epileptic drugs all their life.

Last updated: February 4th 2010