Atonic seizures

Atonic seizures 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 may occur 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?

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
• sudden head drop

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 may fall 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.

There are several different seizure types that may cause a child to fall, including myoclonic seizures and tonic seizures. With myoclonic seizures, there is a sudden, brief, shock-like muscle contraction, which may cause the child to fall. With atonic seizures, the child falls straight to the ground because of muscles suddenly becoming limp, whereas with tonic seizures, the child is pushed forward or backward by muscle contractions. These seizure types can occur together in the same child.

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

How common are atonic seizures in children?

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

What causes atonic seizures?

Researchers do not completely understand the causes of atonic seizures yet. They are seen in some epilepsy syndromes, such as Lennox-Gastaut syndrome and epilepsy with myoclonic atonic seizures. Epilepsies associated with atonic seizures may be caused by genetic abnormalities or structural brain abnormalities.

How are atonic seizures treated?

Atonic seizures are treated with anti-seizure medications. 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 this type of seizure, 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 epilepsy syndrome and the cause of the epilepsy. Some epilepsy syndromes will go away when the child gets older. In other cases, the child may need to keep taking anti-seizure medications.