What Are Seizure Clusters?

Medically Reviewed by Christopher Melinosky, MD on September 11, 2022
Written by Paul Frysh
3 min read

A seizure is a sudden burst of electrical signals between your brain cells that causes symptoms  you can’t control. They can include twitching muscles, stiffness, behavior changes, and even unconsciousness. If you have seizures regularly, doctors call it epilepsy. 

There's no single definition of seizure clusters, also called cluster seizures. In general, it's a group of seizures that happen more often than you're used to within a certain span of time.

Some experts define a cluster as having two or three seizures within 24 hours, recovering between each one. Others define it as having several seizures and recovery periods within a few hours.

Doctors may also refer to seizure clusters as:

  • Seizure flurries
  • Recurrent seizures
  • Cyclical seizures
  • Acute repetitive seizures
  • Serial seizures
  • Crescendo seizures

Doctors don’t know the exact cause, though clusters are more likely to happen if you have trouble controlling your seizures in general.

"Refractory epilepsy" is when you keep having at least one seizure a month for 18 months, even after trying two or more medications. This could raise your risk for clusters.

People who get seizures that start on one side of the brain (called focal onset) are more likely to have clusters. But generalized onset seizures, which start on both sides of the brain, can also cluster in some people. (Some generalized seizures start out as focal onset ones.)

People who've had a head injury are also more likely to get them.

At least a quarter of people with epilepsy will have a cluster of seizures at some point. And some studies show that almost 50% of people with epilepsy have had three or more seizures within a 24-hour period at least once.

For about 30% of people who get them, it’s not clear what triggers a particular cluster.

But in other cases, you or your doctor may recognize things that trigger clusters. These may include:

  • Skipping your epilepsy medication
  • Illness, especially with a fever
  • Sleep loss
  • Stress
  • Using alcohol or recreational drugs
  • Your period

When to see a doctor

Talk to your doctor right away about any seizure, especially if you're having more or they're getting worse.

Without the right treatment, seizure clusters might lead to serious problems like:

  • Status epilepticus. This is a long seizure -- 5 minutes or more -- that might not stop without medical help. It can also be a series of seizures, but you don't return to normal between them. The risk of brain injury goes up if a seizure lasts more than 30 minutes. 
  • The need for emergency care. You’re more likely to go to the emergency room or be admitted to the hospital in general when you have seizures in clusters.
  • Mental illness. You’re more likely to lose touch with reality (psychosis) after a cluster of seizures.
  • Death. People who have seizure clusters have higher death rates.

Keeping track of what triggers your seizures may help you prevent some of them. But if you get seizure clusters, you'll probably need to take medication to avoid the serious problems they can cause.

There are two main types:

Anti-seizure medications. Doctors call them ASMs. They don't cure epilepsy, but they change levels of certain chemicals in your brain to help prevent seizures. They work for about 70% of people. You usually take them every day as a pill or liquid.

Rescue medications. These medications work quickly to stop or interrupt a seizure or cluster as it happens. They're part of a class of drugs that doctors call benzodiazepines (or "benzos”). They stop seizures by raising the level of a chemical messenger in your brain called GABA. 

In the hospital, you'll likely get them as an IV or a shot. For home use, you might take them:

  • As a pill. This is an option if you're able to swallow.
  • Rectally. Using a syringe without a needle, someone injects a gel form of the medication into your rectum. It's able to enter your bloodstream much more quickly than oral benzos. This type may be safer to give during a seizure, especially for children.
  • Nasal. You take them as a spray up your nose. They're easy to use and work quickly.