Seizures aren’t always isolated events. Some people undergo periods of increased seizure activity, called seizure clusters.¹ These periods can leave the person feeling frustrated, anxious, and helpless.
Some demographics of people are at higher risk for seizure clusters. In this article, we cover who’s more likely to get seizure clusters and common triggers to avoid.
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Before we learn about seizure clusters, we will discuss the basics of a seizure. A seizure is defined as a change in awareness, behavior, and consciousness levels due to abnormal electrical activity within the brain.
While seizures and epilepsy are often used interchangeably, epilepsy is defined as a condition of recurrent (usually two or more) unprovoked seizures, meaning you can have a seizure without being diagnosed with epilepsy. A seizure can be serious whether you have epilepsy or not, so it’s important to check in with a health professional if you’ve had one.
While many types of seizures are known, each with its own risk factors and symptoms, they are currently classified into three broad categories — focal onset, generalized onset, or unknown onset seizures — by the International League Against Epilepsy (ILAE). Seizures are then subclassified, if possible, as motor or nonmotor.
Focal seizures (formerly partial seizures) only affect a single brain area. While the vast majority of these types of seizures are harmless, focal impaired awareness seizures (formerly complex partial seizures) can result in loss of awareness, which can be frightening for the person.
Generalized onset seizures affect both halves of the brain at the same time. This type of seizure is generally characterized by loss of consciousness and impaired awareness.
As research investigating seizure clusters is still in its infancy, investigators have been hesitant to define the term. The term ‘cluster’ is not defined by the International League against Epilepsy (ILAE), and historically terms such as acute repetitive seizures or recurrent seizures have been used.
However, it’s generally accepted that seizure clusters are closely grouped, ranging from a few minutes to a few days, i.e., a series of seizures with short interictal timeframes.
Some studies² also suggest that seizure clusters aren’t just about the number of seizures in a given period. They indicate that they should also be defined by the type of seizures experienced due to their effect on the quality of life and mortality rates.
Researchers have often only included focal (partial) seizures in their definitions of seizure clusters, as most generalized seizure disorders, such as Lennox Gastaut syndrome, have a high baseline number of seizures associated with them.
For people with epilepsy, some potential factors may contribute to seizure cluster occurrence. These triggers include:
Previous head trauma
A higher baseline frequency of seizures
A diagnosis of focal epilepsy
Epilepsy onset at an early age (in infancy or childhood)
Longer seizure durations
Lack of seizure-free periods (at least one year of freedom from seizures)
Poor sleep quality and stress
Since research surrounding seizure clusters remains without set definitions, it’s difficult to pinpoint a specific demographic that’s at the highest risk of getting seizure clusters. However, studies indicate that an increase in the frequency and duration of seizures is a significant risk factor for developing seizure clusters.
Generally, people with more frequent seizures are more likely to get seizure clusters than those who’ve had one year of freedom from seizures. So far, neither age, sex, nor smoking status has been identified as being associated with the development of clusters.
If you’re worried that you’re at risk of developing seizure clusters due to the frequency of your seizures, discuss this with your health professional. In most cases, they’ll be able to refer you to an epilepsy specialist.
Due to the severity of most seizure clusters, they can be highly disruptive to the person who experiences them and their loved ones. Furthermore, seizure clusters are associated with status epilepticus, making proper treatment even more important. Treatments are often highly individualized and depend on the type and duration of seizures within a cluster.
For mild seizure clusters, oral or sublingual benzodiazepines (lorazepam, diazepam, or midazolam) have been historically favored. However, buccal, intranasal, and rectal therapies are becoming the administration methods of choice due to their faster onset of action and ability to be administered during a seizure.
Diazepam taken rectally is known as diazepam gel. This treatment has been approved by the FDA for adults and children over age two.
They’re the most commonly administered treatment for people with seizure clusters in the US and are the mainstay of seizure cluster management. Of note, rectal and intranasal diazepam and intranasal midazolam are FDA approved as rescue medication for bouts of increased seizure activity.
Experiencing seizure clusters can be overwhelming, so you should speak to a health professional to have the condition treated with the appropriate medications.
If you or a loved one have epilepsy, it’s important to know the common triggers of seizure clusters, especially for people at high risk of developing them.
While cluster seizures can be scary, they aren't life-threatening if treated with appropriate medications. If left untreated or prolonged, cluster seizures are associated with brain damage, neurological complications, status epilepticus, and even death. Working alongside a health professional is important to get the help you need.
Although the exact definition is not agreed upon by scientists, the most common definition of a seizure cluster is periods of increased seizure activity, such as two or more seizures in 24 hours.
Cluster seizures can happen in people with epilepsy. They’re not influenced by sex, age, or the length of time diagnosed with epilepsy, so they can be difficult to predict. For most people, cluster seizures are caused by risk factors like the frequency of seizures or fever.
Partial epilepsy (2022)
Types of seizures | Epilepsy Foundation
Seizure clusters, status epilepticus, and rescue medication | LGS Foundation