While many people with epilepsy manage their condition with daily medication, an increase in seizure frequency can still occur. A seizure cluster is a specific, concerning pattern of seizure activity that represents an acute change in a person’s typical seizure pattern. Recognizing this event and knowing how to respond is important because clusters significantly increase the risk of injury and progression to a more dangerous state.
Defining Seizure Clusters
A seizure cluster refers to a series of seizures that happen over a short period of time, distinct from an individual’s usual frequency pattern. While there is no single, universally agreed-upon medical definition, it is often described as two or more seizures within a period such as six, eight, or twenty-four hours. The definition is highly individualized, meaning what one patient recognizes as a cluster may be different for another person.
A cluster must be distinguished from a single, prolonged seizure or status epilepticus. In a seizure cluster, the person generally recovers consciousness or returns to their baseline state between individual seizures. Status epilepticus is a medical emergency defined as a single seizure lasting longer than five minutes, or multiple seizures occurring without the patient regaining full consciousness between them. Untreated seizure clusters are concerning because they can transition into status epilepticus, which carries a higher risk of brain injury and requires rapid hospital intervention.
Common Risk Factors and Underlying Causes
Several factors can lower the seizure threshold and precipitate a cluster in someone with epilepsy. The most frequently cited cause is non-adherence to the prescribed anti-seizure medication (ASM) regimen, such as missing one or more doses. The resulting drop in medication levels within the bloodstream can make the brain more susceptible to the electrical disturbances that cause seizures.
Acute physical stressors, like an infection, fever, or any significant illness, can also trigger clusters. Emotional stress and chronic sleep deprivation are other common triggers that disrupt the brain’s stability and increase the likelihood of seizure activity. For some women, hormonal fluctuations related to the menstrual cycle may be a predictable factor in cluster occurrence. The use of alcohol or recreational substances, particularly during withdrawal periods, can also provoke an acute increase in seizure frequency.
Emergency Management and Rescue Medications
When a seizure cluster begins, the immediate goal is to stop the abnormal electrical activity as quickly as possible. This is accomplished using prescription “rescue medications,” which are fast-acting formulations of drugs from the benzodiazepine class. Benzodiazepines work by enhancing the effect of the neurotransmitter GABA, which helps to calm overactive brain signals.
These medications are administered outside of a hospital setting by a caregiver or the patient, following a pre-determined written Seizure Action Plan. The plan specifies exactly when and how to use the rescue drug, based on the patient’s individual seizure pattern. Available rescue medications include midazolam (Nayzilam) and diazepam (Valtoco) administered via nasal spray, or diazepam gel (Diastat) administered rectally. Intranasal administration is often preferred because it is simple and the medication is absorbed quickly through the nasal passages.
The timing of administration is important because delaying treatment can make the cluster less responsive to the medication. After the rescue medication is given, the patient should be closely monitored for recovery and any side effects, such as drowsiness. Emergency services must be called if the rescue medication fails to stop the seizure cluster within the time specified by the physician, or if the seizure activity transitions into status epilepticus.
Adjusting Treatment to Prevent Recurrence
Following an episode of seizure clustering, a neurologist will analyze the event to implement preventative strategies aimed at stabilizing the patient’s long-term seizure control. One of the most common adjustments involves modifying the patient’s daily anti-seizure medication (ASM) regimen. This may mean increasing the dosage of the current drug, changing to a different ASM, or adding a second medication to the daily routine.
These adjustments are intended to raise the overall seizure threshold and reduce the frequency of future cluster events. Lifestyle modifications are also discussed to minimize known risk factors, such as establishing a strict sleep hygiene schedule. Consistent use of a seizure diary is helpful, as it provides specific data on the frequency and timing of seizures, allowing the medical team to identify subtle patterns or triggers. The goal of these changes is to prevent recurrence and decrease reliance on emergency rescue therapies.