What is the standard duration of an acute seizure?

From the Guidelines

The standard duration of an acute seizure is typically less than 5 minutes, with most seizures resolving spontaneously within 1 to 2 minutes without intervention. This is based on the most recent and highest quality study available, which emphasizes the importance of timely intervention for seizures lasting longer than 5 minutes 1.

Key Points to Consider

• Seizures lasting more than 5 minutes may not stop spontaneously and could require emergency medical intervention, such as anticonvulsant medications 1.
• The first aid provider can play a crucial role in preventing unintentional injury during a seizure by ensuring the person is in a safe position and not at risk of aspiration if they vomit during or after the seizure 1.
• For seizures that last beyond 5 minutes, the administration of emergency medication like benzodiazepines (e.g., lorazepam, diazepam, or midazolam) is critical to prevent further neuronal damage and potential complications 1.

Clinical Implications

The timing of a seizure is crucial because the longer it continues, the more challenging it becomes to stop, and the greater the risk of neuronal damage due to excitotoxicity, involving glutamate release and calcium influx 1. Therefore, if you witness someone having a seizure, it is essential to time its duration, ensure the person's safety, and call emergency services if the seizure lasts beyond 5 minutes or if it is the person's first seizure.

Management Approach

• Ensure the person's safety: Clear the area around the person of any objects that could harm them and do not restrain them.
• Time the seizure: If the seizure lasts more than 5 minutes, consider it a medical emergency.
• Administer emergency medication if available and trained to do so: Benzodiazepines are commonly used for this purpose.
• Call for emergency medical services: If the seizure is prolonged, it's the person's first seizure, or if they are injured during the seizure.

Given the potential for significant morbidity and mortality associated with prolonged seizures, it is critical to prioritize timely and appropriate intervention, as supported by the most recent guidelines and studies 1.

From the Research

Definition and Duration of Seizures

• The duration of an acute seizure can vary, but there is no specific standard duration mentioned in the provided studies 2, 3, 4, 5, 6.
• However, a study on non-convulsive seizures in critically ill patients suggests that the median duration of seizures can range from 73 to 99 seconds, depending on the underlying etiology 5.
• The same study proposes a temporal threshold of 10 minutes to define non-convulsive status epilepticus in critically ill patients with a primary neurological diagnosis, and 30 minutes for those with an underlying acute medical illness 5.

Types of Seizures and Their Management

• Acute repetitive seizures are a type of seizure that can be predictable and may require treatment with benzodiazepines, such as rectal diazepam gel or oral, buccal, or sublingual benzodiazepines 2.
• The management of acute symptomatic seizures, which occur shortly after a central nervous system insult, is not well-established and may require individualized treatment plans 4.
• The treatment of status epilepticus involves immediate administration of full doses of benzodiazepines, followed by a full loading dose of IV antiseizure medications, such as fosphenytoin, levetiracetam, or valproic acid 6.

Risk Factors and Prognosis

• The risk of a second seizure after a first unprovoked seizure is around 36% at 2 years and 46% after 5 years, and is doubled in the presence of certain risk factors, such as EEG epileptiform discharges or a brain imaging abnormality 6.
• The prognosis for patients with epilepsy is generally good, with around 60-70% of patients achieving seizure freedom with treatment 3.