Absence Seizure: Causes, Symptom and Treatment

Absence seizures, often called “petit mal seizures,” are a form of epilepsy characterized by brief, sudden lapses in awareness.

These seizures commonly occur in children but can also affect adults. Despite their short duration, they can significantly impact daily life, especially when left untreated.

This article explores absence seizures in detail, including their causes, symptoms, risk factors, differential diagnosis, investigations, and treatment options.

What is an Absence Seizure?

An absence seizure is a type of generalized seizure where the person briefly loses awareness of their surroundings.

These episodes last just a few seconds but may occur multiple times a day. Unlike other types of seizures, absence seizures don’t usually involve convulsions or intense movements, making them harder to recognize.

Epidemiology: Absence seizures account for about 10-15% of epilepsy cases in children. They are most commonly diagnosed between the ages of 4 and 14 years, with some individuals outgrowing them in adolescence.

How Does It Occur?

Absence seizures occur due to abnormal electrical activity in the brain. Think of the brain as an orchestra where every musician (or neuron) must follow the conductor’s rhythm.

In absence seizures, this rhythm is disrupted by sudden bursts of electrical signals, leading to a temporary “disconnect” from reality.

The primary area involved is the thalamocortical circuitry, responsible for regulating consciousness and sensory perception. The result? A brief lapse in awareness, often mistaken for daydreaming or inattentiveness.

What Are the Causes of Absence Seizures?

The exact cause of absence seizures isn’t always clear, but several factors can contribute to their development:

1. Genetic predisposition (60-70%): Studies show that many people with absence seizures have a family history of epilepsy.
2. Abnormal brain activity: Disruptions in the brain’s electrical signaling pathways are the direct cause.
3. Triggers: Hyperventilation or flashing lights can provoke these seizures in some individuals.

Risk Factors

While anyone can develop absence seizures, certain factors increase the likelihood:

• Age: Most cases are diagnosed in children between 4 and 14 years.
• Family history: A genetic predisposition is a significant risk factor.
• Existing neurological disorders: Conditions like ADHD or other forms of epilepsy may predispose someone to absence seizures.
• Triggers: Hyperventilation, stress, or flashing lights can act as catalysts in susceptible individuals.

Children with absence seizures often face academic and social challenges due to their frequent lapses in awareness.

Symptoms of Absence Seizures

The hallmark symptom of an absence seizure is a sudden, brief lapse in awareness. Here’s how they typically present:

• Staring spells: The person appears to “zone out” or stare blankly for a few seconds.
• No response: They are unresponsive to their surroundings during the episode.
• Automatisms: Small repetitive movements like lip-smacking, eye blinking, or finger rubbing may occur.
• Abrupt onset and end: These episodes start and stop suddenly without any warning.

Why do these symptoms occur?
The brain’s electrical misfiring temporarily disconnects the pathways controlling consciousness and responsiveness, leading to these lapses.

Differential Diagnosis

Absence seizures can be easily mistaken for other conditions, so a thorough evaluation is essential. Common differential diagnoses include:

1. Focal seizures: These involve only one part of the brain and may have similar symptoms like staring spells but often include postictal confusion.
2. Daydreaming: Unlike absence seizures, daydreaming doesn’t occur suddenly or interrupt ongoing activities.
3. Attention-deficit hyperactivity disorder (ADHD): Children with ADHD may appear inattentive, but this behavior is usually not episodic.
4. Syncope (fainting): Unlike seizures, syncope involves a loss of muscle tone and consciousness.

Proper diagnosis is critical to ensure appropriate treatment and management.

How to Diagnose Absence Seizures?

The gold standard for diagnosing absence seizures is an electroencephalogram (EEG). Here’s how it’s done:

1. History and observation: A detailed description of the episodes is crucial.
2. EEG: This test records brain activity, showing a characteristic 3 Hz spike-and-wave pattern during seizures.
3. Hyperventilation test: Asking the patient to hyperventilate may provoke an absence seizure, helping confirm the diagnosis.
4. Imaging (if needed): MRI or CT scans may be performed to rule out structural abnormalities.

Treatment of Absence Seizures

Treating absence seizures aims to reduce or eliminate episodes while minimizing side effects. Several effective treatments are available:

1. Medications (First-line treatment)

• Ethosuximide: The most commonly prescribed drug for absence seizures with a high success rate in controlling episodes.
• Valproic acid: An alternative, especially for patients with other seizure types.
• Lamotrigine: A newer option with fewer side effects but slightly less effective.

2. Lifestyle modifications

• Avoid triggers: Manage known triggers like hyperventilation and flashing lights.
• Regular sleep: Sleep deprivation can worsen seizure frequency.
• Stress management: Relaxation techniques like mindfulness can help reduce episodes.

3. Non-pharmacological treatments

• Ketogenic diet: A high-fat, low-carbohydrate diet has shown promise in reducing seizure frequency in some individuals.
• Vagus nerve stimulation (VNS): This involves using a device implanted under the skin to send electrical signals to the brain.

Prognosis

The outlook for absence seizures is generally favorable. Many children outgrow these seizures during adolescence, though some may develop other forms of epilepsy.

Early diagnosis and proper management significantly improve outcomes, reducing the impact on learning and social development.

Conclusion

Absence seizures may seem benign due to their brief duration, but their frequent occurrence can disrupt daily life, especially in children.

With advances in diagnosis and treatment, individuals with absence seizures can lead normal, fulfilling lives. If you or someone you know experiences similar symptoms, seeking medical advice early is the first step toward effective management.

References

1. Fisher, R. S., et al. “ILAE official report: a practical clinical definition of epilepsy.” Epilepsia, 2014.
2. Panayiotopoulos, C. P. “Absence Seizures.” The Epilepsies: Seizures, Syndromes, and Management, 2005.
3. National Institute of Neurological Disorders and Stroke (NINDS). “Absence Seizures Fact Sheet.”
4. Engel, J. “Seizures and Epilepsy: Pathophysiology and Clinical Considerations.” Epilepsy Currents, 2016.
5. Glauser, T., et al. “Ethosuximide, Valproic Acid, and Lamotrigine in Childhood Absence Epilepsy.” New England Journal of Medicine, 2010.