Absence

Definition & Etymology

Absence (from French absence, “being away”) is a type of generalized, non-convulsive epileptic seizure characterized by a brief, sudden lapse of consciousness. The individual abruptly ceases activity, stares blankly, and is unresponsive. The episode typically lasts for a few seconds, ending as suddenly as it begins, with an immediate return to full awareness and no postictal confusion. The term “petit mal,” once used for this seizure type, is now considered outdated.

Clinical Significance

Absence seizures are a hallmark of specific childhood epilepsy syndromes, caused by abnormal, synchronous electrical discharges involving the entire brain. The pathognomonic electroencephalogram (EEG) finding is the generalized 3-Hz spike-and-wave discharge. Clinically, these subtle episodes can be mistaken for daydreaming, potentially delaying diagnosis and impacting a child’s learning. While not convulsive, they can be dangerous if they occur during critical activities like swimming or crossing a street, as awareness is completely impaired.

Related Conditions

The primary condition is Childhood Absence Epilepsy (CAE), an idiopathic generalized epilepsy with onset between ages 4 and 10. They are also a feature in Juvenile Absence Epilepsy (JAE) and Juvenile Myoclonic Epilepsy (JME). The differential diagnosis includes distinguishing them from complex partial seizures, which involve postictal confusion, and non-epileptic conditions such as Attention-Deficit/Hyperactivity Disorder (ADHD), where responsiveness is typically preserved to some degree.

Key Takeaways

• Absence is a generalized seizure defined by a brief, non-convulsive lapse of awareness with a sudden onset and offset.
• The classic EEG signature is a generalized 3-Hz spike-and-wave discharge, confirming its epileptic origin.
• It is the defining seizure for Childhood Absence Epilepsy (CAE) and must be differentiated from behavioral inattention.

Note: This content is for informational purposes only and does not substitute for professional medical advice. Always consult your doctor for diagnosis and treatment.