What are the symptoms of absence seizures?

Symptoms of Absence Seizures

Absence seizures present with brief episodes of altered consciousness lasting seconds, during which the patient appears to "blank out" or stare without falling, and these episodes do not involve the dramatic motor movements seen in tonic-clonic seizures. 1

Core Clinical Features

Consciousness Alteration

• Consciousness is altered rather than completely lost – patients experience impairment of awareness and responsiveness but remain upright during attacks 1
• The impairment can range from severe to mild or even inconspicuous, varying between patients and even between episodes in the same individual 2, 3
• Patients do not fall during absence seizures, which is a key distinguishing feature from other seizure types 1

Duration and Onset

• Episodes are brief, lasting only seconds (typically 2-30 seconds), with sudden onset and abrupt termination 2
• The EEG shows characteristic generalized 3-4 Hz spike-wave discharges during episodes 2

Associated Motor Manifestations

• Myoclonic movements, particularly of facial muscles, are the most common motor component 2
• Other possible motor features include clonic, tonic, or atonic components, though these are less prominent than in other seizure types 2
• Automatisms (repetitive purposeless movements) and autonomic disturbances may occur 2

Distinguishing Features from Other Conditions

Key Differences from Syncope

• No loss of consciousness leading to falls – patients remain standing throughout the episode 1
• Absence of typical syncopal triggers (orthostatic stress, emotional stimuli) 1
• No pallor or sweating, which are common in syncope 1
• Post-event confusion is minimal or absent, whereas syncope typically results in immediate clearheadedness 1

Triggers and Precipitation

• Hyperventilation precipitates absence seizures in approximately 90% of untreated patients 2
• Other triggers include photic stimulation, pattern stimuli, video games, and mental or emotional factors 2
• Episodes are usually spontaneous but can be provoked by these specific stimuli 2

Age and Population Considerations

• Typical absences usually begin in childhood or adolescence 2
• They occur in approximately 10-15% of adults with epilepsy, often combined with other generalized seizure types 2
• The condition may remit with age or persist lifelong, depending on the specific epilepsy syndrome 2

Clinical Pitfalls

• Absence seizures are often misdiagnosed because the brief nature and lack of dramatic motor activity can make them appear as simple inattention or daydreaming 2
• The episodes may be so brief (2-5 seconds) that they go unnoticed by observers 2
• Approximately 30% of patients may develop absence status epilepticus, characterized by prolonged or repeated absence seizures 2