What is the possible diagnosis for a patient experiencing episodes of staring for seconds at a time?

Absence Seizures Are the Most Likely Diagnosis

Episodes of staring for seconds at a time in a patient most likely represent absence seizures, particularly if the episodes are brief (typically 5-15 seconds), involve impaired consciousness without a prodrome, and the patient returns immediately to baseline afterward. 1, 2

Key Diagnostic Features of Absence Seizures

• Duration: Absence seizures typically last 5-15 seconds, though they can extend to 30 seconds 2, 3
• Consciousness: Complete impairment of consciousness occurs during the episode, with the patient being non-responsive to verbal commands 1, 2
• No aura or prodrome: Unlike focal seizures, absence seizures begin abruptly without warning symptoms 4, 2
• Immediate recovery: Patients return to baseline immediately after the episode ends, with no post-ictal confusion or sleepiness 1, 2
• Additional features: Eye blinking (41.5% of seizures) and automatisms (45% of seizures) commonly accompany the staring 3

Critical Distinguishing Features from Other Diagnoses

Absence Seizures vs. Focal Seizures with Impaired Awareness

Focal seizures typically have longer duration (30+ seconds), an aura (especially epigastric rising sensation or unusual smell), and post-ictal confusion or sleepiness lasting minutes. 1, 4

• Focal seizures: Duration averages 74-90 seconds 1
• Focal seizures: Epigastric aura or unusual smell suggests focal onset 1, 4
• Focal seizures: Post-ictal confusion is prolonged, not immediate recovery 1

Absence Seizures vs. Syncope

Syncope involves loss of consciousness lasting only seconds (<30 seconds), is usually triggered by specific situations, and features prodromal symptoms of cerebral hypoperfusion (lightheadedness, visual changes, sweating, pallor). 1

• Syncope: Flaccid collapse is typical, not maintained upright posture 1
• Syncope: Prodrome includes visual darkening, sounds becoming distant, nausea, sweating 1
• Syncope: Movements begin after loss of consciousness (mean 20 seconds later), not at onset 1
• Syncope: Immediate clearheadedness upon recovery 1

Behavioral Staring vs. Epileptic Staring

Non-epileptic behavioral staring can be differentiated by responsiveness to stimuli, variable duration, and lack of stereotyped features. 5, 6, 7

• Behavioral staring: Patient may respond to verbal commands or physical stimulation 6, 7
• Behavioral staring: Episodes vary in duration and characteristics 5, 7
• Behavioral staring: More common in children with developmental disorders (autism, ADHD, intellectual disability) 5, 6

Diagnostic Approach

Hyperventilation for 3-5 minutes during clinical examination will precipitate absence seizures in approximately 90% of untreated patients. 2

• EEG findings: Generalized 3-4 Hz spike-and-wave discharges are diagnostic 1, 2, 3
• Polyspikes on EEG: Presence predicts unfavorable therapeutic outcome with 92% positive predictive value 3
• Video-EEG monitoring: Gold standard when diagnosis is uncertain, especially in patients with developmental disorders where behavioral staring is common 5, 6, 7

Common Pitfalls to Avoid

• Do not assume a normal interictal EEG rules out epilepsy—clinical diagnosis takes precedence, and EEG must be interpreted in clinical context 1, 8
• Do not confuse brief myoclonic jerks or eye blinking with other seizure types—these commonly accompany absence seizures 2, 3
• Do not misdiagnose absence seizures as behavioral inattention in children with autism or ADHD—video-EEG is essential when uncertain 5, 6
• Do not start antiepileptic drugs without confirming the diagnosis—false diagnosis of epilepsy has significant treatment and psychosocial implications 1, 8

Treatment Considerations

First-line therapy includes valproic acid (controls 75% of absences), ethosuximide (controls 70% of absences), or lamotrigine (controls 50-60% of absences). 2

• Valproic acid: Also controls generalized tonic-clonic seizures (70%) and myoclonic jerks (75%), but may be undesirable for women of childbearing potential 2
• Ethosuximide: Unsuitable as monotherapy if other generalized seizures coexist 2
• Lamotrigine: May worsen myoclonic jerks; skin rashes are common 2
• Combination therapy: Low-dose lamotrigine added to valproic acid may have dramatic beneficial effect in resistant cases 2