What is the most likely diagnosis for a previously healthy 21-year-old woman who experiences a strange sensation in her upper abdomen, followed by staring, unresponsiveness for 30 seconds, and post-ictal sleep, with no recall of the episode?

Focal Seizure with Impaired Awareness

The most likely diagnosis is focal seizure with impaired awareness (previously termed complex partial seizure), based on the characteristic epigastric aura, impaired responsiveness, post-ictal sleep, and complete amnesia for the event. 1

Key Diagnostic Features Supporting Focal Seizure with Impaired Awareness

The Epigastric Aura

• The "strange sensation in her upper abdomen" is a classic epigastric aura, which is highly characteristic of focal seizures, particularly those originating from the temporal lobe. 1
• According to the European Heart Journal guidelines, a typical epileptic aura consists of a rising sensation in the abdomen (epigastric aura) and/or an unusual unpleasant smell. 1
• While a rising sensation may rarely occur in syncope, the combination with other features makes seizure far more likely. 1

The Ictal Phase

• The 30-second period of staring and unresponsiveness represents the seizure itself with impaired awareness. 1, 2
• Focal seizures are characterized by arising within networks of a single cerebral hemisphere and can have motor or nonmotor onset symptoms with impaired awareness. 1
• The staring spell is a non-motor manifestation indicative of focal impaired awareness. 2

Post-Ictal Features

• The 2-minute sleep period after the event represents post-ictal state, which is characteristic of seizures rather than syncope. 1
• European Heart Journal guidelines emphasize that patients may be confused post-ictally for a long time in epilepsy, whereas in syncope clearheadedness is usually immediate. 1
• The quick return to baseline after the brief sleep is consistent with focal seizures, which can have variable post-ictal periods. 3

Complete Amnesia

• The lack of recall for the episode is expected in focal seizures with impaired awareness, as consciousness is altered during the event. 1, 2

Why Other Diagnoses Are Less Likely

Absence Seizure - Excluded

• Absence seizures typically last only 5-15 seconds, not 30 seconds. 1
• Absence seizures do not have an aura or prodrome. 1
• Post-ictal sleep does not occur with absence seizures; patients return immediately to baseline. 1
• Absence seizures are primarily a childhood disorder and would be unusual as a new diagnosis in a 21-year-old. 4

Focal Seizure with Intact Awareness - Excluded

• By definition, this patient had impaired awareness as she did not respond to questions during the event. 1, 2
• Focal aware seizures (previously simple partial) maintain consciousness and responsiveness throughout. 1, 2

Vasovagal Syncope - Excluded

• The epigastric aura is not characteristic of vasovagal syncope; syncope prodrome typically includes lightheadedness, blurring of vision, nausea, and feeling of cold sweating. 1
• The 30-second duration of unresponsiveness is too long for typical syncope; loss of consciousness in syncope is usually brief (seconds). 1
• Post-event sleep for 2 minutes is not characteristic of syncope; patients with syncope typically regain clearheadedness immediately. 1
• The absence of triggers (standing, pain, emotional stress) makes vasovagal syncope less likely. 1

Psychogenic Non-Epileptic Spell - Excluded

• Psychogenic non-epileptic seizures (PNES) typically have longer duration (often >5 minutes). 1
• PNES often show pelvic thrusting, eye fluttering, or eyes closed during unconsciousness. 1
• The brief, stereotyped nature of this event with rapid return to baseline is more consistent with epileptic seizure. 1
• PNES would be a consideration if video-EEG monitoring showed no ictal discharges during similar events. 1

Clinical Implications and Next Steps

Diagnostic Workup

• Neurological evaluation is indicated as this patient is suspected to have epilepsy. 1
• EEG should be obtained, though a normal interictal EEG cannot rule out epilepsy and must be interpreted in clinical context. 1
• MRI with epilepsy protocol is recommended as focal seizures are often associated with structural brain lesions (detection rate up to 55%). 2

Risk Assessment

• After a first unprovoked seizure, this patient is at high risk for recurrence given the focal nature with clear semiology. 4
• The frequency of recurrence for focal seizures can be up to 94%. 2

Common Pitfalls to Avoid

• Do not dismiss the epigastric sensation as "just anxiety" or gastrointestinal symptoms. 1
• Do not confuse the brief post-ictal sleep with normal tiredness after a stressful event. 1
• Do not assume a normal interictal EEG rules out epilepsy; clinical diagnosis takes precedence. 1