Diagnosis of Absence Seizures in Children
The most significant criterion to support the diagnosis is D: Loss of awareness of surrounding, which is the essential defining feature of absence seizures and must be present for diagnosis.
Core Diagnostic Criterion
Loss of consciousness/awareness is the fundamental and mandatory component of absence seizures. 1 This impairment of consciousness distinguishes absence seizures from other seizure types and is pharmacologically unique. 1 Without documented loss of awareness, the diagnosis of absence seizures cannot be made, regardless of other features present.
Supporting Clinical Features
The clinical presentation described—dropping pencils and blank staring episodes—is classic for childhood absence epilepsy, but the hierarchy of diagnostic importance is critical:
Primary Feature (Essential)
- Impairment of consciousness (loss of awareness) is one of two essential components required for diagnosis 1
- The severity can vary from severe to mild or even inconspicuous, but must be present 1
Secondary Features (Supportive but Not Essential)
Duration characteristics:
- Brief episodes lasting seconds (typically 2-30 seconds) support the diagnosis 1
- The blank stare lasting less than one minute (Option A) is consistent with absence seizures but is not the most significant criterion since duration alone without confirmed loss of awareness is insufficient 1
Motor manifestations:
- Lip smacking and other automatisms (Option B) are associated motor manifestations that commonly occur with absence seizures 1
- Myoclonic jerks, particularly of facial muscles, are the most common motor symptom and may be rhythmic, synchronous with spike-wave complexes 1, 2
- However, these motor features are secondary to the core feature of impaired consciousness 1
Absence of aura:
- Typical absence seizures do NOT have an aura (Option C is incorrect) 1
- The presence of aura would suggest focal seizures rather than generalized absence seizures 3
- Generalized seizures rapidly affect both hemispheres from onset without warning 3, 4
Clinical Pitfalls to Avoid
Do not diagnose absence seizures based solely on:
- Staring episodes without documented loss of awareness
- Brief duration alone without consciousness impairment
- Motor automatisms in isolation
Key distinguishing point: Focal seizures with impaired awareness (formerly complex partial seizures) can mimic absence seizures but typically have focal features, may have auras, and show different EEG patterns. 5, 3
Confirmatory Testing
While not part of the question, the diagnosis requires EEG confirmation showing generalized 3-4Hz spike/polyspike and slow wave discharges, which is the second essential component alongside impaired consciousness. 1 Hyperventilation precipitates these episodes in approximately 90% of untreated patients. 1