Clinical scenario: Staring episodes | EEG abnormality with hyperventilation
A 7-year-old boy is brought to the neurology clinic because of frequent episodes of sudden loss of awareness and brief jerking movements of both arms. His parents report that he has been having brief staring episodes many times daily for the last 6 months. He also had two generalized tonic-clonic seizures during sleep.
On examination:
- Development is normal
- Neurological examination is normal
EEG shows:
- Generalized 3-Hz spike-and-wave discharges during hyperventilation
Which of the following is the most likely diagnosis?
A. Childhood absence epilepsy
B. Juvenile absence epilepsy
C. Juvenile myoclonic epilepsy
D. Lennox–Gastaut syndrome
E. Benign epilepsy with centrotemporal spikes
Correct answer & Explanation:
Correct Answer:
B. Juvenile absence epilepsy
Explanation
This child has juvenile absence epilepsy (JAE).
Key features:
- Age of onset: usually 9–13 years (but may overlap with childhood absence epilepsy)
- Frequent absence seizures
- Generalized tonic-clonic seizures are common
- Myoclonic jerks may occur
- EEG: generalized 3–5 Hz spike-and-wave activity
The presence of generalized tonic-clonic seizures and older age at onset favors juvenile absence epilepsy rather than childhood absence epilepsy.
Why the other options are incorrect
A. Childhood absence epilepsy
- Usually onset: 4–10 years
- Frequent brief absences
- Usually no other seizure types
- EEG: classic 3-Hz spike-and-wave
- Normal development
B. Juvenile absence epilepsy – Correct
- Older child/adolescent
- Absences + generalized tonic-clonic seizures
- Generalized spike-wave EEG
C. Juvenile myoclonic epilepsy
- Usually begins in adolescence
- Prominent morning myoclonic jerks
- Absence seizures may occur but are not the dominant feature
D. Lennox–Gastaut syndrome
- Multiple seizure types
- Developmental impairment
- EEG: slow spike-and-wave (<2.5 Hz)
E. Benign epilepsy with centrotemporal spikes
- Focal seizures involving face/oropharynx
- EEG: centrotemporal spikes
Learning Point
High-yield differences:
| Syndrome | Age | Key seizure | EEG |
|---|---|---|---|
| Childhood absence epilepsy | 4–10 yr | Absence only | 3-Hz spike-wave |
| Juvenile absence epilepsy | 9–13 yr | Absence + GTCS | 3–5 Hz spike-wave |
| Juvenile myoclonic epilepsy | Adolescence | Morning myoclonus + GTCS | Generalized polyspike-wave |
| Lennox-Gastaut | <8 yr | Multiple seizure types | Slow spike-wave |
