EEG Abnormal Epileptiform Patterns 5 — Questions and Answers
Question 1: Which EEG finding is the ictal correlate of epilepsia partialis continua (Kojewnikow syndrome)?
- Periodic lateralized epileptiform discharges (PLEDs) at 1–2 Hz
- Continuous focal rhythmic delta activity with embedded spikes over the motor cortex (Correct answer)
- Generalized 3-Hz spike-and-wave
- Bilateral independent periodic discharges (BIPDs)
Correct answer: Continuous focal rhythmic delta activity with embedded spikes over the motor cortex
Epilepsia partialis continua produces continuous or near-continuous focal rhythmic discharges, often with embedded spikes, localized to the contralateral motor cortex.
Question 2: On a neonatal EEG, which feature best distinguishes a seizure discharge from a normal sharp transient?
- Amplitude exceeding 100 µV
- Evolution in frequency, amplitude, or spatial distribution over time (Correct answer)
- Occurrence during active sleep
- Presence of a post-ictal suppression lasting 1 second
Correct answer: Evolution in frequency, amplitude, or spatial distribution over time
Neonatal seizures are defined by electrographic evolution — a clear change in frequency, morphology, or field — rather than by a fixed amplitude or sleep-state rule.
Question 3: Generalized paroxysmal fast activity (GPFA) during slow-wave sleep is the characteristic ictal correlate of which seizure type in Lennox-Gastaut syndrome?
- Absence seizures
- Myoclonic seizures
- Tonic seizures (Correct answer)
- Atonic seizures
Correct answer: Tonic seizures
Tonic seizures in Lennox-Gastaut syndrome are associated with generalized paroxysmal fast activity (GPFA, 10–25 Hz) predominantly during NREM sleep.
Question 4: A 6-Hz spike-and-wave burst lasting less than 2 seconds seen in a drowsy young adult is most consistent with:
- Juvenile myoclonic epilepsy ictal discharge
- Phantom spike-and-wave (benign variant) (Correct answer)
- Absence status epilepticus
- Temporal lobe seizure onset
Correct answer: Phantom spike-and-wave (benign variant)
The 6-Hz 'phantom' spike-and-wave is a benign normal variant in drowsy young adults and should not be misinterpreted as pathological epileptiform activity.
Question 5: Which EEG pattern during absence status epilepticus distinguishes it from typical 3-Hz absence discharges?
- The discharges become fragmented, irregular, and slower (< 2.5 Hz) over time (Correct answer)
- Amplitude increases progressively to > 500 µV
- Discharges shift to posterior head regions
- The spike component disappears leaving pure slow waves
Correct answer: The discharges become fragmented, irregular, and slower (< 2.5 Hz) over time
During prolonged absence status epilepticus, the initially regular 3-Hz spike-and-wave tends to slow, fragment, and become irregular as status continues.
Question 6: In juvenile myoclonic epilepsy (JME), the EEG hallmark is polyspike-and-wave discharges typically at which frequency?
- 1–2 Hz
- 3 Hz
- 4–6 Hz (Correct answer)
- 10–12 Hz
Correct answer: 4–6 Hz
JME is characterized by generalized polyspike-and-wave complexes at 4–6 Hz, typically maximal in the morning and activated by sleep deprivation.
Question 7: An EEG shows electrical status epilepticus during slow-wave sleep (ESES), with spike-wave index exceeding 85%. This pattern underlies which syndrome?
- Lennox-Gastaut syndrome
- Continuous spike-waves during slow sleep (CSWS) / Landau-Kleffner syndrome spectrum (Correct answer)
- Ohtahara syndrome
- Childhood absence epilepsy
Correct answer: Continuous spike-waves during slow sleep (CSWS) / Landau-Kleffner syndrome spectrum
ESES (spike-wave index > 85% during NREM sleep) is the electrographic hallmark of CSWS and Landau-Kleffner syndrome, associated with acquired cognitive or language regression.
EEG Abnormal Epileptiform Patterns 5
Which EEG finding is the ictal correlate of epilepsia partialis continua (Kojewnikow syndrome)?