EEG Abnormal Epileptiform Patterns 4

Question 1

Which EEG pattern is characterized by bilateral synchronous 3-Hz spike-and-wave discharges that are typically enhanced by hyperventilation?

Accepted Answer

Childhood absence epilepsy

Answer

Childhood absence epilepsy classically produces bilateral synchronous 3-Hz spike-and-wave discharges that are strongly activated by hyperventilation.

Question 2

A patient's EEG shows slow (1–2.5 Hz) spike-and-wave complexes during sleep alongside atonic and tonic seizures. Which syndrome does this pattern most suggest?

Accepted Answer

Lennox-Gastaut syndrome

Answer

Lennox-Gastaut syndrome is defined by slow (1–2.5 Hz) spike-and-wave, multiple seizure types including atonic and tonic, and intellectual disability.

Question 3

Hypsarrhythmia on EEG is the interictal hallmark of which epilepsy syndrome?

Accepted Answer

West syndrome

Answer

Hypsarrhythmia — chaotic high-amplitude activity with multifocal spikes — is the characteristic interictal EEG pattern of West syndrome (infantile spasms).

Question 4

On EEG, a burst-suppression pattern in a neonate without hypothermia treatment most likely indicates which condition?

Accepted Answer

Ohtahara syndrome

Answer

Burst-suppression in a neonate (outside therapeutic hypothermia) is a hallmark of Ohtahara syndrome (early infantile epileptic encephalopathy).

Question 5

Which epileptiform feature specifically distinguishes a true spike from a sharp wave on EEG?

Accepted Answer

Duration less than 70 ms vs. 70–200 ms

Answer

By convention, a spike has a duration of less than 70 ms, whereas a sharp wave has a duration of 70–200 ms; both may be followed by a slow wave.

EEG - Electroencephalography Practice Test

EEG - Electroencephalography Practice Test

EEG Abnormal Epileptiform Patterns 4