Abnormal Epileptiform Patterns Flashcards

Which EEG pattern is characterized by a spike followed by a slow wave complex occurring at approximately 3 Hz?

Answer: Generalized 3 Hz spike-and-wave

The classic 3 Hz spike-and-wave pattern is the hallmark of childhood absence epilepsy, appearing as generalized, synchronous, bilateral discharges.

What is the typical duration criterion for an EEG spike?

Answer: 20 to 70 milliseconds

By IFCN definition, a spike has a duration of 20 to 70 milliseconds, distinguishing it from sharp waves which last 70 to 200 milliseconds.

Periodic lateralized epileptiform discharges (PLEDs) are most commonly associated with which condition?

Answer: Acute structural brain lesion such as stroke

PLEDs (now called lateralized periodic discharges or LPDs) are strongly associated with acute destructive brain lesions, most commonly stroke, and may indicate ongoing seizure activity.

Which epileptiform pattern consists of high-amplitude, chaotic, multifocal spikes and slow waves seen in infantile spasms?

Answer: Hypsarrhythmia

Hypsarrhythmia is the classic interictal EEG pattern of infantile spasms (West syndrome), characterized by high-amplitude disorganized slow waves with multifocal spikes.

What feature best distinguishes a benign epileptiform transient of sleep (BETS) from a pathological epileptiform discharge?

Answer: BETS are typically small, isolated, and lack an after-going slow wave

BETS (also known as small sharp spikes or SSS) are low-amplitude, brief, isolated transients without after-going slow waves, occurring during drowsiness and light sleep, and are considered benign normal variants.

Generalized periodic discharges (GPDs) at 1-2 Hz intervals with triphasic morphology are most characteristic of which condition?

Answer: Hepatic encephalopathy

Triphasic waves appearing as generalized periodic discharges are classically associated with metabolic encephalopathies, particularly hepatic encephalopathy, though they can be seen in other toxic-metabolic states.