Abnormal Epileptiform Patterns Flashcards
6 cards from real EEG practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Abnormal Epileptiform Patterns flashcards as text
An 8-year-old child presents with frequent staring spells. The EEG recording shows bursts of generalized, synchronous, and symmetric 3 Hz spike-and-wave discharges that are easily provoked by hyperventilation. What is the most likely clinical correlation?
Answer: Childhood absence epilepsy
The classic EEG signature for typical childhood absence epilepsy is generalized, symmetric 3 Hz spike-and-wave discharges, often induced by hyperventilation, which correlates clinically with brief staring spells. Lennox-Gastaut syndrome presents with slow (3 Hz) polyspike-and-wave discharges.
According to the American Clinical Neurophysiology Society (ACNS) guidelines, an epileptiform discharge is classified as a 'sharp wave' based on which of the following duration ranges?
Answer: 70-200 milliseconds
A sharp wave is defined as a transient with a pointed peak and a duration of 70 to 200 milliseconds. Discharges with a duration of less than 70 ms are classified as spikes, and waves lasting longer than 200 ms are considered slow waves.
A 9-month-old infant is evaluated for clusters of sudden, brief flexor spasms. The interictal EEG shows a chaotic, high-voltage, and disorganized pattern of asynchronous slow waves and multifocal spikes. Which of the following terms best describes this EEG pattern?
Answer: Hypsarrhythmia
Hypsarrhythmia is the characteristic interictal EEG pattern associated with Infantile Spasms (West Syndrome). It is defined by its disorganized, high-amplitude, and chaotic appearance, with a mix of random slow waves and multifocal spikes.
An EEG on a 10-year-old child shows high-amplitude, diphasic sharp waves that occur independently over the centrotemporal regions (C3/T3 and C4/T4). The discharges become significantly more frequent during drowsiness and sleep. This pattern is pathognomonic for which epilepsy syndrome?
Answer: Self-limited Epilepsy with Centrotemporal Spikes (SeLECTS)
Self-limited Epilepsy with Centrotemporal Spikes (SeLECTS), formerly known as Benign Rolandic Epilepsy, is characterized by these specific centrotemporal spikes, which show a marked increase during sleep. The location of the discharges is key to this diagnosis.
An EEG performed on a patient with an acute left-hemispheric stroke shows stereotyped sharp waves recurring every 1-1.5 seconds, confined to the left cerebral hemisphere. This pattern is best described as:
Answer: Periodic Lateralized Discharges (PLEDs)
This pattern fits the definition of Periodic Lateralized Discharges (PLEDs), which are stereotyped, periodic complexes that are restricted to one hemisphere. They are often associated with acute structural lesions like stroke or encephalitis. GPDs are bilateral, not lateralized.
In a comatose patient following an anoxic brain injury, the EEG shows periods of high-voltage, mixed-frequency activity lasting 1-3 seconds, which are separated by periods of profound voltage attenuation (<10 µV) lasting 4-8 seconds. This pattern is known as:
Answer: Burst-suppression
The described pattern of alternating high-amplitude 'bursts' with periods of near-isoelectric 'suppression' is the definition of a burst-suppression pattern. It indicates profound cerebral dysfunction and is often seen in conditions like severe anoxia, deep anesthesia, or certain encephalopathies.