Normal EEG Waveforms 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 Normal EEG Waveforms flashcards as text
What is the typical frequency range of theta activity in EEG?
Answer: 4-8 Hz
Theta activity ranges from 4-8 Hz. In adults, mild theta activity is normal during drowsiness but persistent theta during wakefulness suggests encephalopathy. In children, more theta activity is normal.
The wicket rhythm is a benign normal variant that can be confused with:
Answer: Temporal sharp waves or epileptiform discharges
Wicket spikes (or wicket rhythm) are arch-shaped 6-11 Hz waveforms over the temporal regions that can resemble temporal sharp waves, potentially leading to misdiagnosis of temporal lobe epilepsy if not recognized as benign.
The 14-and-6 Hz positive spikes pattern is considered:
Answer: A benign normal variant seen in adolescents during drowsiness and light sleep
14-and-6 Hz positive spikes (also called positive bursts or ctenoids) are a benign normal variant most commonly seen in adolescents during drowsiness and light sleep, predominantly over posterior temporal regions.
Rhythmic midtemporal theta of drowsiness (RMTD) is characterized by:
Answer: Sharply contoured 5-7 Hz rhythmic theta bursts over the midtemporal regions during drowsiness, with a characteristic notched appearance
RMTD (formerly called psychomotor variant) consists of rhythmic, sharply contoured 5-7 Hz theta activity over one or both midtemporal regions during drowsiness, with a distinctive notched or flat-topped morphology.
Subclinical rhythmic electrographic discharges of adults (SREDA) is a rare benign pattern that mimics:
Answer: Electrographic seizure activity with rhythmic theta over widespread or posterior regions
SREDA is a rare benign EEG pattern that closely mimics seizure activity, consisting of sudden-onset widespread or posterior-dominant rhythmic theta (5-7 Hz) that evolves in frequency, potentially leading to misdiagnosis of epilepsy.
During the transition from wakefulness to drowsiness, the expected EEG changes include:
Answer: Attenuation of the posterior dominant rhythm with appearance of diffuse theta activity and slow rolling eye movements
The wake-to-drowsiness transition is marked by progressive attenuation of the posterior dominant rhythm (alpha dropout), replacement by diffuse low-amplitude theta activity, slow lateral eye movements, and eventually vertex sharp waves marking Stage N1.