EEG Flashcards
What wave is seen in the awake, alert state?
Beta waves > 13 Hz (predominant over frontal regions)
What waves are seen in the relaxed, awake state?
Alpha waves 8-13 Hz (seen more in posterior head regions)
What does diffuse theta or delta wave activity in the awake state indicate?
Suggests encephalopathy (but does not distinguish the cause)
What does focal arrhythmic or polymorphic slow activity in the theta or delta range suggest?
Local dysfunction in the underlying brain (e.g. vascular disease)
What are the most common EEG patterns for seizures?
Rhythmic spike or sharp and slow wave discharges or rhythmic slow waves (may be focal or generalized)
What technique can be used to provoke EEG changes in a patient with absence seizures?
Hyperventilation
What technique can be used to provoke EEG changes in a patient with myoclonic seizures?
Photic stimulation
What is the EEG pattern of CJD?
Periodic sharp waves
What EEG pattern is seen in REM sleep?
Low-voltage waves that are random, fast and sawtoothed.
What is EEG pattern of alert wakefulness?
Beta waves - Low voltage, random pattern, with few rhythmic components
What is the EEG pattern of relaxed wakefulness?
Alpha waves - Low voltage, rhythmic alpha, with occasional bursts of the alertness pattern
What is the EEG pattern of NREM stage 1 sleep?
Theta waves (slower in frequency and greater in amplitude than alpha waves) interspersed with alpha waves
What is the EEG pattern of NREM stage 2 sleep?
Theta waves (stage 1 background) with sleep spindles (sudden increase in wave frequency) and K-complexes (sudden increase in wave amplitude) at least every 30 seconds.
What is the EEG pattern of NREM stage 3 sleep (slow wave/deep sleep)?
Delta waves - slowest waves with highest amplitude
What is the EEG pattern of hypersomnolence disorder?
Increased slow wave sleep
What is the EEG pattern of Lennox-Gastaut syndrome?
Slow (1-2 per second) spike-and-wave discharges
What is the EEG pattern of benign rolandic epilepsy?
Centrotemporal spikes
What is the EEG pattern of juvenile myoclonic epilepsy?
4-6 per second polyspike-and-wave
What is the EEG pattern of primary generalized epilepsy of childhood?
3-Hz spike-and-wave
What is hypsarrhythmia?
An abnormal interictal pattern, consisting of high amplitude and irregular waves and spikes in a background of chaotic and disorganized activity seen on electroencephalogram (EEG), and frequently encountered in an infant diagnosed with infantile spasms, although it can be found in other conditions.
What is the EEG pattern seen in hepatic enchephalopathy?
Triphasic waves
