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Normal Variants
practice for EEG registry
Question | Answer |
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Describe MU | Negative arch-shaped 7-11 hz rhythmic activity most often located in C3 or c4 can occur unilaterally or bilaterally and can shift. does not attenuate with eye opening. during wake stops with moving contralateral arm. |
Describe the third rhythm (temporal lobe alpha) and its occurance | alpha range activity located in the temporal region. Occurs in the wake state. seen only in some patients who have a skull defect. |
describe slow alpha variant and its occurence | A sub-harmonic of the posterior dominant alpha rhythm often notched and occurring at-4 to 5 hz.. occurs in wake state with eyes closed attenuates (blocks) with eyes opening |
Describe fast alpha variant and its occurrence | 16 to 20 hz posterior rhythm can be armonic (twice as fast) as the patients alpha rhythm Occurs in the wake state with eyes closed attenuates with eye opening. |
describe subclinical rhythmic electrographic discharge of adults (SREDA) | Periodic sharp activity that progresses into monorhythmic theta pattern of sharply contoured theta. Occurs in the waking state of older patients no symptom or clinical changes are associates with discharge |
Describe rhythmic midtemporal theta of drowsiness and its occurence. | Sharply contoured of 5 to 7 hz theta activity of temporal and central localization often has a notched appearance. occurs in drowsiness or relaxed wakefulness |
Describe 14 and 6 positive spikes and their occurence | Sharply contoured trains of 16 and 6 hz spike waves in the posterior region maximal at T%\T^ best recorded from widely spaced electrodes so best seen on a referential montage contralateral ear drowsy or N1 |
Describe positive occipital sharp transients of sleep (posts) and their occurrence | Surface positive 4 to 5 hz theta waves in the occipital regions n1 /N2 |
Describe lambda and its occurrence | surface positive waves in the occipital regions that are transient activity associated with saccadic eye movements while patient eyes are open that block with eye closure |
Describe wickets spikes and their occurrence. | Sharply contoured waves located in the temporal region; seen bilaterally or independently, no slow wave drowsy and N1 |
Describe phantom spike and wave (6 hz spike and wave and its occurrence | parietal or occipital low voltage spike and wave complexes that occur as a single wave or in brief bursts the spike is very low voltage om comparison with the slow wave drowsiness |
Describe benign epileptiform transients of sleep (BETS) asls called small sharp spike (SSS) and their occurrence | Low voltage sharp waves that occur on one or both sides in the temporal and frontal regions; may mimic EKG artifact seen most often on referential montages occurs n1 and N2 sleep |