EEG Flashcards
Along with k-complexes, which of the following waves characterise the beginning of stage 2 sleep?
Sigma
Delta frequency
1-4Hz
Theta frequency
4-8Hz
Alpha frequency
8-12 Hz
Beta frequency
12-30 Hz
Delta location
Frontally in adults and posteriorly in children
Theta location
Generalised
Alpha location
Posteriorly
Beta location
Frontally
Sigma frequency
12-14 Hz
Gamma frequency
30-100 Hz
Sigma location
Frontal and central regions
Gamma location
No specific areas
Theta is found in/demonstrates…
Young children, drowsy and sleeping adults (stage I) (Purves, 2001), with certain medications, meditation. Small amount seen in awake adults, excessive amount when awake may indicate pathology
Delta is found in/demonstrates…
Slow wave sleep (stages III and IV) (Purves, 2001) and in babies. Should not be present when awake, when present if awake this strongly suggests pathology
Alpha is found in/demonstrates…
When relaxed and when the eyes are closed (whilst awake). Also seen in meditation.
Beta is found in/demonstrates…
When busy or concentrating
Gamma is found in/demonstrates…
Seen in advanced / very experienced meditators
Sigma is found in/demonstrates…
(aka sleep spindles) Bursts of oscillatory activity that occur in stage 2 sleep. Along with k-complexes they are the defining characteristic of stage 2 sleep
EEG in Huntington’s
Low voltage EEG, in particular no alpha (flattening)
EEG in delirium
Diffuse slowing, decreased alpha, increased theta and delta
EEG in DTs
Hyperactive trace, fast
EEG in Sporadic CJD
Early on there is non specific slowing, later periodic biphasic and triphasic synchronous sharp wave complexes superimposed on a slow background rhythm
EEG in Alzheimer’s
Reduced alpha and beta, increased delta and theta
EEG in normal ageing
Diffuse slowing, which can be focal or diffuse, if focal most commonly seen in the left temporal region
EEG in encephalopathy
Diffuse slowing
Clozapine effect on EEG
Alpha - decrease
Beta - varied
Delta - increase
Theta - increase
Lithium effect on EEG
Alpha - increase
Beta - increase
Delta - increase
Theta - increase
Lamotrigine effect on EEG
Alpha - decrease
Beta - decrease
Delta - decrease
Theta - decrease
Valproate effect on EEG
Alpha - decrease
Beta - increase
Delta - inconclusive
Theta - inconclusive
Typical absence (aka petit mal) EEG
Generalised 3 Hz spike-wave
Atypical absence EEG
Slow (<2.5 Hz) generalized spike-and-wave
Focal (previously known as partial) EEG
Focal spikes
Myoclonic EEG
Generalized 3-6 Hz polyspike and wave discharge
Generalised tonic-clonic EEG
EEG often obscured by artifact (movement). Generalized fast rhythmic spikes are seen in the tonic stage. Bursts of spikes and after-coming slow waves are synchronous with clonic jerks. A postictal period of irregular slow activity follows
Atonic (drop attack) EEG
Generalized spike-and-wave is typical, with atonia at the time of the slow wave
