EEGs Flashcards
Delta waves
1-4Hz, Frontally in adults and posteriorly in children
Slow wave sleep and in babies. Should not be present when awake, when present if awake this strongly suggests pathology
Theta waves
4-8Hz, generalised.
Young children, drowsy and sleeping adults, with certain medications, meditation. Small amount seen in awake adults, excessive amount when awake may indicate pathology
Alpha waves
8-12Hz, posteriorly.
When relaxed and when the eyes are closed (whilst awake)
Beta waves
12-30Hz, frontally.
When busy or concentrating
Sigma waves
12-14Hz, frontal and central regions
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
Gamma waves
30-100Hz. Meditation
Sporadic CJD - eeg
Early on there is non specific slowing, later periodic biphasic and triphasic synchronous sharp wave complexes superimposed on a slow background rhythm
Hungtingdon’s - eeg
Low voltage EEG, in particular no alpha (flattening)
Delirium - eeg
Diffuse slowing, decreased alpha, increased theta and delta
Delirium Tremens - eeg
Hyperactive trace, fast
Alzheimer’s - eeg
Reduced alpha and beta, increased delta and theta
Absence seizure
Generalised, bilateral, synchronous, 3Hz (3 waves per second) spike and wave pattern
Generalized epilepsy
Sharp spikes, 25-30Hz
Partial epilepsy
Focal spikes
Myoclonic epilepsy
Generalised spike and wave activity
Encephalopathy - eeg
Diffuse slowing
Normal ageing - eeg
Diffuse slowing, which can be focal or diffuse, if focal most commonly seen in the left temporal region
Typical antipsychotics - eeg
Diffuse slowing, which can be focal or diffuse, if focal most commonly seen in the left temporal region
Antidepressants - eeg
Reduce beta, increase all others
Atypical antipsychotics - eeg
Varied effect, clozapine most significant effect, quetiapine least significant. Clozapine > Olanzapine > Risperidone > Typicals > Quetiapine
Lithium - eeg
Slowing
Benzodiazepines - eeg
Increase beta, decrease alpha
Barbituates - eeg
Increase beta
Stimulants - eeg
Increase alpha
Depressants - eeg
Decrease alpha
Cannabis - eeg
Increase alpha
Stage I sleep
Alpha disappears
Desynchronised theta and delta appear
Stage II sleep
Low voltages and delta waves with sleep spindles and K complexes
Stage III sleep
High voltage slow waves
Delta <50%
Sleep spindles and K complexes diminish
Stage IV sleep
Delta waves >50%
Sleep spindles and K complexes absent
