EEGs

Question 1

Delta waves

Answer 1

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

Question 2

Theta waves

Answer 2

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

Question 3

Alpha waves

Answer 3

8-12Hz, posteriorly.

When relaxed and when the eyes are closed (whilst awake)

Question 4

Beta waves

Answer 4

12-30Hz, frontally.

When busy or concentrating

Question 5

Sigma waves

Answer 5

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

Question 6

Gamma waves

Answer 6

30-100Hz. Meditation

Question 7

Sporadic CJD - eeg

Answer 7

Early on there is non specific slowing, later periodic biphasic and triphasic synchronous sharp wave complexes superimposed on a slow background rhythm

Question 8

Hungtingdon’s - eeg

Answer 8

Low voltage EEG, in particular no alpha (flattening)

Question 9

Delirium - eeg

Answer 9

Diffuse slowing, decreased alpha, increased theta and delta

Question 10

Delirium Tremens - eeg

Answer 10

Hyperactive trace, fast

Question 11

Alzheimer’s - eeg

Answer 11

Reduced alpha and beta, increased delta and theta

Question 12

Absence seizure

Answer 12

Generalised, bilateral, synchronous, 3Hz (3 waves per second) spike and wave pattern

Question 13

Generalized epilepsy

Answer 13

Sharp spikes, 25-30Hz

Question 14

Partial epilepsy

Answer 14

Focal spikes

Question 15

Myoclonic epilepsy

Answer 15

Generalised spike and wave activity

Question 16

Encephalopathy - eeg

Answer 16

Diffuse slowing

Question 17

Normal ageing - eeg

Answer 17

Diffuse slowing, which can be focal or diffuse, if focal most commonly seen in the left temporal region

Question 18

Typical antipsychotics - eeg

Answer 18

Sedative low-potency antipsychotics such as chlorpromazine increase slow waves and decrease alpha activity, whereas non-sedative high-potency antipsychotics such as haloperidol have less effect on slow waves but increase alpha and alpha-adjacent beta activity

Question 19

Antidepressants - eeg

Answer 19

Reduce beta, increase all others

Question 20

Atypical antipsychotics - eeg

Answer 20

Varied effect, clozapine most significant effect, quetiapine least significant. Clozapine > Olanzapine > Risperidone > Typicals > Quetiapine

Question 21

Lithium - eeg

Answer 21

Slowing

Question 22

Benzodiazepines - eeg

Answer 22

Increase beta, decrease alpha

Question 23

Barbituates - eeg

Answer 23

Increase beta

Question 24

Stimulants - eeg

Answer 24

Increase alpha

Question 25

Depressants - eeg

Answer 25

Decrease alpha

Question 26

Cannabis - eeg

Answer 26

Increase alpha

Question 27

Stage I sleep

Answer 27

Alpha disappears

Desynchronised theta and delta appear

Question 28

Stage II sleep

Answer 28

Low voltages and delta waves with sleep spindles and K complexes

Question 29

Stage III sleep

Answer 29

High voltage slow waves
Delta <50%
Sleep spindles and K complexes diminish

Question 30

Stage IV sleep

Answer 30

Delta waves >50%

Sleep spindles and K complexes absent