Electroencephalography

Question 1

Delta

Answer 1

Frequency1-4Hz
Normally foundFrontally in adults and posteriorly in children
Normally seen inSlow wave sleep and in babies. Should not be present when awake, when present if awake this strongly suggests pathology

Question 2

Theta

Answer 2

Frequency4-8Hz
Normally foundGeneralised
Normally seen inYoung 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

Answer 3

Frequency8-12Hz
Normally foundPosteriorly
Normally seen inWhen relaxed and when the eyes are closed (whilst awake)

Question 4

Beta

Answer 4

Frequency12-30Hz
Normally foundFrontally
Normally seen inWhen busy or concentrating

Question 5

Sigma

Answer 5

Frequency12-14Hz
Normally foundFrontal and central regions
Normally seen in(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 😴 Sigma waves mark the beginning of stage 2 sleep and are seen normally in sleep. They generally occur immediately following muscle twitching and are thought to enable the sleeper to remain in a tranquil state.

They are generated in the reticular nucleus of the thalamus and result from interaction between the thalamus and the cortex.

Loss of sigma waves is a feature of familial fatal insomnia (prion disease).

Question 6

Gamma

Answer 6

Frequency30-100Hz
Normally foundNo specific areas
Normally seen inMeditation

Question 7

CJD (sporadic only, does not apply to variant)

Answer 7

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

Question 8

Huntington’s

Answer 8

EEG findingsLow voltage EEG, in particular no alpha (flattening)

Question 9

Delirium

Answer 9

EEG findingsDiffuse slowing, decreased alpha, increased theta and delta

Question 10

Delirium tremens

Answer 10

EEG findingsHyperactive trace, fast

Question 11

Alzheimer’s

Answer 11

EEG findingsReduced alpha and beta, increased delta and theta

Question 12

Petit mal epilepsy (absence seizure)

Answer 12

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

Question 13

Generalised eilepsy

Answer 13

EEG findingsSharp spikes, 25-30Hz

Question 14

Partial epilepsy

Answer 14

EEG findingsFocal spikes

Question 15

Myoclonic epilepsy

Answer 15

Generalised spike and wave activity

Question 16

Encephalopathy

Answer 16

Diffuse slowing

Question 17

Normal aging

Answer 17

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

Question 18

Antipsychotics (typical)

Answer 18

Decreased beta with Increased alpha, and delta, haloperidol least effect

Question 19

Antipsychotics (atypical)

Answer 19

Varied effect, clozapine most significant effect

Question 20

Antidepressants

Answer 20

Reduce beta, increase all others

Question 21

Anticonvulsants

Answer 21

No effect

Question 22

Lithium

Answer 22

Slowing

Question 23

Benzodiazepines

Answer 23

Increase beta, decrease alpha

Question 24

Barbiturates

Answer 24

Increase beta

Question 25

Drug of abuseStimulants (cocaine, nicotine)

Answer 25

Increase alpha

Question 26

Drug of abuseDepressants (alcohol, opioids)

Answer 26

Decrease alpha

Question 27

Cannabis

Answer 27

Increase alpha