MRCPsych Mentor (Jun24) – Questions With Solutions
What are sigma waves? Right Ans - -aka sleep spindles
-Beginning of stage 2 sleep, bursts of oscillatory activity along with K-
complexes
-Occur immediately after muscle twitching, enable sleeper to remain in a
tranquil sleep
Where are sigma waves generated? Right Ans - Reticular nucleus of the
thalamus and result from interaction between the thalamus and the cortex.
Loss of sigma waves is a feature of... Right Ans - familial fatal insomnia
(prion disease)
Role of EEG Right Ans - To exclude organic conditions
- Differentiate dementia from metabolic encephalopathies, CJD, herpes,
encephalitis, non-convulsive status epilepticus, pseudodementia
What may affect results of EEG? Right Ans - Psychotropics (generalized
slowing, may have spike activity)
Procedures - hyperventilation, photic stimulation, drugs, sleep deprivation
EEG waves: delta
- Hz
- location
- characteristic Right Ans - (1-4Hz) - slow wave sleep (stage III), should not
be present when awake. if present - indicative of pathology. also seen in
babies
frontally in adults, posteriorly in children
EEG waves: beta
- Hz
- location
- characteristic Right Ans - (12-30Hz) - when busy/concentrating
frontal location
EEG waves: gamma
- Hz
- location
, - characteristic Right Ans - (30-100Hz) - advanced/very experienced
meditators
no specific location
EEG waves: theta
- Hz
- location
- characteristic Right Ans - (4-8Hz) - young children, drowsy and sleeping
adults (sleep I), small amount seen in awake adults - if excessive --> indicate
pathology. also with certain medication.
generalized location
EEG waves: alpha
- Hz
- location
- characteristic Right Ans - (8-12 hz) -When relaxed and when the eyes are
closed (whilst awake). Also seen in meditation.
posterior location
Specific EEG changes in CJD (sporadic only) Right Ans - Early on there is
non specific slowing, later periodic biphasic and triphasic synchronous sharp
wave complexes superimposed on a slow background rhythm
Not seen in variant
Specific EEG changes in Huntington's Right Ans - Low voltage EEG, in
particular no alpha (flattening)
Specific EEG changes in Delirium Right Ans - Diffuse slowing, decreased
alpha, increased theta and delta
Specific EEG changes in Delirium tremens Right Ans - Hyperactive trace,
fast
Specific EEG changes in Alzheimer's Right Ans - Reduced alpha and beta,
increased delta and theta
Specific EEG changes in normal ageing Right Ans - Diffuse slowing, which
can be focal or diffuse, if focal most commonly seen in the left temporal region
What are sigma waves? Right Ans - -aka sleep spindles
-Beginning of stage 2 sleep, bursts of oscillatory activity along with K-
complexes
-Occur immediately after muscle twitching, enable sleeper to remain in a
tranquil sleep
Where are sigma waves generated? Right Ans - Reticular nucleus of the
thalamus and result from interaction between the thalamus and the cortex.
Loss of sigma waves is a feature of... Right Ans - familial fatal insomnia
(prion disease)
Role of EEG Right Ans - To exclude organic conditions
- Differentiate dementia from metabolic encephalopathies, CJD, herpes,
encephalitis, non-convulsive status epilepticus, pseudodementia
What may affect results of EEG? Right Ans - Psychotropics (generalized
slowing, may have spike activity)
Procedures - hyperventilation, photic stimulation, drugs, sleep deprivation
EEG waves: delta
- Hz
- location
- characteristic Right Ans - (1-4Hz) - slow wave sleep (stage III), should not
be present when awake. if present - indicative of pathology. also seen in
babies
frontally in adults, posteriorly in children
EEG waves: beta
- Hz
- location
- characteristic Right Ans - (12-30Hz) - when busy/concentrating
frontal location
EEG waves: gamma
- Hz
- location
, - characteristic Right Ans - (30-100Hz) - advanced/very experienced
meditators
no specific location
EEG waves: theta
- Hz
- location
- characteristic Right Ans - (4-8Hz) - young children, drowsy and sleeping
adults (sleep I), small amount seen in awake adults - if excessive --> indicate
pathology. also with certain medication.
generalized location
EEG waves: alpha
- Hz
- location
- characteristic Right Ans - (8-12 hz) -When relaxed and when the eyes are
closed (whilst awake). Also seen in meditation.
posterior location
Specific EEG changes in CJD (sporadic only) Right Ans - Early on there is
non specific slowing, later periodic biphasic and triphasic synchronous sharp
wave complexes superimposed on a slow background rhythm
Not seen in variant
Specific EEG changes in Huntington's Right Ans - Low voltage EEG, in
particular no alpha (flattening)
Specific EEG changes in Delirium Right Ans - Diffuse slowing, decreased
alpha, increased theta and delta
Specific EEG changes in Delirium tremens Right Ans - Hyperactive trace,
fast
Specific EEG changes in Alzheimer's Right Ans - Reduced alpha and beta,
increased delta and theta
Specific EEG changes in normal ageing Right Ans - Diffuse slowing, which
can be focal or diffuse, if focal most commonly seen in the left temporal region
