EEG basics and sleep

John O’Donovan Consultant old age psychiatrist

Hans BergerAnother first for psychiatryFirst recorded EEG in 1924The first rhythm he saw was called the alpha rhythm

Interesting man, originally a mathematics student who wanted to be an astromoner

Switched to medicine in an attempt to explain personal belief in telepathy

Was a psychiatrist during WW1

Ended up collaborating with the NAZIs and committed suicide at 68 years of age.

EEG

Principles

• The brain functions via electricity and chemistry.

• The electricity in the form of post synaptic inhibitory and excitatory potentials can be recorded from the scalp and analysed.

• Stunning temporal resolution but poor spatial.• Cortical rhythms tend to be driven via deeper

brain structures in particular the intralaminar nuclei of the thalami.

Doing an EEG

• 30 minutes to one hour. • Patient hooked up to the machine, gel on scalp

and electrodes arranged in scalp in whatever the favoured “montage” is.

• Recording is now done via computer and subject to computer analysis.

• Patient may be subjected to stimulation, for example flashing lights during recording, asked to close or open eyes etc.

Alpha RhythmFirst one Berger saw Seen when eyes are closed and subject is relaxing8-12Hz-dominant thalamic rhythm Dominant background rhythmAnatomically occipital area

It’s a normal rhythm, should always be there. Not present under 3

Reduced by sleep, drowsiness, eyes open.

Mu Similar to alpha but in a different place, nearly the same frequency.

6-8Hz

Somatosensory area

Abolished by contralateral movement and indeed even thinking about movement

Main thing is not to get confused about Mu-it’s not that relevant.

Beta rhythm

12-30 Hz

Normal dominant rhythm when awake

To pass an exam, be awake(way of remembering)

Theta 4-7hz

Seen when drowsy, sleeping

Children

Delirium (not withdrawal)

Coma

Brain injury, epilepsy, encephalitis etc.

Delta0-4hz

High amplitude

Dominant rhythm in young children

Stage 3 and 4 sleep

Otherwise always pathological in adults.

Delta =death

To recap

Other waves

• There are other waves which include lambda, V waves, POSTs (posterior occipital sharp waves) but they will not be asked in any psychiatric exam.

• Focus is alpha,beta,theta and delta

Normal EEG

Abnormal EEG findingsDelirium: In general the EEG gets slow, theta and delta, alpha reduced.

Hepatic encephalopathy: slowing and triphasic waves.

Old variant CJD: triphasic waves and slow

TLE: temporal lobe rhythmic discharge and spikes

Dementia: Alzheimer’s and others, in general slowing, loss of alpha and in Alzhzimer’s spikes

EpilepsyRemember 2 basic types of epilepsy

Idiopathic generalised epilepsy- these are nearly always associated with polyspike and wave, classically petit mal-childhood absence attacks 3-4 hz per minute.

Focal: focal spikes, most commonly originate from temporal areas, ergo rhythmic temporal slowing and spikes.

Psychiatry and the EEG

• Why would a psychiatrist order an EEG?

Epilepsy

• Useful when epilepsy suspected. • Insufficient on its own, remember epilepsy is a

clinical diagnosis. • EEG telemetry is diagnostic for non epileptic

attack disorder• When suspecting epilepsy related psychiatric

disturbance• Forced normalisation/ alternative psychosis, if

you believe in it.

Delirium versus catatonia/psychogenic mutism

• Very useful for diagnosis of delirium, widespread slowing will occur in delirium or other causes of stupor, if psychogenic the EEG will be normal.

• Sometimes types of delirium, withdrawal from alcohol and benzodiazepines is a fast EEG state, lots of beta ( booze and benzos-beta)

Dementia versus pseudodementia

• Preservation of alpha is reassuring• Some dementias have specific alterations for

example CJD periodic complexes/triphasic waves

• Frontal dementias have relatively better EEGs then alzheimer’s disease.

MCQs

Normal EEG • Alpha is present in sleep• Mu is increased by

movement.• Beta is from 2-4hz • Delta is always pathological • Delta in a three year old

may be normal• Spikes always indicate

epilepsy

Abnormal EEG findings• Delirium tremens has a slow EEG• Delirium from hyponatremia has

prominent delta • CJD has periodic complexes/triphasic

waves• Hepatic encephalopathy can look

similar to CJD • Temporal lobe spikes with frequent

feelings of déjà vu suggest TLE• 3-4 hz polyspike and wave in a six year

old child suggest absence seizures. • Alzheimer’s is associated with loss of

alpha rhythm and development of a slow EEG

EEG MCQs

Normal EEG• Theta-4-7hz • Delta-0-4hz • Beta-12-30hz • Alpha-8-12hz • Alpha-dominant posterior• Varies over 24 hours

Abnormal EEG• Herpes encephalitis is

associated with PLEDs• There are EEG findings in

depression. • There are EEG findings in

schizophrenia• A normal EEG in an abnormal

patient is a hard sign.• An abnormal EEG in a normal

patient is a hard sign.

Sleep and consciousness

• Overview • Consciousness • Anatomy • Biochemistry• Normal sleep • Abnormal sleep • MCQs

Consciousness

• Normal consciousness, we all know what that is but try defining it!

• Awake, fully aware of environment and oneself.

• 2 things arousal and cognition.

• Abnormal consciousness

• Coma• Stupor • Torpor • Lethargy • Akinetic mutism • Catatonia• Locked in syndrome

Consciousness and the ARAS

Structures involved

• Ascending reticular activating system • Thalamus bilaterally and particulary

intalaminar nuclei of thalami• Hypothalamus • Thalamic frontal connections

Consciousness

Aroual• ARAS and thalami

Cognitive• Cerebral hemispheres

Basic neurochemistry

Wake promoting• Noradrenaline • Ach • Histamine • Dopamine

Sleep promoting• Melatonin • Gaba

• Note-hypocretins• Hypocretin 1 and hyopcretin

2 human dorsolateral hyopthalamus-important for wake promoting systems, loss is associated with narcolepsy

Sleep

Non rapid eye movement sleep

• Stage 1 and 2=light sleep • Stage 3 and 4=slow wave

sleep (SWS)• SWS needed for CNS repair

and declarative memory

Rapid eye movement sleep• Cycles every night • Skeletal atonia • Dreaming • Physiological arousal, pe

Sleep

• In bed at 10PM with improving book and hot chocolate.

• Lights out 10.20PM • Good sleep by 11PM • Wake up 7am

• What happens?

Poorly understood Drive via suprachiasmatic nucleus of hypothalamus

HT-hemispheres-diencephalon-ARAS

Changes in EEG, EOG and EMG-head, eyes and muscles.

4-wakefullness, light sleep, SWS/deep sleep and REM

SleepStage 1, alpha goes, theta appears, rolling eye movementsStage 2, sleep spindles, bursts of 14-16hz and K complexesStage 3 and stage 4, lots of delta, slow heart, lowered BP, relaxatoin, reduction of BMR by 70%REM: desynchronisagtion of EEG, saccadic eye movements, atonia, limbic regions are active

First rem after 60-90 minutes, cycle continues and quantity of REM increases whilst amount of SWS reduces

Disorders of sleep, firstly is it abnormal or not?

• Firstly consider age of patient, older patients commonly have six EEG defined arousals per night.

• Periodic limb movements occur in up to 1/3 of elderly population

• Children do not have a normal EEG or sleep wake cycle or indeed anything!

• Occasional sleep starts and abnormalities of sleep are common in normal people

Hypersomnias

Excessive daytime sleepiness5% of population Generally secondary to poor sleep at night

If you sleep badly at night, then you will make it up during the day.

Obstructive Sleep Apnoea

Central obesity Poor oropharyngeal muscle tone Rugby forward physiquesSnoring Apneic attacks Headaches Fatigue Loss of libido Poor concentration Treat, weight loss, surgery, CPAP

narcolepsy

1:2000Onset adolescenceLoss of HT neurons containing hypocretin

Clinically:tetrad Daytime sleep attacks Cataplexy- can be partial or total, loss of muscle tone with high emotionSleep paralysis Hypnogogic and hypnopompic hallucinations

Narcolepsy 2

REM sleep gone wild! Autoimmune hypothesisStrong association with HLA DQB1 0602

CSF shows reduced hypocretin, not quite diagnostic

Diagnosis: history, MSLT which shows rapid entry into REM, HLA typing and rarely CSF

Treatment

• Daytime sleepiness, cataplexy and nocturnal sleep

• Planned naps • Wake promotion: modafinil and speed. • Cataplexy: venlafaxine and clomipramine• Nocturnal disruption:clonazepam

Idiopathic hypersomnia

• 1:20,000• Daytime napping• Generally inattentive during day • Sleep good at night as measured by hypnogram • Waking up is difficult• Mood disorders are common• On MSLT, deep non rem achieved quickly but

not rem which happens in narcolepsy

Klein-Levin

• Generally teenage boys• Very rare • Intermittent

hypersomnolence • Cognitive disturbance • Hyperphagia • Hypersexuality • 1-2 weeks and normal

between• May last for a decade and

then resolve spontaneously

Parasomnias

• Problems arising from sleep• Sleep wake transition disorders• Non REM or REM

Sleep wake transition problems

• Hypnic jerks and sensory starts• Head banging “jacatio capitis nocturna”• Propiospinal myoclonus • Periodic limb movements of sleep, lower

limbs, foot dorsiflexion and then spreads over about a second, every 20-40 seconds, happen in 50% of elderly, greater then five per hour is abnormal?,

Non REM

• Night terrors, confusional arousals and sleep walking-partial arousal form deep sleep, SWS, stage 3 and stage 4.

• Memory for events is poor. • May run in families• Can occur in 6% of children• Night terrors; sudden piercing scream, one hour into

sleep, terrible fear and total amnesia for event• Confusional arousals; wake up briefly and stare around• Sleepwalking; unknown what happens, semiarousal from

deep sleep

Sleepwalking

Non REM 2

• Sleep related eating disorder; nocturnal binge eating disorder

• Violence or sexual assault during deep sleep parasomnias has been reported.

• Rarely nocturnal visual hallucinations in the elderly

REM parasomnias

• Nightmares• REM sleep paralysis• REM sleep behaviour disorder, note “oneiric”

behaiour, 87% men, onset in mid 60s, frequently associated with violent behavior, dreams of being attacked etc, frequently associated with synucleinopathies, Parkinson’s disease and LBD, treatment: move out partner, clonazepam

Nightmares

Psychiatric disorders and sleep

• Schizophrenia-short REM latency probably secondary to SWS deficits.

• Restless legs syndrome is common in anxiety disorders

• GAD associated with insomnia• PTSD and nightmares, more REM • Dementias: broken sleep pattern,

suprachiasmatic nucleus gone.

MCQs

In normal sleep• REM occurs within 30

minutes • Stage 1 and 2 have rolling eye

movements• Stage four has mainly theta

and some delta• REM is associated with atonia • Stage 3 and 4 is called SWS • SWS is important for memory

In hypersomnias• HLA typing may be

important • Losing weight is a common

treatment• CPAP is useful for some

patients • Addiction to stimulants can

be a problem• Men are more affected

them women

MCQs

narcolepsyPrevalence of 1:200Has association with HLA DR2 405Is always associated with cataplexy Can cause sleep paralysisCan cause vivid hallucinationsResponds to treatment with modafinil An afternoon nap may be a legitimate treatment

REM sleep parasomnias • Night terrrors are a rem

problem arising from dreams• REM sleep parasomnias have a

link with alpha synuclein • In PTSD nightmares occur in

50% of patients• Sleepwalking is common• Can be reproduced by lesioning

in cats• Pontine stroke can cause bizare

dreams and visual hallucinations

MCQs

In schizophrenia• Clear EEG findings • Reduction of alpha rhythm • Sleep is normal • Reduction of SWS • Medications may interfere

with sleep • Medications are generally

sedating• Some medications used may

cause gross EEG abnormalities

In GAD• The inter rater reliability is

high. • Sleep disorder is comon.

• In depression• Insomnia can be used as a

treatment• EMW is associated with

cortisol hypersecretion