EEG and Epilepsy Alving

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  • EEG and EEG and epilepsyepilepsyPanumPanum InstituteInstitute 31.5.200731.5.2007

    Jrgen Alving, MDDanish Epilepsy Center

    DK-4293 Dianalund

  • EEG and EEG and epilepsyepilepsyEpilepsy is thename of occasional, sudden, excessive rapid and localdischarges of greymatter

    John HughlingsJackson, 1873

  • EEG and EEG and epilepsyepilepsy

    What does the clinician want from theneurophysiologist?They want him/her to prove or disprovethe diagnosis of epilepsy!

  • EEG and EEG and epilepsyepilepsy

    We will neither prove nor disprove thatour vessels carry nuclear weaponswhile visiting your harbours

    Standard explanation given by the US Navy to the Danish Government during the Cold War

  • EEG and EEG and epilepsyepilepsy

    But we can say whether or not there areepileptiform abnormalities in the EEGThe presence of these will give important clues as to which type ofepilepsy is most likely (classification)

  • EEG: EEG: whatwhat is is epileptiformepileptiform? ?

    Epileptiform EEG abnormalitiesfocal or/and generalised paroxysmalabberations from the background EEG whichare strongly correlated to epilepsyThey are rarely seen in persons withoutepilepsy or other neurological diseases

  • EEG and EEG and epilepsyepilepsy

    Epileptiform EEG3 Hz spike-waves3-6 Hz poly-spike-waves2 Hz spike-waves + 10 Hz trains during sleepHypsarrhytmiaAnterior temporal sharp-wave focus withprefrontal spreadCentro-midttemporal sharp-waves + 4-5 Hz Repetitive focal trains of spikes

  • GeneralisedGeneralised spikespike--wavewave paroxysmparoxysm((childhoodchildhood absences)absences)

  • GeneralisedGeneralised polyspikepolyspike--wavewaveparoxysmparoxysm (juvenile (juvenile myoclonicmyoclonic

    epilepsyepilepsy))

  • GeneralisedGeneralised 2 Hz 2 Hz spikespike--wavewaveparoxysmparoxysm (Lennox(Lennox--Gastaut)Gastaut)

  • RhythmicRhythmic 10 Hz 10 Hz traintrain in in sleepsleep(Lennox(Lennox--Gastaut)Gastaut)

  • HypsarrhytmiaHypsarrhytmia (infantile (infantile spasmsspasms))

  • Mesial temporal Mesial temporal epilepsyepilepsy

  • Mesial temporal Mesial temporal epilepsyepilepsy ((ictalictal start)start)

  • RolandicRolandic focusfocus

  • Repetitive Repetitive ictalictal traintrain ofof spikesspikes

  • EEG and EEG and epilepsyepilepsy

    A pitfall: not all paroxysmal EEG activityis epileptiform!Beware of the so-called normal variant patterns

  • EEG: normal variantsEEG: normal variants

    What are normal variants?Apparently paroxysmal EEG events, i.e. alterations with an abrupt and steeplyrising appearance, often with a tendency to rhythmicity

  • EEG: normal variantsEEG: normal variants

    But they are not infrequently seen in normal people and have a lowcorrelation to epilepsyThey are often misinterpreted as providing evidence of epilepsy

  • EEG and EEG and epilepsyepilepsy

    Normal variants I (wake/drowsy)6 and 14 Hz positive spikes6 Hz spike-waveswicket spikesrhythmic theta in drowsiness(psychomotor variant)SREDA (Sublinical RhythmicElectrographic Discharges in Adults)

  • 14 Hz positive spikes (14 Hz positive spikes (CommonCommonAverageAverage Reference)Reference)

  • 14 Hz positive spikes14 Hz positive spikes

    Formerly ascribed to variousneurological and psychiatricdisturbances, includingthalamic/hypothalamic epilepsy, etc.Now considered a normal variant mostly in children and young adultsLocation posttemporal & parietal, synchronous/asynchronous

  • 6 Hz 6 Hz spikespike--wavewave FOLDFOLD ((CommonCommonAverageAverage Reference)Reference)

  • 6 Hz 6 Hz spikespike--wavewave FOLDFOLD (Double (Double BananaBanana))

  • 6 Hz 6 Hz spikespike--wavewave FOLDFOLD(Transversal)(Transversal)

  • 6 Hz 6 Hz spikespike--wavewave

    Two variants:WHAM = wake, high, anterior, maleFOLD = female, occipital, low, drowsyLower amplitude & higher wave-frequency than in generaliseredepileptic paroxysmsDisappear in sleep

  • GeneralisedGeneralised spikespike--wavewaveparoxysmparoxysm ((sleepsleep stage 2)stage 2)

  • WicketWicket spikes (spikes (CommonCommon AverageAverageReference)Reference)

  • WicketWicket rhythmrhythm ((CommonCommonAverageAverage Reference)Reference)

  • WicketWicket spikesspikes

    Seen in 0.5 1 % of normal peopleUsually after age 30 yearsGradual or more abrupt pop-up from background activityLocation temporal, asynchronous/synchronous, in drowsinessNo aftercoming slow wave or otherdisturbance of background activity

  • Mesial temporal Mesial temporal epilepsyepilepsy

  • RhythmicRhythmic temporal temporal thetatheta in in drowsinessdrowsiness

  • RhythmicRhythmic temporal temporal thetatheta in in drowsinessdrowsiness

    Occurrence: 0.5 2 % of normal adultsMostly in younger peopleMostly midtemporalSynchronous or asynchronousDisappears in sleep

  • Mesial temporal Mesial temporal epilepsyepilepsy ((ictalictal start)start)

  • SREDA = SREDA = SublinicalSublinical RhythmicRhythmicElectrographicElectrographic DischargesDischarges in in

    AdultsAdults

  • SREDASREDA

    Occurrence: not given but mostly in persons above age 50 yrsDuration of trains from 20 sec. to several min. (usually 40-80 sec.)Mostly parieto-posttemporalFocal or asynchonous occurrenceConstant frequency during whole train

  • EEG and EEG and epilepsyepilepsy

    Normal variants II (sleep)hypnagogoc hypersynchronyspikey vertex-sharp-wavesmitten pattern K complexespositive sharp transients in sleep(POSTs)

  • HypnagogocHypnagogoc hypersynchronyhypersynchrony

  • HypnagogocHypnagogoc hypersynchronyhypersynchrony

  • SpikeySpikey VV--wavewave ((CommonCommonAverageAverage Reference)Reference)

  • SpikeySpikey VV--wavewave (transversal)(transversal)

  • Mitten Mitten patternpattern K K complexcomplex

  • Mitten KMitten K and and paroxysmalparoxysmalactivityactivity

    Gradual transition: spindles -> mitten K complexes -> generalised polyspike-wave paroxysms (E. Niedermeyer)

  • GeneralisedGeneralised polyspikepolyspike--wavewaveparoxysmparoxysm

  • POSTsPOSTs ((CommonCommon AverageAverageReference)Reference)

  • POSTsPOSTs (Double (Double BananaBanana))

  • EEG and EEG and epilepsyepilepsy

    Epileptiform EEG in epilepsyEpileptiform interictal standard EEGFirst recording 50 %Repeated with relevant provocations 85 %No further yield after 4.-5. recording

    (Salinsky, Kanter & Dashieff, Epilepsia 1987)

  • EEG and EEG and epilepsyepilepsy

    Epileptiform standard EEG in epilepsy1. recording 38 %2. recording 49 %4. recording 66 %6. recording 77 %7. recording no more!

    Doppelbauer et al, Acta Neurol Scand 1993;87:345-52

  • EEG and EEG and epilepsyepilepsyEpileptiform standard EEG in epilepsyTime since latest seizure< 24 hours 53 %24 hours - 1 week 42 %later 36 %

    NB only standard EEG (20 min., wake + hyperventilation & photic stimulation)

    Doppelbauer et al, Acta Neurol Scand 1993;87:345-52

  • Standard EEG and Standard EEG and epilepsyepilepsy

    Sensitivity of 1. EEG (positiveEEG/patients with epilepsy): 35-50 %Specificity of 1. EEG (negativeEEG/very healthy persons): Adults 99,5 % Children 98 %

  • EEG EEG afterafter firstfirst afebrileafebrile seizureseizure??

    Epileptiform EEG -> 2-3 times increased recurrence riskOften seizures before the indexseizure , making the case more complexSpecific epilepsy syndromes may bediagnosed at this early stage

  • EEG EEG afterafter firstfirst afebrileafebrile seizureseizure??

    Subtle seizures (absences and myoclonias) can be recorded on theEEG (simultaneous video)Provoking factors (e g photosensitivity) can be demonstrated

  • EEG and EEG and epilepsyepilepsy

    EEG AND EPILEPSY: WHICH PROVOCATION IS PREFERRABLE?

    Seizure/syndrome Best methodAbsence epilepsies hyperventilationJuvenile myoclonic epilepsy photic stimulation,

    sleep/awakening, sleep deprivation

  • EEG and EEG and epilepsyepilepsy

    EEG AND EPILEPSY: WHICH PROVOCATION IS PREFERRABLE?

    Seizure/syndrome Best methodComplex focal seizures SleepRolandic epilepsyTemporal lobe epilepsyCSWS

  • EEG and EEG and epilepsyepilepsy

    Sleep: how much is needed?Focal and generalised paroxysms in general: ca. 30 min. (sleep stage 2-3) CSWS: for quantitation, a whole-night EEG with EOG is needed (paroxysmal activitydecreases later in the night and especiallyduring REM sleep)

  • EEG and EEG and epilepsyepilepsy

    What to expect from a sleep EEG if first EEG is negative (children)?Negative 1. EEG: 44 % (243/552)Positive sleep EEG: 34 % (61/177)Total positive EEGs: 67 % (370/552)

    Carpay et al, Epilepsia 1997;38:595-599

  • EEG and EEG and epilepsyepilepsy

    What to expect from a sleep EEG if first EEG is negative (children + adults)?Negative 1. EEG: 57 % (171/300)Positive sleep EEG: 35 % (55/158)Total positive EEGs: 61 % (184/300)

    King et al. Lancet 1998;352:1007-1011

  • EEG: EEG: strengthsstrengths

    EEG is a noninvasive window to the brain, and gives as regards temporal resolution an unsurpassed image of normal and abnormalcortical activityIn the definition of epileptic syndromes, EEG is essentialOften difficult to differentiate between focaland generalised epilepsies without EEG

  • EEG: EEG: strengthsstrengths

    Subtle seizures like absences og eyelidmyoclonias only detectable by EEGEEG is the best method of investigationin neonatal seizures