Recording the Electroencephalogram (EEG). Recording the EEG

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Transcript of Recording the Electroencephalogram (EEG). Recording the EEG

  • Recording the Electroencephalogram (EEG)

  • Recording the EEG

  • Analyzing EEG Waves


    Waveform or morphology

    Spatial distribution

  • BetaAlphaThetaDelta76479 64279647277524512.5 - Hz8 -12 Hz4 - 7 Hz0.5 - 3Hz 23 Hz9 Hz6.5 Hz1.7 HzEEG Frequency Bands

  • Factors That Determine Whether an EEG Feature is Normal or AbnormalPatient Related:


    State of consciousness

  • Usefulness of the EEGThe Clinical EEG is of greatest value in:


    Coma atypical or complicated

    Other disturbances of consciousness of uncertain cause

  • The study of the EEG remains essential to the diagnosis and treatment of epilepsy

    History / Clinical impression is not always clearFit, faint or funny turn ?Focal or generalisedIdiopathic / symptomatic / syndromic

  • EEG Patterns and their Specificity

    Signature Patterns

  • 3 /sec Spike and Wave the signature of Typical Absence Seizures1 secOnset epileptiform

  • Hypsarhythmia the signature of West Syndrome ( Infantile Spasms)

  • 13 year-old male childRecurrent headaches and fainting. CT normal, neurologically normal. Description of fainting episodes:Becomes quiet, falls to ground, brief twitching of limbs, followed by confusionFirst episode 2005. Approximately 3 x year. Family Hx Younger sibling with seizures.Can EEG help to confirm a Sz disorder? If so, ? generalized or focalIdiopathic / symptomatic ?

    Usefulness of the EEG in the diagnosis and classification of epilepsy

  • 13yo male EEG Background10 -11 Hz76631P

  • 13yo male Neurology OPD Bipolar recording 76631P

  • Hx of 4 year-old boyDaily staring spells in nursery schoolNo birth injury or traumaNeurologically normalPaternal uncle known with epilepsyReferring doctor:? Absences typical or otherwise

  • 4 year-old boy, awake75241

  • Sensitivity of the EEGIn what proportion of subjects with epilepsy can the EEG confirm epilepsy?50% positive for epilepsy on recording the first routine 20 min EEG.

    Ways to improve sensitivity:Sleep can increase the yield by further 40%Recording during a period of increased number of seizures or shortly after a seizure

    A negative EEG does not rule out possibility of a seizure disorder.