Electroencephalography - EEG • 1929 Johannes Berger performed the first examination, the first experiments in dogs • Simple, repeatable, non-invasive • The patient must cooperate • External influences (medications, skull trauma, movements) • Internal influences (sleep, metabolic effects, alertness) • mainly in epileptology • Sensitivity 25–56%, specificity 78–98% (J Neurol Neurosurg Psychiatry 2005; 76: ii2-ii7) • Sleep medicine – polysomnography • Functions of individual brain areas (short term records x long term monitoring) EEG • Graphical recording of brain biopotential field differences between two registering electrodes as a function of time • Eeg depth – electrocorticogram • Eeg scalp x semiinvasive x invasive • Electrode placement in the “10-20” system • Left-odd number, right-even number • F-frontal, T-temporal, P-parietal, C-central, O-occipital • Special caps with built-in electrodes • Reference x bipolar x power supply EEG (examination in our laboratory / in our workplace) • "Normal eeg is one that occurs in most healthy populations of a given age and condition." • Recording takes 20 minutes, can be completed with activation methods • Hyperventilation (HV) through the nose and mouth - activation method (deep, regular breathing with f 20/min, duration 2-4 minutes, 2min. nose and 2 min. mouth) • Eye opening and closing reactions (AAR, RF) • Photostimulation - activation method (10 seconds stimulation and 10 seconds pause, stimulation rate ascending and descending 1-60 Hz) • SD- eeg after sleep deprivation - activation method (provocation epiGE !!) • EEG curve can be broken down into the simplest components (graphoelements - GE) „normal EEG“ • Occipital quadrant: O1, O2 The most common alpha frequency 9.5-10.5Hz, amplitude 20-50 uV. Alpha activity is attenuated by eye openedand and mental aktivity. • Central area: C3, Cz, C4 Beta activity up to rhythm 18 to 25 Hz, amplitude 20 uV • Temporal region: T3, T4, T5, T6 Rear-intermittent alpha, dispersed theta, superimposed beta Anterior-intermittent irregular beta, dispersed theta, rare flat delta • Frontal area: F3, F4, F7, F8 Beta activity, which is faster and lower than in the C region, may also occur in rare flat delta waves. Common artifacts from eye bulbs. „normal eeg“ EEG curve, individual GE (graphoelements), GE properties • Frequency (number of repetitions in 1 sec.) Alfa 7,5-13 Hz (in the back quadrants with eyes closed) Beta 13,5 a více Hz (F,C adult) Theta 4-7 Hz (child, T – adult) Delta 0,5-3,5 Hz (HV dospívající, N3 spánek, newborn) • Amplitude (uV) • Shape, form (monomorphic, polymorphic) • Occurrence in space (generalized x localized x focal x regional) • Occurence over (continuous x intermittent x periodic x paroxysmal) • Reactivity three types of abnormalities • Background abnormality (deceleration, suppression * flattening, disappearance of EEG background) • Slow abnormality (theta, delta) localized or generalized, rhythmic x arrhythmic • Epileptiform abnormality Spikes under 80ms Sharp waves 80-200ms Complexes - SWC, SSWC, PSWC, localized x generalized DELTA COMA, background EEG disorder, slow abnormality source:www.commons.wikimedia.org Elektrocerebral inactivity, „ EEG silence“ „silence in EEG“ The amplitude does not exceed 2uV Filters 0,3-30Hz ECG Breath curve Somatosensory, auditory, visual stimulation Normotenze Not affected by medication source:www.commons.wikimedia.org Epileptiform abnormality – spikes (70ms), sharp waves (70-200ms) • Non-epileptic epileptiform abnormality - not significantly associated with epilepsy (physiological MU rhythm, sleep graphoelementsPOSTs, vertex sharp waves, hypnagogic hypersynchronia, driving), formulas of uncertain significance: SSS 14a 6 posit spikes, 6Hz spike wave complexes, wicket spikes • Epileptic epileptiform abnormality – morphologically meet epileptiform criteria associated with epileptic disease (SW, SWC, PSWC, temporal spikes, sharp waves) Schematic….….. • Spikes, sharp waves (regional occurrence supports diagnosis of focal epilepsy) Centro-temporal spikes, occipital spikes in beignal focal pediatric epilepsy with good prognosis SWC 3-6Hz in generalized epilepsy • 3SWC child absence syndrome Slow spike and wave complexes SSWC below 2.5Hz- symptomatic epilepsy, some pharmacoresistance with multiple seizures Multiple spikes, PSWC - generalized epilepsy • Hypsarythymia - prognotically unfavorable forms of childhood epilepsy, early age, encephalopathy • The photoparoxysmal response when activated by photostimulation may indicate a higher degree of photosensitivity Hypsarytmia Abnormal eeg • Interictal epileptiform abnormality occurs between seizures • Ictal abnormality during epileptic seizure Frontal epilepsy Zdroj:www.commons.wikimedia.org Frontal epilpsy Zdroj:www.commons.wikimedia.org Temporal epilepsy Zdroj:www.commons.wikimedia.org Centro-temporal epilepsy, with centrotemporal spikes Zdroj:www.commons.wikimedia.org Zdroj:www.commons.wikimedia.org Absence Zdroj:www.commons.wikimedia.org Absence Zdroj:www.commons.wikimedia.org Lennox-Gastaut syndrome Zdroj:www.commons.wikimedia.org Lennox-Gastaut syndrome Zdroj:www.commons.wikimedia.org PSWC Zdroj:www.commons.wikimedia.org Hypsarytmia Zdroj:www.commons.wikimedia.org Hypsarytmia-West syndrome Zdroj:www.commons.wikimedia.org Complex in Jacob-Creutzfeldt disease Zdroj:www.commons.wikimedia.org Herpetic encephalitis complex (HSV) Zdroj:www.commons.wikimedia.org HSV – MRI sagit. Zdroj:www.commons.wikimedia.org Burst-suppression Zdroj:www.commons.wikimedia.org Zdroj:www.commons.wikimedia.org hyperventilation • assumption 1) systemic hypocapnia, vasoconstriction of brain vessels, brain hypoxia 2) hypocapnia causes a decrease in mesencephalic reticular formation 3) respiratory alkalosis leads to hyperexitability of neurons and development of EPI GE • EEG video - EEG and patient video are recorded synchronously. It is possible to correlate EEG curve abnormalities with the current clinical manifestations of the patient. Analysis of ictal semiology, differential diagnosis. PNES x parasomnias x syncopes, seizure type specification, seizure monitoring Very time consuming • Semi-invasive EEG - sphenoid electrodes (closer amygdalo-hiocampal complex) Lateralization of epilepsy of the temporal lobe, localization of the epileptogenic zone • Depth EEG- able to detect pathological manifestations in the depth of the brain, especially in the temporal and temporal lobes of the brain and the medial part of the hemispheres Before epilepsy surgery. Less to distinguish epileptic and non-epileptic seizures. Epileptiform graphoelements • importance for diagnosis of epilepsy (whether paroxysmal condition is epilptic) • epileptic syndrome, generalized epilepsy, focal • it helps in the selection and implementation of antiepileptic therapy • determine the likelihood of another seizure (EPI GE finding after the first seizure predicts the possibility of another seizure EEG indication • Epilepsy • Unconsciousness and Disorders of Consciousness (NCSE) • Sleep Disorders (Polysomnography) • Jakob-Creutzfeldt's disease • Herpetic encephalitis (HSV) • EEG barbiturate conduction, status epilepticus (burst-suppression formula)