Introduction to Epileptic Dischages课件课件.ppt

Focal Interictal Patterns: Epileptic Discharges versus Benign Variants Objectives Introduce the concept of epileptic activity Define a spike and sharp wave Differentiate Epileptic Interictal Activity from benign, physiologic variants. Remember Determine whether waveform is abnormal or a normal physiologic rhythm: Frequency Amplitude Duration Distribution States in which it is present Reactivity Epileptiform Activity Epileptiform = waveform or complex that stands out from the background activity resembling those activity seen in patients with epilepsy. Several types of epileptiform activity: Spike Sharp Wave Spike-Wave-Complex Polyspikes Spike Wave Complex Repetitive occurrences of spikes followed by a slow wave If occur single often indistinguishable from a spike or sharp wave Classifying SWC often requires seeing the SWC discharges in prolonged runs (usually at least 3 seconds) Spike and Sharp Waves Spikes Transient with a pointed peak Duration between 40-80 ms (midway point between baseline and peak) Sharp Waves Transient with duration of 80-120 ms (some will expand to as much as 200 ms) Focal Epileptiform Activity Focal epileptiform activity is likely to be epileptic if: Stands out from the background Associated with slowing Asymmetry with background (decreased) in the same distribution Description for Localization For non-invasive scalp localization it can only be: Regional Multiregional Lateralized Generalized Combination of above (e.g., Generalized and Multiregional Sharp Waves) Reserve term “focal” for invasive EEG studies Benign Variants Temporal Region Benign Variants Physiologic transients which resemble epileptiform activity Seen in normal individuals Can be incorrectly identified as epileptic activity. Small Sharp Spikes (SSS) Benign Epileptiform Transients of Sleep (BETS) Anterior to Mid-temporal Discharge Seen in drowsy state Unilateral or Bilateral Discharges Amplitude 50 uV, duration 40 ms Non-prominent after going slow wave 20-25% of normal indiv