Quantitative EEG Analysis of Terminating Slow Waves in Spike and Wave Activity in Untreated, Non-Absence, Primary Generalized Epilepsy (P04.015)

Abstract

Objective: To analyze the terminating slow wave of spike and wave bursts recorded in patients with non-absence primary generalized epilepsy (PGE) to determine whether a threshold duration exists preventing prolongation of spike and wave runs. Background Quantitative EEG analysis studies have focused on spike and wave frequency and burst duration in PGE. Progressive prolongation of the after-going slow wave in runs of spike and wave has long been recognized but not quantified. The magnitude of cortical inhibition indicated by the duration of the terminating slow wave may help determine which factors inhibit prolonged, potentially dangerous, spike and wave bursts. Design/Methods: The EEGs of 3 patients diagnosed with non-absence PGE, untreated with AEDs were studied. Quantitative EEG analysis was performed on a minimum of 10 spike and wave discharges (SWD) recorded during wakefulness and sleep. The number of discharges and the wave durations in a run of SWDs were measured and averaged. The slow wave duration was measured from the positive turn between the fast and the slow component until the following positive turn. The preceding wave durations were calculated as a percentage of the terminating wave. Results: In a run of SWDs each successive wave progressively increased in duration. The average terminating wave duration was 47% longer than the preceding wave. Spike and wave runs were characterized by absolute slow wave durations of 0.1-0.15 msecs for the initial SWD and 0.2-0.65 msecs for the terminating slow wave. When single polyspike and wave discharges occurred, almost exclusively in slow wave sleep, slow wave durations were still 47% longer than the first slow wave of spike and wave runs. Conclusions: QEEG analysis of the after-going slow wave component of spike and wave bursts may provide insight into mechanisms of spike and wave burst termination. The technique could be helpful in predicting AED efficacy in PGE. Supported by: The FACES foundation. Disclosure: Dr. Fallil has nothing to disclose. Dr. Pacia has nothing to disclose.