Abstracts

Rationale: Very recently we have shown in a proof of concept trial that t-VNS might be an alternative treatment option for patients with epilepsy. In this study we present detailed results concerning quantification of ictal and interictal electrophysiological activity in long term EEG recordings by means of computerized analysis. Methods: t-VNS was applied to 10 patients with pharmacoresistant epilepsy. Subjective documentation about seizure frequency was obtained by patients seizure diary. For a more reliable assessment of efficacy a continuous outpatient video EEG monitoring for one week at baseline and every three months after baseline has been performed. On the basis of the integrated and averaged power for special multi-channel EEG montages the ictal and interictal activity have been investigated with respect to frequency and duration, taking into account an artifact rejection method. Furthermore, a visual inspection of the data by experts was done. Results: An overall assessment of computerized EEG analysis was performed for each of the different monitoring sessions. The automated seizure detection program detected 86% of the video-EEG-documented seizures showing a corresponding EEG activity, while at the same time the number of false positive events per hour was < 0.2/h. In one patient with a huge number of generalized spike wave complexes (GSWs) it was found that after nine months the normalized duration of GSWs with respect to recording time was reduced by approximately 30% . In addition to number of seizures also the duration and intensity was analysed. The quantitative analysis of the integrated power in another patient showing all the time continuous spike wave complexes revealed a significant decrease of the interictal activity, which was in accordance with clinical findings. Conclusions: The computerized analysis of long term EEG recordings based on multi-channel spectral methods provides important information about the ictal and interictal activity. In combination with clinical findings our approach might be interesting for a more reliable assessment of efficacy of medical treatment even in the long-term in epilepsies indicating that not only seizure frequency but also intensity (duration, power) and the quantification of interictal activity is important. REFERENCES: [1] Stefan H, Kreiselmeyer G, Kerling F, Kurzbuch K, Rauch C, Heers M, Kasper BS, Hammen T, Rzonsa M, Pauli E, Ellrich J, Graf W, Hopfengärtner R. Transcutaneous Vagus Nerve Stimulation (t-VNS) in Pharmacoresistant Epilepsies: A Proof of Concept Trial; Epilepsia 2012 (in press). [2] Hopfengärtner R, Kerling F, Bauer V, Stefan H. An efficient, robust and fast method for the offline detection of epileptic seizures in long-term scalp EEG recordings. Clin Neurophysiol 2007;118: 2332-43. (2007).