Non-harmonicity in high-frequency components of the intra-operative corticogram to delineate epileptogenic tissue during surgery

Publication date: Available online 17 November 2016
Source:Clinical Neurophysiology
Author(s): Evelien E. Geertsema, Maryse A. van 't Klooster, Nicole E.C. van Klink, Frans S.S. Leijten, Peter C. van Rijen, Gerhard H. Visser, Stiliyan N. Kalitzin, Maeike Zijlmans
ObjectiveWe aimed to test the potential of auto-regressive model residual modulation (ARRm), an artefact-insensitive method based on non-harmonicity of the high-frequency signal, to identify epileptogenic tissue during surgery.MethodsIntra-operative electrocorticography (ECoG) of 54 patients with refractory focal epilepsy were recorded pre- and post-resection at 2048 Hz. The ARRm was calculated in one-minute epochs in which high-frequency oscillations (HFOs; fast ripples, 250-500 Hz; ripples, 80-250 Hz) and spikes were marked. We investigated the pre-resection fraction of HFOs and spikes explained by the ARRm (h²-index). A general ARRm threshold was set and used to compare the ARRm to surgical outcome in post-resection ECoG (Pearson X²).ResultsARRm was associated strongest with the number of fast ripples in pre-resection ECoG (h²=0.80, P<0.01), but also with ripples and spikes. An ARRm threshold of 0.47 yielded high specificity (95%) with 52% sensitivity for channels with fast ripples. ARRm values >0.47 were associated with poor outcome at channel and patient level (both P<0.01) in post-resection ECoG.ConclusionsThe ARRm algorithm might enable intra-operative delineation of epileptogenic tissue.SignificanceARRm is the first unsupervised real-time analysis that could provide an intra-operative, 'on demand' interpretation per electrode about the need to remove underlying tissue to optimize the chance of seizure freedom.



from Physiology via xlomafota13 on Inoreader http://ift.tt/2g1N8cP
via IFTTT