Significance of very high frequency oscillations (over 1,000 Hz) in epilepsy

This study included thirteen patients with neocortical epilepsy who underwent subdural electrodes implantation and had at least one seizure recorded at 10‐kHz sampling rate, and were followed for more than two years postoperatively. The extent of resection was determined considering the seizure onset zone (SOZ) and irritative zone, structural lesion, and functional areas. The areas showing VHFO and those with HFO were not taken into consideration. The presence or absence of VHFO (>1,000 Hz), HFO (200‐1,000 Hz) and SOZ, and completeness of resection of these areas were compared with postoperative seizure outcome.
Results: Seven patients had favorable (Engel class I‐a) and six had unfavorable outcomes (other classes). VHFO was recorded in six of seven patients with a favorable outcome. On the contrary, VHFO was recorded in only one of six patients with unfavorable outcome. The presence of VHFO was significantly associated with favorable outcome. VHFO was recorded on a limited number of electrodes, and VHFO‐generating areas were resected completely, whereas HFO‐generating areas and/or SOZ were not always resected completely in both favorable and unfavorable outcome groups.
Interpretation: The presence of ictal VHFO may be predictive of favorable outcome. Ictal VHFO may be a more specific marker than ictal HFO or SOZ for identifying the core of epileptogenic zone. This article is protected by copyright. All rights reserved.

Source: Annals of Neurology - May 14, 2015 Category: Neurology Authors: Naotaka Usui, Kiyohito Terada, Koichi Baba, Kazumi Matsuda, Keiko Usui, Takayasu Tottori, Tadahiro Mihara, Yushi Inoue Tags: Research Article Source Type: research