Abstract
BACKGROUNDIn epilepsy surgery for cavernoma with intractable focal epilepsy, removal of the cavernoma with its surrounding hemosiderin deposition and other extended epileptogenic zone has been shown to improve postsurgical seizures. However, there has been no significant association between such an epileptogenic zone and intraoperative electrocorticography (ECoG) findings. The authors recently demonstrated that high regular gamma oscillation (30–70 Hz) regularity (GOR) significantly correlates with epileptogenicity.OBSERVATIONSThe authors evaluated the utility of intraoperative GOR analysis in epilepsy surgery for cavernomas. The authors also analyzed intraoperative ECoG data from 6 patients with cavernomas. The GOR was calculated using a sample entropy algorithm. In 4 patients, the GOR was significantly high in the area with the pathological hemosiderin deposition. In 2 patients with temporal cavernoma, the GOR was significantly high in both the hippocampus and the area with the pathological hemosiderin deposition. ECoG showed no obvious epileptic waveforms in 3 patients, whereas extensive spikes were observed in 3 patients. All patients underwent cavernoma removal plus resection of the area with significantly high GOR. The 2 patients with temporal cavernomas underwent additional hippocampal transection. All patients were seizure free after surgery.LESSONSThe high GOR may be a novel intraoperative marker of the epileptogenic zone in epilepsy surgery for cavernomas.
Highlights
In epilepsy surgery for cavernoma with intractable focal epilepsy, removal of the cavernoma with its surrounding hemosiderin deposition and other extended epileptogenic zone has been shown to improve postsurgical seizures
We recently showed that high gamma oscillation (30–70 Hz) regularity (GOR) calculated with interictal ECoG data analysis could sensitively detect the epileptogenic zone in focal cortical dysplasia.[15,16]
Observations We believe that the significantly high GOR regions may be the epileptogenic zone in patients with cavernomas who have intractable focal epilepsy because (1) the good postsurgical seizure outcome was achieved in our 6 patients after removal of those high GOR locations and (2) the pathological hemosiderin deposition was observed in those regions that are normally difficult to identify microscopically
Summary
In epilepsy surgery for cavernoma with intractable focal epilepsy, removal of the cavernoma with its surrounding hemosiderin deposition and other extended epileptogenic zone has been shown to improve postsurgical seizures. Intraoperative ECoG Data Recordings The grid electrodes (Unique Medical Co., Ltd.) were placed so that the cavernoma lesion was well covered, and they were placed on the surface of the hippocampus in the cases with mesial temporal lobe epilepsy.
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