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Background: Focal motor epilepsy is difficult to localize within the epileptogenic zone because ictal activity quickly spreads to the motor cortex through ictal networks. We previously reported the usefulness of gamma oscillation (30-70 Hz) regularity (GOR) correlation analysis using interictal electrocorticographic (ECoG) data to depict epileptogenic networks. We conducted GOR correlation analysis using ictal ECoG data to visualize the ictal networks originating from the epileptogenic zone in two cases - a 26-year-old woman with negative motor seizures and a 53-year-old man with supplementary motor area (SMA) seizures. Case Description: In both cases, we captured several habitual seizures during monitoring after subdural electrode implantation and performed GOR correlation analysis using ictal ECoG data. A significantly high GOR suggestive of epileptogenicity was identified in the SMA ipsilateral to the lesions, which were connected to the motor cortex through supposed ictal networks. We resected the high GOR locations in the SMA and the patients' previously identified tumors were removed. The patients were seizure-free without any neurological deficits after surgery. Conclusion: The GOR correlation analysis using ictal ECoG data could be a powerful tool for visualizing ictal networks in focal motor epilepsy.
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BACKGROUND: 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. 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. OBSERVATIONS: The 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. LESSONS: The high GOR may be a novel intraoperative marker of the epileptogenic zone in epilepsy surgery for cavernomas.
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BACKGROUND: Although traumatic dural arteriovenous fistula (AVF) is a rare condition, dural injury associated with skull fracture is one of the major factors for the formation of dural AVF at the skull fracture area. We report a case of de novo intraosseous AVF around the anterior condylar confluence after head injury associated with skull base fracture. CASE DESCRIPTION: A woman in her 70s presented with pulsatile tinnitus 3 months after cerebellar infarction and occipital bone fracture. The appearance of de novo intraosseous AVF was confirmed by magnetic resonance imaging and magnetic resonance angiography and treated with coil embolization, which led to symptomatic relief without recurrence on follow-up. CONCLUSIONS: There is no previous report to our knowledge of intraosseous AVF around the anterior condylar confluence proven to appear after skull fracture. This case demonstrates that head injury associated with skull base fracture could be one etiology of dural AVF around the anterior condylar confluence.
