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OBJECTIVE For future artificial intelligence-based brain mapping, development of a rational and safe scoring system for a brain motor mapping algorithm using electrocorticography (ECoG score), which contains various spectral, purely intrinsic brain activities, is necessary for either before or in the absence of electrical cortical stimulation (ECS). METHODS We evaluated 1114 electrodes of 10 consecutive focal epilepsy patients who underwent subdural electrode implantation before epilepsy surgery at Kyoto University Hospital during 2011-2017. Data from ECoG-based mapping (bandpass filter of 0.016-300/600 Hz) to define the primary motor area (M1) localization were used to create an ECoG score (range = 0-4) by assigning 1 point each for the occurrence of ECoG components: very slow movement-related cortical potentials (

Summary: Purpose: Malformations of cortical development (MCDs) are a frequent cause of refractory epilepsy in humans. The in utero radiation model in rats shares many clinical and histopathologic characteristics with human MCDs. Previous studies reported the presence of clinical seizures in radiated rats, but also suggested a dose-dependent differential effect. Methods: Time-pregnant Sprague–Dawley rats were irradiated on embryonic day E17 with 100 cGy (low dose), 145 cGy (medium dose), 175 cGy (high dose), or were left untreated. Their adult litters were implanted with bifrontal epidural and hippocampal depth electrodes and underwent long-term video-EEG monitoring. After 2 weeks of monitoring, the animals were killed and their brains processed for histological studies. Results: Spikes were most frequently found in the rats that were subjected to low- and medium-dose radiation at E17 and were less frequently seen in the animals that were subjected to high-dose radiation. No interictal spikes were found in any of the control animals. Seizures were recorded in three of five animals of the medium-dose group. Histological studies showed a dose-dependent decrease in cortical thickness as well as an increase of cortical and hippocampal disorganization. Conclusions: In vivo epileptogenicity in radiated animals was present only in mild or moderate MCD. No in vivo epileptogenicity was seen in severe radiation-induced MCD.

Summary: Purpose: The study goal was to evaluate the clinical usefulness of intravenous EEG recording by placing wire electrodes in the cavernous sinus (CS) and the superior petrosal sinus (SPS) in patients with intractable temporal lobe epilepsy (TLE), with special emphasis on the ictal recording. Methods: We placed Seeker Lite- 10 guide wire as electrodes in the bilateral CS, SPS, or both to simultaneously record both ictal and interictal EEGs with the scalp EEG in five patients with TLE. In addition, in one patient, we averaged interictal scalp and intravascular EEG time-locked to the epileptiform discharge recorded from the CS/SPS-EEG to further delineate the relationship of the spikes between scalp and intravenous recording. Results: In four of five patients, clinically useful recording was obtained to determine ictal focus. We recorded habitual seizures in three patients, and the detailed characteristics of ictal epileptiform discharges were shown. The averaged waveform of interictal epileptiform discharges clarified the spike distribution in the scalp EEGs, which was otherwise undetectable in the single trace. All of the patients completed the intravenous EEG monitoring without any neurological or psychological problems. Conclusions: The CS/SPS-EEG is a relatively noninvasive method that is useful for the detection of ictal focus and its spreading pattern and thus for the selection of surgical candidate among patients with intractable TLE. Although the number of seizures detected during the short monitoring period may be limited, due to the advantages of its safety and simplicity, it is worth trying for potential surgical candidates before more invasive examinations are applied. A further study with a larger number of patients is needed to estimate its practical risk.

Summary Purpose To quantitatively compare the diagnostic capability of double inversion-recovery (DIR) with F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) for detection of seizure focus laterality in temporal lobe epilepsy (TLE). Methods This study was approved by the institutional review board, and written informed consent was obtained. Fifteen patients with TLE and 38 healthy volunteers were enrolled. All magnetic resonance (MR) images were acquired using a 3T-MRI system. Voxel-based analysis (VBA) was conducted for FDG-PET images and white matter segments of DIR images (DIR-WM) focused on the whole temporal lobe (TL) and the anterior part of the temporal lobe (ATL). Distribution of hypometabolic areas on FDG-PET and increased signal intensity areas on DIR-WM were evaluated, and their laterality was compared with clinically determined seizure focus laterality. Correct diagnostic rates of laterality were evaluated, and agreement between DIR-WM and FDG-PET was assessed using κ statistics. Key Findings Increased signal intensity areas on DIR-WM were located at the vicinity of the hypometabolic areas on FDG-PET, especially in the ATL. Correct diagnostic rates of seizure focus laterality for DIR-WM (0.80 and 0.67 for the TL and the ATL, respectively) were slightly higher than those for FDG-PET (0.67 and 0.60 for the TL and the ATL, respectively). Agreement of laterality between DIR-WM and FDG-PET was substantial for the TL and almost perfect for the ATL (κ = 0.67 and 0.86, respectively). Significance High agreement in localization between DIR-WM and FDG-PET and nearly equivalent detectability of them show us an additional role of MRI in TLE.

Summary: Purpose: Cortical dysplasia (CD) is a frequent cause of medically intractable focal epilepsy. The mechanisms of CD-induced epileptogenicity remain unknown. The difficulty in obtaining and testing human tissue warrants the identification and characterization of animal model(s) of CD that share most of the clinical, electroencephalographic (EEG), and histopathologic characteristics of human CD. In this study, we report on the in vivo EEG characterization of the radiation-induced model of CD. Methods: Timed-pregnant Sprague–Dawley rats were irradiated on E17 using a single dose of 145 cGy or left untreated. Their litters were identified and implanted with bifrontal epidural and hippocampal depth electrodes for prolonged continuous EEG recordings. After prolonged EEG monitoring, animals were killed and their brains sectioned and stained for histologic studies. Results: In utero–irradiated rats showed frequent spontaneous interictal epileptiform spikes and spontaneous seizures arising independently from the hippocampal or the frontal neocortical structures. No epileptiform or seizure activities were recorded from age-matched control rats. Histologic studies showed the presence of multiple cortical areas of neuronal clustering and disorganization. Moreover, pyramidal cell dispersion was seen in the CA1>CA3 areas of the hippocampal formations. Conclusions: Our results further characterize the in vivo EEG characteristics of the in utero radiation model of CD using long-term EEG monitoring. This model may be used to study the molecular and cellular changes in epileptogenic CD and to test the efficacy of newer antiepileptic medications.

Summary: Purpose: We recorded focal ictal DC shifts from scalp electrodes in a 9–year-old boy with intractable, clinically generalized tonic seizures. The patient had a high intensity signal abnormality of the left temporal cortex with thickening of the gyri on T2–weighted MRI. Methods: Scalp digital EEGs were recorded using electrodes made of silver/silver chloride. The low frequency filter (LFF) was set at 0.016 Hz. Recorded seizures were subsequently analyzed with LFF settings of 1.0, 0.016 and 0.03 Hz. Results: All recorded seizures initially showed diffuse, low voltage, high frequency activity (electrodecremental pattern) followed 10–20 s later by quasirhythmic activity over the left frontotemporal region. In two seizures, LFF of 0.016–0.03 Hz revealed a slow negative shift over the left frontotemporal area simultaneously with onset of the bilateral electrodecremental pattern. However, in the other seizures, this initial slow negative shift was obscured by artifacts. Subsequent electrocorticography (ECoG) delineated frequent epileptiform discharges in the left temporal as well as frontal cortex. Conclusions: Scalp-recorded ictal DC shifts may help identify focal epileptogenic brain area in patients with clinically generalized seizures although the technique is vulnerable to artifact.

A 26-year-old man with intractable focal motor seizure beginning with tonic contraction of the left orbicularis oculi muscle had prolonged EEG monitoring with subdural grid electrodes placed over the right perirolandic cortex. Electrical stimulation of the cortex with implanted subdural electrodes showed a relatively low threshold for afterdischarges (ADs) but could not disclose the motor area for the left upper face where or near where the epileptogenic area was expected to be present. Bereitschaftspotential recorded from the subdural electrodes in association with self-paced voluntary blink (eyelid closing) disclosed the motor area specifically related to voluntary movements of the left upper face, which was most likely buried in the sulcus. This observation suggests that recording of Bereitschaftspotential from subdural electrodes is useful for mapping the motor cortex, especially in patients with focal motor seizure with low threshold for ADs to electric stimuli.