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This study evaluated the localization precision of 256-channel dense array electroencephalographic source imaging (dESI) in comparison to conventional noninvasive tools. In addition, the study was designed to analyze the relationship between the 256-channel dESI source patterns and surgical outcome.Forty-three patients with temporal lobe epilepsy (TLE) who underwent one-stage resective surgeries were recruited in this study. We compared dESI with other noninvasive evaluation methods by comparing results with resections that eliminate or significantly reduced seizures according to sub-lobule and lobule criteria. Sensitivity and specificity of multiple evaluation methods were calculated. Kaplan-Meier analysis was performed to evaluate the relationship between source patterns and surgical outcome.dESI showed the best sensitivity (sub-lobule, 91.4%; lobule, 97.1%) and specificity (75%) for both sub-lobule and lobule criteria. The Kaplan-Meier survival analysis showed that cases with "single source" had better prognosis than with "multiple sources" (p0.05); cases of "sources within resection" showed better surgical prognosis than cases of "sources outside resection" (p0.05).In this study, 256-channel dESI provided a higher clinical yield than the other most broadly used noninvasive presurgical workup tools. dESI results with "single source" correlated strongly to good prognosis, while cases with "multiple sources" may cautiously be considered as candidates for one-stage resective surgeries. The resection of the irritative zone identified by interictal epileptiform discharges (IEDs) was related to good surgical prognosis in TLE.In the presurgical workup of TLE, the clinical yield of 256-channel dESI is high. Patterns of dESI results are related to surgical prognosis, and they can be instructive for presurgical planning. The resection of the irritative zone can be related to good surgical prognosis in TLE.

Introduction Dense array EEG (dEEG) covers entire scalp surface by 128 or 256 leads, with shorter inter-electrode distance, making a better spatial resolution. It has been utilized only in selected cases for intractable seizure and a part of the presurgical evaluation. It is time-consuming to analyze EEG because of exceeding number of channels beyond the space of LCD monitor. There was no study that dEEG was applied for routine outpatient EEG evaluation. This result may be compared with routine outpatient EEG by 10–20 recording. Methods We utilized dense array EEG system (dEEG) for patients visiting neurology clinic for mental status change in recent past 2 years. Electrodes were applied by the cap system. EEG was recorded using high-impedance DC amplification system by EGI (Eugene, OR, USA), 128 channels with a sampling frequency of 1000 Hz. We developed “double-banana” based convenient montage so that all relevant leads information can be seen by one monitor size without moving the EEG images up and down, that enabled us to review a large number of dEEG quickly. A recording sensitivity was 7 uV/mm, HFF 120 Hz, LFF 1.0 Hz. Recording duration was 30 min for all the patients. Results 788 dEEG recordings were accumulated in our outpatient clinic. Among them, diffuse background slowing was seen in 117 cases (14.8%), focal slowing in 197 (25%), interictal epileptiform discharges were seen in 285 (36.1%). Among the IID cases, 157 (55.1% of IID cases: 19.9% of total) were electrographic seizure pattern. Moreover, scalp permeating HFO (frequency 50–120 Hz) were seen in 46 (5.8%) Infra-slow delta (Defined as frequency Conclusion 128 channel dEEG is sufficiently increased the special resolution and higher yield of inter-ictal abnormalities including IID and focal slowing. Moreover, it would increase the detecting yield of focal abnormalities, i.e., electrographic rhythmic pattern, Infra-slow delta activities, and scalp permeating HFO. Routine outpatient utilization of dEEG may potentially be more efficient in detection of abnormality than routine 10–20 system recording.

Objective An important goal for functional brain studies using EEG technology is to estimate the location of brain sources that produce the scalp-recorded signals. The accuracy of source estimates is dependent upon many variables, one of which is the accurate description of the scalp positions of the EEG sensors. The objective of the present research was to develop a photogrammatic method for sensor localization that is fast, accurate, and easy to use. Methods With the novel photogrammetric method, multiple cameras were arranged in a geodesic array, and images of the sensors on the subject's head were acquired allowing for the reconstruction of the 3D sensor positions. Results Data from the photogrammetric method were compared with data acquired with the conventional electromagnetic method. The accuracy of the photogrammatic method, quantified as RMS of the measured positions and the actual known positions, was similar (mean error=1.27 mm) to the electromagnetic method (mean error=1.02 mm), and both approximated the localization error of the calibration object (mean error=0.56 mm). Conclusions Accurate determination of 3D sensor positions can be accomplished with minimal demands on the time of the subject and the experimenter using the photogrammetric method.

The purpose of this study is to evaluate the clinical usefulness of dense array EEG (dEEG) for spike detection yield ("sensitivity") and localization ("accuracy") of interictal spikes in temporal lobe epilepsy. The subjects were 6 patients who had implanted subdural electrodes in both mesial and lateral temporal regions for presurgical work-up. Simultaneous dEEG and intracranial EEG (icEEG) were recorded. We calculated dEEG spike detection rate and applied spike source estimation for mesial temporal spikes. 45% of the spikes were detected by dEEG with 256ch head surface array. The average icEEG amplitude of dEEG detectable spikes was 1236 μ V, and that of dEEG undetectable spikes was 894rmuV ( P