Corrigendum: Dense Array EEG Source Estimation in Neocortical Epilepsy

Rationale: Dense array EEG (dEEG) evenly covers the whole head surface with over 100 channels contributing to more accurate electrical source imaging due to the higher spatial and temporal resolution. Several studies have shown the clinical utility of dEEG in presurgical clinical evaluation of epilepsy. However validation studies measuring the accuracy of dEEG source imaging are still needed. This can be achieved through simultaneously recording both scalp dEEG with intracranial electrodes (icEEG), which is considered as the true measure of cortical activity at the source. The purpose of this study is to evaluate the accuracy of 256-channel dEEG electrical source estimation for interictal spikes. Methods: Four patients with medically refractory neocortical epilepsy, all surgical candidates, underwent subdural electrode implantation to determine ictal onset and define functional areas. One patient showed a lesion on the magnetic resonance imaging in the right parietal lobe. The patient underwent simultaneous recording of interictal spikes by both scalp 256-channelsvdEEG and icEEG. The dEEG was used to non-invasively estimate the source of the interictal spikes detected by the 256-channel dEEG array, which was then compared to the activity measured directly at the source by the icEEG. Results: From the four patients, a total of 287 interictal spikes were measured with the icEEG. One hundred fifty-five of the 287 spikes (54%) were visually detected by the dEEG upon examination of the 256 channel head surface array. The spike amplitudes detected by the 256-channel dEEG correlated with icEEG spike amplitudes (p < 0.01). All spikes detected in dEEG were localized to the same lobe correctly. Conclusion: Our study demonstrates that 256-channel dEEG can reliably detect interictal spikes and localize them with reasonable accuracy. Two hundred fifty-six-channel dEEG may be clinically useful in the presurgical workup for epilepsy and also reduce the need for invasive EEG evaluation.

[1]  Christoph M. Michel,et al.  Electrical neuroimaging based on biophysical constraints , 2004, NeuroImage.

[2]  J S Ebersole,et al.  Non-invasive pre-surgical evaluation with EEG/MEG source analysis. , 1997, Electroencephalography and clinical neurophysiology. Supplement.

[3]  H. Otsubo,et al.  Extraoperative cortical stimulation of motor function in children. , 2001, Pediatric neurology.

[4]  Christoph M. Michel,et al.  Epileptic source localization with high density EEG: how many electrodes are needed? , 2003, Clinical Neurophysiology.

[5]  Hiroshi Otsubo,et al.  Confirmation of Two Magnetoencephalographic Epileptic Foci by Invasive Monitoring from Subdural Electrodes in an Adolescent with Right Frontocentral Epilepsy , 1999, Epilepsia.

[6]  Neuromagnetic assessment of epileptogenicity in cerebral arteriovenous malformation , 2000, Neurosurgical Review.

[7]  M. Cook,et al.  Clinical utility of current-generation dipole modelling of scalp EEG , 2007, Clinical Neurophysiology.

[8]  D. Poeppel,et al.  Magnetoencephalography and magnetic source imaging. , 1998, Neuropsychiatry, neuropsychology, and behavioral neurology.

[9]  Hiroshi Shibasaki,et al.  Simultaneous Recording of Epileptiform Discharges by MEG and Subdural Electrodes in Temporal Lobe Epilepsy , 1997, NeuroImage.

[10]  M. Holmes.  Dense array EEG: Methodology and new hypothesis on epilepsy syndromes , 2008, Epilepsia.

[11]  Don M. Tucker,et al.  Integrating Dense Array EEG in the Presurgical Evaluation of Temporal Lobe Epilepsy , 2012, ISRN neurology.

[12]  Geertjan Huiskamp,et al.  Regional Differences in the Sensitivity of MEG for Interictal Spikes in Epilepsy , 2010, Brain Topography.

[13]  M. Murray,et al.  EEG source imaging , 2004, Clinical Neurophysiology.

[14]  Jeffrey G Ojemann,et al.  Comparing Noninvasive Dense Array and Intracranial Electroencephalography for Localization of Seizures , 2010, Neurosurgery.

[15]  J S Ebersole,et al.  Noninvasive Localization of Epileptogenic Foci by EEG Source Modeling , 2000, Epilepsia.

[16]  I. Lemahieu,et al.  Dipole location errors in electroencephalogram source analysis due to volume conductor model errors , 2000, Medical and Biological Engineering and Computing.

[17]  M. Holmes,et al.  Dense array EEG source estimation in neocortical epilepsy , 2013 .

[18]  J. Lewine,et al.  CHAPTER 9 – Magnetoencephalography and Magnetic Source Imaging , 1995 .

[19]  W. Freeman,et al.  Spatial spectra of scalp EEG and EMG from awake humans , 2003, Clinical Neurophysiology.

[20]  Don M. Tucker,et al.  Comparison of dense array EEG with simultaneous intracranial EEG for Interictal spike detection and localization , 2012, Epilepsy Research.

[21]  H. Otsubo,et al.  Positive epileptiform discharges in children with neuronal migration disorders. , 1997, Pediatric neurology.

[22]  G Scheler,et al.  Magnetic brain source imaging of focal epileptic activity: a synopsis of 455 cases. , 2003, Brain : a journal of neurology.

[23]  Claudio Pollo,et al.  Electroencephalographic source imaging: a prospective study of 152 operated epileptic patients , 2011, Brain : a journal of neurology.

[24]  Claudio Pollo,et al.  Electrical source imaging for presurgical focus localization in epilepsy patients with normal MRI , 2010, Epilepsia.

[25]  Stefan Rampp,et al.  Magnetoencephalography in presurgical epilepsy diagnosis , 2007, Expert review of medical devices.

[26]  G. Romani,et al.  Study of focal epilepsy by multichannel neuromagnetic measurements. , 1987, Electroencephalography and clinical neurophysiology.

[27]  Gerald S. Russell,et al.  Geodesic photogrammetry for localizing sensor positions in dense-array EEG , 2005, Clinical Neurophysiology.

[28]  D. Tucker,et al.  Localization of Extratemporal Seizure with Noninvasive Dense-Array EEG , 2008, Pediatric Neurosurgery.

[29]  C. Michel,et al.  128-Channel EEG Source Imaging in Epilepsy: Clinical Yield and Localization Precision , 2004, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[30]  C. Baumgartner.  Controversies in clinical neurophysiology. MEG is superior to EEG in the localization of interictal epileptiform activity: Con , 2004, Clinical Neurophysiology.

[31]  N Nakasato,et al.  Comparisons of MEG, EEG, and ECoG source localization in neocortical partial epilepsy in humans. , 1994, Electroencephalography and clinical neurophysiology.

[32]  H. Otsubo,et al.  Magnetoencephalographic localization in pediatric epilepsy surgery: Comparison with invasive intracranial electroencephalography , 1999, Annals of neurology.

[33]  Hiroshi Masuda,et al.  Epileptic Spikes: Magnetoencephalography versus Simultaneous Electrocorticography , 2002, Epilepsia.

[34]  Stephen T. C. Wong,et al.  Magnetoencephalography in partial epilepsy: Clinical yield and localization accuracy , 1997, Annals of neurology.

[35]  C. Michel,et al.  Propagation of Interictal Epileptiform Activity Can Lead to Erroneous Source Localizations: A 128-Channel EEG Mapping Study , 2003, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[36]  D. Lehmann,et al.  Functional imaging with low-resolution brain electromagnetic tomography (LORETA): a review. , 2002, Methods and findings in experimental and clinical pharmacology.