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Russo A, Lallas M, Jayakar P, Miller I, Hyslop A, Dunoyer C, Resnick T, Duchowny M. The diagnostic utility of 3D-ESI rotating and moving dipole methodology in the pre-surgical evaluation of MRI-negative childhood epilepsy due to focal cortical dysplasia. Epilepsia 2016; 57:1450-7. [DOI: 10.1111/epi.13454] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/05/2016] [Indexed: 01/31/2023]
Affiliation(s)
- Angelo Russo
- Child Neurology Unit; IRCCS; Institute of Neurological Sciences of Bologna; Bologna Italy
| | - Matt Lallas
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
| | - Prasanna Jayakar
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
| | - Ian Miller
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
| | - Ann Hyslop
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
| | - Catalina Dunoyer
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
| | - Trevor Resnick
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
- Department of Neurology; University of Miami Miller School of Medicine; Miami Florida U.S.A
| | - Michael Duchowny
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
- Department of Neurology; University of Miami Miller School of Medicine; Miami Florida U.S.A
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Russo A, Jayakar P, Lallas M, Miller I, Hyslop A, Korman B, Dunoyer C, Resnick T, Duchowny M. The diagnostic utility of 3D electroencephalography source imaging in pediatric epilepsy surgery. Epilepsia 2015; 57:24-31. [DOI: 10.1111/epi.13228] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/06/2015] [Indexed: 11/26/2022]
Affiliation(s)
- Angelo Russo
- Child Neurology Unit; IRCCS; Institute of Neurological Sciences of Bologna; Bologna Italy
| | - Prasanna Jayakar
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
| | - Matt Lallas
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
| | - Ian Miller
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
| | - Ann Hyslop
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
| | - Brandon Korman
- Neuropsychology Section; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
| | - Catalina Dunoyer
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
| | - Trevor Resnick
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
- Department of Neurology; University of Miami Miller School of Medicine; Miami Florida U.S.A
| | - Michael Duchowny
- Department of Neurology and Comprehensive Epilepsy Program; Brain Institute; Nicklaus Children's Hospital; Miami Florida U.S.A
- Department of Neurology; University of Miami Miller School of Medicine; Miami Florida U.S.A
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Storti SF, Boscolo Galazzo I, Del Felice A, Pizzini FB, Arcaro C, Formaggio E, Mai R, Manganotti P. Combining ESI, ASL and PET for quantitative assessment of drug-resistant focal epilepsy. Neuroimage 2014; 102 Pt 1:49-59. [DOI: 10.1016/j.neuroimage.2013.06.028] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 05/03/2013] [Accepted: 06/10/2013] [Indexed: 11/16/2022] Open
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Storti SF, Formaggio E, Franchini E, Bongiovanni LG, Cerini R, Fiaschi A, Michel CM, Manganotti P. A multimodal imaging approach to the evaluation of post-traumatic epilepsy. MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE 2012; 25:345-60. [PMID: 22592963 PMCID: PMC3458199 DOI: 10.1007/s10334-012-0316-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 04/16/2012] [Accepted: 04/17/2012] [Indexed: 11/11/2022]
Abstract
Object Electroencephalography-functional magnetic resonance imaging (EEG-fMRI) coregistration and high-density EEG (hdEEG) can be combined to map noninvasively abnormal brain activation elicited by epileptic processes. By combining noninvasive imaging techniques in a multimodal approach, we sought to investigate pathophysiological mechanisms underlying epileptic activity in seven patients with severe traumatic brain injury. Materials and methods Standard EEG and fMRI data were acquired during a single scanning session. The EEG-fMRI data were analyzed using the general linear model and independent component analysis. Source localization of interictal epileptiform discharges (IEDs) was performed using 256-channel hdEEG. Blood oxygenation level dependent (BOLD) localizations were then compared to EEG source reconstruction. Results On hdEEG, focal source localization was detected in all seven patients; in six out of seven it was concordant with the expected epileptic activity as defined by EEG data and clinical evaluation; and in four out of seven in whom IEDs were recorded, BOLD signal changes were observed. These activities were partially concordant with the source localization. Conclusion Multimodal integration of EEG-fMRI and hdEEG combining two different methods to localize the same epileptic foci appears to be a promising tool to noninvasively map abnormal brain activation in patients with post-traumatic brain injury.
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Affiliation(s)
- Silvia F Storti
- Department of Neurological, Neuropsychological, Morphological and Movement Sciences, Section of Clinical Neurology, University of Verona, Policlinico G.B. Rossi, P.le L.A. Scuro 10, 37134, Verona, Italy.
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Zhang R, Wu T, Wang Y, Liu H, Zou Y, Liu W, Xiang J, Xiao C, Yang L, Fu Z. Interictal magnetoencephalographic findings related with surgical outcomes in lesional and nonlesional neocortical epilepsy. Seizure 2011; 20:692-700. [DOI: 10.1016/j.seizure.2011.06.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Revised: 06/28/2011] [Accepted: 06/28/2011] [Indexed: 12/21/2022] Open
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Shiraishi H, Ahlfors SP, Stufflebeam SM, Knake S, Larsson PG, Hämäläinen MS, Takano K, Okajima M, Hatanaka K, Saitoh S, Dale AM, Halgren E. Comparison of three methods for localizing interictal epileptiform discharges with magnetoencephalography. J Clin Neurophysiol 2011; 28:431-40. [PMID: 21946369 PMCID: PMC3190234 DOI: 10.1097/wnp.0b013e318231c86f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To compare three methods of localizing the source of epileptiform activity recorded with magnetoencephalography: equivalent current dipole, minimum current estimate, and dynamic statistical parametric mapping (dSPM), and to evaluate the solutions by comparison with clinical symptoms and other electrophysiological and neuroradiological findings. METHODS Fourteen children of 3 to 15 years were studied. Magnetoencephalography was collected with a whole-head 204-channel helmet-shaped sensor array. We calculated equivalent current dipoles and made minimum current estimate and dSPM movies to estimate the cortical distribution of interictal epileptiform discharges in these patients. RESULTS The results for four patients with localization-related epilepsy and one patient with Landau-Kleffner Syndrome were consistent among all the three analysis methods. In the rest of the patients, minimum current estimate and dSPM suggested multifocal or widespread activity; in these patients, the equivalent current dipole results were so scattered that interpretation of the results was not possible. For 9 patients with localization-related epilepsy and generalized epilepsy, the epileptiform discharges were wide spread or only slow waves, but dSPM suggested a possible propagation path of the interictal epileptiform discharges. CONCLUSION Minimum current estimate and dSPM could identify the propagation of epileptiform activity with high temporal resolution. The results of dSPM were more stable because the solutions were less sensitive to background brain activity.
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Affiliation(s)
- Hideaki Shiraishi
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA.
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Gerez M, Sada A, Tello A. Amygdalar hyperactivity, a fear-related link between panic disorder and mesiotemporal epilepsy. Clin EEG Neurosci 2011; 42:29-39. [PMID: 21309440 DOI: 10.1177/155005941104200108] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The sudden onset, short duration and stereotyped features of panic attacks, and the fear aura of seizures starting at the mesial aspects of the temporal lobe, suggest common mechanisms underlying panic disorder (PD) and mesiotemporal epilepsy (MTLE). However, current consensus emphasizes the importance of differentiating the two entities based on 1) intact consciousness in panic attacks, 2) poor response to antiepileptics, and 3) unsuccessful electrophysiological attempts to demonstrate a relationship. We report two cases with a diagnosis of PD that had been partially responsive to first line treatments. During the EEG session, both patients developed panic symptoms with minimal EEG changes in response to paper bag-hyperventilation (PB-HV), and several minutes later presented a clear ictal EEG pattern associated with very different clinical symptoms, but both with strong fear content. Z-scored LORETA analysis showed increased current source densities (CSD) at the right amygdala in both subjects during the induced panic symptoms. Several areas were involved during the seizure, different in each subject. Yet, a very significant increase at the amygdala was found in both cases. The LORETA Z-scored source correlation (LSC) analysis also showed similar abnormal patterns during the panic symptoms in both patients, and marked differences during the seizure. These findings show a major role of amygdalar hyperactivity in both fear-related conditions for the two patients, and are discussed in relation to existing models of PD in general. Abnormal overactivation at mesiotemporal regions is poorly represented at the surface recordings but can be detected by the appropriate analytical techniques.
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Affiliation(s)
- M Gerez
- Department of Neurophysiology, Hospital Español de Mexico, Mexico City 11520, USA.
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Colon A, Hofman P, Ossenblok P, Jansen J, ter Beek L, Berting R, Stam C, Boon P. MRS-lateralisation index in patients with epilepsy and focal cortical dysplasia or a MEG-focus using bilateral single voxels. Epilepsy Res 2010; 89:148-53. [DOI: 10.1016/j.eplepsyres.2009.11.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2009] [Revised: 11/07/2009] [Accepted: 11/15/2009] [Indexed: 10/20/2022]
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Goldenholz DM, Ahlfors SP, Hämäläinen MS, Sharon D, Ishitobi M, Vaina LM, Stufflebeam SM. Mapping the signal-to-noise-ratios of cortical sources in magnetoencephalography and electroencephalography. Hum Brain Mapp 2009; 30:1077-86. [PMID: 18465745 DOI: 10.1002/hbm.20571] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Although magnetoencephalography (MEG) and electroencephalography (EEG) have been available for decades, their relative merits are still debated. We examined regional differences in signal-to-noise-ratios (SNRs) of cortical sources in MEG and EEG. Data from four subjects were used to simulate focal and extended sources located on the cortical surface reconstructed from high-resolution magnetic resonance images. The SNR maps for MEG and EEG were found to be complementary. The SNR of deep sources was larger in EEG than in MEG, whereas the opposite was typically the case for superficial sources. Overall, the SNR maps were more uniform for EEG than for MEG. When using a noise model based on uniformly distributed random sources on the cortex, the SNR in MEG was found to be underestimated, compared with the maps obtained with noise estimated from actual recorded MEG and EEG data. With extended sources, the total area of cortex in which the SNR was higher in EEG than in MEG was larger than with focal sources. Clinically, SNR maps in a patient explained differential sensitivity of MEG and EEG in detecting epileptic activity. Our results emphasize the benefits of recording MEG and EEG simultaneously.
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Affiliation(s)
- Daniel M Goldenholz
- Athinoula A. Martinos Center For Biomedical Imaging, Massachusetts General Hospital, Charlestown, USA.
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Westmijse I, Ossenblok P, Gunning B, van Luijtelaar G. Onset and propagation of spike and slow wave discharges in human absence epilepsy: A MEG study. Epilepsia 2009; 50:2538-48. [PMID: 19519798 DOI: 10.1111/j.1528-1167.2009.02162.x] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE A nonlinear association and a source localization technique were used to describe the onset and propagation of spike-and-slow-wave discharges (SWDs) in children with absence seizures. Previous studies have emphasized a leading cortical role in the generation of absence seizures in genetic epileptic rats. METHODS Synchronization between all magnetoencephalography (MEG) sensor-couples before and during SWDs in five patients was investigated over time. A source localization [beamformer, SAM(g(2))] technique was used to find brain regions associated with the origin of the spikes of the SWDs. RESULTS The onset of SWDs was characterized by high associations at left and right frontal regions. An alternating pattern of high synchronization was found during trains of SWDs: generalized during the wave and localized during the spike; the origin of the spike was different from the onset of SWDs, more frontal lateral and medial parietal. The localization of this latter region was confirmed with SAM(g(2)). DISCUSSION The outcome of the nonlinear association techniques demonstrated that SWDs have a local cortical onset, whereas the association and beamformer technique support a local or even a focal cortical involvement in the occurrence of the spike in a train of SWDs. In all, the cortex contains local frontal and parietal sites relevant before the onset of the generalized pattern of SWDs and other ones that might contain the driving force behind the spike in trains of 3-4 Hz SWDs.
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Affiliation(s)
- Inge Westmijse
- Donders Centre for Cognition, Radboud University Nijmegen, The Netherlands
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Ossenblok P, de Munck JC, Colon A, Drolsbach W, Boon P. Magnetoencephalography Is More Successful for Screening and Localizing Frontal Lobe Epilepsy than Electroencephalography. Epilepsia 2007; 48:2139-49. [PMID: 17662061 DOI: 10.1111/j.1528-1167.2007.01223.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
PURPOSE The diagnosis of frontal lobe epilepsy may be compounded by poor electroclinical localization, due to distributed or rapidly propagating epileptiform activity. This study aimed at developing optimal procedures for localizing interictal epileptiform discharges (IEDs) of patients with localization related epilepsy in the frontal lobe. To this end the localization results obtained for magnetoencephalography (MEG) and electroencephalography (EEG) were compared systematically using automated analysis procedures. METHODS Simultaneous recording of interictal EEG and MEG was successful for 18 out of the 24 patients studied. Visual inspection of these recordings revealed IEDs with varying morphology and topography. Cluster analysis was used to classify these discharges on the basis of their spatial distribution followed by equivalent dipole analysis of the cluster averages. The locations of the equivalent dipoles were compared with the location of the epileptogenic lesions of the patient or, if these were not visible at MRI with the location of the interictal onset zones identified by subdural electroencephalography. RESULTS Generally IEDs were more abundantly in MEG than in the EEG recordings. Furthermore, the duration of the MEG spikes, measured from the onset till the spike maximum, was in most patients shorter than the EEG spikes. In most patients, distinct spike subpopulations were found with clearly different topographical field maps. Cluster analysis of MEG spikes followed by dipole localization was successful (n = 14) for twice as many patients as for EEG source analysis (n = 7), indicating that the localizability of interictal MEG is much better than of interictal EEG. CONCLUSIONS The automated procedures developed in this study provide a fast screening method for identifying the distinct categories of spikes and the brain areas responsible for these spikes. The results show that MEG spike yield and localization is superior compared with EEG. This finding is of importance for the diagnosis and preoperative evaluation of patients with frontal lobe epilepsy.
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Lopes da Silva FH. What is magnetoencephalography and why it is relevant to neurosurgery? Adv Tech Stand Neurosurg 2005; 30:51-67. [PMID: 16350452 DOI: 10.1007/3-211-27208-9_2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Magnetoencephalography (MEG) is a relatively novel technique that allows the study of the dynamic properties of cortical activity. The functional localization of brain sources of MEG signals depends on the models used and it always has a certain degree of uncertainty. Nevertheless, MEG can be very useful in assisting the neurosurgeon in planning and carrying out brain surgery in, or around, eloquent brain areas, and in epilepsy surgery in pharmaco-resistant patients. The following three areas of application of MEG in neurosurgery are reviewed: (i) Presurgical functional localization of somatomotor eloquent cortex; (ii) Presurgical evaluation of epileptic patients. (iii) Functional localization of speech relevant brain areas. The performance of MEG in comparison with EEG and fMRI is discussed.
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Affiliation(s)
- F H Lopes da Silva
- Section Neurobiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
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Stefan H, Scheler G, Hummel C, Walter J, Romstöck J, Buchfelder M, Blümcke I. Magnetoencephalography (MEG) predicts focal epileptogenicity in cavernomas. J Neurol Neurosurg Psychiatry 2004; 75:1309-13. [PMID: 15314122 PMCID: PMC1739222 DOI: 10.1136/jnnp.2003.021972] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
OBJECTIVE The aim of this study was to identify the irritative epileptic zone in patients with cavernomas by means of magnetoencephalography (MEG). METHOD Among 82 patients operated for epilepsy, whose presurgical evaluation had included MEG, histological assessment of the tissue removed had confirmed cavernomas in eight. These eight patients had epilepsy since 18.6 (SD 12.7) years on average. The monitoring lasted about 2.1 (SD 1.3) hours and a median 20.9 (SD 14.3) spikes per hour were recorded. Spontaneous brain activity was recorded by means of a 74 channel dual unit MEG system (Magnes II, 4-D Neuroimaging) with simultaneous EEG recording (31 scalp electrodes). Spike analysis was performed using different source (moving dipole, current density reconstruction) and head models (spherical shells, BEM). Co-registration of neurophysiological and imaging data (MRI) was based upon anatomical landmarks. RESULTS In 6/8 patients co-localisation from the cavernoma and epileptic zone was found. In two patients the focus was localised in the parieto-occipital lobe, in three patients in the frontal lobe and in three patients in the temporal lobe. In one case of temporal and one case of frontal lobe focus localisation there was no spatial relationship to the cavernoma. CONCLUSION In cases of focal seizures due to a single cavernoma, MEG may precisely delineate the epileptogenic tissue bordering the lesion. In patients with multiple cavernomas or dual pathology, MSI may reveal the complexity of the case, and contribute to the decision about further invasive diagnostics and more sophisticated therapeutic measures. MEG is a promising method for prediction of the epileptic zone in cavernoma related epilepsies, and thus it can contribute to decision making about and planning of epilepsy surgery.
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Affiliation(s)
- H Stefan
- Department of Neurology, Epilepsy and Neuro-Center, University of Erlangen-Nürnberg, Germany.
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Van 't Ent D, Manshanden I, Ossenblok P, Velis DN, de Munck JC, Verbunt JPA, Lopes da Silva FH. Spike cluster analysis in neocortical localization related epilepsy yields clinically significant equivalent source localization results in magnetoencephalogram (MEG). Clin Neurophysiol 2003; 114:1948-62. [PMID: 14499757 DOI: 10.1016/s1388-2457(03)00156-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
OBJECTIVE In magnetoencephalogram (MEG) recordings of patients with epilepsy several types of sharp transients with different spatiotemporal distributions are commonly present. Our objective was to develop a computer based method to identify and classify groups of epileptiform spikes, as well as other transients, in order to improve the characterization of irritative areas in the brain of epileptic patients. METHODS MEG data centered on selected spikes were stored in signal matrices of C channels by T time samples. The matrices were normalized and euclidean distances between spike representations in vector space R(CxT) were input to a Ward's hierarchical clustering algorithm. RESULTS The method was applied to MEG data from 4 patients with localization-related epilepsy. For each patient, distinct spike subpopulations were found with clearly different topographical field maps. Inverse computations to selected spike subaverages yielded source solutions in agreement with seizure classification and location of structural lesions, if present, on magnetic resonance images. CONCLUSIONS With the proposed method a reliable categorization of epileptiform spikes is obtained, that can be applied in an automatic way. Computation of subaverages of similar spikes enhances the signal-to-noise ratio of spike field maps and allows for more accurate reconstruction of sources generating the epileptiform discharges.
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Affiliation(s)
- D Van 't Ent
- MEG Centre, Vrije Universiteit medical centre (VUmc) Amsterdam, Out-Patient Clinic Reception C, PO Box 7057, 1007 MB, Amsterdam, The Netherlands.
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