Does magnetoencephalography add to scalp video-EEG as a diagnostic tool in epilepsy surgery?

Pataraia, Ekaterina; Simos, Panagiotis G.; Castillo, Eduardo M.; Billingsley, R.L.; Sarkari, Shirin; Wheless, James W.; Maggio, V.; Maggio, W.; Baumgartner, James E.; Swank, Paul R.; Breier, Joshua I.; Papanicolaou, Andrew C.

doi:10.1212/01.wnl.0000115122.81621.fe

Cited by 118 publications

(74 citation statements)

References 27 publications

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“…No spike averaging was performed. The location, orientation, and strength of dipole sources that best fit the measured magnetic fields were calculated using the SECD model (Stefan et al, 2003;Pataraia et al, 2004). The following statistics criteria were used when reviewing the SECD results: goodness of fit 480%, confidence volume 51000 mm 3 , reduced 2 5 1.5, and dipole moment between 100-500 nAm.…”

Section: Megmentioning

confidence: 99%

Correlating magnetoencephalography to stereo-electroencephalography in patients undergoing epilepsy surgery

Murakami

Wang

Marashly

et al. 2016

Brain

135

103

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) for a scientific commentary on this article.Magnetoencephalography and stereo-electroencephalography are often necessary in the course of the non-invasive and invasive presurgical evaluation of challenging patients with medically intractable focal epilepsies. In this study, we aim to examine the significance of magnetoencephalography dipole clusters and their relationship to stereo-electroencephalography findings, area of surgical resection, and seizure outcome. We also aim to define the positive and negative predictors based on magnetoencephalography dipole cluster characteristics pertaining to seizure-freedom. Included in this retrospective study were a consecutive series of 50 patients who underwent magnetoencephalography and stereo-electroencephalography at the Cleveland Clinic Epilepsy Center. Interictal magnetoencephalography localization was performed using a single equivalent current dipole model. Magnetoencephalography dipole clusters were classified based on tightness and orientation criteria. Magnetoencephalography dipole clusters, stereo-electroencephalography findings and area of resection were reconstructed and examined in the same space using the patient's own magnetic resonance imaging scan. Seizure outcomes at 1 year postoperative were dichotomized into seizurefree or not seizure-free. We found that patients in whom the magnetoencephalography clusters were completely resected had a much higher chance of seizure-freedom compared to the partial and no resection groups (P = 0.007). Furthermore, patients had a significantly higher chance of being seizure-free when stereo-electroencephalography completely sampled the area identified by magnetoencephalography as compared to those with incomplete or no sampling of magnetoencephalography results (P = 0.012). Partial concordance between magnetoencephalography and interictal or ictal stereo-electroencephalography was associated with a much lower chance of seizure freedom as compared to the concordant group (P = 0.0075). Patients with one single tight cluster on magnetoencephalography were more likely to become seizure-free compared to patients with a tight cluster plus scatter (P = 0.0049) or patients with loose clusters (P = 0.018). Patients whose magnetoencephalography clusters had a stable orientation perpendicular to the nearest major sulcus had a better chance of seizure-freedom as compared to other orientations (P = 0.042). Our data demonstrate that stereo-electroencephalography exploration and subsequent resection are more likely to succeed, when guided by positive magnetoencephalography findings. As a corollary, magnetoencephalography clusters should not be ignored when planning the stereo-electroencephalography strategy. Magnetoencephalography tight cluster and stable orientation are positive predictors for a good seizure outcome after resective surgery, whereas the presence of scattered sources diminishes the probability of favourable outcomes. The concordance pattern between magnetoencephalography and stereo-electroencephalography is a strong...

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Section: Megmentioning

confidence: 99%

Correlating magnetoencephalography to stereo-electroencephalography in patients undergoing epilepsy surgery

Murakami

Wang

Marashly

et al. 2016

Brain

135

103

View full text Add to dashboard Cite

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“…Several studies have shown that this method can provide reliable and useful information in presurgical patients with partial epilepsy (Stefan et al, 2003;Wu et al, 2006;RamachandranNair et al, 2007), and have concluded that non-invasive MEG techniques might eventually partly replace invasive intracranial recording techniques (Pataraia et al, 2004;Papanicolaou et al, 2005;Knowlton et al, 2006). However, the analysis procedures require that each dipole is manually reviewed and classified as either corresponding to a real spike or as corresponding to a non-epileptic origin, which can be timeconsuming, requires trained and experienced scorers, and introduces a sizeable amount of subjectivity in the results.…”

Section: Introductionmentioning

confidence: 99%

Fast oscillations associated with interictal spikes localize the epileptogenic zone in patients with partial epilepsy

et al. 2008

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Although interictal epileptic spikes are defined as fast transient activity, the spatial distribution of spike-related high-frequency power changes is unknown. In this study, we localized the sources of spike-locked power increases in the beta and gamma band with magnetoencephalography and an adaptive spatial filtering technique, and tested the usefulness of these reconstructions for determining the epileptogenic zone in a population of 27 consecutive presurgical patients with medication refractory partial epilepsies. The reliability of this approach was compared to the performance of conventional MEG techniques such as equivalent current dipole (ECD) models. In patients with good surgical outcome after a mean follow up time of 16 months (Engel class I or II), the surgically resected area was identified with an accuracy of 85% by sources of spike-locked beta/gamma activity, which compared favourably with the accuracy of 69% found for ECD models of single spikes. In patients with a total of more than 50 spikes in their recordings, the accuracies increased to 100% vs. 88%, respectively. Imaging of spike-locked beta/gamma power changes therefore seems to be a reliable and fast alternative to conventional MEG techniques for localizing epileptogenic tissue, in particular if more than 50 interictal spikes can be recorded.

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“…The localization of the origin of interictal epileptiform discharges (IEDs) plays a major role in the presurgical work-up of patients with focal refractory epilepsy, especially, using MEG (Englot et al, 2015;Knowlton, 2008;Ossenblok et al, 2007;Pataraia et al, 2004;Stefan et al, 2003) and more recently simultaneous EEG and fMRI (Thornton et al, 2010;Zijlmans et al, 2002). Nowadays the identification of the network underlying the IEDs is an auxiliary tool for the question where to place an intracortical grid or stereotactic depth electrodes for presurgical evaluation in refractory candidates (Pataraia et al, 2004;Schulz et al, 2000;van Houdt et al, 2013van Houdt et al, , 2012Walczak et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

“…Nowadays the identification of the network underlying the IEDs is an auxiliary tool for the question where to place an intracortical grid or stereotactic depth electrodes for presurgical evaluation in refractory candidates (Pataraia et al, 2004;Schulz et al, 2000;van Houdt et al, 2013van Houdt et al, , 2012Walczak et al, 1990). Furthermore, the presence of localized IEDs has been employed to differentiate between the type of epilepsy (focal or generalized) in relation with post surgical outcome (Holmes et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Spatiotemporal mapping of interictal epileptiform discharges in human absence epilepsy: A MEG study

2016

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a b s t r a c tPurpose: Although absence epilepsy is considered to be a prototypic type of generalized epilepsy, it is still under debate whether generalized 3 Hz spike-and-wave discharges (SWDs) might have a cortical focal origin. Here it is investigated whether focal interictal epileptiform discharges (IEDs), which typically occur in the electro-(EEG) and magnetoencephalogram (MEG) in case of focal epilepsy, are present in the MEG of children with absence epilepsy. Next, the location of the sources of the IEDs is established, and it is investigated whether the location is concordant to the earlier established focal cortical regions involved in the generalized SWDs of these children. Methods: Whole head MEG recordings of seven children with absence epilepsy were reviewed with respect to the presence of IEDs (spikes and sharp waves). These IEDs were grouped into distinct clusters, in which each contribution to a cluster yields a comparable magnetic field distribution. Source localization was then performed onto the average signal of each cluster using an equivalent current dipole model and a realistic head model of the cortical surface. Results: IEDs were detected in 6 out of 7 patients. Source reconstruction indicated most often frontal, central or parietal origins of the IED in either the left and or right hemisphere. Spatiotemporal assessment of the IEDs indicated a stable location of the averages of these discharges, indicating a single underlying cortical source. Discussion: The outcome of this pilot study shows that MEG is well suited for the detection of IEDs and suggests that their estimated sources coincide rather well with the cortical regions involved during the spikes of the SWDs. It is discussed whether the presence of IEDs, classically seen as a marker of focal epilepsies, indicate that absence epilepsy should be considered as a focal type of epilepsy, in which changes in the network are evolving rapidly.

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Does magnetoencephalography add to scalp video-EEG as a diagnostic tool in epilepsy surgery?

Abstract: MEG is most useful for presurgical planning in patients who have either partially or nonlocalizing V-EEG results.

Cited by 118 publications

References 27 publications

Correlating magnetoencephalography to stereo-electroencephalography in patients undergoing epilepsy surgery

Correlating magnetoencephalography to stereo-electroencephalography in patients undergoing epilepsy surgery

Fast oscillations associated with interictal spikes localize the epileptogenic zone in patients with partial epilepsy

Spatiotemporal mapping of interictal epileptiform discharges in human absence epilepsy: A MEG study

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