Effect of epilepsy magnetic source imaging on intracranial electrode placement

Knowlton, Robert C.; Razdan, Shantanu N.; Limdi, Nita A.; Elgavish, Rotem A.; Killen, Jeff; Blount, Jeffrey P.; Burneo, Jorge G.; Hoef, Lawrence Ver; Paige, Lebron; Faught, Edward; Kankirawatana, Pongkiat; Bartolucci, Al; Riley, Kristen; Kuzniecky, Ruben

doi:10.1002/ana.21660

Cited by 141 publications

(123 citation statements)

References 29 publications

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“…In line with previous studies, our study demonstrates that a single tight MEG cluster is a positive indicator of good seizure outcome, whereas patients with a loose MEG cluster or multiple clusters have less favourable outcomes (Oishi et al, 2006;Knowlton et al, 2009;Almubarak et al, 2014). Intuitively, it is believed that a single tight cluster indicates a restricted epileptogenic generator, whereas the presence of a loose cluster or multiple clusters is suggestive of a more extensive and complicated epileptogenic region, which cannot be adequately removed with a restricted focal resection.…”

Section: The Value Of Meg In Guiding Surgical Resectionsupporting

confidence: 89%

“…In addition, our study highlights the potential danger of ignoring a clearly positive MEG result by not sampling this region with intracranial electrodes to assess its relationship to the epileptogenic generator. Previous studies examined MEG's value in guiding subdural grid and depth electrode placement, and demonstrated that MEG can offer unique, non-redundant information and help identify implantation sites, where other non-invasive methods failed (Mamelak et al, 2002;Sutherling et al, 2008;Knowlton et al, 2009;Agirre-Arrizubieta et al, 2014). Along the same lines, our study demonstrates the additional value of MEG, specifically in patients implanted with SEEG.…”

Section: The Value Of Meg In Guiding Invasive Electrode Implantationsupporting

confidence: 70%

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Correlating magnetoencephalography to stereo-electroencephalography in patients undergoing epilepsy surgery

Murakami

Wang

Marashly

et al. 2016

Brain

134

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: The Value Of Meg In Guiding Surgical Resectionsupporting

confidence: 89%

Section: The Value Of Meg In Guiding Invasive Electrode Implantationsupporting

confidence: 70%

Correlating magnetoencephalography to stereo-electroencephalography in patients undergoing epilepsy surgery

Murakami

Wang

Marashly

et al. 2016

Brain

134

103

View full text Add to dashboard Cite

show abstract

“…The influence of the skull is estimated to be much less important on components of MEG signals than on those of EEG signals (Lau et al 2013), resulting in good spatial properties of MSI in terms of source localization results and source separation . It has been demonstrated that MSI increases the chance that the seizure onset zone is sampled when patients undergo intracranial investigations for presurgical assessment (Knowlton et al 2009). Moreover, MEG and EEG are characterized by distinct sensitivities according to spatial organizations and functional aspects of the generator.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Source Imaging in Posterior Cortex Epilepsies

et al. 2014

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Posterior cortex epilepsies (PCE) are characterized by less satisfying postoperative results than temporal lobe epilepsies and are thus challenging for non-invasive presurgical investigations. The objective of this study was to evaluate the performance of magnetic source imaging (MSI) in PCE, validating the results by the SEEG (stereoelectroencephalography) definition of irritative and epileptogenic zones (IZ and EZ). Fourteen PCE surgery candidates were investigated using MSI and SEEG. LCMV (Linearly Constrained Minimum Variance) and MUSIC algorithms were used. IZ was quantified using a semi-automatic detection of interictal spikes. EZ was quantified using the epileptogenicity index (EI) method that accounts for both the propensity of a brain area to generate rapid discharges and the time for this area to get involved in the seizure. EI values range from 0 (no epileptogenicity) to 1 (maximal epileptogenicity). Levels of concordance between MSI and IZ, MSI and EZ were determined as follows: A = localized on MSI and SEEG for the site of value 1 (IZ and EZ quantification), B = localized on MSI and SEEG for a part of the IZ or a structure involved in the EZ (without the maximal value 1), C = localized on MSI and not SEEG, D = localized on SEEG and not MSI, E = localized on MSI and SEEG, discordant for site. Five PCE cases were characterized by focal IZ, nine by distributed IZ between several distant brain areas. MSI allowed to determinate IZ in 4/5 focal IZ cases. In case of distributed IZ, levels of concordance were A (2 cases), B (4 cases) and D (3 cases). In most distributed cases, MSI allowed to localize only a part of the IZ. Medial temporal involvement in the IZ was frequent (9/12 cases) and not evidenced by MSI. The brain area that demonstrated the maximal value of EI was shown by MSI in four out of five (80 %) focal IZ cases, in two out of nine (22 %) distributed cases. MSI results depend on IZ characteristics. A distributed IZ organization presents difficulties for MSI and highlights the need for further methodological approaches.

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“…Globally, the reported accuracy of sECD is above 75% for the majority of the studies (Knowlton, 2006;Minassian et al, 1999;Stefan, 1993). In addition, MEG was also shown to be valuable for appropriately determining the subsequent icEEG coverage zone (Fischer et al, 2005;Knowlton et al, 2009;Mamelak et al, 2002). Unfortunately, only a few studies report sECD investigation of ICE.…”

Section: Megmentioning

confidence: 91%