Magnetoencephalography for epileptic focus localization in a series of 1000 cases

Rampp, Stefan; Stefan, Hermann; Wu, Xintong; Kaltenhäuser, Martin; Maeß, Burkhard; Schmitt, Friedhelm C.; Wolters, Carsten H.; Hamer, Hajo M.; Kasper, Burkhard S.; Schwab, Stefan; Doerfler, A.; Blümcke, Ingmar; Rössler, Karl; Buchfelder, Michael

doi:10.1093/brain/awz231

Cited by 123 publications

(99 citation statements)

References 50 publications

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“…Unlike EEG, the MEG signal is not affected by the smearing effects of skull and scalp and has better immunity to muscle artifact, both of which enable a greater ability to detect epileptic activity . MEG has been shown to provide useful additional information to EEG, which significantly contributes to patient selection, focus localization, and long‐term seizure freedom after epilepsy surgery . However, use of MEG in epilepsy thus far has been limited to the presurgical evaluation of patients with drug‐refractory epilepsies.…”

Section: Introductionmentioning

confidence: 99%

“…1 MEG has been shown to provide useful additional information to EEG, which significantly contributes to patient selection, focus localization, and long-term seizure freedom after epilepsy surgery. [2][3][4] However, use of MEG in epilepsy thus far has been limited to the presurgical evaluation of patients with drug-refractory epilepsies. This is because current clinical MEG uses an array of cryogenically cooled sensors termed superconducting quantum interference devices or SQUIDs, placed around the head, 5,6 making MEG systems cumbersome and restrictive as sensor positions are fixed in a limited selection of helmet sizes.…”

Section: Introductionmentioning

confidence: 99%

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Optically pumped magnetoencephalography in epilepsy

Vivekananda

Mellor

Tierney

et al. 2020

Ann Clin Transl Neurol

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We demonstrate the first use of Optically Pumped Magnetoencephalography (OP‐MEG) in an epilepsy patient with unrestricted head movement. Current clinical MEG uses a traditional SQUID system, where sensors are cryogenically cooled and housed in a helmet in which the patient’s head is fixed. Here, we use a different type of sensor (OPM), which operates at room temperature and can be placed directly on the patient’s scalp, permitting free head movement. We performed OP‐MEG recording in a patient with refractory focal epilepsy. OP‐MEG‐identified analogous interictal activity to scalp EEG, and source localized this activity to an appropriate brain region.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optically pumped magnetoencephalography in epilepsy

Vivekananda

Mellor

Tierney

et al. 2020

Ann Clin Transl Neurol

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show abstract

“…Magnetoencephalography (MEG) has become a vital tool for studying human brain function in both basic and clinical settings (Bagic, Bowyer, Kirsch, Funke, & Burgess, 2017;Baillet, 2017;Matti S Hämäläinen, Hari, Ilmoniemi, Knuutila, & Lounasmaa, 1993;Rampp et al, 2019). Simulation studies show that MEG system performance continues to improve with an increase in channel count as long as channel noise is uncorrelated (Jiri Vrba & Robinson, 2002).…”

Section: Introductionmentioning

confidence: 99%

Pragmatic spatial sampling for wearable MEG arrays

Tierney

Mellor

O'Neill

et al. 2019

Preprint

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Several new technologies have recently emerged promising new MEG systems in which the sensors can be placed close to the scalp. One such technology, Optically Pumped Magnetometry MEG (OP-MEG) allows for a scalp mounted flexible system that provides field measurements within mm of the scalp surface. A question that arises in developing on-scalp systems, such as OP-MEG scanners, is: how many sensors are necessary to achieve adequate performance/spatial discrimination? There are many factors to consider in answering this question such as the signal to noise ratio (SNR), the locations and depths of the sources of interest, the density of spatial sampling, sensor gain errors (due to interference, subject movement, cross-talk, etc.) and, of course, the desired spatial discrimination. In this paper, we provide simulations which show the impact these factors have on designing sensor arrays for wearable MEG. While OP-MEG has the potential to provide high information content at dense spatial samplings, we find that adequate spatial discrimination of sources (<1cm) can be achieved with relatively few sensors (<100) at coarse spatial samplings (~30mm) at high SNR. Comparable discrimination for traditional cryogenic systems require far more channels by these same metrics. Finally we show that sensor gain errors have the greatest impact on discrimination between deep sources at high SNR.

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“…EMSI had a concordance of 53%-89% with the irritative zone and 35%-73% with the seizure onset zone. 4 The above studies and others 7,15,18,20 collectively point to the role of MSI in the presurgical workup of patients with intractable epilepsy. MSI is likely to impact outcome in approximately 20% of patients when used as an investigation added to other presurgical assessment modalities.…”

Section: Fig 2 Msi Results and Clinical Correlation Amentioning

confidence: 91%

“…Patients with mesial temporal lobe epilepsy were excluded if imaging showed ipsilateral mesial temporal sclerosis on MRI. The standard presurgical evaluation included VEEG recording of seizures, high-resolution cerebral MRI (Achieva Dual 3.0T system, Philips Medical Systems), ictal SPECT, and 18 fluoro-deoxy-glucose PET.…”

Section: Patientsmentioning

confidence: 99%

Utility of magnetic source imaging in nonlesional focal epilepsy: a prospective study

Mohamed

Toffa²,

Robert

et al. 2020

Neurosurgical Focus

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OBJECTIVEFor patients with nonlesional refractory focal epilepsy (NLRFE), localization of the epileptogenic zone may be more arduous than for other types of epilepsy and frequently requires information from multiple noninvasive presurgical modalities and intracranial EEG (icEEG). In this prospective, blinded study, the authors assessed the clinical added value of magnetic source imaging (MSI) in the presurgical evaluation of patients with NLRFE.METHODSThis study prospectively included 57 consecutive patients with NLRFE who were considered for epilepsy surgery. All patients underwent noninvasive presurgical evaluation and then MSI. To determine the surgical plan, discussion of the results of the presurgical evaluation was first undertaken while discussion participants were blinded to the MSI results. MSI results were then presented. MSI influence on the initial management plan was assessed.RESULTSMSI results influenced patient management in 32 patients. MSI results led to the following changes in surgical strategy in 14 patients (25%): allowing direct surgery in 6 patients through facilitating the detection of subtle cortical dysplasia in 4 patients and providing additional concordant diagnostic information to other presurgical workup in another 2 patients; rejection of surgery in 3 patients originally deemed surgical candidates; change of plan from direct surgery to icEEG in 2 patients; and allowing icEEG in 3 patients deemed not surgical candidates. MSI results led to changed electrode locations and contact numbers in another 18 patients. Epilepsy surgery was performed in 26 patients influenced by MSI results and good surgical outcome was achieved in 21 patients.CONCLUSIONSThis prospective, blinded study showed that information provided by MSI allows more informed icEEG planning and surgical outcome in a significant percentage of patients with NLRFE and should be included in the presurgical workup in those patients.

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Magnetoencephalography for epileptic focus localization in a series of 1000 cases

Cited by 123 publications

References 50 publications

Optically pumped magnetoencephalography in epilepsy

Optically pumped magnetoencephalography in epilepsy

Pragmatic spatial sampling for wearable MEG arrays

Utility of magnetic source imaging in nonlesional focal epilepsy: a prospective study

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