Clinical relevance of source location in frontal lobe epilepsy and prediction of postoperative long-term outcome

Mu, Jie; Rampp, Stefan; Carrette, Evelien; Rössler, Karl; Sommer, Björn; Schmitt, Friedhelm C.; Tiège, Xavier De; Hamer, Hajo M.; Boon, Paul; Pauli, E.; Blümcke, Ingmar; Zhou, Dong; Buchfelder, Michael; Stefan, Hermann

doi:10.1016/j.seizure.2014.04.006

Cited by 43 publications

(47 citation statements)

References 35 publications

(69 reference statements)

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“…taking localizations of interictal spikes into account. It has been repeatedly shown, that this enables significantly higher rates of seizure freedom (Mu et al, 2014, Vadera et al, 2013). …”

Section: Discussionmentioning

confidence: 97%

The delta between postoperative seizure freedom and persistence: Automatically detected focal slow waves after epilepsy surgery

Schönherr

Stefan

Hamer

et al. 2017

NeuroImage: Clinical

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ObjectiveIn this study, we use a novel automated method for localization and quantitative comparison of magnetoencephalographic (MEG) delta activity in patients with and without recurrent seizures after epilepsy surgery as well as healthy controls.MethodsWe identified the generators of delta activity by source location in frequency domain between 1 and 4 Hz in spontaneous MEG data. Comparison with healthy control subjects by z-transform emphasized relative changes of activation in patients. The individual results were compared to spike localizations and statistical group analysis was performed. Additionally, MEG results were compared to 1–4 Hz activity in invasive EEG (iEEG) in two patients, in whom this data was available.ResultsPatients with recurrent seizures exhibited significantly increased focal MEG delta activity both in comparison to healthy controls and seizure free patients. This slow activity showed a correlation to interictal epileptic activity and was not explained by consequences of the resection alone. In two patients with iEEG, iEEG analysis was concordant with the MEG findings.SignificanceThe quantity of delta activity could be used as a diagnostic marker for recurrent seizures. The close relation to epileptic spike localizations and the resection volume of patients with successful second surgery imply involvement in seizure recurrence. This initial evidence suggests a potential application in the planning of second epilepsy surgery.

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Section: Discussionmentioning

confidence: 97%

The delta between postoperative seizure freedom and persistence: Automatically detected focal slow waves after epilepsy surgery

Schönherr

Stefan

Hamer

et al. 2017

NeuroImage: Clinical

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“…1 Furthermore, most of FCD type II has higher signal-to-noise ratio (SNR) of epileptic activity to provide the accurate Epilepsia, 57 (7):1169-1178, 2016 doi: 10.1111/epi.13399 localization of clustered MEG spike dipoles overlapping the lesion. 21,[31][32][33] However, BOSD may not provide the MEG cluster. If two cortical areas have an opposite orientation, such as facing sulcus walls, cancellation occurs, and no voltage field from them is evident at the scalp.…”

Section: Epileptic Discharges At Opposing Walls In Fcdbmentioning

confidence: 99%

Remote MEG dipoles in focal cortical dysplasia at bottom of sulcus

et al. 2016

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SUMMARYObjective: To investigate whether the magnetoencephalography (MEG) single moving dipole (SMD) method could delineate the epileptic zone of focal cortical dysplasia (FCD) at the bottom of sulcus (FCDB). Methods: We retrospectively analyzed 17 children (11 male; mean age 8.8 years, range 3-17 years) with FCD type II who underwent epilepsy surgery. We compared spatial congruence between the following: (1) MEG cluster and FCDB and (2) MEG cluster and FCD at the brain surface (FCDS). We measured the volume and depth of magnetic resonance imaging (MRI)-visible lesions to investigate whether they affect spatial congruence between MEG cluster and MRI-visible lesion. Results: Eight children had FCDB and the other nine children had FCDS. ). There was a tendency for a smaller volume of MRI-visible lesion for FCDB, relative to FCDS(p = 0.079). In FCDB, six children showed clusters of MEG dipoles and two children showed scattered MEG dipoles for interictal spikes. The spatial congruence between the MEG result and FCDB was partially overlapping in four children and discordant in another four children. In FCDS, eight children had MEG cluster and one child had MEG scatter alone. The spatial congruence between MEG result and FCDS was overlapping in eight of nine children (fully two; partially six) and discordant in one of nine children. Fifteen children (88%; FCDB eight; FCDS seven) became seizure-free after resective surgery. MEG spike dipole resection ratio in the cluster ranged from 4-100% (mean 67%) in 6 FCDB and 23-99% (mean 77%) in 8 FCDS. Significance: The SMD method may drift MEG spike dipoles for FCDB. Lesionectomy can control seizures for four of eight patients in FCDB despite the remote MEG dipoles. The FCDB or FCDS partially overlapped with MEG cluster may have an extending/invisible epileptogenic zone consecutive to the MRI-visible lesion.

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“…However, without detailed analysis of postoperative seizure outcome, only limited conclusions can be drawn regarding the predictive value of MEG in achieving long‐term seizure freedom. Although other studies have directly related MEG findings to surgical outcome, their statistical conclusions have been limited by small sample size . Furthermore, given the additional technical challenges related to source localization of deeper brain structures such as the mesial temporal lobe, some have argued that MEG has diminished clinical utility in TLE compared to neocortical epilepsy .…”

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Epileptogenic zone localization using magnetoencephalography predicts seizure freedom in epilepsy surgery

et al. 2015

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Objective The efficacy of epilepsy surgery depends critically upon successful localization of the epileptogenic zone. Magnetoencephalography (MEG) enables non-invasive detection of interictal spike activity in epilepsy, which can then be localized in three dimensions using magnetic source imaging (MSI) techniques. However, the clinical value of MEG in the pre-surgical epilepsy evaluation is not fully understood, as studies to date are limited by either a lack of long-term seizure outcomes or small sample size. Methods We performed a retrospective cohort study of focal epilepsy patients who received MEG for interictal spike mapping followed by surgical resection at our institution. Results We studied 132 surgical patients, with mean post-operative follow-up of 3.6 years (minimum 1 year). Dipole source modelling was successful in 103 (78%) patients, while no interictal spikes were seen in others. Among patients with successful dipole modelling, MEG findings were concordant with and specific to: i) the region of resection in 66% of patients, ii) invasive electrocorticography (ECoG) findings in 67% of individuals, and iii) the MRI abnormality in 74% of cases. MEG showed discordant lateralization in ~5% of cases. After surgery, 70% of all patients achieved seizure-freedom (Engel class I outcome). Whereas 85% of patients with concordant and specific MEG findings became seizure-free, this outcome was achieved by only 37% of individuals with MEG findings that were non-specific or discordant with the region of resection (χ2 = 26.4, p < 0.001). MEG reliability was comparable in patients with or without localized scalp EEG, and overall, localizing MEG findings predicted seizure freedom with an odds ratio of 5.11 (2.23–11.8, 95% CI). Significance MEG is a valuable tool for non-invasive interictal spike mapping in epilepsy surgery, including patients with non-localized findings on long-term EEG monitoring, and localization of the epileptogenic zone using MEG is associated with improved seizure outcomes.

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Clinical relevance of source location in frontal lobe epilepsy and prediction of postoperative long-term outcome

Abstract: MSI contributes to the clinical prediction of postoperative outcome in FLE patients. MSI may non-invasively disclose early epileptogenic lesions, pointing to a resectable lesion, and it then facilitates shortcut route of presurgical evaluation.

Cited by 43 publications

References 35 publications

The delta between postoperative seizure freedom and persistence: Automatically detected focal slow waves after epilepsy surgery

The delta between postoperative seizure freedom and persistence: Automatically detected focal slow waves after epilepsy surgery

Remote MEG dipoles in focal cortical dysplasia at bottom of sulcus

Epileptogenic zone localization using magnetoencephalography predicts seizure freedom in epilepsy surgery

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