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Published on: September 20, 2024
MEG in MRI-Negative Patients with Focal Epilepsy
Rudolf Kreidenhuber1, Kai-Nicolas Poppert2, Matthias Mauritz2
1Department of Radiology, Paracelsus Medical University Salzburg, 5020 Salzburg, Austria.
Objectives:
To review the evidence on the clinical value of magnetic source imaging (MSI) in patients with refractory focal epilepsy without evidence for an epileptogenic lesion on magnetic resonance imaging ("MRI-negative" or "non-lesional MRI").
Methods:
We conducted a systematic literature search on PUBMED, which was extended by researchrabbit.ai using predefined criteria to identify studies that applied MSI in MRI-negative patients with epilepsy. We extracted data on patient characteristics, MSI methods, localization results, surgical outcomes, and correlation with other modalities.
Results:
We included 23 studies with a total of 512 non-lesional epilepsy patients who underwent MSI. Most studies used equivalent current dipole (ECD) models to estimate the sources of interictal epileptic discharges (IEDs). MEG detected IEDs in 32-100% of patients. MSI results were concordant with other modalities, such as EEG, PET, and SPECT, in 3892% of cases. If MSI concordant surgery was performed, 52-89% of patients achieved seizure freedom. MSI contributed to the decision-making process in 28-75% of cases and altered the surgical plan in 5-33% of cases.
Conclusions:
MSI is a valuable diagnostic tool for MRI-negative patients with epilepsy, as it can detect and localize IEDs with high accuracy and sensitivity, and provides useful information for surgical planning and predicts outcomes. MSI can also complement and refine the results of other modalities, such as EEG and PET, and optimize the use of invasive recordings. MSI should be considered as part of the presurgical evaluation, especially in patients with non-lesional refractory epilepsy.
Insights
Magnetic source imaging (MSI) is valuable for epilepsy patients with normal MRI scans. It accurately detects and localizes seizure sources, aiding surgical decisions and improving outcomes.
Area of Science:
- Epileptology
- Neuroimaging
- Neurosurgery
Background:
- Refractory focal epilepsy often presents without clear lesions on MRI.
- Accurate localization of the epileptogenic zone is crucial for surgical planning in these cases.
Purpose of the Study:
- To evaluate the clinical utility of magnetic source imaging (MSI) in patients with refractory focal epilepsy and non-lesional MRI.
- To assess MSI's ability to detect and localize interictal epileptic discharges (IEDs) and guide surgical interventions.
Main Methods:
- Systematic literature search of PUBMED, augmented by researchrabbit.ai.
- Inclusion of 23 studies involving 512 MRI-negative epilepsy patients.
- Data extraction on MSI methods, localization accuracy, surgical outcomes, and concordance with other neuroimaging modalities.
Main Results:
- MSI detected IEDs in 32-100% of patients, with high concordance (38-92%) with other modalities like EEG, PET, and SPECT.
- Surgery guided by MSI concordant localization resulted in seizure freedom in 52-89% of patients.
- MSI influenced decision-making in 28-75% of cases and altered surgical plans in 5-33%.
Conclusions:
- MSI is a valuable tool for localizing seizure sources in MRI-negative epilepsy.
- It enhances presurgical evaluation, complements other diagnostic methods, and predicts surgical success.
- MSI should be considered in the presurgical workup of patients with non-lesional refractory epilepsy.
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