Passive language mapping with magnetoencephalography in pediatric patients with epilepsy

Clinical article

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Functional mapping is important for determining surgical candidacy and also in epilepsy surgery planning. However, in young children and uncooperative patients, language mapping has been particularly challenging despite the advances in performing noninvasive functional studies. In this study the authors review a series of children with epilepsy who underwent language mapping with magnetoencephalography (MEG) while sedated or sleeping, to determine receptive language localization for presurgical evaluation.


The authors undertook a retrospective review of patients who underwent MEG between December 2007 and July 2009, and identified 15 individuals who underwent passive language testing as part of their presurgical evaluation because they were unable to participate in traditional language testing, such as Wada or functional MRI. Factors necessitating passive language testing included age and neurocognitive development.


Three of the 15 patients were deemed candidates for epilepsy surgery based on the results from standard preoperative testing, including video electroencephalography, MRI, and passive receptive language testing using MEG technology. The MEG studies were used successfully to localize language in all 3 patients, creating opportunities for seizure freedom through surgery that would not otherwise have been available. All 3 patients then underwent resective epilepsy surgery without experiencing postoperative language deficits.


This case series is the first to look at language mapping during sleep (passive language mapping) in which MEG was used and is the first to evaluate passive language testing in a patient population with intracranial pathological entities. This case series demonstrates that MEG can provide an alternative method for receptive language localization in patients with barriers to more traditional language testing, and in these 3 cases surgery was performed safely based on the results.

Abbreviations used in this paper:EEG = electroencephalography; fMRI = functional MRI; MEG = magnetoencephalography; MSI = magnetic source imaging; VNS = vagus nerve stimulation.

Article Information

Address correspondence to: Frederick A. Boop, M.D., Semmes-Murphey Clinic, 6325 Humphreys Boulevard, Memphis, Tennessee 38120. email:

Please include this information when citing this paper: published online June 22, 2012; DOI: 10.3171/2012.4.PEDS11301.

© AANS, except where prohibited by US copyright law.



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    Axial T2-weighted MRI studies showing abnormalities (arrows) within the left anterior temporal lobe suggestive of cortical dysplasia.

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    Axial MEG images showing epileptiform discharges localized to the left temporal lobe. The yellow triangle designates the epilepsy dipoles, and the red crosshairs denote the receptive language areas.

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    Axial T2-weighted MRI study showing left temporal lobectomy, with resection extending back to 6.5 cm on the superior temporal gyrus and 7.5 cm on the middle and inferior temporal gyri.

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    Axial CT (A), FLAIR MRI (B), and T2-weighted MRI (C) studies showing calcification and dysplastic cortex (arrows) in the left temporoparietal area.

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    Axial MEG/MSI data, with yellow triangles representing epileptiform dipoles and red circles representing receptive language area. the left temporoparietal area.

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    Axial T2-weighted (left) and coronal FLAIR (right) MRI studies showing the extent of resection and no evidence of residual disease.


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