Magnetoencephalography in Patients with Tuberous Sclerosis and Localization‐related Epilepsy

Abstract

Summary:Purpose: To clarify the usefulness of magnetoencephalography (MEG) for diagnosis of the spatial relations between spike foci and suspicious epileptogenic tubers on MRI in patients with tuberous sclerosis (TS) and to compare MEG spike foci with single-photon emission computed tomography (SPECT) findings.Methods: We analyzed magnetic fields of epileptic spike discharges in 15 patients with TS and localization-related epilepsy (LRE) by using MEG (a whole-head 204-channel magnetometer system). We investigated the spatial relation between the equivalent current dipoles (ECDs) of interictal spike discharges and visible cortical tubers on MRI. We also compared results of MEG and MRI with SPECT findings.Results: MEG detected a cluster of ECDs around one cortical tuber in six of 15 patients and clusters of ECDs around two cortical tubers in five patients. Interictal SPECT was disappointing in detection of epileptic foci in TS. However, MEG spike foci showed spatial consistency with ictal hyperperfusion areas in two patients. Three patients with single ECD clusters underwent surgical treatment: two have been seizure free, and one has obtained seizure reduction of >90%.Conclusions: ECDs were located around visible tuber nodules. MEG enabled precise localization of the epileptic foci and provided crucial information for surgical treatment in patients with TS and partial epilepsy. TS patients showing a single ECD cluster on MEG may be appropriate candidates for surgical treatment.

Analysis of the dynamics and origin of epileptic activity in patients with tuberous sclerosis evaluated for surgery of epilepsy

“…In clinical neurophysiology the analysis of ictal EEG, which is of fundamental importance for the selection of patients for surgery of epilepsy, has lagged behind the analysis of the interictal spikes (Jansen et al, 2006; Iida et al, 2005; Kamimura et al, 2006;Sperli et al, 2006) mainly due to the poorer signal to noise ratio (SNR). Several additional factors contribute to this, but the more important ones are the movement and EMG artifacts induced by the ictal behavioral manifestations and also the dynamic character of the epileptic activity which spreads to various brain areas using complex and poorly understood pathways.…”

Magnetoencephalography for Pediatric Epilepsy: How We Do It

“…One or 2 language tests are administered via a video screen placed in front of the patient: picture-naming (via the modified Boston Diagnostic Aphasia Examination) and word recall, to evaluate event-related desynchronization (ERD) in the alpha (8 -15 Hz), beta (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), and low gamma (25-50 Hz) bands associated with linguistic computation in a 500-ms latency range immediately before the patient's behavioral response. 39 Visual assessment of hemispheric differences in ERD is made for frontal and posterior temporal regions (Broca and Wernicke areas, respectively).…”

“…MEG localization is particularly valuable when an anatomic lesion cannot be found, even on high-field thin-section volumetric brain MR imaging, [20][21][22][23][24] as well as when multifocal or diffuse disease is clinically suggested. 15,16,22,[25][26][27][28][29][30][31] Our experience with MEG in pediatric patients with epilepsy studied at our institution is reviewed. We compare the localization of the IOZ and functional cortex on the basis of traditional evaluation (including clinical seizure features, interictal electroencephalography [EEG], ictal EEG, MR imaging, nuclear imaging, neuropsychological testing, Wada procedure, and functional cortical mapping) with localization on MEG.…”

α-[ 11 C]-Methyl- l -tryptophan–PET in 191 patients with tuberous sclerosis complex

“…Interictal magnetoencephalography has also been used. 11 We previously reported, in a relatively small number of patients with TSC, that a-[ 11 C]-methyl-Ltryptophan (AMT)-PET scanning may differentiate between epileptogenic tubers (high AMT uptake) and nonepileptogenic tubers (low AMT uptake) and that the location of high AMT uptake corresponds to the seizure focus on EEG. 6,12,13 …”

“…Interictal magnetoencephalography has also been used. 11 We previously reported, in a relatively small number of patients with TSC, that a-[ 11 C]-methyl-Ltryptophan (AMT)-PET scanning may differentiate between epileptogenic tubers (high AMT uptake) and nonepileptogenic tubers (low AMT uptake) and that the location of high AMT uptake corresponds to the seizure focus on EEG. 6,12,13 The present study was performed in 191 patients with TSC and intractable epilepsy who underwent AMT-PET during epilepsy surgery evaluation to address whether i) presence of increased AMT uptake is related to duration of seizure intractability, ii) increased AMT uptake in epileptogenic tubers is related to specific TSC gene mutations, and iii) there is concordance between areas of increased AMT uptake and seizure lateralization/localization on scalp EEG.…”