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S10-6 MEG and intracranial video EEG in pediatric neocortical epilepsy
29th International Congress of Clinical Neurophysiology to EEG. However, MEG is almost exclusively sensitive to signals from tangential and oblique sources and mainly reflects activities from fissural or basal pyramidal cells. In contrast, EEG depicts activities from sources with variable orientations. EEG signals are dominated by activities of neurons with radial orientation located in the gyral crowns. Cortical lesions may lead to anatomical changes with abnormal gyration, thus resulting in marked differences between EEG and MEG analysis. Thus, simultaneous recording of EEG with MEG is recommended. S10-3 Simultaneous recordings of interictal discharges through MEG and subdural electrodes (iEEG) A.C. Papanicolaou1 , E.M. Castillo1 1 University of Texas Medical School, USA Data of simultaneous recordings of interictal discharges using subdural electrode grids and MEG from six consecutive epilepsy surgery candidates will be presented and discussed. The purpose of these recordings was to assess the sensitivity of MEG to interictal discharges arising from the ictal onset zone (as determined by ictal EEG, both invasive and non-invasive) with the ultimate goal of assessing the degree to which interictal MEG can identify the ictal onset zone. Preliminary analysis of the data reveals that 30% of the 859 interictal discharges recorded by the grid electrodes were also visible in the MEG record and 43 of those originated in the ictal onset zone. The implication of these findings for assessing objectivity the degree to which interictal MEG may be expected to specify the ictal onset zone will be discussed. S10-4 Spatial and temporal dynamics of language-related and face recognition brain functions by electrocorticogram and MEG K. Kamada1 , N. Kunii2 , T. Ota2 , K. Kawai2 , N. Saito2 Department of Neurosurgery, Asahikawa Medical College, 2 Neurosurgery, The University of Tokyo
1
We validated the ECoG results with semantic tasks by electrical cortical stimulation (ECS). Thirty-two patients underwent implantation of subdural electrodes bilaterally for diagnostic. Purpose. SemanticECoG was recorded with word, figure and face recognition and memory tasks. The ECoG raw data was processed by averaging and timefrequency analysis. ECS was applied to identify the eloquent areas of language- and memory-related functions. Simultaneous recording of ECoG and MEG with spontaneous state and semantic tasks was recorded to compare the source localization The basal temporal-occipital cortex was activated within 250 msec after visual object presentations. Face stimulation evoked significantly higher ECoG amplitudes than other stimuli. The superior temporal and inferior frontal regions were alternatively activated until 800 msec with the word recognition. Profiles of semantic MEG showed similar with those of ECoG. Time-frequency analysis showed three major spots with increased gamma-band activity in the frontal, posterior temporal and temporal base. Semantic MEG demonstrated decrease of lower frequency bands between 20 and 40 Hz. ECS to the Gamma-band ECoG spots induced impairment of specific cognitive functions. Semantic-ECoG is a powerful technique to detect and decode the human brain functions. S10-5 Electrophysiological signatures of language impairment in autism spectrum disorders: developmental trajectory and correlation with clinical indices T.P.L. Roberts1 1 University of Pennsylvania School of Medicine, USA Language impairment (LI) is a core aspect of the autism phenotype. Abnormal auditory processing has been suggested as a neural underpinning of such impairment. MEG determination of evoked response latencies to (i) isolated tones, and (ii) oddball paradigms of differing sounds is used to index successive stages of auditory processing. Separately, diffusion tensor imaging (DTI) is used to assess integrity of auditory pathway white matter tracts (acoustic radiations). 100 children (6 15 years; ~40 typically developing; ~60 ASD) underwent MEG recording and DTI study using a 275-channel biomagnetometer (VSM MedTech) and a 3T Siemens Verio™ MRI and a diffusion weighted imaging sequence with 30 non-collinear encoding directions and 2 mm isotropic spatial resolution. Clinical determination of LI was assessed behaviorally
S21 using the Clinical Evaluation of Language Fundamentals-IV (CELF-4) test, using a standardized score of <85 to indicate impairment. Main findings are: (1) delayed M100 response latencies (~10 20 ms) in children with ASD vs. typically-developing peers; this does not distinguish children with ASD with and without LI. (2) Delayed “normalization” of M100 latency with developmental age in children with ASD vs. M100 latency shortens with age in both typically-developing peers groups, but at a slower rate in ASD. The age-mediated M100 latency in typical development is associated with increasing fractional anisotropy of the acoustic radiations (interpreted as an index of white matter integrity/maturation). (3) MMF latencies are prolonged in children with ASD, but this effect is especially pronounced in children with ASD with LI (~50 ms). An age-covaried mixed-model with hemisphere (2), tone (2) and group (3) found a main effect of group, with pair-wise comparisons all significant indicating resolution of ASD with LI from ASD without LI and from typical development. Electrophysiological measures of auditory processing at various stages may offer diagnostic insight with early responses discriminating ASD per se, and later responses showing resolution of LI sub-groups. S10-6 MEG and intracranial video EEG in pediatric neocortical epilepsy H. Otsubo1 The Hospital for Sick Children, Canada
1
Clinical applications of MEG in children include the evaluation and treatment of intractable epilepsy. We reviewed interictal MEG spike sources (MEGSS) with ictal findings on intracranial video EEG (IVEEG) for epilepsy surgery in children with intractable neocortical epilepsy. We classified the distributions of MEGSSs. Clustered MEGSSs consisted of <6 MEGSSs with >1 cm distance. Scattered MEGSSs consisted <6 MEGSSs or regardless MEGSSs with >1 cm distance. Using 3D surface rendering MRI we compared the distributions of MEGSSs with those of ictal high frequency oscillations (HFOs). We analyzed correlations among the surgical resection area, MEGSSs, ictal HFOs and surgical oucome. The clustered MEGSSs were localized within the ictal onset zone with ictal HFOs in most cases. The extent of ictal symptomatic zone with consecutive HFOs were not overlapped with clustered MEGSSs, but along with scattered MEGSSs in some cases. The complete resection of clustered MEGSSs and maximum resection of the ictal zone with faster and higher power of HFOs provided seizure free outcome. The distribution of clustered MEGSSs indicated the ictal onset zone and the epileptogenic zone with ictal HFOs. The extended HFOs during clinical seizures beyond clustered MEGSSs might be explained by different states between MEG and IVEEG including seizures and medications. S11. Clinical application of rTMS S11-1 Safety of TMS S. Rossi1,2,3,4,5 1 Department of Neuroscience, Unit of Neurology, University of Siena, Siena, Italy, 2 Unit of Neurology, Florence Health Authority, Florence, Italy, 3 Department of Psychology, University of Florence, Florence, Italy, 4 Department of Neuroscience, Unit of Psychiatry, University of Siena, Siena, Italy, 5 Salute-Vita University, San Raffaele Hospital, Milano, Italy A consensus conference, which took place in Certosa di Pontignano, Siena (Italy) was organized on behalf of the International Federation of Clinical Neurophysiology, to update the previous safety guidelines for the application of transcranial magnetic stimulation (TMS) in research and clinical settings. In these years the number of applications of conventional TMS has grown impressively, new paradigms of stimulation have been developed (e.g., patterned repetitive TMS) and technical advances have led to new device designs and to the real-time integration of TMS with electroencephalography (EEG), positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). Thousands of healthy subjects and patients with various neurological and psychiatric diseases have undergone TMS allowing a better assessment of relative risks. The occurrence of seizures (i.e., the most serious TMS-related acute adverse effect) has been extremely rare, with most of the few new cases receiving rTMS exceeding previous guidelines, often in patients under treatment with drugs which potentially lower the seizure threshold. Here, some these and some other issues will be briefly revised: risk
1
We validated the ECoG results with semantic tasks by electrical cortical stimulation (ECS). Thirty-two patients underwent implantation of subdural electrodes bilaterally for diagnostic. Purpose. SemanticECoG was recorded with word, figure and face recognition and memory tasks. The ECoG raw data was processed by averaging and timefrequency analysis. ECS was applied to identify the eloquent areas of language- and memory-related functions. Simultaneous recording of ECoG and MEG with spontaneous state and semantic tasks was recorded to compare the source localization The basal temporal-occipital cortex was activated within 250 msec after visual object presentations. Face stimulation evoked significantly higher ECoG amplitudes than other stimuli. The superior temporal and inferior frontal regions were alternatively activated until 800 msec with the word recognition. Profiles of semantic MEG showed similar with those of ECoG. Time-frequency analysis showed three major spots with increased gamma-band activity in the frontal, posterior temporal and temporal base. Semantic MEG demonstrated decrease of lower frequency bands between 20 and 40 Hz. ECS to the Gamma-band ECoG spots induced impairment of specific cognitive functions. Semantic-ECoG is a powerful technique to detect and decode the human brain functions. S10-5 Electrophysiological signatures of language impairment in autism spectrum disorders: developmental trajectory and correlation with clinical indices T.P.L. Roberts1 1 University of Pennsylvania School of Medicine, USA Language impairment (LI) is a core aspect of the autism phenotype. Abnormal auditory processing has been suggested as a neural underpinning of such impairment. MEG determination of evoked response latencies to (i) isolated tones, and (ii) oddball paradigms of differing sounds is used to index successive stages of auditory processing. Separately, diffusion tensor imaging (DTI) is used to assess integrity of auditory pathway white matter tracts (acoustic radiations). 100 children (6 15 years; ~40 typically developing; ~60 ASD) underwent MEG recording and DTI study using a 275-channel biomagnetometer (VSM MedTech) and a 3T Siemens Verio™ MRI and a diffusion weighted imaging sequence with 30 non-collinear encoding directions and 2 mm isotropic spatial resolution. Clinical determination of LI was assessed behaviorally
S21 using the Clinical Evaluation of Language Fundamentals-IV (CELF-4) test, using a standardized score of <85 to indicate impairment. Main findings are: (1) delayed M100 response latencies (~10 20 ms) in children with ASD vs. typically-developing peers; this does not distinguish children with ASD with and without LI. (2) Delayed “normalization” of M100 latency with developmental age in children with ASD vs. M100 latency shortens with age in both typically-developing peers groups, but at a slower rate in ASD. The age-mediated M100 latency in typical development is associated with increasing fractional anisotropy of the acoustic radiations (interpreted as an index of white matter integrity/maturation). (3) MMF latencies are prolonged in children with ASD, but this effect is especially pronounced in children with ASD with LI (~50 ms). An age-covaried mixed-model with hemisphere (2), tone (2) and group (3) found a main effect of group, with pair-wise comparisons all significant indicating resolution of ASD with LI from ASD without LI and from typical development. Electrophysiological measures of auditory processing at various stages may offer diagnostic insight with early responses discriminating ASD per se, and later responses showing resolution of LI sub-groups. S10-6 MEG and intracranial video EEG in pediatric neocortical epilepsy H. Otsubo1 The Hospital for Sick Children, Canada
1
Clinical applications of MEG in children include the evaluation and treatment of intractable epilepsy. We reviewed interictal MEG spike sources (MEGSS) with ictal findings on intracranial video EEG (IVEEG) for epilepsy surgery in children with intractable neocortical epilepsy. We classified the distributions of MEGSSs. Clustered MEGSSs consisted of <6 MEGSSs with >1 cm distance. Scattered MEGSSs consisted <6 MEGSSs or regardless MEGSSs with >1 cm distance. Using 3D surface rendering MRI we compared the distributions of MEGSSs with those of ictal high frequency oscillations (HFOs). We analyzed correlations among the surgical resection area, MEGSSs, ictal HFOs and surgical oucome. The clustered MEGSSs were localized within the ictal onset zone with ictal HFOs in most cases. The extent of ictal symptomatic zone with consecutive HFOs were not overlapped with clustered MEGSSs, but along with scattered MEGSSs in some cases. The complete resection of clustered MEGSSs and maximum resection of the ictal zone with faster and higher power of HFOs provided seizure free outcome. The distribution of clustered MEGSSs indicated the ictal onset zone and the epileptogenic zone with ictal HFOs. The extended HFOs during clinical seizures beyond clustered MEGSSs might be explained by different states between MEG and IVEEG including seizures and medications. S11. Clinical application of rTMS S11-1 Safety of TMS S. Rossi1,2,3,4,5 1 Department of Neuroscience, Unit of Neurology, University of Siena, Siena, Italy, 2 Unit of Neurology, Florence Health Authority, Florence, Italy, 3 Department of Psychology, University of Florence, Florence, Italy, 4 Department of Neuroscience, Unit of Psychiatry, University of Siena, Siena, Italy, 5 Salute-Vita University, San Raffaele Hospital, Milano, Italy A consensus conference, which took place in Certosa di Pontignano, Siena (Italy) was organized on behalf of the International Federation of Clinical Neurophysiology, to update the previous safety guidelines for the application of transcranial magnetic stimulation (TMS) in research and clinical settings. In these years the number of applications of conventional TMS has grown impressively, new paradigms of stimulation have been developed (e.g., patterned repetitive TMS) and technical advances have led to new device designs and to the real-time integration of TMS with electroencephalography (EEG), positron emission tomography (PET) and functional magnetic resonance imaging (fMRI). Thousands of healthy subjects and patients with various neurological and psychiatric diseases have undergone TMS allowing a better assessment of relative risks. The occurrence of seizures (i.e., the most serious TMS-related acute adverse effect) has been extremely rare, with most of the few new cases receiving rTMS exceeding previous guidelines, often in patients under treatment with drugs which potentially lower the seizure threshold. Here, some these and some other issues will be briefly revised: risk