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Localization of epileptic foci in children with intractable epilepsy secondary to multiple cortical tubers by using synthetic aperture magnetometry kurtosis.
J Neurosurg Pediatr. 2009 Dec; 4(6):515-22.JN

Abstract

OBJECT

Magnetoencephalography (MEG) has been typically used to localize epileptic activity by modeling interictal activity as equivalent current dipoles (ECDs). Synthetic aperture magnetometry (SAM) is a recently developed adaptive spatial filtering algorithm for MEG that provides some advantages over the ECD approach. The SAM-kurtosis algorithm (also known as SAM[g2]) additionally provides automated temporal detection of spike sources by using excess kurtosis value (steepness of epileptic spike on virtual sensors). To evaluate the efficacy of the SAM(g2) method, the authors applied it to readings obtained in children with intractable epilepsy secondary to tuberous sclerosis complex (TSC), and compared them to localizations obtained with ECDs.

METHODS

The authors studied 13 children with TSC (7 girls) whose ages ranged from 13 months to 16.3 years (mean 7.3 years). Video electroencephalography, MR imaging, and MEG studies were analyzed. A single ECD model was applied to localize ECD clusters. The SAM(g2) value was calculated at each SAM(g2) virtual voxel in the patient's MR imaging-defined brain volume. The authors defined the epileptic voxels of SAM(g2) (evSAM[g2]) as those with local peak kurtosis values higher than half of the maximum. A clustering of ECDs had to contain > or = 6 ECDs within 1 cm of each other, and a grouping of evSAM(g2)s had to contain > or = 3 evSAM(g2)s within 1 cm of each other. The authors then compared both ECD clusters and evSAM(g2) groups with the resection area and correlated these data with seizure outcome.

RESULTS

Seizures started when patients were between 6 weeks and 8 years of age (median 6 months), and became intractable secondary to multiple tubers in all cases. Ictal onset on scalp video electroencephalography was lateralized in 8 patients (62%). The MEG studies showed multiple ECD clusters in 7 patients (54%). The SAM(g2) method showed multiple groups of epileptic voxels in 8 patients (62%). Colocalization of grouped evSAM(g2) with ECD clusters ranged from 20 to 100%, with a mean of 82%. Eight patients underwent resection of single (1 patient) and multiple (7 patients) lobes, with 6 patients achieving freedom from seizures. Of 8 patients who underwent surgery, in 7 the resection area covered ECD clusters and grouped evSAM(g2)s. In the remaining patient the resection area partially included the ECD cluster and grouped evSAM(g2)s. Six of the 7 patients became seizure free.

CONCLUSIONS

The combination of SAM(g2) and ECD analyses succeeded in localizing the complex epileptic zones in children with TSC who had intractable epilepsy secondary to multiple cortical tubers. For the subset of children with TSC who present with early-onset and nonlateralized seizures, MEG studies in which SAM(g2) and ECD are used might identify suitable candidates for resection to control seizures.

Authors+Show Affiliations

Divisions of Neurology, The Hospital for Sick Children, University of Toronto, Ontario, Canada.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Case Reports
Comparative Study
Evaluation Study
Journal Article

Language

eng

PubMed ID

19951036

Citation

Sugiyama, Ichiro, et al. "Localization of Epileptic Foci in Children With Intractable Epilepsy Secondary to Multiple Cortical Tubers By Using Synthetic Aperture Magnetometry Kurtosis." Journal of Neurosurgery. Pediatrics, vol. 4, no. 6, 2009, pp. 515-22.
Sugiyama I, Imai K, Yamaguchi Y, et al. Localization of epileptic foci in children with intractable epilepsy secondary to multiple cortical tubers by using synthetic aperture magnetometry kurtosis. J Neurosurg Pediatr. 2009;4(6):515-22.
Sugiyama, I., Imai, K., Yamaguchi, Y., Ochi, A., Akizuki, Y., Go, C., Akiyama, T., Snead, O. C., Rutka, J. T., Drake, J. M., Widjaja, E., Chuang, S. H., Cheyne, D., & Otsubo, H. (2009). Localization of epileptic foci in children with intractable epilepsy secondary to multiple cortical tubers by using synthetic aperture magnetometry kurtosis. Journal of Neurosurgery. Pediatrics, 4(6), 515-22. https://doi.org/10.3171/2009.7.PEDS09198
Sugiyama I, et al. Localization of Epileptic Foci in Children With Intractable Epilepsy Secondary to Multiple Cortical Tubers By Using Synthetic Aperture Magnetometry Kurtosis. J Neurosurg Pediatr. 2009;4(6):515-22. PubMed PMID: 19951036.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Localization of epileptic foci in children with intractable epilepsy secondary to multiple cortical tubers by using synthetic aperture magnetometry kurtosis. AU - Sugiyama,Ichiro, AU - Imai,Katsumi, AU - Yamaguchi,Yu, AU - Ochi,Ayako, AU - Akizuki,Yoko, AU - Go,Cristina, AU - Akiyama,Tomoyuki, AU - Snead,O Carter,3rd AU - Rutka,James T, AU - Drake,James M, AU - Widjaja,Elysa, AU - Chuang,Sylvester H, AU - Cheyne,Doug, AU - Otsubo,Hiroshi, PY - 2009/12/3/entrez PY - 2009/12/3/pubmed PY - 2009/12/25/medline SP - 515 EP - 22 JF - Journal of neurosurgery. Pediatrics JO - J Neurosurg Pediatr VL - 4 IS - 6 N2 - OBJECT: Magnetoencephalography (MEG) has been typically used to localize epileptic activity by modeling interictal activity as equivalent current dipoles (ECDs). Synthetic aperture magnetometry (SAM) is a recently developed adaptive spatial filtering algorithm for MEG that provides some advantages over the ECD approach. The SAM-kurtosis algorithm (also known as SAM[g2]) additionally provides automated temporal detection of spike sources by using excess kurtosis value (steepness of epileptic spike on virtual sensors). To evaluate the efficacy of the SAM(g2) method, the authors applied it to readings obtained in children with intractable epilepsy secondary to tuberous sclerosis complex (TSC), and compared them to localizations obtained with ECDs. METHODS: The authors studied 13 children with TSC (7 girls) whose ages ranged from 13 months to 16.3 years (mean 7.3 years). Video electroencephalography, MR imaging, and MEG studies were analyzed. A single ECD model was applied to localize ECD clusters. The SAM(g2) value was calculated at each SAM(g2) virtual voxel in the patient's MR imaging-defined brain volume. The authors defined the epileptic voxels of SAM(g2) (evSAM[g2]) as those with local peak kurtosis values higher than half of the maximum. A clustering of ECDs had to contain > or = 6 ECDs within 1 cm of each other, and a grouping of evSAM(g2)s had to contain > or = 3 evSAM(g2)s within 1 cm of each other. The authors then compared both ECD clusters and evSAM(g2) groups with the resection area and correlated these data with seizure outcome. RESULTS: Seizures started when patients were between 6 weeks and 8 years of age (median 6 months), and became intractable secondary to multiple tubers in all cases. Ictal onset on scalp video electroencephalography was lateralized in 8 patients (62%). The MEG studies showed multiple ECD clusters in 7 patients (54%). The SAM(g2) method showed multiple groups of epileptic voxels in 8 patients (62%). Colocalization of grouped evSAM(g2) with ECD clusters ranged from 20 to 100%, with a mean of 82%. Eight patients underwent resection of single (1 patient) and multiple (7 patients) lobes, with 6 patients achieving freedom from seizures. Of 8 patients who underwent surgery, in 7 the resection area covered ECD clusters and grouped evSAM(g2)s. In the remaining patient the resection area partially included the ECD cluster and grouped evSAM(g2)s. Six of the 7 patients became seizure free. CONCLUSIONS: The combination of SAM(g2) and ECD analyses succeeded in localizing the complex epileptic zones in children with TSC who had intractable epilepsy secondary to multiple cortical tubers. For the subset of children with TSC who present with early-onset and nonlateralized seizures, MEG studies in which SAM(g2) and ECD are used might identify suitable candidates for resection to control seizures. SN - 1933-0715 UR - https://www.unboundmedicine.com/medline/citation/19951036/Localization_of_epileptic_foci_in_children_with_intractable_epilepsy_secondary_to_multiple_cortical_tubers_by_using_synthetic_aperture_magnetometry_kurtosis_ DB - PRIME DP - Unbound Medicine ER -