Localization of epileptic foci in children with intractable epilepsy secondary to multiple cortical tubers by using synthetic aperture magnetometry kurtosis: Clinical article

Ichiro Sugiyama, Katsumi Imai, Yu Yamaguchi, Ayako Ochi, Yoko Akizuki, Cristina Go, Tomoyuki Akiyama, O. Carter Snead, James T. Rutka, James M. Drake, Elysa Widjaja, Sylvester H. Chuang, Doug Cheyne, Hiroshi Otsubo

Research output: Contribution to journalArticle

29 Citations (Scopus)

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 ≥ 6 ECDs within 1 cm of each other, and a grouping of evSAM(g2)s had to contain ≥ 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.

Original languageEnglish
Pages (from-to)515-522
Number of pages8
JournalJournal of Neurosurgery: Pediatrics
Volume4
Issue number6
DOIs
Publication statusPublished - Dec 2009
Externally publishedYes

Fingerprint

Magnetometry
Magnetoencephalography
Seizures
Tuberous Sclerosis
Drug Resistant Epilepsy
Electroencephalography
Scalp
Neuroimaging

Keywords

  • Epilepsy surgery
  • Equivalent current dipole
  • Intractable epilepsy
  • Magnetoencephalography
  • Synthetic aperture magnetometry-kurtosis
  • Tuberous sclerosis complex

ASJC Scopus subject areas

  • Clinical Neurology
  • Surgery
  • Pediatrics, Perinatology, and Child Health
  • Medicine(all)

Cite this

Localization of epileptic foci in children with intractable epilepsy secondary to multiple cortical tubers by using synthetic aperture magnetometry kurtosis : Clinical article. / Sugiyama, Ichiro; Imai, Katsumi; Yamaguchi, Yu; Ochi, Ayako; Akizuki, Yoko; Go, Cristina; Akiyama, Tomoyuki; Snead, O. Carter; Rutka, James T.; Drake, James M.; Widjaja, Elysa; Chuang, Sylvester H.; Cheyne, Doug; Otsubo, Hiroshi.

In: Journal of Neurosurgery: Pediatrics, Vol. 4, No. 6, 12.2009, p. 515-522.

Research output: Contribution to journalArticle

Sugiyama, I, Imai, K, Yamaguchi, Y, Ochi, A, Akizuki, Y, Go, C, Akiyama, T, Snead, OC, Rutka, JT, Drake, JM, Widjaja, E, Chuang, SH, 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: Clinical article', Journal of Neurosurgery: Pediatrics, vol. 4, no. 6, pp. 515-522. https://doi.org/10.3171/2009.7.PEDS09198
Sugiyama, Ichiro ; Imai, Katsumi ; Yamaguchi, Yu ; Ochi, Ayako ; Akizuki, Yoko ; Go, Cristina ; Akiyama, Tomoyuki ; Snead, O. Carter ; Rutka, James T. ; Drake, James M. ; Widjaja, Elysa ; Chuang, Sylvester H. ; Cheyne, Doug ; Otsubo, Hiroshi. / Localization of epileptic foci in children with intractable epilepsy secondary to multiple cortical tubers by using synthetic aperture magnetometry kurtosis : Clinical article. In: Journal of Neurosurgery: Pediatrics. 2009 ; Vol. 4, No. 6. pp. 515-522.
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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 ≥ 6 ECDs within 1 cm of each other, and a grouping of evSAM(g2)s had to contain ≥ 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.",
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author = "Ichiro Sugiyama and Katsumi Imai and Yu Yamaguchi and Ayako Ochi and Yoko Akizuki and Cristina Go and Tomoyuki Akiyama and Snead, {O. Carter} and Rutka, {James T.} and Drake, {James M.} and Elysa Widjaja and Chuang, {Sylvester H.} and Doug Cheyne and Hiroshi Otsubo",
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TY - JOUR

T1 - Localization of epileptic foci in children with intractable epilepsy secondary to multiple cortical tubers by using synthetic aperture magnetometry kurtosis

T2 - Clinical article

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

AU - Rutka, James T.

AU - Drake, James M.

AU - Widjaja, Elysa

AU - Chuang, Sylvester H.

AU - Cheyne, Doug

AU - Otsubo, Hiroshi

PY - 2009/12

Y1 - 2009/12

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 ≥ 6 ECDs within 1 cm of each other, and a grouping of evSAM(g2)s had to contain ≥ 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.

AB - 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 ≥ 6 ECDs within 1 cm of each other, and a grouping of evSAM(g2)s had to contain ≥ 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.

KW - Epilepsy surgery

KW - Equivalent current dipole

KW - Intractable epilepsy

KW - Magnetoencephalography

KW - Synthetic aperture magnetometry-kurtosis

KW - Tuberous sclerosis complex

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