Magnetoencephalography spike sources interrelate the extensive epileptogenic zone of tuberous sclerosis complex.
We hypothesized that the extensive epileptic network in patients with tuberous sclerosis complex (TSC) manifests as clustered and scattered distributions of magnetoencephalography spike sources (MEGSS).



We retrospectively analyzed pre-surgical MEG in 15 patients with TSC. We performed single moving dipole analysis to localize and classify clustered and scattered MEGSS. We compared the number of electrodes within the resected area (RA) and the proportions of clustered and scattered MEGSS within RA with the seizure outcome.



The number of electrodes within RA ranged from 29 to 83 (mean=51). The MEGSS were distributed over multiple lobes (3-8; mean=5.9) and bilaterally in 14 patients. Clusters of MEGSS ranged from 1 to 4 (mean=1.4). The number of MEGSS ranged in total from 28 to 139 (mean=70); in the clusters, 10-128 (mean=49); and in the scatters, 0-45 (mean=21). Four patients achieved an Engel class I surgical outcome, four, a class II outcome; five, a class III outcome; and two, a class IV outcome. The proportion of MEGSS ranged in total from 0 to 92% (mean=57%) within RA; 0-100% (mean=67%) in the resection hemisphere; 0-100% (mean=63%) in the clusters; and 0-81% (mean=28%) in the scatters. Univariate ordinal logistic regression analyses showed that the proportion of scattered MEGSS within RA (p=0.049) significantly correlated with seizure outcomes. Multivariate analyses using three covariates (number of electrodes, proportions of clustered and scattered MEGSS within RA) showed that only the proportion of scattered MEGSS within RA significantly correlated with seizure outcomes (p=0.016).



MEG data showed a wide distribution of multilobar MEGSS in patients with TSC. The seizure outcome was not related to the clustered MEGSS within RA, since the grids were essentially planned to cover and resect the clustered MEGSS surrounding tubers. The maximal possible resection of scattered MEGSS correlated with improved seizure outcome in TSC. Some parts of the epileptogenic zone disrupted by multiple tubers did not have a sufficiently large area to produce clustered MEGSS. Although the wide distribution of scattered MEGSS is not interpreted as epileptogenic, they might be interrelated with clustered MEGSS to project a complex epilepsy network and be part of the extensive epileptogenic zones found in TSC.
Division of Neurology, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada. Electronic address: okanishipediatrics@gmail.com.
Tohru
T
Okanishi
Division of Neurology, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada; Department of Child Neurology, Okayama University Hospital, PO Box 700, 0914 Okayama, Japan.
Tomoyuki
T
Akiyama
Division of Neurology, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada.
Ellen
E
Mayo
Division of Neurology, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada.
Yasunori
Y
Honda
Division of Neurology, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada.
Chihiro
C
Ueda-Kawada
Division of Neurology, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada.
Midori
M
Nakajima
Department of General Internal Medicine, Seirei-Hamamatsu General Hospital, PO Box 430, 8558, Hamamatsu, Shizuoka, Japan.
Yoichiro
Y
Homma
Division of Neurology, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada.
Ayako
A
Ochi
Division of Neurology, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada.
Cristina
C
Go
Division of Diagnostic Imaging, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada.
Elysa
E
Widjaja
Division of Diagnostic Imaging, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada.
Sylvester H
SH
Chuang
Division of Neurosurgery, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada.
James T
JT
Rutka
Division of Neurosurgery, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada.
James
J
Drake
Division of Neurology, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada.
O Carter
OC
Snead
Division of Neurology, The Hospital for Sick Children, PO Box M5G, 1X8, Toronto, Ontario, Canada.
Hiroshi
H
Otsubo
D000293:Adolescent; D001921:Brain / Q000503:physiopathology* / Q000601:surgery; D002648:Child; D002675:Child, Preschool; D000069279:Drug Resistant Epilepsy / Q000209:etiology / Q000503:physiopathology* / Q000601:surgery; D000069280:Electrocorticography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D015999:Multivariate Analysis; D011300:Preoperative Care; D012189:Retrospective Studies; D012640:Seizures / Q000209:etiology / Q000503:physiopathology / Q000601:surgery; D016896:Treatment Outcome; D014402:Tuberous Sclerosis / Q000150:complications / Q000503:physiopathology* / Q000601:surgery
Epilepsy surgery; Epileptic network; Intractable epilepsy; Magnetoencephalography; Seizure outcome; Tuberous sclerosis complex