Magnetoencephalography-guided resection of epileptogenic foci in children

Clinical article

Full access

Object

Resective surgery is increasingly used in the management of pediatric epilepsy. Frequently, invasive monitoring with subdural electrodes is required to adequately map the epileptogenic focus. The risks of invasive monitoring include the need for 2 operations, infection, and CSF leak. The aim of this study was to evaluate the feasibility and outcomes of resective epilepsy surgery guided by magnetoencephalography (MEG) in children who would have otherwise been candidates for electrode implantation.

Methods

The authors reviewed the records of patients undergoing resective epilepsy surgery at the Hospital for Sick Children between 2001 and 2010. They identified cases in which resections were based on MEG data and no intracranial recordings were performed. Each patient's chart was reviewed for presentation, MRI findings, MEG findings, surgical procedure, pathology, and surgical outcome.

Results

Sixteen patients qualified for the study. All patients had localized spike clusters on MEG and most had abnormal findings on MRI. Resection was carried out in each case based on the MEG data linked to neuronavigation and supplemented with intraoperative neuromonitoring. Overall, 62.5% of patients were seizure free following surgery, and 20% of patients experienced an improvement in seizures without attaining seizure freedom. In 2 cases, additional surgery was performed subsequently with intracranial monitoring in attempts to obtain seizure control.

Conclusions

MEG is a viable alternative to invasive monitoring with intracranial electrodes for planning of resective surgery in carefully selected pediatric patients with localization-related epilepsy. Good candidates for this approach include patients who have a well-delineated, localized spike cluster on MEG that is concordant with findings of other preoperative evaluations and patients with prior brain pathologies that make the implantation of subdural and depth electrodes somewhat problematic.

Abbreviations used in this paper:EEG = electroencephalography; fMRI = functional MRI; MEG = magnetoencephalography; PET = positron emission tomography; SPECT = single-photon emission CT; VEEG = video EEG.

Object

Resective surgery is increasingly used in the management of pediatric epilepsy. Frequently, invasive monitoring with subdural electrodes is required to adequately map the epileptogenic focus. The risks of invasive monitoring include the need for 2 operations, infection, and CSF leak. The aim of this study was to evaluate the feasibility and outcomes of resective epilepsy surgery guided by magnetoencephalography (MEG) in children who would have otherwise been candidates for electrode implantation.

Methods

The authors reviewed the records of patients undergoing resective epilepsy surgery at the Hospital for Sick Children between 2001 and 2010. They identified cases in which resections were based on MEG data and no intracranial recordings were performed. Each patient's chart was reviewed for presentation, MRI findings, MEG findings, surgical procedure, pathology, and surgical outcome.

Results

Sixteen patients qualified for the study. All patients had localized spike clusters on MEG and most had abnormal findings on MRI. Resection was carried out in each case based on the MEG data linked to neuronavigation and supplemented with intraoperative neuromonitoring. Overall, 62.5% of patients were seizure free following surgery, and 20% of patients experienced an improvement in seizures without attaining seizure freedom. In 2 cases, additional surgery was performed subsequently with intracranial monitoring in attempts to obtain seizure control.

Conclusions

MEG is a viable alternative to invasive monitoring with intracranial electrodes for planning of resective surgery in carefully selected pediatric patients with localization-related epilepsy. Good candidates for this approach include patients who have a well-delineated, localized spike cluster on MEG that is concordant with findings of other preoperative evaluations and patients with prior brain pathologies that make the implantation of subdural and depth electrodes somewhat problematic.

Resection of epileptogenic foci has become a widely accepted therapy for the treatment of medically refractory epilepsy in children. A recent review from the University of California, Los Angeles, found a 58% increase in the number of resections performed for epilepsy comparing the decade prior to 1997 to the decade after.7 Contrary to the experience in adult epilepsy surgery, many resections in children are extratemporal, accounting for over 50% of cases.7,12 This difference likely reflects the different pathologies encountered in children, including cortical dysplasia, tumors, tuberous sclerosis, Rasmussen encephalitis, and a number of congenital disorders.2,7,9,12 Temporal lobe resections in adults have proven to be more effective than best medical therapy in a randomized controlled trial.26 No such trial exists in children, but the available evidence suggests that while extratemporal resections are less effective than temporal lobectomy at controlling seizures, outcomes are still favorable with regard to seizure freedom7,12 and quality of life.13

The preoperative evaluation of pediatric patients with epilepsy is critical for proper localization of the seizure focus and maximization of outcome. The Pediatric Epilepsy Surgery Subcommission of the International League Against Epilepsy has proposed guidelines for the evaluation of surgical candidates, including interictal and video electroencephalography (VEEG), structural imaging with MRI and/or CT, functional imaging with single-photon emission CT (SPECT) or positron emission tomography (PET), and neuropsychological evaluation.2 Despite these recommendations, there remains institutional variability in the evaluation of these patients.5 At the Hospital for Sick Children, all patients undergo VEEG in the epilepsy monitoring unit, brain MRI with a 3-T scanner, functional MRI (fMRI), PET, and neuropsychological evaluation. In addition, magnetoencephalography (MEG) is performed on all patients at our institution.

Depending on the results of the noninvasive evaluation, subdural and depth electrodes may be implanted for further characterization of the epileptogenic focus. While these implanted electrodes can provide valuable information for the planning of operative resection, they may be associated with significant risks. Due to the implanted hardware and need for at least 2 operations, infection is a significant risk, reported to be as high as 2.4%. Other risks include CSF leak, intracranial hematoma, and cerebral edema.9,19

MEG is used at the Hospital for Sick Children as a guide for resection in a select group of patients in lieu of invasive monitoring. These patients all have localized spike clusters, as previously described.8 In addition, the results of other noninvasive evaluations are concordant with the MEG data. In these patients, resection may be undertaken in an attempt to avoid implantation of subdural and depth electrodes and proceed directly to resective surgery. Here we report a retrospective review of these cases to determine the success of this approach.

Methods

We reviewed the medical records of patients undergoing resection for the treatment of medically intractable epilepsy at the Hospital for Sick Children. We included patients who had localized spike clusters identified on MEG preoperatively. We excluded patients who underwent invasive electroencephalography (EEG) monitoring or who had seizures secondary to a well-defined lesion on neuroimaging, such as a neoplasm or vascular malformation, who would generally be immediately offered a 1-stage lesionectomy and would not be considered for invasive monitoring. We also excluded patients with mesial temporal sclerosis, given the overall favorable surgical outcome of this condition and the questionable utility of both MEG and invasive monitoring in this circumstance. Finally, we excluded patients for whom a resective strategy with curative intent was not considered. This included patients with hemispheric syndromes and children who underwent palliative procedures such as vagus nerve stimulator implantation and corpus callosotomy.

The records were reviewed for demographic information; details of the seizure history, including previous treatments; the surgical procedure performed and any associated complications; and outcome with regard to seizure control and need for additional interventions. Seizure outcome was recorded according to the Engel classification.3 Pathology reports and imaging studies were also reviewed.

This study was approved by the Research Ethics Board at the Hospital for Sick Children.

Results

We identified 16 patients who met the inclusion criteria. All patients underwent surgery between 2001 and 2010. These patients represent a minority of the epilepsy cases performed at the Hospital for Sick Children each year. Of these patients, 9 (56%) were male. The patients' mean age at the time of surgery was 11.6 years (range 1.6–17.6 years).

All patients underwent preoperative evaluation including brain imaging by MRI and MEG (Fig. 1). Fifteen patients (93.7%) had clear structural lesions on MRI (Table 1). Most of these patients had either presumed cortical dysplasia or postoperative changes from previous surgery. Most of these previous surgeries were prior attempts at surgical control of epilepsy (Cases 7, 8, 10, and 15), although 1 patient had undergone previous resection of a dysembryoplastic neuroepithelial tumor (Case 13).

Fig. 1.
Fig. 1.

A–C: Axial images from preoperative FLAIR MRI (A), preoperative MEG (B), and postoperative CT (C) studies obtained in a 16-year-old female with a history of severe traumatic brain injury with resulting epilepsy. She was seizure free after surgery. D–F: Axial images from preoperative FLAIR MRI (D), preoperative MEG (E), and postoperative CT (F) studies obtained in a 6.8-year-old girl with a history of germinal matrix hemorrhage with resulting cerebral palsy and epilepsy. She was seizure free after surgery.

TABLE 1:

Preoperative evaluation and operative procedure performed in each of the 16 cases*

Case No.SemiologyScalp EEGMRIPETMEG ClustersSurgery
1CPSright temporalnormalright temporal hypometabolismright temporal, parietal inferior frontal spike clustertemporal lobectomy
2CPSleft posteriorleft parietooccipital MCDleft occipital hypometabolismleft posterior spike clusterresection of occipital pole & lateral occipital cortex
3CPS, SPSright posteriorright-sided encephalomalacianot performedright parietooccipital spike clusterparietooccipital clusterectomy
4ISleft posteriorleft occipital heterotopialeft posterior inferomedial temporalperilesional occipital & occipitotemporoparietal clusteroccipital lobectomy
5CPS, sGTCright frontalright mesial frontal lobe MCDnot performedright frontal lobe clusterfrontal lobectomy
6sGTC, CPSright fronto-temporalright diffuse encephalomalacianot performedright inferior frontal/perisylvian clusterresection of frontal operculum/superior temporal gyrus/insula, amygdalohippocampectomy, frontobasal disconnection
7CPS, sGTCright frontalright hemispheric cystic changesnot performedleft inferior frontal clustercompletion of frontal lobectomy
8CPSleft frontalleft frontal gliosisnot performedperilesional cluster, posterior to lesionextension of prior resection (posteriorly)
9SPSleft occipitalleft occipital MCDnot performedleft occipital clusteroccipital lesionectomy
10SPSleft centro-parietalleft frontal post-surgical changesnot performedperilesional spike clusterresection of frontal operculum
11CPS, sGTCleft posterior temporalleft MCA infarctnot performedleft occipital, left parietal, & left inferior frontal spike clustersanterior temporal lobectomy, amygdalohippocampectomy, inferior frontoparietal topectomy, posterior temporal topectomy, anterior occipital topectomy
12sGTCright posteriorright parietooccipital MCDnot performedright occipital spike clusteroccipital lobectomy
13CPS, sGTCperilesional dischargesright frontal post-surgical changesnot performedperi–resection cavity spike clustersuperior temporal & angular topectomies
14ISright frontal dischargesright frontal MCDnot performedperilesional spike clusterfrontal lesionectomy
15IS, CPS, sGTCright hemisphereright temporal gliosisnot performedright temporal lobe spike cluster & perilesional spike clusterinsular & parietal lesionectomies
16CPSunclear originright hemispheric encephalomalacianot performedright frontal spike clusterclusterectomy

CPS = complex partial seizures; IS = infantile spasms; MCA = middle cerebral artery; MCD = malformation of cortical development; sGTC = secondarily generalized tonic-clonic seizures; SPS = simple partial seizures.

In each case, MEG helped to identify the suspected seizure focus. All patients included in this study had at least 1 localized spike cluster—as defined in a previous publication as at least 6 dipoles with no more than 1 cm between sources.8 In the patients with abnormal MRI findings, the spike clusters were consistently spatially related to the lesion or abnormal finding.

Surgical procedures were tailored to the location of the MEG spike clusters (Fig. 2). Five patients underwent anatomical lobectomies. Two additional patients had temporal lobectomies with additional cortical resection as guided by MEG. The 5 patients with a history of surgery had extension of the previous resection (Table 1). There were no intraoperative complications. The neuropathological findings are listed in Table 2.

Fig. 2.
Fig. 2.

Intraoperative screen shot from the BrainLab system demonstrating intraoperative image-guided mapping of an MEG spike cluster.

TABLE 2:

Pathology results from resected tissue in 16 patients undergoing resective epilepsy surgery based on MEG data*

PathologyNo. of Patients
cortical dysplasia8
heterotopia2
gliosis5
postoperative changes1
nondiagnostic/normal2

Two patients had multiple pathologies.

One patient was lost to follow-up 1 month after surgery. The remaining 15 children had a mean follow-up time of 2.4 years (range 7 months to 9 years). Of these patients, 4 (26.7%) had postoperative complications. These issues were minor and consisted of headaches, behavior changes, transient neurological deficit, and delayed wound healing with a stitch abscess. There were no deaths. Seizure outcomes were favorable. Ten patients (62.5%) were seizure free at follow-up (Engel Class I). One of these patients exhibited a “running-down” phenomenon, whereby seizure freedom was achieved in a delayed manner. An additional 3 patients (20%) had improvement in seizures (Engel Classes II and III). One patient had no change in seizures (Engel Class IVA) and an additional patient had worsening of seizures (Engel Class IVC). Both patients with Engel Class IV outcomes underwent subsequent surgery with intracranial electrode monitoring and additional resection. One of these children had ongoing seizures following the second attempt at resection.

Discussion

The American Clinical MEG Society has released a policy statement supporting the routine use of MEG in the evaluation of epilepsy.1 In addition, numerous studies have examined the utility of MEG in the preoperative evaluation of candidates for epilepsy surgery. In one study, MEG changed the surgical plan in 33% of patients. In some cases, the change entailed addition of electrodes, in others it involved placing unilateral rather than bilateral electrodes, and in a few cases MEG resulted in vagus nerve stimulation being performed rather than intracranial monitoring.23 Previous work from our institution demonstrated that interictal MEG accurately predicted the epileptogenic zone as determined by intracranial recording in 10 of 11 patients.14 MEG has also been used in the evaluation of patients with lesional epilepsy,20 recurrent epilepsy following a previous resection,17 refractory status epilepticus,16 insular/peri-insular epilepsy,6,15 and MRI-negative epilepsy10 and as part of the evaluation for hemispherotomy.24 In addition, previous reports have demonstrated more favorable seizure outcomes when the resection area includes the MEG spike cluster.4,21 A recent study from another institution demonstrated similar results for patients with extratemporal epilepsy. That series included 31 patients who did not undergo invasive monitoring, including several with temporal lobe epilepsy.25 Our series focuses on exclusively pediatric patients who would otherwise be candidates for invasive monitoring.

While the precise indications for invasive monitoring with intracranial electrodes vary between institutions, general guidelines include their use in patients with normal neuroimaging, cases in which the pathology involved is unlikely to be fully delineated on imaging, cases with multiple lesions or lesions secondary to cerebral insults, cases in which scalp EEG does not adequately localize the seizure onset zone, and cases which require mapping of eloquent cortex.18 In our series, 1 patient had normal neuroimaging (Case 1) and 5 patients had lesions whose extent would likely extend beyond what is seen on imaging (cortical dysplasia in Cases 2, 5, 9, 12, and 14). One patient had heterotopias seen on neuroimaging (Case 4), but these were noted to be indistinct and difficult to visualize. The remaining patients all had prior cerebral insults. Many of these were from previous attempts at epilepsy surgery (Cases 7, 8, 10, and 15) or prior tumor resection (Case 13). An additional 4 patients had encephalomalacia or evidence of prior stroke (Cases 3, 6, 11, and 16). Therefore, all patients included in this series would have been candidates for intracranial electrode implantation had MEG not been available.

The 62.5% seizure-free rate in our cohort of patients compares favorably with previously published reports of outcomes in extratemporal epilepsy surgery. Recently pub lished series report seizure-free rates of 57%–74%.7,11,12,22 Most patients in our series derived some benefit in seizure control from the operation. Only 2 patients had Engel Class IV outcomes requiring additional surgical intervention.

The primary advantage of using MEG to guide resection for epilepsy is the avoidance of invasive monitoring. The use of intracranial electrodes is associated with several risks including CSF leak, cerebral edema, hemorrhage, infection, and blood loss requiring a transfusion.19 There were no infections or CSF leaks in our series. The primary disadvantages to routine use of MEG are the cost and limited availability of this technology. In addition, most MEG recordings are interictal, although occasionally ictal activity is recorded.

The decision to use MEG instead of intracranial electrodes is complex and depends on numerous factors. Certainly, the MEG data must be concordant with other available information including seizure semiology, VEEG, structural MRI, and PET when available. Techniques do exist for mapping of language and motor cortex with MEG, however the spatial resolution is limited. With these limitations, MEG-guided resection is appropriate in a small subset of patients. We estimate that 115 patients underwent implantation of subdural grids during the same time period. Intraoperatively, the MEG data may be fused with diffusion tensor imaging to predict the location of eloquent cortex. Intraoperative mapping may also be used for mapping of eloquent cortex during surgery.

Conclusions

In this study, we have demonstrated that the outcome in selected patients who undergo surgery based on MEG data is comparable to the outcome reported from resection based on data from invasive monitoring. In addition, there was a low complication rate, with no CSF leaks, infections, or intracranial hematomas, which can occur in patients undergoing invasive monitoring.

Acknowledgment

We would like to thank Ms. Maria Lamberti-Pascilli, R.N., for her assistance with the identification of these patients.

Disclosure

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author contributions to the study and manuscript preparation include the following. Conception and design: Rutka. Acquisition of data: Albert, Ibrahim. Analysis and interpretation of data: Rutka, Albert, Ibrahim. Drafting the article: Albert. Critically revising the article: all authors. Reviewed submitted version of manuscript: all authors. Statistical analysis: Albert.

This article contains some figures that are displayed in color online but in black-and-white in the print edition.

This work has been previously presented at the 36th Annual Meeting of the American Society of Pediatric Neurosurgeons, Princeville, Hawaii, February 12, 2013.

References

  • 1

    Bagic AFunke MEEbersole J: ACMEGS Position Statement Committee: American Clinical MEG Society (ACMEGS) position statement: the value of magnetoencephalography (MEG)/magnetic source imaging (MSI) in noninvasive presurgical evaluation of patients with medically intractable localization-related epilepsy. J Clin Neurophysiol 26:2902932009

  • 2

    Cross JHJayakar PNordli DDelalande ODuchowny MWieser HG: Proposed criteria for referral and evaluation of children for epilepsy surgery: recommendations of the Subcommission for Pediatric Epilepsy Surgery. Epilepsia 47:9529592006

  • 3

    Engel J JrVan Ness PCRasmussen TBOjemann LMOutcome with respect to epileptic seizures. Engel J Jr: Surgical Treatment of the Epilepsies ed 2New YorkRaven Press1993. 609621

  • 4

    Fischer MJMScheler GStefan H: Utilization of magnetoencephalography results to obtain favourable outcomes in epilepsy surgery. Brain 128:1531572005

  • 5

    Harvey ASCross JHShinnar SMathern GW: Defining the spectrum of international practice in pediatric epilepsy surgery patients. Epilepsia 49:1461552008. (Erratum in Epilepsia 54: 1140 2013)

  • 6

    Heers MRampp SStefan HUrbach HElger CEvon Lehe M: MEG-based identification of the epileptogenic zone in occult peri-insular epilepsy. Seizure 21:1281332012

  • 7

    Hemb MVelasco TRParnes MSWu JYLerner JTMatsumoto JH: Improved outcomes in pediatric epilepsy surgery: the UCLA experience, 1986-2008. Neurology 74:176817752010

  • 8

    Iida KOtsubo HMatsumoto YOchi AOishi MHolowka S: Characterizing magnetic spike sources by using magnetoencephalography-guided neuronavigation in epilepsy surgery in pediatric patients. J Neurosurg 102:2 Suppl1871962005

  • 9

    Johnston JM JrMangano FTOjemann JGPark TSTrevathan ESmyth MD: Complications of invasive subdural electrode monitoring at St. Louis Children's Hospital, 1994-2005. J Neurosurg 105:5 Suppl3433472006

  • 10

    Jung JBouet RDelpuech CRyvlin PIsnard JGuenot M: The value of magnetoencephalography for seizure-onset zone localization in magnetic resonance imaging-negative partial epilepsy. Brain 136:317631862013

  • 11

    Kan PVan Orman CKestle JR: Outcomes after surgery for focal epilepsy in children. Childs Nerv Syst 24:5875912008

  • 12

    Kim SKWang KCHwang YSKim KJChae JHKim IO: Epilepsy surgery in children: outcomes and complications. J Neurosurg Pediatr 1:2772832008

  • 13

    Mikati MAAtaya NFerzli JKurdi REl-Banna DRahi A: Quality of life after surgery for intractable partial epilepsy in children: a cohort study with controls. Epilepsy Res 90:2072132010

  • 14

    Minassian BAOtsubo HWeiss SElliott IRutka JTSnead OC III: Magnetoencephalographic localization in pediatric epilepsy surgery: comparison with invasive intracranial electroencephalography. Ann Neurol 46:6276331999

  • 15

    Mohamed ISGibbs SARobert MBouthillier ALeroux JMKhoa Nguyen D: The utility of magnetoencephalography in the presurgical evaluation of refractory insular epilepsy. Epilepsia 54:195019592013

  • 16

    Mohamed ISOtsubo HDonner EOchi ASharma RDrake J: Magnetoencephalography for surgical treatment of refractory status epilepticus. Acta Neurol Scand 115:4 Suppl29362007

  • 17

    Mohamed ISOtsubo HOchi AElliott IDonner EChuang S: Utility of magnetoencephalography in the evaluation of recurrent seizures after epilepsy surgery. Epilepsia 48:215021592007

  • 18

    Nair DRBurgess RMcIntyre CCLüders H: Chronic subdural electrodes in the management of epilepsy. Clin Neurophysiol 119:11282008

  • 19

    Onal COtsubo HAraki TChitoku SOchi AWeiss S: Complications of invasive subdural grid monitoring in children with epilepsy. J Neurosurg 98:101710262003

  • 20

    Otsubo HOchi AElliott IChuang SHRutka JTJay V: MEG predicts epileptic zone in lesional extrahippocampal epilepsy: 12 pediatric surgery cases. Epilepsia 42:152315302001

  • 21

    RamachandranNair ROtsubo HShroff MMOchi AWeiss SKRutka JT: MEG predicts outcome following surgery for intractable epilepsy in children with normal or nonfocal MRI findings. Epilepsia 48:1491572007

  • 22

    Seo JHNoh BHLee JSKim DSLee SKKim TS: Outcome of surgical treatment in non-lesional intractable childhood epilepsy. Seizure 18:6256292009

  • 23

    Sutherling WWMamelak ANThyerlei DMaleeva TMinazad YPhilpott L: Influence of magnetic source imaging for planning intracranial EEG in epilepsy. Neurology 71:9909962008

  • 24

    Torres CVFallah AIbrahim GMCheshier SOtsubo HOchi A: The role of magnetoencephalography in children undergoing hemispherectomy. Clinical article. J Neurosurg Pediatr 8:5755832011

  • 25

    Vadera SJehi LBurgess RCShea KAlexopoulos AVMosher J: Correlation between magnetoencephalography-based “clusterectomy” and postoperative seizure freedom. Neurosurg Focus 34:6E92013

  • 26

    Wiebe SBlume WTGirvin JPEliasziw M: A randomized, controlled trial of surgery for temporal-lobe epilepsy. N Engl J Med 345:3113182001

If the inline PDF is not rendering correctly, you can download the PDF file here.

Article Information

Address correspondence to: James T. Rutka, M.D., Ph.D., Division of Neurosurgery, The Hospital for Sick Children, 555 University Ave., Toronto, ON M5G 1X8, Canada. email: james.rutka@sickkids.ca.

Please include this information when citing this paper: published online September 19, 2014; DOI: 10.3171/2014.8.PEDS13640.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    A–C: Axial images from preoperative FLAIR MRI (A), preoperative MEG (B), and postoperative CT (C) studies obtained in a 16-year-old female with a history of severe traumatic brain injury with resulting epilepsy. She was seizure free after surgery. D–F: Axial images from preoperative FLAIR MRI (D), preoperative MEG (E), and postoperative CT (F) studies obtained in a 6.8-year-old girl with a history of germinal matrix hemorrhage with resulting cerebral palsy and epilepsy. She was seizure free after surgery.

  • View in gallery

    Intraoperative screen shot from the BrainLab system demonstrating intraoperative image-guided mapping of an MEG spike cluster.

References

  • 1

    Bagic AFunke MEEbersole J: ACMEGS Position Statement Committee: American Clinical MEG Society (ACMEGS) position statement: the value of magnetoencephalography (MEG)/magnetic source imaging (MSI) in noninvasive presurgical evaluation of patients with medically intractable localization-related epilepsy. J Clin Neurophysiol 26:2902932009

  • 2

    Cross JHJayakar PNordli DDelalande ODuchowny MWieser HG: Proposed criteria for referral and evaluation of children for epilepsy surgery: recommendations of the Subcommission for Pediatric Epilepsy Surgery. Epilepsia 47:9529592006

  • 3

    Engel J JrVan Ness PCRasmussen TBOjemann LMOutcome with respect to epileptic seizures. Engel J Jr: Surgical Treatment of the Epilepsies ed 2New YorkRaven Press1993. 609621

  • 4

    Fischer MJMScheler GStefan H: Utilization of magnetoencephalography results to obtain favourable outcomes in epilepsy surgery. Brain 128:1531572005

  • 5

    Harvey ASCross JHShinnar SMathern GW: Defining the spectrum of international practice in pediatric epilepsy surgery patients. Epilepsia 49:1461552008. (Erratum in Epilepsia 54: 1140 2013)

  • 6

    Heers MRampp SStefan HUrbach HElger CEvon Lehe M: MEG-based identification of the epileptogenic zone in occult peri-insular epilepsy. Seizure 21:1281332012

  • 7

    Hemb MVelasco TRParnes MSWu JYLerner JTMatsumoto JH: Improved outcomes in pediatric epilepsy surgery: the UCLA experience, 1986-2008. Neurology 74:176817752010

  • 8

    Iida KOtsubo HMatsumoto YOchi AOishi MHolowka S: Characterizing magnetic spike sources by using magnetoencephalography-guided neuronavigation in epilepsy surgery in pediatric patients. J Neurosurg 102:2 Suppl1871962005

  • 9

    Johnston JM JrMangano FTOjemann JGPark TSTrevathan ESmyth MD: Complications of invasive subdural electrode monitoring at St. Louis Children's Hospital, 1994-2005. J Neurosurg 105:5 Suppl3433472006

  • 10

    Jung JBouet RDelpuech CRyvlin PIsnard JGuenot M: The value of magnetoencephalography for seizure-onset zone localization in magnetic resonance imaging-negative partial epilepsy. Brain 136:317631862013

  • 11

    Kan PVan Orman CKestle JR: Outcomes after surgery for focal epilepsy in children. Childs Nerv Syst 24:5875912008

  • 12

    Kim SKWang KCHwang YSKim KJChae JHKim IO: Epilepsy surgery in children: outcomes and complications. J Neurosurg Pediatr 1:2772832008

  • 13

    Mikati MAAtaya NFerzli JKurdi REl-Banna DRahi A: Quality of life after surgery for intractable partial epilepsy in children: a cohort study with controls. Epilepsy Res 90:2072132010

  • 14

    Minassian BAOtsubo HWeiss SElliott IRutka JTSnead OC III: Magnetoencephalographic localization in pediatric epilepsy surgery: comparison with invasive intracranial electroencephalography. Ann Neurol 46:6276331999

  • 15

    Mohamed ISGibbs SARobert MBouthillier ALeroux JMKhoa Nguyen D: The utility of magnetoencephalography in the presurgical evaluation of refractory insular epilepsy. Epilepsia 54:195019592013

  • 16

    Mohamed ISOtsubo HDonner EOchi ASharma RDrake J: Magnetoencephalography for surgical treatment of refractory status epilepticus. Acta Neurol Scand 115:4 Suppl29362007

  • 17

    Mohamed ISOtsubo HOchi AElliott IDonner EChuang S: Utility of magnetoencephalography in the evaluation of recurrent seizures after epilepsy surgery. Epilepsia 48:215021592007

  • 18

    Nair DRBurgess RMcIntyre CCLüders H: Chronic subdural electrodes in the management of epilepsy. Clin Neurophysiol 119:11282008

  • 19

    Onal COtsubo HAraki TChitoku SOchi AWeiss S: Complications of invasive subdural grid monitoring in children with epilepsy. J Neurosurg 98:101710262003

  • 20

    Otsubo HOchi AElliott IChuang SHRutka JTJay V: MEG predicts epileptic zone in lesional extrahippocampal epilepsy: 12 pediatric surgery cases. Epilepsia 42:152315302001

  • 21

    RamachandranNair ROtsubo HShroff MMOchi AWeiss SKRutka JT: MEG predicts outcome following surgery for intractable epilepsy in children with normal or nonfocal MRI findings. Epilepsia 48:1491572007

  • 22

    Seo JHNoh BHLee JSKim DSLee SKKim TS: Outcome of surgical treatment in non-lesional intractable childhood epilepsy. Seizure 18:6256292009

  • 23

    Sutherling WWMamelak ANThyerlei DMaleeva TMinazad YPhilpott L: Influence of magnetic source imaging for planning intracranial EEG in epilepsy. Neurology 71:9909962008

  • 24

    Torres CVFallah AIbrahim GMCheshier SOtsubo HOchi A: The role of magnetoencephalography in children undergoing hemispherectomy. Clinical article. J Neurosurg Pediatr 8:5755832011

  • 25

    Vadera SJehi LBurgess RCShea KAlexopoulos AVMosher J: Correlation between magnetoencephalography-based “clusterectomy” and postoperative seizure freedom. Neurosurg Focus 34:6E92013

  • 26

    Wiebe SBlume WTGirvin JPEliasziw M: A randomized, controlled trial of surgery for temporal-lobe epilepsy. N Engl J Med 345:3113182001

TrendMD

Metrics

Metrics

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 173 173 5
PDF Downloads 144 144 5
EPUB Downloads 0 0 0

PubMed

Google Scholar