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

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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Temporoparietooccipital disconnection in children with intractable epilepsy

Journal of Neurosurgery Pediatrics ◽

10.3171/2011.4.peds10454 ◽

2011 ◽

Vol 7 (6) ◽

pp. 660-670 ◽

Cited By ~ 24

Author(s):

Ahmad R. Mohamed ◽

Jeremy L. Freeman ◽

Wirginia Maixner ◽

Catherine A. Bailey ◽

Jacquie A. Wrennall ◽

...

Keyword(s):

Mr Imaging ◽

Intractable Epilepsy ◽

Motor Deficits ◽

Seizure Outcome ◽

Developmental Progress ◽

Generalized Seizures ◽

Signal Change ◽

Posterior Quadrant ◽

Epileptogenic Lesion

Object Temporoparietooccipital (TPO) disconnection is described mainly in children with diffuse posterior quadrant lesions and concordant electroencephalography (EEG) findings. The authors report on 16 children who underwent TPO surgery, including 4 with no definite epileptogenic lesion and 8 with generalized electroclinical manifestations. Methods The authors conducted a retrospective review of clinical, neuropsychological, EEG, imaging, and histopathological data in 16 children with intractable epilepsy who underwent TPO disconnection and/or resection at their center between December 1998 and March 2010. Results Seizure onset occurred between the ages of 1 and 24 months, and TPO surgery was performed between the ages of 0.2 and 17 years. All children had refractory seizures, including epileptic spasms in 10 and tonic seizures in 7, and all had developmental delay. Twelve children had epileptogenic lesions on MR imaging, including 6 with posterior quadrant dysplasia. Four children had only subtle white matter signal change or unusual sulcation on MR imaging, associated with subtle but concordant EEG and functional imaging abnormalities. After a mean follow-up of 52 months (range 12–114 months), 9 children (56%) are seizure-free and 5 (31%) experienced seizure reduction of greater than 50%. Focal or regional background slowing on EEG was correlated with favorable seizure outcome. Five children showed developmental progress and 3 had acceleration in development following surgery. None of the children developed new motor deficits postoperatively. Conclusions Temporoparietooccipital disconnection is an effective, motor-sparing epilepsy surgery procedure for selected children with refractory focal or generalized seizures with localization to the posterior quadrant on 1 side, with or without a discrete lesion on MR imaging.

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Surgical treatment of occipital lobe epilepsy

Journal of Neurosurgery ◽

10.3171/jns/2008/109/7/0057 ◽

2008 ◽

Vol 109 (1) ◽

pp. 57-69 ◽

Cited By ~ 64

Author(s):

Devin K. Binder ◽

Marec Von Lehe ◽

Thomas Kral ◽

Christian G. Bien ◽

Horst Urbach ◽

...

Keyword(s):

Visual Field ◽

Mr Imaging ◽

Vascular Malformations ◽

Significant Proportion ◽

Intractable Epilepsy ◽

Occipital Lobe ◽

Class I ◽

Seizure Outcome ◽

Occipital Lobe Epilepsy ◽

Visual Field Deficits

Object Occipital lobe epilepsy (OLE) accounts for a small percentage of extratemporal epilepsies and only few and mostly small patient series have been reported. Preoperative findings, surgical strategies, histopathological bases, and postoperative outcomes for OLE remain to be elucidated. Methods A group of 54 patients with occipital lobe involvement were identified from a prospective epilepsy surgery database established in 1989. Medical charts, surgical reports, MR imaging, and histopathology data were reviewed, and patients with additional temporal and/or parietal involvement were categorized separately. Seizure outcome was classified according to the Engel classification scheme (Classes I–IV). Two patients were excluded due to incomplete data sets. Fifty-two patients with intractable epilepsy involving predominantly the occipital lobe were included in the study, comprising 17.8% of 292 patients undergoing operations for extratemporal epilepsies. Results In nearly all cases (50 [96.2%] of 52), a structural lesion was visible on preoperative MR imaging. Of these cases, 29 (55.8%) had “pure” OLE with no temporal or parietal lobe involvement. Most patients (83%) had complex partial seizures, and 60% also had generalized seizures. All patients underwent occipital lesionectomies or topectomies; 9 patients (17.3%) underwent additional multiple subpial transections. Histopathology results revealed 9 cortical dysplasias (17.3%), 9 gangliogliomas (17.3%), 6 other tumors (11.5%), 13 vascular malformations (25%), and 15 glial scars (28.8%). Visual field deficits were present in 36.4% of patients preoperatively, and 42.4% had new or aggravated visual field deficits after surgery. After a mean follow-up of 80 months, 36 patients were seizure free (69.2% Engel Class I), 4 rarely had seizures (7.7% Engel Class II), 8 improved more than 75% (15.4% Engel Class III), and 4 had no significant improvement (7.7% Engel Class IV). Multifactorial logistic regression analysis revealed that early age at epilepsy manifestation (p = 0.031) and shorter epilepsy duration (p = 0.004) were predictive of better seizure control. All other clinical and surgical factors were not significant in predicting outcome. Conclusions Occipital lobe epilepsy is an infrequent but significant cause of extratemporal epilepsy. Satisfactory results (Engel Class I or II) were obtained in 77% of patients in our series. Postoperative visual field deficits occurred in a significant proportion of patients. In the modern MR imaging era, lesions should be investigated in patients with OLE and lesionectomies should be performed early for a better outcome.

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Volumetric localization of epileptic activity using wavelet-based synthetic aperture magnetometry

International Congress Series ◽

10.1016/j.ics.2007.03.003 ◽

2007 ◽

Vol 1300 ◽

pp. 697-700 ◽

Cited By ~ 2

Author(s):

Jing Xiang ◽

Yingying Wang ◽

Zheng Xiao ◽

Christina Balioussis ◽

Hongmei Zhu ◽

...

Keyword(s):

Epileptic Activity ◽

Synthetic Aperture ◽

Synthetic Aperture Magnetometry

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Neurosurgical management of intractable rolandic epilepsy in children: role of resection in eloquent cortex

Journal of Neurosurgery Pediatrics ◽

10.3171/2009.3.peds08459 ◽

2009 ◽

Vol 4 (3) ◽

pp. 199-216 ◽

Cited By ~ 62

Author(s):

Mony Benifla ◽

Francesco Sala ◽

John Jane ◽

Hiroshi Otsubo ◽

Ayako Ochi ◽

...

Keyword(s):

Mr Imaging ◽

Functional Outcome ◽

Neuropsychological Testing ◽

Intractable Epilepsy ◽

Seizure Outcome ◽

Invasive Monitoring ◽

Rolandic Epilepsy ◽

Age At Surgery ◽

The Mean ◽

Rolandic Region

Object The authors undertook this study to review their experience with cortical resections in the rolandic region in children with intractable epilepsy. Methods The authors retrospectively reviewed the medical records obtained in 22 children with intractable epilepsy arising from the rolandic region. All patients underwent preoperative electroencephalography (EEG), MR imaging, prolonged video-EEG recordings, functional MR imaging, magnetoencephalography, and in some instances PET/SPECT studies. In 21 patients invasive subdural grid and depth electrode monitoring was performed. Resection of the epileptogenic zones in the rolandic region was undertaken in all cases. Seizure outcome was graded according to the Engel classification. Functional outcome was determined using validated outcome scores. Results There were 10 girls and 12 boys, whose mean age at seizure onset was 3.2 years. The mean age at surgery was 10 years. Seizure duration prior to surgery was a mean of 7.4 years. Nine patients had preoperative hemiparesis. Neuropsychological testing revealed impairment in some domains in 19 patients in whom evaluation was possible. Magnetic resonance imaging abnormalities were identified in 19 patients. Magnetoencephalography was performed in all patients and showed perirolandic spike clusters on the affected side in 20 patients. The mean duration of invasive monitoring was 4.2 days. The mean number of seizures during the period of invasive monitoring was 17. All patients underwent resection that involved primary motor and/or sensory cortex. The most common pathological entity encountered was cortical dysplasia, in 13 children. Immediately postoperatively, 20 patients had differing degrees of hemiparesis, from mild to severe. The hemiparesis improved in all affected patients by 3–6 months postoperatively. With a mean follow-up of 4.1 years (minimum 2 years), seizure outcome in 14 children (64%) was Engel Class I and seizure outcome in 4 (18%) was Engel Class II. In this series, seizure outcome following perirolandic resection was intimately related to the child's age at the time of surgery. By univariate logistic regression analysis, age at surgery was a statistically significant factor predicting seizure outcome (p < 0.024). Conclusions Resection of rolandic cortex for intractable epilepsy is possible with expected morbidity. Accurate mapping of regions of functional cortex and epileptogenic zones may lead to improved seizure outcome in children with intractable rolandic epilepsy. It is important to counsel patients and families preoperatively to prepare them for possible worsened functional outcome involving motor, sensory and/or language pathways.

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Seizure outcome of lesional vs nonlesional frontal lobectomy for intractable epilepsy

Electroencephalography and Clinical Neurophysiology ◽

10.1016/s0013-4694(97)88615-8 ◽

1997 ◽

Vol 103 (1) ◽

pp. 136 ◽

Cited By ~ 5

Author(s):

R Mosewich

Keyword(s):

Intractable Epilepsy ◽

Seizure Outcome ◽

Frontal Lobectomy

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Magnetic source imaging for the surgical evaluation of electroencephalography-confirmed secondary bilateral synchrony in intractable epilepsy

Journal of Neurosurgery ◽

10.3171/2009.6.jns081376 ◽

2009 ◽

Vol 111 (6) ◽

pp. 1248-1256 ◽

Cited By ~ 26

Author(s):

Edward F. Chang ◽

Srikantan S. Nagarajan ◽

Mary Mantle ◽

Nicholas M. Barbaro ◽

Heidi E. Kirsch

Keyword(s):

Mr Imaging ◽

Intractable Epilepsy ◽

Focal Lesion ◽

Seizure Type ◽

Source Imaging ◽

Magnetic Source Imaging ◽

Ms Imaging ◽

Epileptiform Discharges ◽

Magnetic Source ◽

Imaging Results

Object Routine scalp electroencephalography (EEG) cannot always distinguish whether generalized epileptiform discharges are the result of primary bilateral synchrony or secondary bilateral synchrony (SBS) from a focal origin; this is an important distinction because the latter may be amenable to resection. Whole-head magnetoencephalography (MEG) has superior spatial resolution compared with traditional EEG, and can potentially elucidate seizure foci in challenging epilepsy cases in which patients are undergoing evaluation for surgery. Methods Sixteen patients with medically intractable epilepsy in whom SBS was suspected were referred for magnetic source (MS) imaging. All patients had bilateral, synchronous, widespread, and most often generalized spike-wave discharges on scalp EEG studies, plus some other clinical (for example, seizure semiology) or MR imaging feature (for example, focal lesion) suggesting focal onset and hence possible surgical candidacy. The MS imaging modality is the combination of whole-head MEG and parametric reconstruction of corresponding electrical brain sources. An MEG and simultaneous EEG studies were recorded with a 275-channel whole-head system. Single-equivalent current dipoles were estimated from the MEG data, and dipole locations and orientations were superimposed on patients' MR images. Results The MS imaging studies revealed focal dipole clusters in 12 (75%) of the 16 patients, of which a single dipole cluster was identified in 7 patients (44%). Patient age, seizure type, duration of disease, video-EEG telemetry, and MR imaging results were analyzed to determine factors predictive of having clusters revealed on MS imaging. Of these factors, only focal MR imaging anatomical abnormalities were associated with dipole clusters (chi-square test, p = 0.03). Selective resections (including the dipole cluster) in 7 (87%) of 8 patients resulted in seizure-free or rare seizure outcomes (Engel Classes I and II). Conclusions Magnetic source imaging may provide noninvasive anatomical and neurophysiological confirmation of localization in patients in whom there is a suspicion of SBS (based on clinical or MR imaging data), especially in those with an anatomical lesion. Identification of a focal seizure origin has significant implications for both resective and nonresective treatment of intractable epilepsy.

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Resection of cerebral gangliogliomas causing drug-resistant epilepsy: short- and long-term outcomes using intraoperative MRI and neuronavigation

Neurosurgical FOCUS ◽

10.3171/2014.10.focus14616 ◽

2015 ◽

Vol 38 (1) ◽

pp. E5 ◽

Cited By ~ 14

Author(s):

Björn Sommer ◽

Cornelia Wimmer ◽

Roland Coras ◽

Ingmar Blumcke ◽

Bogdan Lorber ◽

...

Keyword(s):

Diffusion Tensor ◽

Intraoperative Imaging ◽

Intractable Epilepsy ◽

Complete Resection ◽

Blood Oxygenation ◽

Seizure Outcome ◽

Incomplete Resection ◽

Brain Areas ◽

Total Resection

OBJECT Cerebral gangliogliomas (GGs) are highly associated with intractable epilepsy. Incomplete resection due to proximity to eloquent brain regions or misinterpretation of the resection amount is a strong negative predictor for local tumor recurrence and persisting seizures. A potential method for dealing with this obstacle could be the application of intraoperative high-field MRI (iopMRI) combined with neuronavigation. METHODS Sixty-nine patients (31 female, 38 male; median age 28.5 ± 15.4 years) suffering from cerebral GGs were included in this retrospective study. Five patients received surgery twice in the observation period. In 48 of the 69 patients, 1.5-T iopMRI combined with neuronavigational guidance was used. Lesions close to eloquent brain areas were resected with the implementation of preoperative diffusion tensor imaging tractography and blood oxygenation level–dependent functional MRI (15 patients). RESULTS Overall, complete resection was accomplished in 60 of 69 surgical procedures (87%). Two patients underwent biopsy only, and in 7 patients, subtotal resection was accomplished because of proximity to critical brain areas. Excluding the 2 biopsies, complete resection using neuronavigation/iopMRI was documented in 33 of 46 cases (72%) by intraoperative imaging. Remnant tumor mass was identified intraoperatively in 13 of 46 patients (28%). After intraoperative second-look surgery, the authors improved the total resection rate by 9 patients (up to 91% [42 of 46]). Of 21 patients undergoing conventional surgery, 14 (67%) had complete resection without the use of iopMRI. Regarding epilepsy outcome, 42 of 60 patients with seizures (70%) became completely seizure free (Engel Class IA) after a median follow-up time of 55.5 ± 36.2 months. Neurological deficits were found temporarily in 1 (1.4%) patient and permanently in 4 (5.8%) patients. CONCLUSIONS Using iopMRI combined with neuronavigation in cerebral GG surgery, the authors raised the rate of complete resection in this series by 19%. Given the fact that total resection is a strong predictor of long-term seizure control, this technique may contribute to improved seizure outcome and reduced neurological morbidity.

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