-
[show abstract]
[hide abstract]
ABSTRACT: PURPOSE: The white matter (WM) is considered critical for linking cortical processing networks necessary for cognition. The aim of this study was to assess diffusion tensor imaging (DTI) measures of regional WM in children with nonlesional localization-related epilepsy in comparison to controls, and to determine the relation between lobar WM and neuropsychological performance. METHODS: Forty children with nonlesional localization-related epilepsy and 25 healthy controls with no neurological or psychiatric disorders and normal magnetic resonance imaging (MRI) were recruited. All patients and controls underwent neuropsychological testing that evaluated intelligence, language, memory, executive function, and motor function, as well as DTI to assess regional WM measures of fractional anisotropy (FA) and mean diffusivity (MD). The regional FA and MD were compared between patients and controls, and correlated with neuropsychological function. The relations between regional FA and MD with age at seizure onset and duration of epilepsy were assessed. KEY FINDINGS: Twenty-one patients had left-sided and 19 patients had right-sided epilepsy. There were no significant differences in seizure-related variables including age at seizure onset, duration of epilepsy, seizure frequency, and number of antiepileptic medications, as well as no significant differences in neuropsychological function and DTI measures of white matter in left-sided compared to right-sided epilepsy. Therefore, all the patients with epilepsy were treated as one group. Patients with epilepsy performed significantly worse on intelligence (p < 0.001), language (p < 0.001), and executive function (p = 0.001) evaluation than controls. Patients had significantly reduced FA in left frontal (p = 0.015), right frontal (p = 0.004), left temporal (p = 0.039), right temporal (p = 0.003), right parietal (p = 0.014), and right occipital (p = 0.025) WM relative to controls. There were no significant regional WM differences (all p > 0.05) in MD between patients and controls. There was a significant positive correlation between right temporal FA with language (r = 0.535, p < 0.001) and executive function (r = 0.617, p < 0.001), as well as between body of corpus callosum FA with intelligence (r = 0.536, p < 0.001) and language (r = 0.529, p < 0.001) in patients. Left parietal MD was significantly correlated with language (r = -0.545, p < 0.001) in patients. FA of right temporal WM was significantly associated with age at seizure onset (t = 4.97, p < 0.001). SIGNIFICANCE: There was widespread regional WM abnormality in children with nonlesional localization-related epilepsy, which was associated with impaired neuropsychological function. The impairment in WM may reflect disruption in the connectivity for cortical processing networks, which is necessary for the development of cognition.
Epilepsia 05/2013; · 3.96 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Network analysis is an emerging tool for the study of complex systems. Antiepileptic drug (AED) polytherapy in children with medically intractable epilepsy may be considered a complex system, given the heterogeneity of drug combinations that are frequently modified according to clinical indications. The current article presents a concise review of network theory and its application to the characterization of AED use in children with refractory epilepsy. Current and previous AEDs prescribed to 27 children with refractory, localization-related epilepsy were recorded, and network theory was applied to identify patterns of drug administration. Of the fifteen unique AEDs prescribed, levetiracetam possessed the highest betweenness centrality within the network. Furthermore, first generation AEDs were often discontinued, while lacosamide and topiramate were most likely to be initiated. We also identified three subnetworks of AEDs that were commonly coadministered. We conclude that network analysis is an effective method to characterize the complexity of AED administration patterns in children with epilepsy with many promising future applications.
Epilepsy & Behavior 05/2013; 28(1):22-25. · 2.34 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: PURPOSE: 2-[18F]Fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET) and magnetoencephalography (MEG) may assist in identifying the epileptogenic zone in children with nonlesional localization-related epilepsy. The aim of this study was to evaluate sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of FDG-PET, MEG, FDG-PET + MEG, and FDG-PET/MEG in children with nonlesional localization-related epilepsy. METHODS: Twenty-six children with localization-related epilepsy and who had normal or subtle changes on magnetic resonance imaging (MRI) underwent FDG-PET and MEG. Twenty-two patients had surgical resection, and surgical outcome was assessed using Engel classification. In patients with Engel I seizure outcome, we assessed the sensitivity, specificity, PPV, and NPV of lobar localization of MEG, FDG-PET, FDG-PET + MEG, and FDG-PET/MEG. KEY FINDINGS: Sixteen (72.7%) of 22 had Engel I seizure outcome. MEG was concordant with surgical resection in 18 patients, 14 had Engel I, and four had Engel II-IV outcomes. MEG was nonlocalizing or nonconcordant in four patients; two patients had Engel I and two had Engel II-IV outcomes. FDG-PET was concordant with surgical resection in 14 patients; 9 had Engel I outcome, and 5 had Engel II-IV outcome. FDG-PET was nonlocalizing or nonconcordant in seven patients with Engel I, and one with Engel III outcome. The sensitivity, specificity, PPV, and NPV of MEG were 85.0%, 99.1%, 94.4%, and 97.3%, respectively. The sensitivity, specificity, PPV, and NPV of FDG-PET were 65.0%, 94.4%, 68.4%, and 93.6%, respectively. There was no significant difference between MEG and FDG-PET for concordance with surgical resection (χ(2) = 2.794, p = 0.095). FDG-PET + MEG, defined as two tests concordant with surgical resection, had reduced sensitivity and NPV, but increased specificity and PPV (55.0%, 92.3%, 100%, and 100%, respectively) relative to individual tests. FDG-PET/MEG, defined as one or both test(s) concordant with surgical resection, had increased sensitivity and NPV but reduced specificity (95.0%, 99.0%, and 93.5%, respectively) relative to individual tests. SIGNIFICANCE: The two tests FDG-PET and MEG were complementary in the assessment of children with localization-related epilepsy, particularly when one test was nonlocalizing or nonconcordant.
Epilepsia 02/2013; · 3.96 Impact Factor
-
Aria Fallah,
Gordon H Guyatt, O Carter Snead,
Shanil Ebrahim,
George M Ibrahim,
Alireza Mansouri,
Deven Reddy,
Stephen D Walter,
Abhaya V Kulkarni,
Mohit Bhandari,
Laura Banfield,
Neera Bhatnagar,
Shuli Liang,
Federica Teutonico,
Jianxiang Liao,
James T Rutka
[show abstract]
[hide abstract]
ABSTRACT: To perform a systematic review and individual participant data meta-analysis to identify preoperative factors associated with a good seizure outcome in children with Tuberous Sclerosis Complex undergoing resective epilepsy surgery.
Electronic databases (MEDLINE, EMBASE, CINAHL and Web of Science), archives of major epilepsy and neurosurgery meetings, and bibliographies of relevant articles, with no language or date restrictions.
We included case-control or cohort studies of consecutive participants undergoing resective epilepsy surgery that reported seizure outcomes. We performed title and abstract and full text screening independently and in duplicate. We resolved disagreements through discussion.
One author performed data extraction which was verified by a second author using predefined data fields including study quality assessment using a risk of bias instrument we developed. We recorded all preoperative factors that may plausibly predict seizure outcomes.
To identify predictors of a good seizure outcome (i.e. Engel Class I or II) we used logistic regression adjusting for length of follow-up for each preoperative variable.
Of 9863 citations, 20 articles reporting on 181 participants were eligible. Good seizure outcomes were observed in 126 (69%) participants (Engel Class I: 102(56%); Engel class II: 24(13%)). In univariable analyses, absence of generalized seizure semiology (OR = 3.1, 95%CI = 1.2-8.2, p = 0.022), no or mild developmental delay (OR = 7.3, 95%CI = 2.1-24.7, p = 0.001), unifocal ictal scalp electroencephalographic (EEG) abnormality (OR = 3.2, 95%CI = 1.4-7.6, p = 0.008) and EEG/Magnetic resonance imaging concordance (OR = 4.9, 95%CI = 1.8-13.5, p = 0.002) were associated with a good postoperative seizure outcome.
Small retrospective cohort studies are inherently prone to bias, some of which are overcome using individual participant data. The best available evidence suggests four preoperative factors predictive of good seizure outcomes following resective epilepsy surgery. Large long-term prospective multicenter observational studies are required to further evaluate the risk factors identified in this review.
PLoS ONE 01/2013; 8(2):e53565. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Epilepsy is associated with an abnormal expression of neural oscillations and their synchronization across brain regions. Oscillatory brain activation and synchronization also play an important role in cognition, perception and motor control. Childhood epilepsy is associated with a variety of cognitive and motor deficits, but the relationship between altered functional brain responses in various frequency ranges and functional impairment in these children remains poorly understood. We investigated functional magnetoencephalographic (MEG) responses from motor cortex in multiple functionally relevant frequency bands following median nerve stimulation in twelve children with epilepsy, including four children with motor impairments. We demonstrated that children with motor impairments exhibit an excessive gamma-band response from Rolandic cortex, and that the magnitude of this Rolandic gamma response is negatively associated with motor function. Abnormal responses from motor cortex were also associated with ictal desynchronization of oscillations within Rolandic cortex measured using intracranial EEG (iEEG). These results provide the evidence that ictal disruption of motor networks is associated with an altered functional response from motor cortex, which is in turn associated with motor impairment.
PLoS ONE 01/2013; 8(1):e54943. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: PURPOSE: Resective surgical strategies are increasingly applied to treat medically-intractable epilepsy in children as uncontrolled seizures are associated with poor cognitive, developmental and behavioral outcomes. Innovative surgical strategies are, however, needed to improve outcomes and minimize the morbidity of such procedures. METHOD: The current article utilizes an axiological approach to explore and highlight ethical issues in the use of high frequency oscillations (HFOs) to guide surgical resections in children with medically-intractable epilepsy. We frame our discussion in the context of the broader challenges in the application of surgical innovation to patient care. RESULTS: Despite a paucity of knowledge regarding their pathogenesis, limited evidence suggests the use of HFOs as biomarkers of epileptogenicity in resective procedures can improve seizure outcome. Clinicians must therefore weigh deficiencies in knowledge against the limited evidence supporting the utility of HFOs and make ethical decisions for the treatment of individual patients. Important ethical considerations for clinicians include the extent of deviation from established practice, the extent of evidence required to establish clinical validity, and the impact of technique implementation on equitable distribution of healthcare. CONCLUSION: The use of HFO signatures to guide neocortical resections represents a novel approach for the treatment of epilepsy. It is hoped that the issues discussed herein will contribute to and advance meaningful dialog on the ethical application of this surgical innovation to the treatment of a very vulnerable patient population.
Seizure 08/2012; · 1.80 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Circadian rhythm of seizure is underestimated in the study of focal epilepsies. A review of the current literature revealed a clear correlation between cortical epileptogenic focus and the circadian phase of seizure peak occurrence in adult patients. A single diurnal peak at 19:00 was found in seizures originating from the occipital lobe, between 5:00 and 7:00 in frontal lobe seizures, and between 16:00 and 17:00 h in temporal lobe seizures. Two diurnal peaks, between 5:00 and 7:00, and at 23:00 are reported in seizures from the parietal lobe, and between 7:00 to 8:00 and 16:00 to 17:00 in mesial temporal onset seizures. This circadian character of seizure occurrence in focal epilepsies may not be unique to partial seizures since recent clinical and experimental data indicate that generalized seizures also demonstrate circadian effects. The clinical evidence on generalized seizures and epilepsies is not recent, but a formal integration of circadian rhythmicity in our understanding and clinical management of epilepsies may be warranted.
Seizure 04/2012; 21(6):412-6. · 1.80 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The number of times that a published article is cited is one indicator of its scientific impact. An article is termed a "Citation Classic" once it has accumulated more than 400 citations. Trends in these highly cited works allow projection of future directions of high-impact research within a field. Herein, we identified 89 articles in the field of epilepsy published in 35 different journals that have been cited more than 400 times (citation range 401-3,749). The journal that published the greatest number of Citation Classics was Epilepsia (9 articles with 656 mean citations per article). Laboratory studies constituted the fastest growing area of highly cited epilepsy research, whereas clinical studies showed a bimodal distribution in representation among Citation Classics. There were also considerably fewer epilepsy-specific Citation Classics compared to other disciplines. In this study, we find that the Citation Classics of epilepsy comprise a heterogeneous group of articles and that changes in the trends of these highly cited works represent the evolution of epilepsy research over time. The results of this study should inform the academic community and provide a guide of essential literature for scientists who are engaged in epilepsy research.
Epilepsia 03/2012; 53(5):765-70. · 3.96 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Epilepsy is a common childhood condition associated with a considerable medical and psychosocial burden. Children in whom medical treatment fails to reduce seizure burden represent an especially vulnerable patient population because prolonged, uncontrolled seizures are associated with poor developmental and neurocognitive outcomes. Surgical treatment in the form of cortical resection, functional disconnection, or neuromodulation may alleviate or significantly reduce the disease burden for a subset of these patients. However, there remains a dichotomy between the perceived benefits of surgery and the implementation of surgical strategies in the management of medically intractable epilepsy. The current paper presents an analysis of the bioethical implications of existing inequities in access to pediatric epilepsy surgery that result from inconsistent referral practices and discrepant evaluation techniques. The authors provide a basic bioethical framework composed of 5 primary expectations to inform public, institutional, and personal policies toward the provision of epilepsy surgery to afflicted children.
Neurosurgical FOCUS 03/2012; 32(3):E2. · 2.87 Impact Factor
-
George M Ibrahim,
Aria Fallah,
Gregory W Albert,
Teresa Withers,
Hiroshi Otsubo,
Ayako Ochi,
Tomoyuki Akiyama,
Elizabeth J Donner,
Shelly Weiss, O Carter Snead,
James M Drake,
James T Rutka
[show abstract]
[hide abstract]
ABSTRACT: Occipital lobe epilepsy (OLE) poses a diagnostic challenge to clinicians. Here, we present our experience in the surgical management of OLE in children using magnetoencephalography (MEG) in the pre-operative evaluation.
Retrospective chart review was performed from 2000 to 2010 to identify patients with OLE. Patients were analyzed in two categories: isolated OLE (11 patients) and extended OLE (parietooccipital, temporooccipital, and temporoparietooccipital; 30 patients). Survival analysis and multivariate Cox proportional hazards regression were used to identify independent predictors of seizure outcome.
Forty-one patients with a mean follow-up of 3.1 years were identified with an overall 68% rate of satisfactory seizure outcome. Patients with extended OLE had younger ages at seizure onset and different seizure semiologies compared with those with isolated OLE. None of the latter underwent insertion of subdural grid electrodes for localization of the epileptogenic zone compared with 77% of the former (p<0.001). On multivariate analysis, the strongest independent predictor of unsatisfactory outcome was MEG dipoles in the occipital lobe contralateral to resection.
Here, we find similar seizure outcomes for isolated and extended OLE foci despite the use of less invasive strategies for the former. Furthermore, we describe the role of MEG in evaluation, surgical planning and prognostication of children with OLE.
Epilepsy research 01/2012; 99(3):335-45. · 2.48 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Introduction. Tuberous sclerosis (TS) is the leading cause of genetic epilepsy worldwide. Here, we evaluate changes in seizure outcomes following resective epilepsy surgery in children with TS over time. Methods. A systematic review of the literature was performed to identify studies reporting seizure outcomes following resective epilepsy surgery in children with TS. Using an individual participant meta-analysis approach, seizure outcomes and associated covariates were combined. Multivariate logistic regression was used to determine significant associations between seizure outcomes and time of surgery. Results. Twenty studies from 1966 to present, yielding 186 participants, met the inclusion criteria for the study. On univariate analysis, there was a significant improvement in seizure outcomes in children who underwent resective epilepsy surgery within the last 15 years compared to older cohorts (chi-square 4.1; P = 0.043). On multivariate analysis, adjusting for length of followup, this trend was not significant (OR 0.52; 95% CI 0.23-1.17; P = 0.11). In the last 15 years, a greater proportion of younger children also underwent resective surgery compared to older cohorts (OR 0.93; 95% CI 0.89-0.97; P < 0.01). Conclusions. A trend towards improved seizure outcomes following resective surgery for TS was observed from 1966 to present on multivariate analysis.
Epilepsy research and treatment. 01/2012; 2012:135364.
-
[show abstract]
[hide abstract]
ABSTRACT: Although children with epilepsy exhibit numerous neurological and cognitive deficits, the mechanisms underlying these impairments remain unclear. Synchronization of oscillatory neural activity in the gamma frequency range (>30 Hz) is purported to be a mechanism mediating functional integration within neuronal networks supporting cognition, perception and action. Here, we tested the hypothesis that seizure-induced alterations in gamma synchronization are associated with functional deficits. By calculating synchrony among electrodes and performing graph theoretical analysis, we assessed functional connectivity and local network structure of the hand motor area of children with focal epilepsy from intracranial electroencephalographic recordings. A local decrease in inter-electrode phase synchrony in the gamma bands during ictal periods, relative to interictal periods, within the motor cortex was strongly associated with clinical motor weakness. Gamma-band ictal desychronization was a stronger predictor of deficits than the presence of the seizure-onset zone or lesion within the motor cortex. There was a positive correlation between the magnitude of ictal desychronization and impairment of motor dexterity in the contralateral, but not ipsilateral hand. There was no association between ictal desynchronization within the hand motor area and non-motor deficits. This study uniquely demonstrates that seizure-induced disturbances in cortical functional connectivity are associated with network-specific neurological deficits.
PLoS ONE 01/2012; 7(6):e39326. · 4.09 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Hemispherectomy is an established neurosurgical procedure for medication-resistant epilepsy in children. Despite the effectiveness of this technique, there are patients who do not achieve an optimum outcome after surgery; possible causes of suboptimal results include the presence of bilateral independent epileptogenic foci. Magnetoencephalography (MEG) is an emerging tool that has been found to be useful in the management of lesional and nonlesional epilepsy. The authors analyzed the relative contribution of MEG in patient selection for hemispherectomy.
The medical records of children undergoing hemispherectomy at the Hospital for Sick Children were reviewed. Those patients who underwent MEG as part of the presurgical evaluation were selected.
Thirteen patients were included in the study. Nine patients were boys. The mean age at the time of surgery was 66 months (range 10-149 months). Seizure etiology was Rasmussen encephalitis in 6 patients, hemimegalencephaly in 2 patients, and cortical dysplasia in 4 patients. In 8 patients, video-EEG and MEG results were consistent to localize the primary epileptogenic hemisphere. In 2 patients, video-EEG lateralized the ictal onset, but MEG showed bilateral spikes. Two patients had bilateral video-EEG and MEG spikes. Engel Class I, II, and IV outcomes were seen in 10, 2, and 1 patients, respectively. In 2 of the patients who had an outcome other than Engel Class I, the MEG clusters were concentrated in the disconnected hemisphere. The third patient had bilateral clusters and potentially independent epileptogenic foci from bilateral cortical dysplasia.
The presence of unilateral MEG spike waves correlated with good outcomes following hemispherectomy. In some cases, MEG provides information that differs from that obtained from video-EEG and conventional MR imaging studies. Further studies with a greater number of patients are needed to assess the role of MEG in the preoperative assessment of candidates for hemispherectomy.
Journal of Neurosurgery Pediatrics 12/2011; 8(6):575-83. · 1.53 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The widespread inclusion of surgical strategies in the treatment of medically intractable epilepsy is largely justified by the medical and psychosocial burden of the illness. Performing these procedures in pediatric populations is associated with distinct challenges ranging from unique seizure etiologies to issues surrounding brain development and functional plasticity. As the trend toward more aggressive surgical intervention continues, the ethical foundation of current and emerging practices must be increasingly scrutinized. Here, we present the first article discussing ethical issues in the surgical management of medically intractable epilepsies in children. We discuss principles of informed consent, harm reduction, and justice in this vulnerable patient population. We also highlight the unique ethical challenge of surgical decision making concerning developmentally delayed children. The recognition of these issues is essential to providing patient-centered, responsible, and ethical care.
Epilepsy & Behavior 08/2011; 22(2):154-7. · 2.34 Impact Factor
-
Ayako Ochi,
Ryan Hung,
Shelly Weiss,
Elysa Widjaja,
Tonia To,
Yoshihiro Nawa,
Taiki Shima,
Cristina Go,
Tomoyuki Akiyama,
Elizabeth Donner,
James Drake,
James T Rutka, O Carter Snead,
Hiroshi Otsubo
[show abstract]
[hide abstract]
ABSTRACT: We assessed lateralization of interictal epileptiform discharges (IEDs) in children with intractable epilepsy secondary to tuberous sclerosis complexes (TSCs) during rapid eye movement sleep (R), compared with non-rapid eye movement sleep (NR) and wakefulness (W), to determine epileptogenicity of R-IEDs.
We retrospectively studied 23 children with TSC, who underwent prolonged scalp video-electroencephalography (EEG) and magnetic resonance imaging (MRI). We determined the lateralization of ictal EEG, clinical semiology, and the largest tuber on MRI. We analyzed a minimum of 100 IEDs during R, NR, and W to classify right/left/generalized spikes to compare the lateralization with ictal EEG, clinical semiology, and MRI.
R-IEDs were lateralized in 22 patients (96%), W-IEDs in 19 (83%), and NR-IEDs in 16 (70%). Ictal EEGs were lateralized in 15 patients (65%) and clinical semiology in 5 (22%). Ictal EEG lateralization was concordant to R-IEDs in 14 patients (93%), W-IEDs in 11 (73%), and NR-IEDs in 10 (67%). The lateralization of clinical semiology was concordant with R-IEDs in 4 (80%), W-IEDs in 3 (60%), and NR-IEDs in 2 (40%). MRI lateralization of the largest tuber was concordant with R-IEDs in 16 (70%), W-IEDs in 12 (52%), and NR-IEDs in 11 (48%). Thirteen patients (57%) underwent resective surgery, the hemisphere of which was concordant with R-IEDs in 13 (100%), W-IEDs in 8 (62%), and NR-IEDs in 8 (62%). Nine (69%) of them achieved good seizure control after surgery.
R provoked the most lateralized IEDs compared to NR and W in children with TSC. Lateralization of R-IEDs corresponded with the hemisphere of ictal EEG and largest tuber, and can be used to identify surgical candidacy in TSC children with intractable epilepsy.
Epilepsia 07/2011; 52(11):1986-94. · 3.96 Impact Factor
-
Tomoyuki Akiyama,
Bláthnaid McCoy,
Cristina Y Go,
Ayako Ochi,
Irene M Elliott,
Mari Akiyama,
Elizabeth J Donner,
Shelly K Weiss, O Carter Snead,
James T Rutka,
James M Drake,
Hiroshi Otsubo
[show abstract]
[hide abstract]
ABSTRACT: High-frequency oscillations (HFOs), termed ripples at 80-200 Hz and fast ripples (FRs) at >200/250 Hz, recorded by intracranial electroencephalography (EEG), may be a valuable surrogate marker for the localization of the epileptogenic zone. We evaluated the relationship of the resection of focal brain regions containing high-rate interictal HFOs and the seizure-onset zone (SOZ) determined by visual EEG analysis with the postsurgical seizure outcome, using extraoperative intracranial EEG monitoring in pediatric patients and automated HFO detection.
We retrospectively analyzed 28 pediatric epilepsy patients who underwent extraoperative intracranial video-EEG monitoring prior to focal resection. Utilizing the automated analysis, we identified interictal HFOs during 20 min of sleep EEG and determined the brain regions containing high-rate HFOs. We investigated spatial relationships between regions with high-rate HFOs and SOZs. We compared the size of these regions, the surgical resection, and the amount of the regions with high-rate HFOs/SOZs within the resection area with seizure outcome.
Ten patients were completely seizure-free and 18 were not at 2 years after surgery. The brain regions with high-rate ripples were larger than those with high-rate FRs (p = 0.0011) with partial overlap. More complete resection of the regions with high-rate FRs significantly correlated with a better seizure outcome (p = 0.046). More complete resection of the regions with high-rate ripples tended to improve seizure outcome (p = 0.091); however, the resection of SOZ did not influence seizure outcome (p = 0.18). The size of surgical resection was not associated with seizure outcome (p = 0.22-0.39).
The interictal high-rate FRs are a possible surrogate marker of the epileptogenic zone. Interictal ripples are not as specific a marker of the epileptogenic zone as interictal FRs. Resection of the brain regions with high-rate interictal FRs in addition to the SOZ may achieve a better seizure outcome.
Epilepsia 07/2011; 52(10):1802-11. · 3.96 Impact Factor
-
Tomoyuki Akiyama,
Makoto Osada,
Masahide Isowa,
Cristina Y Go,
Ayako Ochi,
Irene M Elliott,
Mari Akiyama, O Carter Snead,
James T Rutka,
James M Drake,
Hiroshi Otsubo
[show abstract]
[hide abstract]
ABSTRACT: We determined whether kurtosis analysis of intracranial electroencephalogram (EEG) can estimate the localization of the epileptogenic zone.
We analyzed 29 pediatric epilepsy patients who underwent intracranial EEG before focal resective surgery. We localized the brain regions with high kurtosis, the seizure onset zone (SOZ) and the regions with high-rate, high-amplitude and long-duration interictal paroxysms ≥20 Hz. We tested correlations between the surgical resection of those regions and post-surgical seizure outcome, and correlations between kurtosis and the rate/amplitude/duration of interictal paroxysms.
The resection of the regions with high kurtosis correlated with 1-year post-surgical seizure outcome (p=0.028) but not with 2-year outcome. Kurtosis showed more significant correlation with 1-year seizure outcome than the SOZ and the rate/amplitude/duration of interictal paroxysms. Kurtosis showed positive, independent correlations with the amplitude and duration of interictal paroxysms (p<0.0001) but not with the rate (p=0.4).
The regions with high kurtosis provide more reliable information to predict seizure outcome than the SOZ and the regions with high-rate/amplitude and long-duration interictal paroxysms. Kurtosis reflects combined effects of the amplitude and duration of the interictal paroxysms.
High kurtosis suggests the regions with acquired ictogenicity within the irritative zone.
Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 07/2011; 123(1):93-9. · 3.12 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Jeavons syndrome (JS) is one of the underreported epileptic syndromes characterized by eyelid myoclonia (EM), eye closure-induced seizures/electroencephalography (EEG) paroxysms, and photosensitivity. JS has been proposed as idiopathic generalized epilepsy (IGE) because of normal posterior dominant background activity and paroxysmal generalized ictal epileptiform discharges (EDs). However, we noticed subtle occipital EDs preceding EM and interictal posterior EDs using digital video-EEG. We studied clinical and EEG findings in JS to determine the specific occipital lobe relation to this "eye closure-induced" reflex IGE.
We identified 12 children who met the diagnostic criteria of JS from January 2004 to April 2009 at the Hospital for Sick Children, Toronto, Canada. All patients had EM captured by video-EEG. We reviewed and described ictal EEG patterns, interictal abnormalities, and demographics, clinical, and neuroimaging findings.
All patients but one were female (92%). Age at seizure onset ranged from 1.5 to 9 years, with a mean age of 4.9 years. Six patients (50%) were previously diagnosed as having absence epilepsy and 10 patients were on antiepileptic medications. All 12 patients had normal posterior dominant alpha rhythm, reactive to eye opening and closure. Spiky posterior alpha activity was noted with sustained eye closure in six patients (50%). Interictally, there were generalized EDs found in 10 patients (83%); four of them also had focal interictal EDs over the posterior head region. Eleven patients (92%) had evidence of focal posterior ictal EDs. EM and/or paroxysmal EDs were induced by photic stimulation in 9 (75%) and hyperventilation in 7 (58%).
We observed two neurophysiologic findings in JS: (1) focal interictal EDs from posterior head region; and (2) predominant focal posterior ictal EDs preceding generalized EDs. Further clinical observations of seizures induced by eye closure, photic stimulation, and hyperventilation along with EEG paroxysms would raise the possibility of the occipital cortex initiating generalized epilepsy network involving the brainstem, and thalamocortical and transcortical pathways in JS.
Epilepsia 07/2011; 52(7):1273-9. · 3.96 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We utilized the high temporal resolution, whole head coverage and novel analysis methodology of magnetoencephalography (MEG) to record the dynamics of cerebellar activation during focal motor seizures. We analyzed ictal MEG data from a four-year old using an event-related beamformer to localize and display ictal changes over the motor cortex and cerebellum. Contralateral activation of the cerebellum was seen 14s after MEG ictal onset over the motor cortex. These findings represent the first indication of ictal activity within the cerebellum in humans, measured non-invasively with MEG.
Epilepsy research 06/2011; 96(3):283-7. · 2.48 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Spread of seizure activity outside the frontal lobe due to cortico-cortical connections can result in alteration in the cortex beyond the frontal lobe in children with intractable frontal lobe epilepsy (FLE). The aim of this study was to identify regions of reduced cortical thickness in children with intractable FLE.
High-resolution volumetric T(1)-weighted imaging was performed on 17 children with FLE, who were being evaluated for epilepsy surgery, and 26 age-matched healthy controls. The cortical thickness of 12 patients with left FLE and 5 patients with right FLE was compared to controls. The clusters of cortical thinning were regressed against age of seizure onset, duration of epilepsy, seizure frequency, and number of medications.
In children with left FLE, cortical thinning was present in the left superior frontal, paracentral, precuneus, cingulate, inferior parietal, supramarginal, postcentral, and superior temporal gyri, as well as in the right superior and middle frontal, medial orbitofrontal, supramarginal, postcentral, banks of superior temporal sulcus, and parahippocampal gyri. In children with right FLE, cortical thinning was present in the right precentral, postcentral, transverse temporal, parahippocampal, lingual, and lateral occipital gyri, as well as in the left superior frontal, inferior parietal, postcentral, superior temporal, posterior cingulate, and lingual gyri. In children with left FLE, following exclusion of one outlier, there was no significant association between age at seizure onset, duration of epilepsy, seizure frequency and number of medications with clusters of cortical thinning. In children with right FLE, age at seizure onset, duration of epilepsy, frequency of seizures, and number of medications were not associated with clusters of cortical thinning within the right and left hemispheres.
Cortical changes were present in the frontal and extrafrontal cortex in children with intractable FLE. These changes may be related to spread of seizure activity, large epileptogenic zones involving both frontal and extrafrontal lobes, and development of secondary epileptogenic zones that over time lead to cortical abnormality. Further studies correlating cortical changes with neurocognitive measures are needed to determine if the cortical changes relate to cognitive function.
Epilepsia 05/2011; 52(9):1685-91. · 3.96 Impact Factor
