Shelly K Weiss

University of Toronto, Toronto, Ontario, Canada

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Publications (37)86.37 Total impact

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    ABSTRACT: The literature has been highly informative for when to use actigraphy and its validity in pediatric research. However, minimal literature exists on how to perform actigraphy, especially in special populations. We determined whether providing actigraphy training to parents and coordinators increased the nights of actigraphy data that could be scored. We compared two studies in children with autism spectrum disorders, one of which provided a basic level of training in a single-site trial and the other of which provided more detailed training to parents and coordinators in a multisite trial. There was an increase in scorable nights in the multisite trial containing a one-hour structured parent training session. Our results support the use of educational tools in clinical trials that use actigraphy.
    Behavioral Sleep Medicine 03/2014; · 1.13 Impact Factor
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    ABSTRACT: Children with epilepsy have frequent sleep disturbance and challenges in learning and memory. There is little research on the consolidation of memory during sleep in this population. The goal of this pilot study was to determine whether children with epilepsy are able to consolidate memories better after a sleep versus wake period as has been demonstrated in typically developing children. This study was a prospective evaluation of children with epilepsy to determine if sleep improved episodic memory (using word lists) as compared with memory following a wake period of similar duration. The study was conducted in patients in the Epilepsy Monitoring Unit at a single academic health science center. In the sleep recall condition, the learning trials were presented in the evening, and delayed recall of the words was tested in the morning. In the wake condition, the learning took place in the morning, and the delayed recall took place later in the day. Subjects wore an actigraph to evaluate sleep/wake patterns. Data regarding the children's epilepsy, antiepileptic medications, and frequency of interictal epileptiform discharges were also documented. Ten children (agd 8-17years) participated in the study. For the entire sample, recall after sleep was better than recall after awake (p=0.03), and 7 of the 10 children showed this effect. However, reanalyses removing an outlier showed no difference between the two recall conditions. The mean number of interictal epileptiform discharges was 8.8 during the recall after sleep and 7.8 during the recall after awake. Three children had seizures during the evaluation. In this pilot study, we demonstrated that a small cohort of children with epilepsy, with similar interictal epileptiform discharges during sleep and wake, showed no advantage in memory for a word list after a period of sleep than after a period of being awake. This finding requires further study in a larger cohort. Poor memory consolidation during sleep may contribute to the cognitive deficits in children with epilepsy.
    Epilepsy & Behavior 01/2014; 31C:176-180. · 2.06 Impact Factor
  • Sleep Medicine Clinics 01/2014; 9(2):149–168.
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    ABSTRACT: Background The relationship between epilepsy and sleep is bidirectional as seizures disrupt sleep and coexisting sleep disorders have detrimental effects on seizure control and quality of life for both the children and their families. Previous research has reported on sleep disturbance in children with epilepsy primarily by subjective parental reports. Actigraphy may provide a more accurate objective evaluation of sleep, but the validity of this sleep measure for children with epilepsy has not yet been assessed. The primary objective of this study was to validate the use of actigraphy as a tool in studying sleep patterns in children with epilepsy. Methods This was a prospective study comparing sleep and wake epochs recorded for 24 h simultaneously by actigraphy and by continuous video-electroencephalography (VEEG) monitoring in 27 patients aged 2–18 years with medically refractory epilepsy. Results Strong correlations were found between actigraphy and VEEG sleep variables including night sleep period (r = 0.99), night sleep time (r = 0.96), duration of night wake time (r = 0.93) and number of significant wakings during the night (r = 0.81). Conclusion The study results validate that actigraphy is a reliable and objective clinical and research tool for evaluating sleep and wakefulness in children with epilepsy.
    Sleep Medicine. 01/2014;
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    ABSTRACT: Sleep problems are common among children with chronic illnesses such as Juvenile Idiopathic Arthritis (or JIA). However, little is known about the frequency and severity of sleep disturbance(s) and the factors that are associated with sleep problems in children with JIA. The mechanism(s) of the relationships characterizing the development or exacerbation of sleep problems in children with JIA are still unknown, however studies have reported an association. The purpose of this study was to synthesize existing research related to sleep problems in children with JIA.
    Pediatric rheumatology online journal. 01/2014; 12:19.
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    ABSTRACT: A systems analysis perspective was undertaken to evaluate access to surgery for children with medically refractory epilepsy (MRE) in Ontario, the largest province in Canada. The analysis focused on the assessment of referral patterns, healthcare utilization, time intervals and patient flow to determine surgical candidacy in children with MRE. The purpose of this systems analysis study was to identify rate limiting steps that may lead to delayed surgical candidacy decision and surgery. Prolonged video electroencephalography (vEEG) is the common entry point into the process for all potential epilepsy surgery candidates. Therefore, a single centre retrospective chart review of children and adolescents referred to the epilepsy monitoring unit (EMU) for vEEG monitoring at the primary referral centre for paediatric epilepsy surgery in the province. Basic demographic and referral data were abstracted for all screened cases. Included cases were: (1) age <19 years old at time of first EMU admission, (2) date of EMU admission between April 1, 2004 and March 31, 2006 and (3) referral for elective vEEG and/or overnight with vEEG greater than 8h duration. Data were collected on number of seizure conferences, surgical candidacy, surgical outcomes (seizure free and seizure reduction), resource utilization, and recorded time stamps for each event to estimate system delays. During the two-year period, 463 patients were referred to the EMU of whom 349 received prolonged vEEG (>8h). Forty five percent (n=160) of patients came to seizure conference for discussion of their data, of whom 40% (64/160) were considered surgical candidates. Time from first seizure to EMU referral was approximately 4.6 years. Time from referral to admission and admission to first seizure conference were approximately 103 days and 71 days, respectively. From initial EMU referral to surgery ranged from 1.6 to 1.1 years depending on whether the patient required invasive monitoring with intracranial EEG. Overall, 95% of surgical patients had a reduction in seizure frequency, 74% were seizure free after one year post-surgery. Referral rates for surgical assessment are low relative to the estimated number of children living with MRE in Ontario, less than 2%. Hence, only a limited number of children with this disorder in the province of Ontario who could benefit from epilepsy surgery are being assessed for surgical candidacy. The majority of Ontario children with MRE are not being provided the potential opportunity to be seizure free and live without functional limitations following surgical intervention. These data document the critical need for health system redesign in Ontario, the goal of which should be to provide more consistent and just access to evidence-based medical and surgical care for those citizens of the province who suffer from epilepsy.
    Epilepsy research 09/2013; · 2.48 Impact Factor
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    ABSTRACT: This study provided sleep education to parents of children with autism spectrum disorder (ASD) to determine whether an individual or group format was more effective in improving sleep and aspects of daytime behavior and family functioning. Eighty children, ages 2-10 years, with ASD and sleep onset delay completed the study. Actigraphy and parent questionnaires were collected at baseline and 1 month after treatment. Mode of education did not affect outcomes. Sleep latency, insomnia subscales on the Children's Sleep Habits Questionnaire, and other outcomes related to child and family functioning improved with treatment. Parent-based sleep education, delivered in relatively few sessions, was associated with improved sleep onset delay in children with ASD. Group versus individualized education did not affect outcome.
    Journal of Autism and Developmental Disorders 06/2013; · 3.06 Impact Factor
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    ABSTRACT: Purpose:  Cognitive impairment is observed commonly in children with a history of infantile spasms (IS). The goal of this study was to prospectively examine the effect on cognitive outcome of a neuroprotective agent used as adjunctive therapy during treatment of the spasms. Methods:  In a randomized controlled trial, patients received a standardized therapy plus flunarizine or placebo. The standardized treatment consisted of vigabatrin as first-line therapy. Nonresponders were switched to intramuscular synthetic adrenocorticotropic hormone (sACTH depot) after 2 weeks and, if necessary, to topiramate after two additional weeks. The Vineland Adaptive Behavior Scale (VABS) and Bayley Scales of Infant Development (BSID) were used as outcome measures 24 months after the intervention. Key Findings:  Sixty-eight of 101 children diagnosed over 3 years in seven centers in Canada received either adjunctive flunarizine or placebo. Sixty-five of the 68 children (96%) became spasm-free within 8 weeks and no late relapse occurred. Bayley and Vineland results were available at baseline and at 24 months in 45 children. There was no significant difference in the BSID developmental quotient between the flunarizine- and placebo-treated children at baseline (44.3 ± 35.5 vs. 30.9 ± 29.8; p = 0.18) or 24 months later (56.9 ± 33.3 vs. 46 ± 34.2; p = 0.29). However, the 10 flunarizine-treated children with no identified etiology had a better outcome than the eight controls at 24 months on both the Vineland Scale (84.1 ± 11.3 vs. 72.3 ± 9.8; p = 0.03) and the Bayley Scale (87.6 ± 14.7 vs. 69.9 ± 25.3; p = 0.07). Significance:  Our study failed to demonstrate a protective effect of flunarizine on cognitive outcome in a cohort of children with IS. An analysis of subgroups suggested that flunarizine may further improve cognitive outcome in children with no identified etiology.
    Epilepsia 08/2012; 53(9):1570-1576. · 3.96 Impact Factor
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    ABSTRACT: Pediatric frontal lobe epilepsy (FLE) remains a challenging condition for neurosurgeons and epileptologists to manage. Postoperative seizure outcomes remain far inferior to those observed in temporal lobe epilepsies, possibly due to inherent difficulties in delineating and subsequently completely resecting responsible epileptogenic regions. In this study, the authors review their institutional experience with the surgical management of FLE and attempt to find predictors that may help to improve seizure outcome in this population. All surgically treated cases of intractable FLE from 1990 to 2008 were reviewed. Demographic information, preoperative and intraoperative imaging and electrophysiological investigations, and follow-up seizure outcome were assessed. Inferential statistics were performed to look for potential predictors of seizure outcome. Forty patients (20 male, 20 female) underwent surgical management of FLE during the study period. Patients were an average of 5.6 years old at the time of FLE onset and 11.7 years at the time of surgery; patients were followed for a mean of 40.25 months. Most patients displayed typical FLE semiology. Twenty-eight patients had discrete lesions identified on MRI. Eight patients underwent 2 operations. Cortical dysplasia was the most common pathological diagnosis. Engel Class I outcome was obtained in 25 patients (62.5%), while Engel Class II outcome was observed in 5 patients (12.5%). No statistically significant predictors of outcome were found. Control of FLE remains a challenging problem. Favorable seizure outcome, obtained in 62% of patients in this series, is still not as easily obtained in FLE as it is in temporal lobe epilepsy. While no statistically significant predictors of seizure outcome were revealed in this study, patients with FLE continue to require extensive workup and investigation to arrive at a logical and comprehensive neurosurgical treatment plan. Future studies with improved neuroimaging and advanced invasive monitoring strategies may well help define factors for success in this form of epilepsy that is difficult to control.
    Journal of Neurosurgery Pediatrics 07/2012; 10(3):206-16. · 1.63 Impact Factor
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    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
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    ABSTRACT: We developed a technique to produce images of dynamic changes in ictal high-frequency oscillations (HFOs) >40 Hz recorded on subdural electroencephalography (EEG) that are time-locked to the ictal EEG and ictal semiology video. We applied this technique to Jacksonian seizures to demonstrate ictal HFO propagation along the homunculus in the primary sensory-motor cortex to visualize the underlying epileptic network. We analyzed intracranial ictal EEGs from two patients with intractable Jacksonian seizures who underwent epilepsy surgery. We calculated the degrees of increase in amplitude within 40-80, 80-200, and 200-300 Hz frequency bands compared to the interictal period and converted them into topographic movies projected onto the brain surface picture. We combined these data with the ictal EEGs and video of the patient demonstrating ictal semiology. The ictal HFOs began in the sensory cortex and appeared concomitantly with the sensory aura. They then propagated to the motor cortex at the same time that focal motor symptoms evolved. As the seizure progressed, the ictal HFOs spread or reverberated in the rolandic region. However, even when the seizure became secondarily generalized, the ictal HFOs were confined to the rolandic region. In both cases, there was increased amplitude of higher frequency bands during seizure initiation compared to seizure progression. This combined movie showed the ictal HFO propagation corresponding to the ictal semiology in Jacksonian seizures and revealed the epileptic network involved in seizure initiation and progression. This method may advance understanding of neural network activities relating to clinical seizure generation and propagation.
    Epilepsia 11/2010; 52(1):75-83. · 3.96 Impact Factor
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    ABSTRACT: We examined potential differences in the effects of pathology type on language lateralization in pediatric epilepsy. We examined findings from intracarotid sodium amobarbital procedure (IAP/Wada) in a large consecutive sample of children with refractory epilepsy. Subjects were assigned to one of three pathology groups: developmental (n = 28), acquired (n = 26), and tumor (n = 20); groups were compared for language lateralization. Rates of atypical language lateralization did not differ across groups. Greater than half of the subjects with left hemisphere insults and seizure onset before 6 years of age had atypical language lateralization, independent of pathology type. Atypical language lateralization may occur in the context of developmental, acquired, and/or tumor pathology.
    Epilepsia 03/2009; 50(6):1498-504. · 3.96 Impact Factor
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    ABSTRACT: Studies of adults who underwent temporal lobectomy for intractable temporal lobe epilepsy (TLE) demonstrated declining seizure free rates over time. Using seizure and social parameters, we followed patients who had temporal lobe surgery (TLS) in childhood to determine long-term outcomes. We identified 42 patients who underwent TLS for medically intractable epilepsy during childhood. Follow-up data were collected from 10 to 20 years after surgery (median, 12 years). We studied histopathology, seizure outcome, employment, school enrolment, and driver's licensing. Patients or parents graded their satisfaction with TLS. Number of Engel class I patients was 34 (81%) after 6 months; 32 (76%) after 1 year; 30 (71%) after 5 years; and 28 (67%) at last >or=10 years follow-up. Nineteen (79%) of 24 children with tumors or cavernous angioma achieved class I outcomes in contrast to 9 (50%) of 18 children with other pathologies (p<0.05). Ten (56%) of 18 recurrent seizure patients experienced seizures within the first year; 4 required reoperation for seizure freedom. More seizure free patients (24, 86%) than residual seizure patients (8, 57%) were employed or in school (p=0.05). Twelve (63%) of 19 eligible patients obtained driver's licenses. Twenty-three (82%) of 28 seizure free patients discontinued anticonvulsants. Surgery grading averaged "satisfied." Class I patients reported greater satisfaction than class III/IV patients (p<0.001). Two-thirds of children who underwent TLS achieved seizure freedom at >or=10 year follow-up. Children with tumors or cavernous angiomas achieved better long-term outcomes than those with other histopathologies. Long-term seizure free patients were most often satisfied with surgery and employed or in school.
    Epilepsy research 10/2008; 82(2-3):133-8. · 2.48 Impact Factor
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    ABSTRACT: To investigate whether visual deficits in children with infantile spasm (IS) are the result of seizure activity or of treatment with the anticonvulsant drug vigabatrin (VGB). Vision function was determined in three experiments by determining peak contrast sensitivity (CS) and grating acuity (GA) with the sweep visual evoked potential. Cross-sectional study A: 34 children, including 11 patients with childhood epilepsy with exposure to VGB for at least 6 months, 10 with childhood epilepsy exposed to antiepileptic drugs other than VGB, and 13 normally developing children. Cross-sectional study B: 32 children, including 16 with IS naïve to VGB and 16 normally developing children. Longitudinal study: seven children with IS naïve to VGB, with subsequent follow-up 5 to 10 months after starting VGB. In cross-sectional study A, the median CS was reduced by 0.5 log units (P = 0.025) in children with epilepsy exposed to VGB compared with those exposed to other antiepileptic drugs and normally developing children. In cross-sectional study B, the median CS was reduced by 0.25 log units (P = 0.0015) in children with IS (VGB naïve) compared with normally developing children. Longitudinal assessment showed no decrease in CS in children with IS who were followed up 5 to 10 months after starting VGB. There was no difference in GA among groups in any of the experiments. Patients with IS have CS deficits, but a sparing of GA. This deficit is present before VGB treatment and does not worsen with treatment onset. Results suggest that visual dysfunction is largely the result of the seizures themselves.
    Investigative Ophthalmology &amp Visual Science 09/2007; 48(8):3610-5. · 3.44 Impact Factor
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    ABSTRACT: We investigated language representation in nine children (six male, three female; 5.6-17.7 years of age) who underwent surgical treatment of medically intractable epilepsy of the left hemisphere. Although interhemispheric reorganization has been previously documented in similar groups, this is the first study to systematically evaluate possible intrahemispheric effects of early insult. All cases had left hemisphere seizure foci and underwent extraoperative stimulation mapping (ESM) for language localization prior to receiving cortical resections. To compare ESM findings across subjects and to assess intrahemispheric reorganization, we developed a novel coregistration technique whereby independent raters plotted two-dimensional (2D) ESM findings in 3D standard space. Expressive language sites identified with ESM were compared with a structural probability map of pars opercularis, or Broca's area. The average difference between independent raters' estimates of 28 language sites was 3.9 mm (SD = 2.0), indicating excellent agreement; the coregistration procedure permitted assessment of 2D ESM findings in 3D standard space. We observed language sites in regions substantially anterior and superior to canonical Broca's area, possibly reflecting intrahemispheric reorganization. Findings suggest that left hemisphere insult in young children may result in anterior displacement of language within the frontal cortex.
    Journal of the International Neuropsychological Society 06/2007; 13(3):505-16. · 2.70 Impact Factor
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    ABSTRACT: To identify the predictors of postsurgical seizure freedom in children with refractory epilepsy and normal or nonfocal MRI findings. We analyzed 22 children with normal or subtle and nonfocal MRI findings, who underwent surgery for intractable epilepsy following extraoperative intracranial EEG. We compared clinical profiles, neurophysiological data (scalp EEG, magnetoencephalography (MEG) and intracranial EEG), completeness of surgical resection and pathology to postoperative seizure outcomes. Seventeen children (77%) had a good postsurgical outcome (defined as Engel class IIIA or better), which included eight (36%) seizure-free children. All children with postsurgical seizure freedom had an MEG cluster in the final resection area. Postsurgical seizure freedom was obtained in none of the children who had bilateral MEG dipole clusters (3) or only scattered dipoles (1). All five children in whom ictal onset zones were confined to < or = 5 adjacent intracranial electrodes achieved seizure freedom compared to three of 17 children with ictal onset zones that extended over >5 electrodes (p = 0.002). None of six children with more than one type of seizure became seizure-free, compared to eight of 16 children with a single seizure type (p = 0.04). Complete resection of the preoperatively localized epileptogenic zone resulted in seizure remission in 63% (5/8) and incomplete resections, in 21% (3/14) (p = 0.06). Age of onset, duration of epilepsy, number of lobes involved in resection, and pathology failed to correlate with seizure freedom. Surgery for intractable epilepsy in children with normal MRI findings provided good postsurgical outcomes in the majority of our patients. As well, restricted ictal onset zone predicted postoperative seizure freedom. Postoperative seizure freedom was less likely to occur in children with bilateral MEG dipole clusters or only scattered dipoles, multiple seizure types and incomplete resection of the proposed epileptogenic zone. Seizure freedom was most likely to occur when there was concordance between EEG and MEG localization and least likely to occur when these results were divergent.
    Epilepsia 02/2007; 48(1):149-57. · 3.91 Impact Factor
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    ABSTRACT: Temporal lobectomy is a well-established neurosurgical procedure for temporal lobe epilepsy. In this study, we conducted a retrospective review of children with drug-resistant temporal lobe epilepsy to evaluate seizure outcome after temporal lobe surgery. We reviewed the medical records of 126 children who had surgery for temporal lobe epilepsy at The Hospital for Sick Children between 1983 and 2003. The records were examined for preoperative and intraoperative factors that could predict patient outcome after surgery. The mean age at seizure onset was 5.9 years. The mean seizure duration before surgery was 5.6 years. All patients had preoperative computed tomographic scans, magnetic resonance imaging scans, or both. The mean age at the time of surgery was 13.5 years. Sixty-two patients underwent left temporal resections and 64 patients underwent right temporal resections. The histopathology of the temporal resections revealed low-grade brain tumors in 65 children (52%) and cavernous malformations in four children. Ganglioglioma and astrocytoma were the most common tumors encountered. Mesial temporal sclerosis was found in 16 patients (13%), astrogliosis in 15 patients (12%), and cortical dysplasia in eight patients (7%). Postoperative follow-up of at least 2 years was available for 106 patients and ranged up to 13.0 years. Seventy-four percent of patients had an Engel Class I or II outcome. Patients with temporal lobe lesions had better outcomes compared with those without lesions (P < 0.05). Patients without a history of secondary generalization of seizures also had a better outcome when compared with those with secondary generalization. Complications in the form of contralateral homonymous hemianopsia, dysphasia, and infection were found in 5% of patients. Twelve patients had a second temporal lobe procedure for intractable recurrent seizures. After a second procedure, seven patients returned to a seizure-free state. Temporal lobe resections for epilepsy in children are effective and safe procedures, with a favorable impact on seizure control. Repeat temporal resections for recurrent seizures may also be effective in restoring a seizure-free outcome to children.
    Neurosurgery 01/2007; 59(6):1203-13; discussion 1213-4. · 2.53 Impact Factor
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    ABSTRACT: To understand the rapid dynamic changes of ictal intracranial high-frequency oscillations (HFOs) in neocortical epilepsy. We integrated multiple band frequency analysis and brain-surface topographic maps of HFOs from ictal subdural EEG (SDEEG) recordings. We used SDEEG to record partial seizures consisting of right-arm jerks with secondary generalization in a 17-year-old right-handed girl. We selected 20-s EEG sections that included preclinical seizure recordings. We averaged the HFO power between 60 and 120 Hz for 25 selected electrodes, made topographic maps from these averaged powers, and superimposed the maps on the brain-surface image. We filmed consecutive HFO maps at a 10-ms frame rate. Before clinical seizure onset, high-power HFOs emerged at the superior portion of the left precentral gyrus, then appeared in the middle of the left postcentral gyrus, and subsequently reverberated between both regions as well as the posterior portion of the left postcentral gyrus. Right-arm extension and facial grimacing started as the HFO power decreased. As generalized tonic-clonic seizures evolved, HFO power increased but remained within the central region. Topographic movies of intracranial HFOs on the brain surface allow visualization of the dynamic ictal changes in neocortical epilepsy.
    Epilepsia 12/2006; 47(11):1953-7. · 3.91 Impact Factor
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    ABSTRACT: Magnetoencephalography (MEG) has been used for the preoperative localization of epileptic equivalent current dipoles (ECDs) in neocortical epilepsy. Spatial filtering can be applied to MEG data by means of synthetic aperture magnetometry (SAM), and SAM virtual sensor analysis can be used to estimate the strength and temporal course of the epileptic source in the region of interest. To evaluate the clinical usefulness of this approach, the authors compare the results of SAM virtual sensor analysis to the results of ECD analysis, subdural electroencephalography (EEG) findings, and surgical outcomes in pediatric patients with neocortical epilepsy. Ten pediatric patients underwent MEG, invasive subdural EEG, and cortical resection for neocortical epilepsy. The authors compared the morphological characteristics, quantity, location, and distribution of the epileptiform discharges assessed using SAM and ECD analysis, and subdural EEG findings (interictal discharges and ictal onset zones). In nine patients, MEG revealed clustered ECDs. The region exhibiting the maximum percentage (> or = 70%) of spikes/sharp waves on SAM was colocalized to clustered ECDs in seven patients. In six patients, SAM demonstrated focal spikes; in two, diffuse spikes; and in two others, focal rhythmic sharp waves. These epileptiform discharges were similar to those recorded on subdural EEG. In nine patients, concordant regions containing the maximum percentage of spikes/sharp waves were revealed by SAM and subdural EEG data. The region of the maximum percentage of spikes/sharp waves as demonstrated by SAM was colocalized to the ictal onset zone identified by subdural EEG findings in seven patients and partially colocalized in two. The SAM virtual sensor analysis revealed morphological characteristics, location, and distribution of epileptiform discharges similar to those shown by subdural EEG recordings. By using SAM it is possible to predict intracerebral interictal epileptiform discharges in the region of interest from noninvasively collected preoperative MEG data. The maximum interictal discharge zone identified by SAM virtual sensors correlated to clustered ECDs and the ictal onset zone on subdural EEG findings. Complementary analyses of ECDs and SAM on three-dimensional MR images can improve delineation of epileptogenic zones and lesions in neocortical epilepsy.
    Journal of Neurosurgery 07/2006; 105(1 Suppl):41-9. · 3.15 Impact Factor
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    ABSTRACT: To evaluate the impact of steroid treatment on cerebral swelling and seizures during subdural grid EEG (SGEEG) monitoring. We reviewed data from 37 pediatric patients with intractable epilepsy who underwent SGEEG monitoring and divided the patients into those who received dexamethasone and those who did not. We then correlated administration of steroids to incidence of cerebral swelling on computed tomography (CT) scans and to frequency of seizures during SGEEG. Twenty-three patients received dexamethasone prophylactically every 6 hours (dosage range, 1-7.5 mg; mean, 3.2 mg) from the first day of SGEEG placement (group A); 14 patients received no dexamethasone (group B). Eight (21.6%) of 37 patients experienced cerebral swelling on CT: two (9%) were in group A, and six (42.9%) were in group B (p < 0.05). SGEEG monitoring time for recording habitual seizures that localized cortical areas for surgical excision was longer in group A (1-6 days; mean, 3.0) than it was in group B (1-3 days; mean, 2.2), (p < 0.05). Habitual seizures were recorded in 36 patients. One group A patient experienced obtundation due to cerebral swelling, and monitoring in this patient was discontinued. The prophylactic administration of steroids to pediatric patients during SGEEG monitoring is efficacious for reducing cerebral swelling. Although it decreases the frequency of habitual seizures and increases seizure-monitoring time, dexamethasone reduces the risk of complications from cerebral swelling during the SGEEG procedure.
    Epilepsia 02/2006; 47(1):176-80. · 3.91 Impact Factor

Publication Stats

543 Citations
86.37 Total Impact Points

Institutions

  • 2005–2014
    • University of Toronto
      • • Division of Neurology
      • • Hospital for Sick Children
      Toronto, Ontario, Canada
    • The University of Tennessee Health Science Center
      • Department of Neurology
      Memphis, TN, United States
  • 2002–2014
    • SickKids
      • Division of Neurology
      Toronto, Ontario, Canada