15 results on '"Thornton, Rachel C"'
Search Results
2. Advances in EEG: home video telemetry, high frequency oscillations and electrical source imaging
- Author
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Patel, Anjla C., Thornton, Rachel C., Mitchell, Tejal N., and Michell, Andrew W.
- Published
- 2016
- Full Text
- View/download PDF
3. fMRI in Epilepsy
- Author
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Thornton, Rachel C., primary, van Graan, Louis André, additional, Powell, Robert H., additional, and Lemieux, Louis, additional
- Published
- 2016
- Full Text
- View/download PDF
4. EEG-fMRI in the presurgical evaluation of temporal lobe epilepsy
- Author
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Coan, Ana C, Chaudhary, Umair J, Frédéric Grouiller, Campos, Brunno M, Perani, Suejen, De Ciantis, Alessio, Vulliemoz, Serge, Diehl, Beate, Beltramini, Guilherme C, Carmichael, David W, Thornton, Rachel C, Covolan, Roberto J, Cendes, Fernando, and Lemieux, Louis
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- 2016
- Full Text
- View/download PDF
5. Techniques and applications of EMG: measuring motor units from structure to function
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Thornton, Rachel C. and Michell, Andrew W.
- Published
- 2012
- Full Text
- View/download PDF
6. Mapping preictal and ictal haemodynamic networks using video-electroencephalography and functional imaging
- Author
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Chaudhary, Umair J., Carmichael, David W., Rodionov, Roman, Thornton, Rachel C., Bartlett, Phillipa, Vulliemoz, Serge, Micallef, Caroline, McEvoy, Andrew W., Diehl, Beate, Walker, Matthew C., Duncan, John S., and Lemieux, Louis
- Published
- 2012
- Full Text
- View/download PDF
7. With or without spikes: localization of focal epileptic activity by simultaneous electroencephalography and functional magnetic resonance imaging
- Author
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Grouiller, Frédéric, Thornton, Rachel C., Groening, Kristina, Spinelli, Laurent, Duncan, John S., Schaller, Karl, Siniatchkin, Michael, Lemieux, Louis, Seeck, Margitta, Michel, Christoph M., and Vulliemoz, Serge
- Published
- 2011
- Full Text
- View/download PDF
8. Microelectrode recordings in human epilepsy: a case for clinical translation
- Author
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Chari, Aswin, primary, Thornton, Rachel C, additional, Tisdall, Martin M, additional, and Scott, Rodney C, additional
- Published
- 2020
- Full Text
- View/download PDF
9. The UK experience of stereoelectroencephalography in children: An analysis of factors predicting the identification of a seizure‐onset zone and subsequent seizure freedom.
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Chari, Aswin, Moeller, Friederike, Boyd, Stewart, Tahir, M Zubair, Cross, J Helen, Eltze, Christin, Das, Krishna, van Dalen, Thijs, Scott, Rod C, Pressler, Ronit, Thornton, Rachel C, Tisdall, Martin M, Warren, Elliott, Patel, Jayesh, Carter, Michael, Kane, Nicholas, Mallick, Andrew A, Likeman, Marcus, Rushton, Sarah, and Cole, Danielle
- Subjects
FACTOR analysis ,EPILEPSY surgery ,SEIZURES (Medicine) ,PEDIATRIC surgery ,TEMPORAL lobectomy ,PARTIAL epilepsy ,CHILDHOOD epilepsy - Abstract
Objective: Stereoelectroencephalography (SEEG) is being used more frequently in the pre‐surgical evaluation of children with focal epilepsy. It has been shown to be safe in children, but there are no multicenter studies assessing the rates and factors associated with the identification of a putative seizure‐onset zone (SOZ) and subsequent seizure freedom following SEEG‐guided epilepsy surgery. Methods: Multicenter retrospective cohort study of all children undergoing SEEG at six of seven UK Children's Epilepsy Surgery Service centers from 2014 to 2019. Demographics, noninvasive evaluation, SEEG, and operative factors were analyzed to identify variables associated with the identification of a putative SOZ and subsequent seizure freedom following SEEG‐guided epilepsy surgery. Results: One hundred thirty‐five patients underwent 139 SEEG explorations using a total of 1767 electrodes. A putative SOZ was identified in 117 patients (85.7%); odds of successfully finding an SOZ were 6.4 times greater for non‐motor seizures compared to motor seizures (p = 0.02) and 3.6 times more if four or more seizures were recorded during SEEG (p = 0.03). Of 100 patients undergoing surgical treatment, 47 (47.0%) had an Engel class I outcome at a median follow‐up of 1.3 years; the only factor associated with outcome was indication for SEEG (p = 0.03); an indication of "recurrence following surgery/treatment" had a 5.9 times lower odds of achieving seizure freedom (p = 0.002) compared to the "lesion negative" cohort, whereas other indications ("lesion positive, define extent," "lesion positive, discordant noninvasive investigations" and "multiple lesions") were not statistically significantly different. Significance: This large nationally representative cohort illustrates that SEEG‐guided surgery can still achieve high rates of seizure freedom. Seizure semiology and the number of seizures recorded during SEEG are important factors in the identification of a putative SOZ, and the indication for SEEG is an important factor in postoperative outcomes. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
10. Mapping preictal and ictal haemodynamic networks using video-electroencephalography and functional imaging
- Author
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Chaudhary, Umair J., Carmichael, David W., Rodionov, Roman, Thornton, Rachel C., Bartlett, Phillipa, Vulliemoz, Serge, Micallef, Caroline, McEvoy, Andrew W., Diehl, Beate, Walker, Matthew C., Duncan, John S., Lemieux, Louis, Chaudhary, Umair J., Carmichael, David W., Rodionov, Roman, Thornton, Rachel C., Bartlett, Phillipa, Vulliemoz, Serge, Micallef, Caroline, McEvoy, Andrew W., Diehl, Beate, Walker, Matthew C., Duncan, John S., and Lemieux, Louis
- Abstract
Ictal patterns on scalp-electroencephalography are often visible only after propagation, therefore rendering localization of the seizure onset zone challenging. We hypothesized that mapping haemodynamic changes before and during seizures using simultaneous video-electroencephalography and functional imaging will improve the localization of the seizure onset zone. Fifty-five patients with ≥2 refractory focal seizures/day, and who had undergone long-term video-electroencephalography monitoring were included in the study. ‘Preictal' (30 s immediately preceding the electrographic seizure onset) and ictal phases, ‘ictal-onset'; ‘ictalestablished' and ‘late ictal', were defined based on the evolution of the electrographic pattern and clinical semiology. The functional imaging data were analysed using statistical parametric mapping to map ictal phase-related haemodynamic changes consistent across seizures. The resulting haemodynamic maps were overlaid on co-registered anatomical scans, and the spatial concordance with the presumed and invasively defined seizure onset zone was determined. Twenty patients had typical seizures during functional imaging. Seizures were identified on video-electroencephalography in 15 of 20, on electroencephalography alone in two and on video alone in three patients. All patients showed significant ictal-related haemodynamic changes. In the six cases that underwent invasive evaluation, the ictal-onset phase-related maps had a degree of concordance with the presumed seizure onset zone for all patients. The most statistically significant haemodynamic cluster within the presumed seizure onset zone was between 1.1 and 3.5 cm from the invasively defined seizure onset zone, which was resected in two of three patients undergoing surgery (Class I post-surgical outcome) and was not resected in one patient (Class III post-surgical outcome). In the remaining 14 cases, the ictal-onset phase-related maps had a degree of concordance with the presumed seizure
- Published
- 2017
11. With or without spikes: localization of focal epileptic activity by simultaneous electroencephalography and functional magnetic resonance imaging
- Author
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Grouiller, Frédéric, Thornton, Rachel C., Groening, Kristina, Spinelli, Laurent, Duncan, John S., Schaller, Karl, Siniatchkin, Michael, Lemieux, Louis, Seeck, Margitta, Michel, Christoph M., Vulliemoz, Serge, Grouiller, Frédéric, Thornton, Rachel C., Groening, Kristina, Spinelli, Laurent, Duncan, John S., Schaller, Karl, Siniatchkin, Michael, Lemieux, Louis, Seeck, Margitta, Michel, Christoph M., and Vulliemoz, Serge
- Abstract
In patients with medically refractory focal epilepsy who are candidates for epilepsy surgery, concordant non-invasive neuroimaging data are useful to guide invasive electroencephalographic recordings or surgical resection. Simultaneous electroencephalography and functional magnetic resonance imaging recordings can reveal regions of haemodynamic fluctuations related to epileptic activity and help localize its generators. However, many of these studies (40-70%) remain inconclusive, principally due to the absence of interictal epileptiform discharges during simultaneous recordings, or lack of haemodynamic changes correlated to interictal epileptiform discharges. We investigated whether the presence of epilepsy-specific voltage maps on scalp electroencephalography correlated with haemodynamic changes and could help localize the epileptic focus. In 23 patients with focal epilepsy, we built epilepsy-specific electroencephalographic voltage maps using averaged interictal epileptiform discharges recorded during long-term clinical monitoring outside the scanner and computed the correlation of this map with the electroencephalographic recordings in the scanner for each time frame. The time course of this correlation coefficient was used as a regressor for functional magnetic resonance imaging analysis to map haemodynamic changes related to these epilepsy-specific maps (topography-related haemodynamic changes). The method was first validated in five patients with significant haemodynamic changes correlated to interictal epileptiform discharges on conventional analysis. We then applied the method to 18 patients who had inconclusive simultaneous electroencephalography and functional magnetic resonance imaging studies due to the absence of interictal epileptiform discharges or absence of significant correlated haemodynamic changes. The concordance of the results with subsequent intracranial electroencephalography and/or resection area in patients who were seizure free after surge
- Published
- 2017
12. Mapping human preictal and ictal haemodynamic networks using simultaneous intracranial EEG-fMRI
- Author
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Chaudhary, Umair J., Centeno, Maria, Thornton, Rachel C., Rodionov, Roman, Vulliemoz, Serge, McEvoy, Andrew W., Diehl, Beate, Walker, Matthew C., Duncan, John S., Carmichael, David W., and Lemieux, Louis
- Subjects
Adult ,Male ,genetic structures ,Image Processing ,Brain Waves/physiology ,lcsh:Computer applications to medicine. Medical informatics ,lcsh:RC346-429 ,Computer-Assisted ,Oxygen/blood ,Brain/blood supply/diagnostic imaging/physiopathology ,Image Processing, Computer-Assisted ,Humans ,lcsh:Neurology. Diseases of the nervous system ,Brain Mapping ,Epilepsy ,Brain ,Electroencephalography ,Regular Article ,Brain Waves ,Magnetic Resonance Imaging ,ddc:616.8 ,Oxygen ,nervous system ,Nonlinear Dynamics ,lcsh:R858-859.7 ,Epilepsy/pathology/physiopathology ,psychological phenomena and processes - Abstract
Accurately characterising the brain networks involved in seizure activity may have important implications for our understanding of epilepsy. Intracranial EEG-fMRI can be used to capture focal epileptic events in humans with exquisite electrophysiological sensitivity and allows for identification of brain structures involved in this phenomenon over the entire brain. We investigated ictal BOLD networks using the simultaneous intracranial EEG-fMRI (icEEG-fMRI) in a 30 year-old male undergoing invasive presurgical evaluation with bilateral depth electrode implantations in amygdalae and hippocampi for refractory temporal lobe epilepsy. One spontaneous focal electrographic seizure was recorded. The aims of the data analysis were firstly to map BOLD changes related to the ictal activity identified on icEEG and secondly to compare different fMRI modelling approaches. Visual inspection of the icEEG showed an onset dominated by beta activity involving the right amygdala and hippocampus lasting 6.4 s (ictal onset phase), followed by gamma activity bilaterally lasting 14.8 s (late ictal phase). The fMRI data was analysed using SPM8 using two modelling approaches: firstly, purely based on the visually identified phases of the seizure and secondly, based on EEG spectral dynamics quantification. For the visual approach the two ictal phases were modelled as ‘ON’ blocks convolved with the haemodynamic response function; in addition the BOLD changes during the 30 s preceding the onset were modelled using a flexible basis set. For the quantitative fMRI modelling approach two models were evaluated: one consisting of the variations in beta and gamma bands power, thereby adding a quantitative element to the visually-derived models, and another based on principal components analysis of the entire spectrogram in attempt to reduce the bias associated with the visual appreciation of the icEEG. BOLD changes related to the visually defined ictal onset phase were revealed in the medial and lateral right temporal lobe. For the late ictal phase, the BOLD changes were remote from the SOZ and in deep brain areas (precuneus, posterior cingulate and others). The two quantitative models revealed BOLD changes involving the right hippocampus, amygdala and fusiform gyrus and in remote deep brain structures and the default mode network-related areas. In conclusion, icEEG-fMRI allowed us to reveal BOLD changes within and beyond the SOZ linked to very localised ictal fluctuations in beta and gamma activity measured in the amygdala and hippocampus. Furthermore, the BOLD changes within the SOZ structures were better captured by the quantitative models, highlighting the interest in considering seizure-related EEG fluctuations across the entire spectrum., Highlights • First seizure recorded on icEEG-fMRI • Two modelling approaches to investigate seizure related BOLD networks • Seizure related BOLD network involving the seizure onset zone and remote area • Quantitative modelling of seizure revealed BOLD changes in the seizure onset zone for specific electrophysiological activity.
- Published
- 2015
13. Mapping human preictal and ictal haemodynamic networks using simultaneous intracranial EEG-fMRI
- Author
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Chaudhary, Umair J., primary, Centeno, Maria, additional, Thornton, Rachel C., additional, Rodionov, Roman, additional, Vulliemoz, Serge, additional, McEvoy, Andrew W., additional, Diehl, Beate, additional, Walker, Matthew C., additional, Duncan, John S., additional, Carmichael, David W., additional, and Lemieux, Louis, additional
- Published
- 2016
- Full Text
- View/download PDF
14. Mapping preictal and ictal haemodynamic networks using video-electroencephalography and functional imaging
- Author
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Chaudhary, Umair J., Carmichael, David W., Rodionov, Roman, Thornton, Rachel C., Bartlett, Phillipa, Vulliemoz, Serge, Micallef, Caroline, McEvoy, Andrew W., Diehl, Beate, Walker, Matthew C., Duncan, John S., Lemieux, Louis, Chaudhary, Umair J., Carmichael, David W., Rodionov, Roman, Thornton, Rachel C., Bartlett, Phillipa, Vulliemoz, Serge, Micallef, Caroline, McEvoy, Andrew W., Diehl, Beate, Walker, Matthew C., Duncan, John S., and Lemieux, Louis
- Abstract
Ictal patterns on scalp-electroencephalography are often visible only after propagation, therefore rendering localization of the seizure onset zone challenging. We hypothesized that mapping haemodynamic changes before and during seizures using simultaneous video-electroencephalography and functional imaging will improve the localization of the seizure onset zone. Fifty-five patients with ≥2 refractory focal seizures/day, and who had undergone long-term video-electroencephalography monitoring were included in the study. ‘Preictal' (30 s immediately preceding the electrographic seizure onset) and ictal phases, ‘ictal-onset'; ‘ictalestablished' and ‘late ictal', were defined based on the evolution of the electrographic pattern and clinical semiology. The functional imaging data were analysed using statistical parametric mapping to map ictal phase-related haemodynamic changes consistent across seizures. The resulting haemodynamic maps were overlaid on co-registered anatomical scans, and the spatial concordance with the presumed and invasively defined seizure onset zone was determined. Twenty patients had typical seizures during functional imaging. Seizures were identified on video-electroencephalography in 15 of 20, on electroencephalography alone in two and on video alone in three patients. All patients showed significant ictal-related haemodynamic changes. In the six cases that underwent invasive evaluation, the ictal-onset phase-related maps had a degree of concordance with the presumed seizure onset zone for all patients. The most statistically significant haemodynamic cluster within the presumed seizure onset zone was between 1.1 and 3.5 cm from the invasively defined seizure onset zone, which was resected in two of three patients undergoing surgery (Class I post-surgical outcome) and was not resected in one patient (Class III post-surgical outcome). In the remaining 14 cases, the ictal-onset phase-related maps had a degree of concordance with the presumed seizure
15. With or without spikes: localization of focal epileptic activity by simultaneous electroencephalography and functional magnetic resonance imaging
- Author
-
Grouiller, Frédéric, Thornton, Rachel C., Groening, Kristina, Spinelli, Laurent, Duncan, John S., Schaller, Karl, Siniatchkin, Michael, Lemieux, Louis, Seeck, Margitta, Michel, Christoph M., Vulliemoz, Serge, Grouiller, Frédéric, Thornton, Rachel C., Groening, Kristina, Spinelli, Laurent, Duncan, John S., Schaller, Karl, Siniatchkin, Michael, Lemieux, Louis, Seeck, Margitta, Michel, Christoph M., and Vulliemoz, Serge
- Abstract
In patients with medically refractory focal epilepsy who are candidates for epilepsy surgery, concordant non-invasive neuroimaging data are useful to guide invasive electroencephalographic recordings or surgical resection. Simultaneous electroencephalography and functional magnetic resonance imaging recordings can reveal regions of haemodynamic fluctuations related to epileptic activity and help localize its generators. However, many of these studies (40-70%) remain inconclusive, principally due to the absence of interictal epileptiform discharges during simultaneous recordings, or lack of haemodynamic changes correlated to interictal epileptiform discharges. We investigated whether the presence of epilepsy-specific voltage maps on scalp electroencephalography correlated with haemodynamic changes and could help localize the epileptic focus. In 23 patients with focal epilepsy, we built epilepsy-specific electroencephalographic voltage maps using averaged interictal epileptiform discharges recorded during long-term clinical monitoring outside the scanner and computed the correlation of this map with the electroencephalographic recordings in the scanner for each time frame. The time course of this correlation coefficient was used as a regressor for functional magnetic resonance imaging analysis to map haemodynamic changes related to these epilepsy-specific maps (topography-related haemodynamic changes). The method was first validated in five patients with significant haemodynamic changes correlated to interictal epileptiform discharges on conventional analysis. We then applied the method to 18 patients who had inconclusive simultaneous electroencephalography and functional magnetic resonance imaging studies due to the absence of interictal epileptiform discharges or absence of significant correlated haemodynamic changes. The concordance of the results with subsequent intracranial electroencephalography and/or resection area in patients who were seizure free after surge
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