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Nourhashemi M, Mahmoudzadeh M, Heberle C, Wallois F. Preictal neuronal and vascular activity precedes the onset of childhood absence seizure: direct current potential shifts and their correlation with hemodynamic activity. NEUROPHOTONICS 2023; 10:025005. [PMID: 37114185 PMCID: PMC10128878 DOI: 10.1117/1.nph.10.2.025005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Accepted: 03/20/2023] [Indexed: 06/19/2023]
Abstract
SIGNIFICANCE AIMS The neurovascular mechanisms underlying the initiation of absence seizures and their dynamics are still not well understood. The objective of this study was to better noninvasively characterize the dynamics of the neuronal and vascular network at the transition from the interictal state to the ictal state of absence seizures and back to the interictal state using a combined electroencephalography (EEG), functional near-infrared spectroscopy (fNIRS), and diffuse correlation spectroscopy (DCS) approach. The second objective was to develop hypotheses about the neuronal and vascular mechanisms that propel the networks to the 3-Hz spikes and wave discharges (SWDs) observed during absence seizures. APPROACHES We evaluated the simultaneous changes in electrical (neuronal) and optical dynamics [hemodynamic, with changes in (Hb) and cerebral blood flow] of 8 pediatric patients experiencing 25 typical childhood absence seizures during the transition from the interictal state to the absence seizure by simultaneously performing EEG, fNIRS, and DCS. RESULTS Starting from ∼ 20 s before the onset of the SWD, we observed a transient direct current potential shift that correlated with alterations in functional fNIRS and DCS measurements of the cerebral hemodynamics detecting the preictal changes. DISCUSSION Our noninvasive multimodal approach highlights the dynamic interactions between the neuronal and vascular compartments that take place in the neuronal network near the time of the onset of absence seizures in a very specific cerebral hemodynamic environment. These noninvasive approaches contribute to a better understanding of the electrical hemodynamic environment prior to seizure onset. Whether this may ultimately be relevant for diagnostic and therapeutic approaches requires further evaluation.
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Affiliation(s)
- Mina Nourhashemi
- Université de Picardie Jules Verne, Inserm U1105, GRAMFC, CURS, Amiens, France
| | - Mahdi Mahmoudzadeh
- Université de Picardie Jules Verne, Inserm U1105, GRAMFC, CURS, Amiens, France
- Amiens University Hospital, Pediatric Neurophysiology Unit, Amiens, France
| | - Claire Heberle
- Amiens University Hospital, Pediatric Neurophysiology Unit, Amiens, France
| | - Fabrice Wallois
- Université de Picardie Jules Verne, Inserm U1105, GRAMFC, CURS, Amiens, France
- Amiens University Hospital, Pediatric Neurophysiology Unit, Amiens, France
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Gruenbaum BF. Comparison of anaesthetic- and seizure-induced states of unconsciousness: a narrative review. Br J Anaesth 2021; 126:219-229. [PMID: 32951841 PMCID: PMC7844374 DOI: 10.1016/j.bja.2020.07.056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 06/23/2020] [Accepted: 07/20/2020] [Indexed: 10/23/2022] Open
Abstract
In order to understand general anaesthesia and certain seizures, a fundamental understanding of the neurobiology of unconsciousness is needed. This review article explores similarities in neuronal and network changes during general anaesthesia and seizure-induced unconsciousness. Both seizures and anaesthetics cause disruption in similar anatomical structures that presumably lead to impaired consciousness. Despite differences in behaviour and mechanisms, both of these conditions are associated with disruption of the functionality of subcortical structures that mediate neuronal activity in the frontoparietal cortex. These areas are all likely to be involved in maintaining normal consciousness. An assessment of the similarities in the brain network disruptions with certain seizures and general anaesthesia might provide fresh insights into the mechanisms of the alterations of consciousness seen in these particular unconscious states, allowing for innovative therapies for seizures and the development of anaesthetic approaches targeting specific networks.
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Widespread pH abnormalities in patients with malformations of cortical development and epilepsy: a phosphorus-31 brain MR spectroscopy study. Brain Dev 2014; 36:899-906. [PMID: 24485900 DOI: 10.1016/j.braindev.2013.12.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Revised: 12/26/2013] [Accepted: 12/27/2013] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Neuroimaging studies demonstrate that not only the lesions of malformations of cortical development (MCD) but also the normal-appearing parenchyma (NAP) present metabolic impairments, as revealed with (1)H-MRS. We have previously detected biochemical disturbances in MCD lesions with phosphorus-31 magnetic resonance spectroscopy (31P-MRS). Our hypothesis is that pH abnormalities extend beyond the visible lesions. METHODS Three-dimensional 31P-MRS at 3.0 T was performed in 37 patients with epilepsy and MCD, and in 31 matched-control subjects. The patients were assigned into three main MCD subgroups: cortical dysplasia (n=10); heterotopia (n=14); schizencephaly/polymicrogyria (n=13). Voxels (12.5 cm3) were selected in five homologous regions containing NAP: right putamen; left putamen; frontoparietal parasagittal cortex; right centrum semiovale; and left centrum semiovale. Robust methods of quantification were applied, and the intracellular pH was calculated with the chemical shifts of inorganic phosphate (Pi) relative to phosphocreatine (PCr). RESULTS In comparison to controls and considering a Bonferroni adjusted p-value <0.01, MCD patients presented significant reduction in intracellular pH in the frontoparietal parasagittal cortex (6.985±0.022), right centrum semiovale (7.004±0.029), and left centrum semiovale (6.995±0.030), compared to controls (mean values±standard deviations of 7.087±0.048, 7.096±0.042, 7.088±0.045, respectively). Dunnet and Dunn tests demonstrated that the differences in pH values remained statistically significant in all MCD subgroups. No significant differences were found for the putamina. CONCLUSION The present study demonstrates widespread acidosis in the NAP, and reinforces the idea that MCD visible lesions are only the tip of the iceberg.
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Singh H, Cooper RJ, Wai Lee C, Dempsey L, Edwards A, Brigadoi S, Airantzis D, Everdell N, Michell A, Holder D, Hebden JC, Austin T. Mapping cortical haemodynamics during neonatal seizures using diffuse optical tomography: a case study. Neuroimage Clin 2014; 5:256-65. [PMID: 25161892 PMCID: PMC4141980 DOI: 10.1016/j.nicl.2014.06.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 06/25/2014] [Accepted: 06/26/2014] [Indexed: 01/08/2023]
Abstract
Seizures in the newborn brain represent a major challenge to neonatal medicine. Neonatal seizures are poorly classified, under-diagnosed, difficult to treat and are associated with poor neurodevelopmental outcome. Video-EEG is the current gold-standard approach for seizure detection and monitoring. Interpreting neonatal EEG requires expertise and the impact of seizures on the developing brain remains poorly understood. In this case study we present the first ever images of the haemodynamic impact of seizures on the human infant brain, obtained using simultaneous diffuse optical tomography (DOT) and video-EEG with whole-scalp coverage. Seven discrete periods of ictal electrographic activity were observed during a 60 minute recording of an infant with hypoxic-ischaemic encephalopathy. The resulting DOT images show a remarkably consistent, high-amplitude, biphasic pattern of changes in cortical blood volume and oxygenation in response to each electrographic event. While there is spatial variation across the cortex, the dominant haemodynamic response to seizure activity consists of an initial increase in cortical blood volume prior to a large and extended decrease typically lasting several minutes. This case study demonstrates the wealth of physiologically and clinically relevant information that DOT-EEG techniques can yield. The consistency and scale of the haemodynamic responses observed here also suggest that DOT-EEG has the potential to provide improved detection of neonatal seizures.
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Affiliation(s)
- Harsimrat Singh
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Robert J. Cooper
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Chuen Wai Lee
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Neonatal Unit, Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, UK
| | - Laura Dempsey
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Andrea Edwards
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Neonatal Unit, Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, UK
| | - Sabrina Brigadoi
- Department of Developmental Psychology, University of Padova, Padova, Italy
| | - Dimitrios Airantzis
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Nick Everdell
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Andrew Michell
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Neurophysiology, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, UK
| | - David Holder
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Jeremy C. Hebden
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Department of Medical Physics and Bioengineering, University College London, London WC1E 6BT, UK
| | - Topun Austin
- neoLAB, The Evelyn Perinatal Imaging Centre, Rosie Hospital, Cambridge CB2 0QQ, UK
- Neonatal Unit, Rosie Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge CB2 0QQ, UK
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Desai A, Bekelis K, Thadani VM, Roberts DW, Jobst BC, Duhaime AC, Gilbert K, Darcey TM, Studholme C, Siegel A. Interictal PET and ictal subtraction SPECT: sensitivity in the detection of seizure foci in patients with medically intractable epilepsy. Epilepsia 2012; 54:341-50. [PMID: 23030361 DOI: 10.1111/j.1528-1167.2012.03686.x] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE Interictal positron emission tomography (PET) and ictal subtraction single photon emission computed tomography (SPECT) of the brain have been shown to be valuable tests in the presurgical evaluation of epilepsy. To determine the relative utility of these methods in the localization of seizure foci, we compared interictal PET and ictal subtraction SPECT to subdural and depth electrode recordings in patients with medically intractable epilepsy. METHODS Between 2003 and 2009, clinical information on all patients at our institution undergoing intracranial electroencephalography (EEG) monitoring was charted in a prospectively recorded database. Patients who underwent preoperative interictal PET and ictal subtraction SPECT were selected from this database. Patient characteristics and the findings on preoperative interictal PET and ictal subtraction SPECT were analyzed. Sensitivity of detection of seizure foci for each modality, as compared to intracranial EEG monitoring, was calculated. KEY FINDINGS Fifty-three patients underwent intracranial EEG monitoring with preoperative interictal PET and ictal subtraction SPECT scans. The average patient age was 32.7 years (median 32 years, range 1-60 years). Twenty-seven patients had findings of reduced metabolism on interictal PET scan, whereas all 53 patients studied demonstrated a region of relative hyperperfusion on ictal subtraction SPECT suggestive of an epileptogenic zone. Intracranial EEG monitoring identified a single seizure focus in 45 patients, with 39 eventually undergoing resective surgery. Of the 45 patients in whom a seizure focus was localized, PET scan identified the same region in 25 cases (56% sensitivity) and SPECT in 39 cases (87% sensitivity). Intracranial EEG was concordant with at least one study in 41 cases (91%) and both studies in 23 cases (51%). In 16 (80%) of 20 cases where PET did not correlate with intracranial EEG, the SPECT study was concordant. Conversely, PET and intracranial EEG were concordant in two (33%) of the six cases where the SPECT did not demonstrate the seizure focus outlined by intracranial EEG. Thirty-three patients had surgical resection and >2 years of follow-up, and 21 of these (64%) had Engel class 1 outcome. No significant effect of imaging concordance on seizure outcome was seen. SIGNIFICANCE Interictal PET and ictal subtraction SPECT studies can provide important information in the preoperative evaluation of medically intractable epilepsy. Of the two studies, ictal subtraction SPECT appears to be the more sensitive. When both studies are used together, however, they can provide complementary information.
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Affiliation(s)
- Atman Desai
- Section of Neurosurgery, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire 03756, USA.
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Cooper R, Hebden JC, O'Reilly H, Mitra S, Michell A, Everdell N, Gibson A, Austin T. Transient haemodynamic events in neurologically compromised infants: A simultaneous EEG and diffuse optical imaging study. Neuroimage 2011; 55:1610-6. [DOI: 10.1016/j.neuroimage.2011.01.022] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 12/20/2010] [Accepted: 01/08/2011] [Indexed: 11/24/2022] Open
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Jafari-Khouzani K, Elisevich K, Karvelis KC, Soltanian-Zadeh H. Quantitative multi-compartmental SPECT image analysis for lateralization of temporal lobe epilepsy. Epilepsy Res 2011; 95:35-50. [PMID: 21454055 DOI: 10.1016/j.eplepsyres.2011.02.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 02/19/2011] [Accepted: 02/21/2011] [Indexed: 11/16/2022]
Abstract
This study assesses the utility of compartmental analysis of SPECT data in lateralizing ictal onset in cases of a putative mesial temporal lobe epilepsy (mTLE). An institutional archival review provided 46 patients (18M, 28F) operated for a putative mTLE who achieved an Engel class Ia postoperative outcome. This established the standard to assure a true ictal origin. Ictal and interictal SPECT images were separately coregistered to T1-weighted (T1W) magnetic resonance (MR) image using a rigid transformation and the intensities matched with an l(1) norm minimization technique. The T1W MR image was segmented into separate structures using an atlas-based automatic segmentation technique with the hippocampi manually segmented to improve accuracy. Mean ictal-interictal intensity difference values were calculated for select subcortical structures and the accuracy of lateralization evaluated using a linear classifier. Hippocampal SPECT analysis yielded the highest lateralization accuracy (91%) followed by the amygdala (87%), putamen (67%) and thalamus (61%). Comparative FLAIR and volumetric analyses yielded 89% and 78% accuracies, respectively. A multi-modality analysis did not generate a higher accuracy (89%). A quantitative anatomically compartmented approach to SPECT analysis yields a particularly high lateralization accuracy in the case of mTLE comparable to that of quantitative FLAIR MR imaging. Hippocampal segmentation in this regard correlates well with ictal origin and shows good reliability in the preoperative analysis.
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Affiliation(s)
- Kourosh Jafari-Khouzani
- Department of Diagnostic Radiology, Henry Ford Hospital, One Ford Place, Detroit, MI 48202, USA.
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Cho JW, Hong SB, Lee JH, Kang JW, Lee MJ, Lee JY, Park HS, Suh M, Joo EY, Seo DW. Contralateral hyperperfusion and ipsilateral hypoperfusion by ictal SPECT in patients with mesial temporal lobe epilepsy. Epilepsy Res 2010; 88:247-54. [DOI: 10.1016/j.eplepsyres.2009.12.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2009] [Revised: 11/30/2009] [Accepted: 12/10/2009] [Indexed: 11/16/2022]
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Varghese GI, Purcaro MJ, Motelow JE, Enev M, McNally KA, Levin AR, Hirsch LJ, Tikofsky R, Paige AL, Zubal IG, Spencer SS, Blumenfeld H. Clinical use of ictal SPECT in secondarily generalized tonic-clonic seizures. ACTA ACUST UNITED AC 2009; 132:2102-13. [PMID: 19339251 DOI: 10.1093/brain/awp027] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Partial seizures produce increased cerebral blood flow in the region of seizure onset. These regional cerebral blood flow increases can be detected by single photon emission computed tomography (ictal SPECT), providing a useful clinical tool for seizure localization. However, when partial seizures secondarily generalize, there are often questions of interpretation since propagation of seizures could produce ambiguous results. Ictal SPECT from secondarily generalized seizures has not been thoroughly investigated. We analysed ictal SPECT from 59 secondarily generalized tonic-clonic seizures obtained during epilepsy surgery evaluation in 53 patients. Ictal versus baseline interictal SPECT difference analysis was performed using ISAS (http://spect.yale.edu). SPECT injection times were classified based on video/EEG review as either pre-generalization, during generalization or in the immediate post-ictal period. We found that in the pre-generalization and generalization phases, ictal SPECT showed significantly more regions of cerebral blood flow increases than in partial seizures without secondary generalization. This made identification of a single unambiguous region of seizure onset impossible 50% of the time with ictal SPECT in secondarily generalized seizures. However, cerebral blood flow increases on ictal SPECT correctly identified the hemisphere (left versus right) of seizure onset in 84% of cases. In addition, when a single unambiguous region of cerebral blood flow increase was seen on ictal SPECT, this was the correct localization 80% of the time. In agreement with findings from partial seizures without secondary generalization, cerebral blood flow increases in the post-ictal period and cerebral blood flow decreases during or following seizures were not useful for localizing seizure onset. Interestingly, however, cerebral blood flow hypoperfusion during the generalization phase (but not pre-generalization) was greater on the side opposite to seizure onset in 90% of patients. These findings suggest that, with appropriate cautious interpretation, ictal SPECT in secondarily generalized seizures can help localize the region of seizure onset.
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Affiliation(s)
- G I Varghese
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520-8018, USA
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Abstract
Although the precise mechanisms for control of consciousness are not fully understood, emerging data show that conscious information processing depends on the activation of certain networks in the brain and that the impairment of consciousness is related to abnormal activity in these systems. Epilepsy can lead to transient impairment of consciousness, providing a window into the mechanisms necessary for normal consciousness. Thus, despite differences in behavioral manifestations, cause, and electrophysiology, generalized tonic-clonic, absence, and partial seizures engage similar anatomical structures and pathways. We review prior concepts of impaired consciousness in epilepsy, focusing especially on temporal lobe complex partial seizures, which are a common and debilitating form of epileptic unconsciousness. We discuss a "network inhibition hypothesis" in which focal temporal lobe seizure activity disrupts normal cortical-subcortical interactions, leading to depressed neocortical function and impaired consciousness. This review of the major prior theories of impaired consciousness in epilepsy allows us to put more recent data into context and to reach a better understanding of the mechanisms important for normal consciousness.
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MESH Headings
- Consciousness Disorders/diagnosis
- Consciousness Disorders/etiology
- Consciousness Disorders/physiopathology
- Consciousness Disorders/psychology
- Epilepsy/complications
- Epilepsy/physiopathology
- Epilepsy/psychology
- Epilepsy, Complex Partial/complications
- Epilepsy, Complex Partial/physiopathology
- Epilepsy, Complex Partial/psychology
- Epilepsy, Temporal Lobe/complications
- Epilepsy, Temporal Lobe/physiopathology
- Epilepsy, Temporal Lobe/psychology
- Functional Laterality/physiology
- Humans
- Models, Neurological
- Models, Psychological
- Neocortex/physiopathology
- Nerve Net/physiopathology
- Tomography, Emission-Computed, Single-Photon
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Affiliation(s)
- Lissa Yu
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | - Hal Blumenfeld
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
- Department of Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
- Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut 06520, USA
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Hur YJ, Lee JS, Kang HC, Park HJ, Yun MJ, Kim HD. Ictal single-photon emission computed tomography with slow dye injection for determining primary epileptic foci in infantile spasms. KOREAN JOURNAL OF PEDIATRICS 2009. [DOI: 10.3345/kjp.2009.52.7.804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Yun Jung Hur
- Department of Pediatrics, Pochon Cha University College of Medicine, Korea
| | - Joon Soo Lee
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea
- Handicapped Children's Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Hoon Chul Kang
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea
- Handicapped Children's Institute, Yonsei University College of Medicine, Seoul, Korea
| | - Hye Jung Park
- Department of Diagnostic Radiology, Yonsei University College of Medicine, Seoul, Korea
| | - Mi Jin Yun
- Department of Diagnostic Radiology, Yonsei University College of Medicine, Seoul, Korea
| | - Heung Dong Kim
- Department of Pediatrics, Yonsei University College of Medicine, Seoul, Korea
- Handicapped Children's Institute, Yonsei University College of Medicine, Seoul, Korea
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Rossman M, Adjouadi M, Ayala M, Yaylali I. An interactive interface for seizure focus localization using SPECT image analysis. Comput Biol Med 2006; 36:70-88. [PMID: 16318848 DOI: 10.1016/j.compbiomed.2004.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2004] [Revised: 09/07/2004] [Accepted: 09/07/2004] [Indexed: 11/17/2022]
Abstract
Accurate epileptic focus localization using single photon emission computed tomography (SPECT) images has proven to be a challenging endeavor. First, commonly used radiopharmaceuticals such as hexamethylpropylene amine oxime (HMPAO) quantitatively underestimate large blood flows, leading to subtracted SPECT images that do not reflect the true cerebral physiological conditions, and often display non-distinct epileptic foci. The proposed relative change subtraction method of SPECT image analysis helps alleviate this quantitative burden. Second, the image analysis process traditionally performed by physicians is time consuming and prone to error. Toward this end, an automated algorithm was designed to analyze SPECT images and provide feedback to users through a visual interface.
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Affiliation(s)
- Mark Rossman
- Department of Electrical & Computer Engineering, Florida International University, 10555 W.Flagler Street, Miami, FL 33174, USA
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Leonhardt G, de Greiff A, Weber J, Ludwig T, Wiedemayer H, Forsting M, Hufnagel A. Brain Perfusion Following Single Seizures. Epilepsia 2005; 46:1943-9. [PMID: 16393160 DOI: 10.1111/j.1528-1167.2005.00336.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE The aim of this study was to assess the regional relative interictal and postictal perfusion changes in temporal and parietal lobe epilepsy. METHODS We investigated interictal and postictal magnet resonance perfusion changes in five patients with temporal lobe epilepsy either with hippocampal sclerosis (n = 3) or without (n = 2), and in one patient with extratemporal (parietal lobe) epilepsy. T(2)*-weighted single-shot echo-planar images were acquired after bolus application of 0.2 mmol/kg gadolinium-diethylene triamine pentaacetic acid (GD-DTPA) at baseline and after intervals of 2-12 min, 15-23 min, 28-50 min, 63-72 min, and 180-240 min. The bolus-peak ratio was calculated in regions of interest in the hippocampus (HIP), parahippocampal gyrus (PHG), thalamus (THA), cortex (COR), and white matter (WM), yielding relative perfusion changes. RESULTS Interictally, we found relative hyperperfusion of the ictogenic side in five of six patients in the HIP. Postictally, the perfusion decreased in the HIP by 25-39% as compared to baseline, whereas the PHG showed a reverse pattern. In the late postictal phase, perfusion increased in the HIP again and decreased in the PHG. In the THA, the inter- and postictal changes were small (5-19%). COR and WM showed equivocal results. CONCLUSION Postictal relative hypoperfusion in the HIP appears to be associated with the cessation of neuronal ictal discharge, whereas postictal hyperperfusion in the PHG lags behind and may reflect increased metabolism to restore the interictal state of neuronal excitability.
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Affiliation(s)
- Georg Leonhardt
- Department of Neurology, University of Essen, Essen, Germany.
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Chassagnon S, de Vasconcelos AP, Ferrandon A, Koning E, Marescaux C, Nehlig A. Time course and mapping of cerebral perfusion during amygdala secondarily generalized seizures. Epilepsia 2005; 46:1178-87. [PMID: 16060926 DOI: 10.1111/j.1528-1167.2005.07505.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE Measurement of local cerebral blood flow (LCBF) is routinely used to locate the areas involved in generation and spread of seizures in epilepsy patients. Because the spatial distribution and extent of ictal CBF depends on the epileptogenic network, but also on the timing of injection of tracer, we used a rat model of amygdala-kindled seizures to follow the time-dependent changes in the distribution of LCBF changes. METHODS Rats were implanted in the left amygdala and were fully kindled. LCBF was measured by the quantitative [(14)C]iodoantipyrine autoradiographic technique bilaterally in 35 regions. The tracer was injected at 30 s before seizure induction (early ictal), simultaneous with the application of stimulation (ictal), at 60 s after stimulation (late ictal), at the end of the electrical afterdischarge (early postictal), and at 6 min after the stimulation (late postictal). RESULTS Rates of LCBF increased over control levels during the early ictal phase ipsilaterally in medial amygdala, frontal cortex, and ventromedian thalamus and bilaterally in the whole hippocampus, thalamic nuclei, and basal ganglia. During the ictal phase, all regions underwent hyperperfusion (81-416% increases). By 60 s after stimulation, rates of LCBF returned to control levels in most brain areas, despite ongoing seizure activity. At later times, localized foci of hypoperfusion were observed in hippocampus bilaterally, with a slight predominance in CA1 on the side of origin of the seizures. CONCLUSION This study shows a rapid spread of activation from the stimulated amygdala bilaterally to numerous limbic, cortical, and subcortical structures. The largest hyperperfusion was recorded during the ictal period with tracer injections simultaneous with the stimulation. The unilateral site of origin of seizures led to minor asymmetrical and lateralized findings, merely at early ictal and late postictal times, whereas intermediate tracer injections induced bilateral changes. Only late postictal measurements allowed the identification of significant changes in focal structures: the hippocampus is known to play a critical role in the spread of limbic seizures.
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Wichert-Ana L, Velasco TR, Terra-Bustamante VC, Alexandre V, Guarnieri R, Walz R, Kato M, Araújo WM, Carlotti CG, Araújo D, Carlos Dos Santos A, Sakamoto AC. Ictal chronology and interictal spikes predict perfusion patterns in temporal lobe epilepsy: a multivariate study. Seizure 2004; 13:346-57. [PMID: 15158707 DOI: 10.1016/j.seizure.2003.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Typical (TPP) and atypical (APP) perfusion patterns (PP) may be seen in ictal SPECT of patients with temporal lobe epilepsy (TLE). APP may pose problem in the lateralization of the epileptogenic zone (EZ). We aimed to investigate predictive variables for the occurrence of TPP and APP. Fifty-one TLE patients were submitted to successful anterior-mesial temporal lobectomy. Univariate (UVA) and multivariate (MVA) analysis were performed upon clinical data, distribution of interictal spikes, and ictal chronology of seizures. From MVA, a final predictive model (FPM) was determined to better predict TPP and APP. Forty patients showed TPP (78.5%) and 11 patients APP (21.5%). Accuracy of ictal SPECT was higher in the unilateral (UIS) than in the bilateral (BIS) interictal spikes group (P = 0.05). FPM showed that patients exhibiting BIS, with shorter proportion of the electrographic seizure occurring after completion of tracer injection, and longer clinical than EEG seizure duration had more APP (P = 0.003). Generalized tonic-clonic seizures did not result in more APP. We concluded that analysis of ictal SPECT in TLE requires the knowledge of TPP and APP, the distribution of interictal spikes on temporal lobes and the ictal chronology of seizures. BIS showed that beyond a more complex epileptogenicity and seizure propagation, they may also lead to APP.
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Affiliation(s)
- Lauro Wichert-Ana
- Department of Neurology, Epilepsy Surgery Center (CIREP), Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.
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André V, Henry D, Nehlig A. Dynamic variations of local cerebral blood flow in maximal electroshock seizures in the rat. Epilepsia 2002; 43:1120-8. [PMID: 12366724 DOI: 10.1046/j.1528-1157.2002.17702.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE Measurement of cerebral blood flow is routinely used to locate the areas involved in generation and spread of seizures in epilepsy patients. Because the nature of the hyperperfused regions varies with the timing of injection of tracer, in this study, we used a rat model of maximal electroshock seizures to follow up the time-dependent changes in the distribution of seizure-induced cerebral blood flow (CBF) changes. METHODS CBF was measured by the quantitative autoradiographic [14C]iodoantipyrine technique over a 30-s duration. The tracer was injected either at 15 s before seizure induction, simultaneous with the application of the electroshock (tonic phase), at the onset of the clonic phase, or at 3 and 6 min after the seizure (postictal phase). RESULTS Rates of CBF underwent dynamic changes during the different phases of seizure activity and largely increased over control levels (< or =400%) in the 45 regions studied during all phases of the seizure (first 3 times). CBF remained higher than control levels in 35 and 15 areas at 3 and 6 min after the seizure, respectively. CONCLUSIONS The distribution of maximal CBF increases showed a good correlation with their known involvement in the circuits underlying the clinical expression of the different types of seizure activity, tonic versus clonic.
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Abstract
Like normal cerebral function, epileptic seizures involve widespread network interactions between cortical and subcortical structures. Although the cortex is often emphasized as the site of seizure origin, accumulating evidence points to a crucial role for subcortical structures in behavioral manifestations, propagation, and, in some cases, initiation of epileptic seizures. Extensive previous studies have shown the importance of subcortical structures in animal seizure models, but corresponding human studies have been relatively few. We review the existing evidence supporting the importance of the thalamus, basal ganglia, hypothalamus, cerebellum, and brain stem in human epilepsy. We also propose a "network inhibition hypothesis" through which focal cortical seizures disrupt function in subcortical structures (such as the medial diencephalon and pontomesencephalic reticular formation), leading secondarily to widespread inhibition of nonseizing cortical regions, which may in turn be responsible for behavioral manifestations such as loss of consciousness during complex partial seizures.
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Affiliation(s)
- Andrew D. Norden
- Departments of Neurology and Neurobiology, Yale University School of Medicine, 333 Cedar Street, New Haven, 06520-8018, CT, USA
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Abstract
The ability to continuously acquire simultaneous EEG and fMRI data during seizures presents a formidable challenge both clinically and technically. Published ictal fMRI reports have so far been unable to benefit from simultaneous electrographic recordings and remain largely assumptive. Unique findings from a Continuous EEG-correlated fMRI experiment are presented in which a focal subclinical seizure was captured in its entirety. For the first time dynamic and biphasic Blood Oxygen Level Dependent (BOLD) signal changes are shown using statistical parametric mapping time-locked to the ictal EEG activity localizing seizure generation and propagation sites, with millimeter resolution, to electroclinically concordant gray matter structures. Though presently of limited clinical applicability, a new avenue is opened for further research.
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Affiliation(s)
- Afraim Salek-Haddadi
- Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College London, Queen Square, London, United Kingdom
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Wichert-Ana L, Velasco TR, Terra-Bustamante VC, Araújo D, Júnior VA, Kato M, Leite JP, Assirati JA, MacHado HR, Bastos AC, Sakamoto AC. Typical and atypical perfusion patterns in periictal SPECT of patients with unilateral temporal lobe epilepsy. Epilepsia 2001; 42:660-6. [PMID: 11380575 DOI: 10.1046/j.1528-1157.2001.41900.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To characterize perfusion patterns of periictal single-photon emission tomography (SPECT) in patients with unilateral temporal lobe epilepsy (TLE) and to determine their relationship to the epileptogenic zone (EZ). METHODS We studied periictal SPECT scans of 53 patients after anterior mesial temporal lobectomy who had good seizure outcome after surgery. Ictal SPECT scans were performed during video-EEG monitoring. Typical SPECT patterns consisted of ipsilateral ictal hyperperfusion or ipsilateral postictal hypoperfusion. Atypical ictal patterns included normal scans, bilateral temporal hyperperfusion, or contralateral patterns. These perfusion patterns were retrospectively analyzed searching for concordance rate with the EZ. RESULTS We obtained 51 ictal and two early postictal scans. In the typical group, 40 (75.4%) patients had ipsilateral ictal temporal lobe hyperperfusion, and one (1.9%) patient had ipsilateral postictal temporal lobe hypoperfusion. Twelve (22.7%) patients exhibited atypical perfusion patterns: seven (13.2%) patients had bitemporal ictal hyperperfusion (four cases showed asymmetric temporal lobe changes), four (7.6%) patients had contralateral hyperperfusion, and one (1.9%) patient had a normal SPECT scan. All four patients with bitemporal asymmetric hyperperfusions showed greater perfusion lateralized to the side of the EZ. Three of the four patients who had contralateral hyperperfusion also had a complex postictal-like pattern in the ipsilateral temporal lobe consisting of anteromesial hyperperfusion with adjacent lateral hypoperfusion. CONCLUSIONS This study analyzed typical and atypical perfusion patterns in unilateral TLE, and suggested that not only typical, but also some atypical perfusion patterns may contribute to the lateralization of EZ.
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Affiliation(s)
- L Wichert-Ana
- Department of Neurology-Center for Epilepsy Surgery (CIREP), University of São Paulo, Ribeirão Preto, Brazil.
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