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Carisch L, Lindt B, Richter H, Del Chicca F. Regional ADC values of the morphologically normal canine brain. Front Vet Sci 2023; 10:1219943. [PMID: 38026624 PMCID: PMC10663295 DOI: 10.3389/fvets.2023.1219943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023] Open
Abstract
Introduction Diffusion-weighted magnetic resonance imaging is increasingly available for investigation of canine brain diseases. Apparent diffusion coefficient (ADC) of normal canine brains is reported only in small numbers of subjects. The aim of the study was to investigate the ADC of different anatomical regions in the morphologically normal brain in a large population of canine patients in clinical setting. Additionally, possible influence on the ADC value of patient-related factors like sex, age and body weight, difference between the left and right side of the cerebral hemispheres, and between gray and white matter were investigated. Methods Brain magnetic resonance studies including diffusion-weighted images of dogs presented at the Vetsuisse Faculty-University Zurich between 2015 and 2020 were reviewed retrospectively. Only morphologically normal brain magnetic resonance studies of dogs presented with neurological signs or non-neurological signs were included. Apparent diffusion coefficient values of 12 regions of interest (ROIs) in each hemisphere and an additional region in the cerebellar vermis were examined in each dog. Results A total of 321 dogs (including 247 dogs with neurological signs and 62 dogs with non-neurological signs) of various breeds, sex and age were included. Apparent diffusion coefficient significantly varied among most anatomical brain regions. A significantly higher ADC was measured in the gray [median 0.79 (range 0.69-0.90) × 10-3 mm2/s] compared to the white matter [median 0.70 (range 0.63-0.85) × 10-3 mm2/s]. No significant differences were found between the left and right cerebral hemispheres in most of the regions, neither between sexes, different reproductive status, and not consistently between body weight groups. Age was correlated first with a decrease from dogs <1 year of age to middle-age (⩾3 to <8 years) dogs and later with an increase of ADC values in dogs ⩾8 years. Discussion Apparent diffusion coefficient values of 25 ROIs were described in 321 morphologically normal canine brains in clinical setting. Apparent diffusion coefficient differences depending on the brain anatomical region are present. Apparent diffusion coefficient differences among age classes are present, likely consistent with brain maturation and aging. The described data can be a reference for future studies in clinical settings on the canine brain.
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Affiliation(s)
- Lea Carisch
- Clinic for Diagnostic Imaging, Department of Diagnostics and Clinical Services, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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2
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Gangolli M, Wang WT, Gai ND, Pham DL, Butman JA. Simultaneous Acquisition of Diffusion Tensor and Dynamic Diffusion MRI. J Magn Reson Imaging 2023; 57:1079-1092. [PMID: 36056625 PMCID: PMC9981815 DOI: 10.1002/jmri.28407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 08/08/2022] [Accepted: 08/09/2022] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Dynamic diffusion magnetic resonance imaging (ddMRI) metrics can assess transient microstructural alterations in tissue diffusivity but requires additional scan time hindering its clinical application. PURPOSE To determine whether a diffusion gradient table can simultaneously acquire data to estimate dynamic and diffusion tensor imaging (DTI) metrics. STUDY TYPE Prospective. SUBJECTS Seven healthy subjects, 39 epilepsy patients (15 female, 31 male, age ± 15). FIELD STRENGTH/SEQUENCE Two-dimensional diffusion MRI (b = 1000 s/mm2 ) at a field strength of 3 T. Sessions in healthy subjects-standard ddMRI (30 directions), standard DTI (15 and 30 directions), and nested cubes scans (15 and 30 directions). Sessions in epilepsy patients-two 30 direction (standard ddMRI, 10 nested cubes) or two 15 direction scans (standard DTI, 5 nested cubes). ASSESSMENT Fifteen direction DTI was repeated twice for within-session test-retest measurements in healthy subjects. Bland-Altman analysis computed bias and limits of agreement for DTI metrics using test-retest scans and standard 15 direction vs. 5 nested cubes scans. Intraclass correlation (ICC) analysis compared tensor metrics between 15 direction DTI scans (standard vs. 5 nested cubes) and the coefficients of variation (CoV) of trace and apparent diffusion coefficient (ADC) between 30 direction ddMRI scans (standard vs. 10 nested cubes). STATISTICAL TESTS Bland-Altman and ICC analysis using a P-value of 0.05 for statistical significance. RESULTS Correlations of mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were strong and significant in gray (ICC > 0.95) and white matter (ICC > 0.95) between standard vs. nested cubes DTI acquisitions. Correlation of white matter fractional anisotropy was also strong (ICC > 0.95) and significant. ICCs of the CoV of dynamic ADC measured using repeated cubes and nested cubes acquisitions were modest (ICC >0.60), but significant in gray matter. CONCLUSION A nested cubes diffusion gradient table produces tensor-based and dynamic diffusion measurements in a single acquisition. LEVEL OF EVIDENCE 2 TECHNICAL EFFICACY: Stage 1.
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Affiliation(s)
- Mihika Gangolli
- Center for Neuroscience and Regenerative Medicine
- The Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc
| | - Wen-Tung Wang
- National Institutes of Health, Radiology and Imaging Sciences
| | - Neville D. Gai
- National Institutes of Health, National Heart Lung and Blood Institute
| | - Dzung L. Pham
- Center for Neuroscience and Regenerative Medicine
- Uniformed Services University, Radiology and Radiological Sciences
| | - John A. Butman
- Center for Neuroscience and Regenerative Medicine
- National Institutes of Health, Radiology and Imaging Sciences
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3
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Huang T, Lai M, Chen Y, Huang C. Brain Imaging in Epilepsy-Focus on Diffusion-Weighted Imaging. Diagnostics (Basel) 2022; 12:2602. [PMID: 36359445 PMCID: PMC9689253 DOI: 10.3390/diagnostics12112602] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 10/23/2022] [Accepted: 10/24/2022] [Indexed: 11/30/2022] Open
Abstract
Epilepsy is a common neurological disorder; 1% of people worldwide have epilepsy. Differentiating epileptic seizures from other acute neurological disorders in a clinical setting can be challenging. Approximately one-third of patients have drug-resistant epilepsy that is not well controlled by current antiepileptic drug therapy. Surgical treatment is potentially curative if the epileptogenic focus is accurately localized. Diffusion-weighted imaging (DWI) is an advanced magnetic resonance imaging technique that is sensitive to the diffusion of water molecules and provides additional information on the microstructure of tissue. Qualitative and quantitative analysis of peri-ictal, postictal, and interictal diffusion images can aid the differential diagnosis of seizures and seizure foci localization. This review focused on the fundamentals of DWI and its associated techniques, such as apparent diffusion coefficient, diffusion tensor imaging, and tractography, as well as their impact on epilepsy in terms of differential diagnosis, epileptic foci determination, and prognosis prediction.
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Chau Loo Kung G, Chiu A, Davey Z, Mouchawar N, Carlson M, Moein Taghavi H, Martin D, Graber K, Razavi B, McNab J, Zeineh M. High-resolution hippocampal diffusion tensor imaging of mesial temporal sclerosis in refractory epilepsy. Epilepsia 2022; 63:2301-2311. [PMID: 35751514 DOI: 10.1111/epi.17330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 06/10/2022] [Accepted: 06/13/2022] [Indexed: 11/30/2022]
Abstract
OBJECTIVE We explore the possibility of using diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) to discern microstructural abnormalities in the hippocampus indicative of mesial temporal sclerosis (MTS) at the subfield level. METHODS We analyzed data from 57 patients with refractory epilepsy who previously underwent 3.0-T magnetic resonance imaging (MRI) including DTI as a standard part of presurgical workup. We collected information about each subject's seizure semiology, conventional electroencephalography (EEG), high-density EEG, positron emission tomography reports, surgical outcome, and available histopathological findings to assign a final diagnostic category. We also reviewed the radiology MRI report to determine the radiographic category. DTI- and NODDI-based metrics were obtained in the hippocampal subfields. RESULTS By examining diffusion characteristics among subfields in the final diagnostic categories, we found lower orientation dispersion indices and elevated axial diffusivity in the dentate gyrus in MTS compared to no MTS. By similarly examining among subfields in the different radiographic categories, we found all diffusion metrics were abnormal in the dentate gyrus and CA1. We finally examined whether diffusion imaging would better inform a radiographic diagnosis with respect to the final diagnosis, and found that dentate diffusivity suggested subtle changes that may help confirm a positive radiologic diagnosis. SIGNIFICANCE The results suggest that diffusion metric analysis at the subfield level, especially in dentate gyrus and CA1, maybe useful for clinical confirmation of MTS.
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Affiliation(s)
- Gustavo Chau Loo Kung
- Bioengineering Department, Stanford University, Stanford, California, USA.,Radiology Department, Stanford University, Stanford, California, USA
| | - Andrew Chiu
- Radiology Department, Stanford University, Stanford, California, USA
| | - Zach Davey
- Neurology and Neurological Sciences, Stanford Medicine, Stanford University, Stanford, California, USA
| | - Nicole Mouchawar
- Radiology Department, Stanford University, Stanford, California, USA
| | - Mackenzie Carlson
- Bioengineering Department, Stanford University, Stanford, California, USA.,Radiology Department, Stanford University, Stanford, California, USA
| | | | | | - Kevin Graber
- Neurology and Neurological Sciences, Stanford Medicine, Stanford University, Stanford, California, USA
| | - Babak Razavi
- Neurology and Neurological Sciences, Stanford Medicine, Stanford University, Stanford, California, USA
| | - Jennifer McNab
- Radiology Department, Stanford University, Stanford, California, USA
| | - Michael Zeineh
- Radiology Department, Stanford University, Stanford, California, USA
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Muralidhar A, Kumar A, Prakash A, Krishnamurthy U, S M, Majeed R. Magnetic Resonance Imaging Characterization of the Hippocampi in Temporal Lobe Epilepsy: Correlation of Volumetry and Apparent Diffusion Coefficient with Laterality and Duration of Seizures. Indian J Radiol Imaging 2021; 31:109-115. [PMID: 34316118 PMCID: PMC8299500 DOI: 10.1055/s-0041-1729672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Background and Purpose It is estimated that hippocampal damage is seen in 50 to 70% of patients with temporal lobe epilepsy (TLE). Although most magnetic resonance imaging (MRI) studies are adequate to detect gross hippocampal atrophy, subtle changes that may characterize early disease in TLE, such as visually nonappreciable volume loss, may often be missed if objective volumetric analysis is not undertaken. Materials and Methods We conducted a hospital-based prospective analytical study in which 40 patients with partial seizures of temporal lobe origin were included and their hippocampal volumes (HVs) were determined by manual volumetric analysis. The findings were recorded and correlated with the side of seizure and its duration. The quantitative assessment was allotted different grades accordingly. Also, the apparent diffusion coefficient (ADC) values of bilateral hippocampi were estimated and their correlation with the side of seizure was determined. Results Most patients in the study were in the age group of 11 to 20 years (37.5%). In total, 57.5% had seizures for a period of 1 to 5 years. While 67.5% ( n = 27) had seizure on the right, 32.5% ( n = 13) had on the left. The mean HV estimated on the right and left were correlated with the side of seizure and found to be statistically significant ( p < 0.001 in those with right-sided seizures and p = 0.02 in those with left-sided seizures). Simultaneously the ADC values estimated were found to correlate with the laterality of seizures with a statistical difference ( p < 0.01) . Duration of seizures however did not show a positive correlation with the HV. Conclusion MRI with quantitative estimation of HV and ADC values can depict the presence and laterality in TLE with accuracy rates that exceed those achieved by visual inspection alone. Thus, quantitative MRI provides a useful means for translating volumetric analysis into clinical practice.
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Affiliation(s)
- Apoorva Muralidhar
- Department of Radio-diagnosis, M. S. Ramaiah Medical College, Bengaluru, Karnataka, India
| | - Ashok Kumar
- Department of Radio-diagnosis, M. S. Ramaiah Medical College, Bengaluru, Karnataka, India
| | - Arjun Prakash
- Department of Radio-diagnosis, Bangalore Medical College & Research Institute, Bengaluru, Karnataka, India
| | - Umesh Krishnamurthy
- Department of Radio-diagnosis, M. S. Ramaiah Medical College, Bengaluru, Karnataka, India
| | - Manjunath S
- Department of Radio-diagnosis, M. S. Ramaiah Medical College, Bengaluru, Karnataka, India
| | - Roshni Majeed
- Department of Radio-diagnosis, M. S. Ramaiah Medical College, Bengaluru, Karnataka, India
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Tsougos I, Kousi E, Georgoulias P, Kapsalaki E, Fountas KN. Neuroimaging methods in Epilepsy of Temporal Origin. Curr Med Imaging 2018; 15:39-51. [DOI: 10.2174/1573405613666170622114920] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 05/04/2017] [Accepted: 05/11/2017] [Indexed: 11/22/2022]
Abstract
Background:
Temporal Lobe Epilepsy (TLE) comprises the most common form of
symptomatic refractory focal epilepsy in adults. Accurate lateralization and localization of the
epileptogenic focus are a significant prerequisite for determining surgical candidacy once the
patient has been deemed medically intractable. Structural MR imaging, clinical,
electrophysiological, and neurophysiological data have an established role in the localization of the
epileptogenic foci. Nevertheless, hippocampal sclerosis cannot be detected on MR images in more
than 30% of patients with TLE, and the presurgical assessment remains controversial.
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Discussion: In the last years, advanced MR imaging techniques, such as 1H-MRS, DWI, DTI,
DSCI, and fMRI, may provide valuable additional information regarding the physiological and
metabolic characterization of brain tissue. MR imaging has shifted towards functional and
molecular imaging, thus, promising to improve the accuracy regarding the lateralization and the
localization of the epileptogenic focus. Additionally, nuclear medicine studies, such as SPECT and
PET imaging modalities, have become an asset for the decoding of brain function and activity, and
can be diagnostically helpful as well, since they provide valuable data regarding the altered
metabolic activity of the seizure foci.
Conclusion:
Overall, advanced MRI, SPECT, and PET imaging techniques are increasingly
becoming an essential part of TLE diagnostics, when the epileptogenic area is not identified on
structural MRI or when structural MRI, clinical, and electrophysiological findings are not in
concordance.
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Affiliation(s)
- Ioannis Tsougos
- Department of Medical Physics, School of Medicine, University of Thessaly, Larisa, Greece
| | - Evanthia Kousi
- The Royal Marsden NHS Foundation Trust, London, United Kingdom
| | - Panagiotis Georgoulias
- Department of Medical Physics, School of Medicine, University of Thessaly, Larisa, Greece
| | - Eftychia Kapsalaki
- Department of Medical Physics, School of Medicine, University of Thessaly, Larisa, Greece
| | - Kostas N. Fountas
- Department of Medical Physics, School of Medicine, University of Thessaly, Larisa, Greece
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Hartmann A, Sager S, Failing K, Sparenberg M, Schmidt MJ. Diffusion-weighted imaging of the brains of dogs with idiopathic epilepsy. BMC Vet Res 2017; 13:338. [PMID: 29141638 PMCID: PMC5688626 DOI: 10.1186/s12917-017-1268-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 11/10/2017] [Indexed: 02/07/2023] Open
Abstract
Background Idiopathic epilepsy is one of the most common neurological disorders in dogs. Unfortunately, up to 30% of dogs with idiopathic epilepsy show no improvement under antiepileptic drug treatment. Diffusion-weighted imaging is used in human medicine to identify epileptogenic foci in the brain to allow for more invasive treatments such as deep brain stimulation or surgical removal. The aim of this study was to ass the feasibility of interictal diffusion-weighted MRI in dogs and to evaluate the distribution of diffusion in the brains of dogs with idiopathic epilepsy (IE) and to compare these values to previously published values from healthy beagle dogs. Client-owned dogs with the final diagnosis of IE were included in this study. MRI examination was carried out using a 1.0Tesla superconductive magnet. Diffusion-weighted images using a single shot echo planar imaging sequence (SSh-EPI) with a b value of b = 0 s/mm2 and b = 800 s/mm2 were acquired in a dorsal and transverse plane with diffusion gradients in all three planes (x-, y- and z-plane). An ADC (apparent diffusion coefficient) map of the isometric image of each acquired slice was generated. Regions of interest (ROIs) were manually drawn around the caudate nucleus, the thalamus, the piriform lobe including the amygdala, the hippocampus, the semioval center and the temporal cerebral cortex by one of the authors. ROI drawings were repeated 5 times at different time points to assess intra-obersver variability. A multi-way mixed-model analysis of variance (ANOVA) and two-way ANOVA were used during statistical analysis. A p value of p < 0.05 was considered significant. Results Dogs with IE showed a significantly increased ADC in the amygdala within the piriform lobe and in the semioval center (p < 0.05) compared with the healthy control group. Conclusion Changes in the piriform lobe in cases of epilepsy are reported infrequently in human and veterinary medicine. Similar to our results, ADC changes in the interictal phase usually include an increase in ADC due to cell loss and increased intercellular spaces. Diffusion MRI might be a promising technique for the examination of canine epileptic patients lacking other gross neuromorphological abnormalities.
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Affiliation(s)
- Antje Hartmann
- Department of Clinical Veterinary Medicine, Vetsuisse Faculty, University of Bern, Länggassstraße 128, 3012, Bern, Switzerland.
| | - Steffen Sager
- Department of Veterinary Clinical Sciences, Small Animal Clinic, Justus-Liebig-University Giessen, Frankfurter Straße 108, 35392, Giessen, Germany
| | - Klaus Failing
- Unit for Biomathematics and Data Processing Faculty of Veterinary Medicine Justus Liebig-University, Frankfurter Straße 95, 35392, Giessen, Germany
| | - Marion Sparenberg
- Unit for Biomathematics and Data Processing Faculty of Veterinary Medicine Justus Liebig-University, Frankfurter Straße 95, 35392, Giessen, Germany
| | - Martin J Schmidt
- Department of Veterinary Clinical Sciences, Small Animal Clinic, Justus-Liebig-University Giessen, Frankfurter Straße 108, 35392, Giessen, Germany
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Gaxiola-Valdez I, Singh S, Perera T, Sandy S, Li E, Federico P. Seizure onset zone localization using postictal hypoperfusion detected by arterial spin labelling MRI. Brain 2017; 140:2895-2911. [PMID: 29053782 DOI: 10.1093/brain/awx241] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 08/03/2017] [Indexed: 11/15/2022] Open
Abstract
Neurological dysfunction following epileptic seizures is a well-recognized phenomenon. Several potential mechanisms have been suggested to explain postictal dysfunction, with alteration in cerebral blood flow being one possibility. These vascular disturbances may be long lasting and localized to brain areas involved in seizure generation and propagation, as supported by both animal and human studies. Therefore, measuring perfusion changes in the postictal period may help localize the seizure onset zone. Arterial spin labelling is a non-invasive, rapid and reproducible magnetic resonance imaging technique that measures cerebral perfusion. To this end, we measured postictal perfusion in patients with drug resistant focal epilepsy who were admitted to our seizure-monitoring unit for presurgical evaluation. Twenty-one patients were prospectively recruited and underwent arterial spin labelling scanning within 90 min of a habitual seizure. Patients also underwent a similar scan in the interictal period, after they were seizure-free for at least 24 h. The acquired scans were subtracted to identify the areas of significant postictal hypoperfusion. The location of the maximal hypoperfusion was compared to the presumed seizure onset zone to assess for concordance. Also, the localizing value of this technique was compared to other structural and functional imaging modalities. Postictal perfusion reductions of >15 units (ml/100 g/l) were seen in 15/21 patients (71.4%). In 12/15 (80%) of these patients, the location of the hypoperfusion was partially or fully concordant with the location of the presumed seizure onset zone. This technique compared favourably to other neuroimaging modalities, being similar or superior to structural magnetic resonance imaging in 52% of cases, ictal single-photon emission computed tomography in 60% of cases and interictal positron emission tomography in 71% of cases. Better arterial spin labelling results were obtained in patients in whom the seizure onset zone was discernible based on non-invasive data. Thus, this technique is a safe, non-invasive and relatively inexpensive tool to detect postictal hypoperfusion that may provide useful data to localize the seizure onset zone. This technique may be incorporated into the battery of conventional investigations for presurgical evaluation of patients with drug resistant focal epilepsy.
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Affiliation(s)
- Ismael Gaxiola-Valdez
- Hotchkiss Brain Institute, University of Calgary, Calgary, Canada.,Seaman Family MR Research Centre, University of Calgary, Calgary, Canada
| | - Shaily Singh
- Hotchkiss Brain Institute, University of Calgary, Calgary, Canada.,Department of Clinical Neurosciences, University of Calgary, Calgary, Canada
| | - Tefani Perera
- Hotchkiss Brain Institute, University of Calgary, Calgary, Canada.,Seaman Family MR Research Centre, University of Calgary, Calgary, Canada
| | - Sherry Sandy
- Department of Clinical Neurosciences, University of Calgary, Calgary, Canada
| | - Emmy Li
- Hotchkiss Brain Institute, University of Calgary, Calgary, Canada.,Seaman Family MR Research Centre, University of Calgary, Calgary, Canada.,Department of Neuroscience, University of Calgary, Calgary, Canada
| | - Paolo Federico
- Hotchkiss Brain Institute, University of Calgary, Calgary, Canada.,Seaman Family MR Research Centre, University of Calgary, Calgary, Canada.,Department of Clinical Neurosciences, University of Calgary, Calgary, Canada.,Department of Neuroscience, University of Calgary, Calgary, Canada.,Department of Radiology, University of Calgary, Calgary, Canada
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Hamamoto Y, Hasegawa D, Mizoguchi S, Yu Y, Wada M, Kuwabara T, Fujiwara-igarashi A, Fujita M. Changes in the interictal and early postictal diffusion and perfusion magnetic resonance parameters in familial spontaneous epileptic cats. Epilepsy Res 2017; 133:76-82. [DOI: 10.1016/j.eplepsyres.2017.04.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 04/13/2017] [Accepted: 04/20/2017] [Indexed: 11/23/2022]
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10
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Kwon OY, Yoo SK, Kim YS. Brain Lesions Attributed to Acute Seizures. J Neurocrit Care 2016. [DOI: 10.18700/jnc.160089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Stylianou P, Hoffmann C, Blat I, Harnof S. Neuroimaging for patient selection for medial temporal lobe epilepsy surgery: Part 1 Structural neuroimaging. J Clin Neurosci 2015; 23:14-22. [PMID: 26362835 DOI: 10.1016/j.jocn.2015.04.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Revised: 03/27/2015] [Accepted: 04/05/2015] [Indexed: 11/19/2022]
Abstract
The objective of part one of this review is to present the structural neuroimaging techniques that are currently used to evaluate patients with temporal lobe epilepsy (TLE), and to discuss their potential to define patient eligibility for medial temporal lobe surgery. A PubMed query, using Medline and Embase, and subsequent review, was performed for all English language studies published after 1990, reporting neuroimaging methods for the evaluation of patients with TLE. The extracted data included demographic variables, population and study design, imaging methods, gold standard methods, imaging findings, surgical outcomes and conclusions. Overall, 56 papers were reviewed, including a total of 1517 patients. This review highlights the following structural neuroimaging techniques: MRI, diffusion-weighted imaging, tractography, electroencephalography and magnetoencephalography. The developments in neuroimaging during the last decades have led to remarkable improvements in surgical precision, postsurgical outcome, prognosis, and the rate of seizure control in patients with TLE. The use of multiple imaging methods provides improved outcomes, and further improvements will be possible with future studies of larger patient cohorts.
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Affiliation(s)
- Petros Stylianou
- Department of Neurosurgery, The Chaim Sheba Medical Center, Nissim Aloni 16, Tel Aviv-Yafo 62919, Israel.
| | - Chen Hoffmann
- Department of Radiology, The Chaim Sheba Medical Center, Tel Hashomer, Israel
| | - Ilan Blat
- Department of Neurology, The Chaim Sheba Medical Center, Tel Hashomer, Israel
| | - Sagi Harnof
- Department of Neurosurgery, The Chaim Sheba Medical Center, Nissim Aloni 16, Tel Aviv-Yafo 62919, Israel
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Ciumas C, Saignavongs M, Ilski F, Herbillon V, Laurent A, Lothe A, Heckemann RA, de Bellescize J, Panagiotakaki E, Hannoun S, Marinier DS, Montavont A, Ostrowsky-Coste K, Bedoin N, Ryvlin P. White matter development in children with benign childhood epilepsy with centro-temporal spikes. Brain 2014; 137:1095-106. [DOI: 10.1093/brain/awu039] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Abstract
Epilepsy is the most common serious neurological disease. Seizures are refractory to medication in approximately 30% of patients with focal epilepsy, and surgical treatment is potentially curative should the epileptic focus be accurately localized. MRI has revolutionized the investigation of such patients; however, up to 20% of patients with refractory focal epilepsy have an undetermined etiological basis for their epilepsy despite extensive investigation. Diffusion imaging is an advanced MRI technique that is sensitive to the molecular displacement of water molecules and provides additional information on the microstructural arrangement of tissue. Both qualitative and quantitative analyses of the interictal and peri-ictal states are possible and provide valuable insights into the epileptic brain in vivo. Furthermore, advanced postacquisition processing can reveal additional information on, for example, anatomical connectivity. The description, application and limitations of diffusion imaging in epilepsy are the focus of this review. Future directions of research required in this area are also discussed in the context of existing literature.
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Affiliation(s)
- Fergus J Rugg-Gunn
- Institute of Neurology, Department of Clinical & Experimental Epilepsy, University College London, Queen Square, London, UK.
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Förster A, Griebe M, Gass A, Kern R, Hennerici MG, Szabo K. Diffusion-weighted imaging for the differential diagnosis of disorders affecting the hippocampus. Cerebrovasc Dis 2011; 33:104-15. [PMID: 22179485 DOI: 10.1159/000332036] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 08/17/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The human hippocampus can be affected in a large variety of very different neurological diseases, of which acute ischemic stroke, transient global amnesia, epilepsy, and limbic encephalitis are the most common. Less frequent etiologies include various infections and encephalopathy of different origins. Clinical presentation notably comprises confusional state, altered vigilance, memory deficits of various extent and seizures. While in hypoxic or hypoglycemic encephalopathy, clinical presentation and surrounding circumstances provide some clues to reach the correct diagnosis, in the above-listed more common disorders, signs and symptoms might overlap, making the differential diagnosis difficult. This review presents recent studies using the diffusion-weighted imaging (DWI) technique in diseases involving the hippocampus. METHODS References for the review were identified through searches of PubMed from 1965 to January 2011. Only papers published in English were reviewed. Full articles were obtained and references were checked for additional material where appropriate. RESULTS All pathologies affecting the hippocampus are associated with distinct lesion patterns on magnetic resonance imaging, and especially DWI has the ability to demonstrate even minute and transient hippocampal lesions. In acute ischemic stroke in the posterior cerebral artery territory, involvement of the hippocampal formation occurs in four distinct patterns on DWI that can be easily differentiated and correspond to the known vascular anatomy of the hippocampus. In the subacute phase after transient global amnesia (TGA), dot-like hyperintense lesions are regularly found in the lateral aspect of the hippocampus on DWI. The DWI lesions described after prolonged seizures or status epilepticus include unilateral or bilateral hippocampal, thalamic, and cortical lesions of various extent, not restricted to vascular territories. In limbic encephalitis, DWI lesions are only infrequently found and usually affect the hippocampus, uncus and amygdala. Furthermore, in some rare cases DWI lesions of different etiology may coexist. CONCLUSION In patients with diseases affecting the hippocampus, DWI appears to be useful in differentiating between underlying pathologies and may facilitate a definite diagnosis conducive to an optimal treatment. With a careful clinical examination, experience with the interpretation of DWI findings and knowledge of associated phenomena, it is indeed possible to differentiate between ischemic, ictal, metabolic, and TGA-associated findings.
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Affiliation(s)
- A Förster
- Department of Neurology, UniversitätsMedizin Mannheim, University of Heidelberg, Mannheim, Germany.
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Chatzikonstantinou A, Gass A, Förster A, Hennerici MG, Szabo K. Features of acute DWI abnormalities related to status epilepticus. Epilepsy Res 2011; 97:45-51. [PMID: 21802259 DOI: 10.1016/j.eplepsyres.2011.07.002] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2011] [Revised: 07/01/2011] [Accepted: 07/03/2011] [Indexed: 12/01/2022]
Abstract
We analyzed the phenomenon of transient regional diffusion-weighted MRI (DWI) hyperintensity in a series of status epilepticus (SE) patients with respect to seizure type, epileptogenic lesions and EEG findings. A prospective series of 54 patients (30 men, 24 women, mean age 61.5 years) admitted with SE was analyzed with regard to clinical semiology, EEG and MRI findings including DWI and EEG recordings in the acute peri-ictal phase. DWI abnormalities occurred most frequently in patients with complex-partial SE (27/50%) and generalized SE (18/33.3%). Forty patients (74.1%) had symptomatic, 13/24.1% cryptogenic and 1/1.9% idiopathic epilepsies. On DWI, the hippocampus was affected in 37/68.5% cases, often in combination with other brain areas (15/40.5%), in particular the pulvinar was affected in 14/25.9% patients. Bilateral DWI changes were found in 8/14.8% patients. No correlation with a specific seizure type was observed. In 21/38.9%, DWI changes were ipsilateral to the epileptogenic brain lesion (p<0.001) and in 5/9.3% contralateral, whereas in the majority of patients, either bilateral changes or no specific epileptogenic lesion were found. EEG abnormalities correlated with lateralization of DWI abnormalities in 44/81.5% (p<0.001). The most common localization of DWI abnormalities associated with ictal activity was the hippocampus and the pulvinar. Combined DWI-MRI and EEG analysis provides clues to seizure localization and propagation, as well as to identify brain structures affected by continuous or frequent ictal activity. This large series of patients with different features (SE type and cause, various epileptogenic lesions) demonstrates the heterogeneity of the phenomenon of peri-ictal DWI changes.
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Abstract
The postictal state is defined as manifestation of seizure-induced reversible alterations in neuronal function, but not structure. Following a seizure, it is common to experience feelings of exhaustion, both mental and physical, that can last a day or two. There are three major hypotheses regarding what cellular and molecular mechanisms could cause the observed postictal symptoms: neurotransmitter depletion or changes in receptor concentration, active inhibition, and cerebral blood flow changes. Here, we describe the contributions of functional neuroimaging studies to the understanding of postictal symptoms.
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Affiliation(s)
- Matthias J Koepp
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, London, UK.
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Abstract
Neuroimaging in epilepsy is a very large and growing field. Researchers in this area have quickly adopted new methods, resulting in a lively literature. Basic features of common epilepsies are well known, but, outside of the specific area of epilepsy surgery evaluation, new methods evolving in the last few years have had limited new beneficial clinical impact. Here, an overview of the epilepsy neuroimaging literature of the last 5 years, with an emphasis on mesial temporal lobe epilepsy, idiopathic generalized epilepsies, presurgical evaluation and new developments in functional MRI is presented. The need for attention to clinical translation, as well as immediate opportunities and future trends in this field, are discussed.
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Affiliation(s)
- Mark Richardson
- P043 Institute of Psychiatry, De Crespigny Park, London SE5 8AF, UK.
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Kim CH, Koo BB, Chung CK, Lee JM, Kim JS, Lee SK. Thalamic changes in temporal lobe epilepsy with and without hippocampal sclerosis: A diffusion tensor imaging study. Epilepsy Res 2010; 90:21-7. [DOI: 10.1016/j.eplepsyres.2010.03.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2009] [Revised: 02/25/2010] [Accepted: 03/01/2010] [Indexed: 10/19/2022]
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Munasinghe JP, Banerjee M, Acosta MT, Banks M, Heffer A, Silva AC, Koretsky A, Theodore WH. Arterial spin labeling demonstrates that focal amygdalar glutamatergic agonist infusion leads to rapid diffuse cerebral activation. Acta Neurol Scand 2010; 121:209-16. [PMID: 19951270 DOI: 10.1111/j.1600-0404.2009.01188.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To investigate acute effects of intra-amygdalar excitatory amino acid administration on blood flow, relaxation time and apparent diffusion coefficient in rat brain. MATERIALS AND METHODS Several days after MR-compatible cannula placement in right basolateral amygdala, anesthetized rats were imaged at 7 T. Relative cerebral blood flow (CBF) was measured before and 60 min after infusion of 10 nmol KA, cAMPA, ATPA, or normal saline using arterial spin labeling. Quantitative T(2) and diffusion-weighted images were acquired. rCBF, T(2) and ADC values were evaluated in bilateral basolateral amygdala, hippocampus, basal ganglia, frontal and parietal regions. RESULTS KA led to the highest, and ATPA lowest bilateral rCBF increases. Time courses varied among drugs. T(2) for KA and AMPA was higher while ADC was lower for KA. CONCLUSIONS Intra-amygdalar injection of GluR agonists evoked bilateral seizure activity and increased rCBF, greater for KA and AMPA than selective ATPA GluR5 activation.
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Affiliation(s)
- J P Munasinghe
- MRI Research Facility, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
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Richardson M. Current themes in neuroimaging of epilepsy: brain networks, dynamic phenomena, and clinical relevance. Clin Neurophysiol 2010; 121:1153-75. [PMID: 20185365 DOI: 10.1016/j.clinph.2010.01.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Revised: 12/24/2009] [Accepted: 01/05/2010] [Indexed: 11/15/2022]
Abstract
Brain scanning methods were first applied in patients with epilepsy more than 30years ago. A very substantial literature now exists in this field, which is exponentially increasing. Contemporary neuroimaging studies in epilepsy reflect new concepts in the epilepsies, as well as current methodological developments. In particular, this area is emphasising the role of networks in epileptogenicity, the existence of dynamic phenomena which can be captured by imaging, and is beginning to validate the implementation of neuroimaging in the clinic. Here, recent studies of the last 5years are reviewed, covering the full range of neuroimaging methods with SPECT, PET and MRI in epilepsy.
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Affiliation(s)
- Mark Richardson
- P043 Institute of Psychiatry, De Crespigny Park, London SE5 8AF, UK.
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Marchi N, Betto G, Fazio V, Fan Q, Ghosh C, Machado A, Janigro D. Blood-brain barrier damage and brain penetration of antiepileptic drugs: role of serum proteins and brain edema. Epilepsia 2009; 50:664-77. [PMID: 19175391 PMCID: PMC2824251 DOI: 10.1111/j.1528-1167.2008.01989.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Increased blood-brain barrier (BBB) permeability is radiologically detectable in regions affected by drug-resistant epileptogenic lesions. Brain penetration of antiepileptic drugs (AEDs) may be affected by BBB damage. We studied the effects of BBB damage on brain distribution of hydrophilic [deoxy-glucose (DOG) and sucrose] and lipophilic (phenytoin and diazepam) molecules. We tested the hypothesis that lipophilic and hydrophilic drug distribution is differentially affected by BBB damage. METHODS In vivo BBB disruption (BBBD) was performed in rats by intracarotid injection of hyperosmotic mannitol. Drugs (H3-sucrose, 3H-deoxy-glucose, 14C-phenytoin, and C14-diazepam) or unlabeled phenytoin was measured and correlated to brain water content and protein extravasation. In vitro hippocampal slices were exposed to different osmolarities; drug penetration and water content were assessed by analytic and densitometric methods, respectively. RESULTS BBBD resulted in extravasation of serum protein and radiolabeled drugs, but was associated with no significant change in brain water. Large shifts in water content in brain slices in vitro caused a small effect on drug penetration. In both cases, total drug permeability increase was greater for lipophilic than hydrophilic compounds. BBBD reduced the amount of free phenytoin in the brain. DISCUSSION After BBBD, drug binding to protein is the main controller of total brain drug accumulation. Osmotic BBBD increased serum protein extravasation and reduced free phenytoin brain levels. These results underlie the importance of brain environment and BBB integrity in determining drug distribution to the brain. If confirmed in drug-resistant models, these mechanisms could contribute to drug brain distribution in refractory epilepsies.
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Affiliation(s)
- Nicola Marchi
- Department of Neurological Surgery, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Cell Biology, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Cerebrovascular Research, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
| | - Giulia Betto
- Department of Neurological Surgery, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Cell Biology, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Cerebrovascular Research, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
| | - Vincent Fazio
- Department of Neurological Surgery, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Cell Biology, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Cerebrovascular Research, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
| | - Quinyuan Fan
- Department of Neurological Surgery, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Cell Biology, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Cerebrovascular Research, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
| | - Chaitali Ghosh
- Department of Neurological Surgery, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Cell Biology, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Cerebrovascular Research, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
| | - Andre Machado
- Center for Restorative Neuroscience, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
| | - Damir Janigro
- Department of Neurological Surgery, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Cell Biology, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Cerebrovascular Research, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
- Department of Molecular Medicine, Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A
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Katramados AM, Burdette D, Patel SC, Schultz LR, Gaddam S, Mitsias PD. Periictal diffusion abnormalities of the thalamus in partial status epilepticus. Epilepsia 2009; 50:265-75. [PMID: 18717714 DOI: 10.1111/j.1528-1167.2008.01736.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE To identify and describe thalamic dysfunction in patients with temporal as well as extratemporal status epilepticus (SE) and to also analyze the specific clinical, radiological, and electroencephalography (EEG) characteristics of patients with acute thalamic involvement. METHODS We retrospectively identified patients who presented with clinical and electrographic evidence of partial SE and had thalamic abnormalities on diffusion-weighted imaging (DWI) within 5 days of documentation of lateralized epileptiform discharges (group 1). The spatial and temporal characteristics of the periodic lateralized epileptiform discharges (PLEDs) and the recorded electrographic seizures were analyzed and correlated with magnetic resonance imaging (MRI)-DWI hyperintense lesions. The findings of group 1 patients were compared with those of patients with partial SE without thalamic abnormalities on DWI (group 2). RESULTS The two groups were similar with regard to clinical presentation and morphology of epileptiform discharges. Group 1 patients had thalamic hyperintense lesions on DWI that appeared in the region of the pulvinar nucleus, ipsilateral to the epileptiform activity. Statistically significant relationship was noted between the presence of thalamic lesions and ipsilateral cortical laminar involvement (p = 0.039) as well as seizure origin in the posterior quadrants (p = 0.038). A trend towards PLEDs originating in the posterior quadrants was also noted (p = 0.077). DISCUSSION Thalamic DWI hyperintense lesions may be observed after prolonged partial SE and are likely the result of excessive activity in thalamic nuclei having reciprocal connections with the involved cortex. The thalamus likely participates in the evolution and propagation of partial seizures in SE.
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Affiliation(s)
- Angelos M Katramados
- Departments of Neurology, Henry Ford Health Sciences Center, Detroit, Michigan, USA.
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Chen Q, Lui S, Li CX, Jiang LJ, Ou-Yang L, Tang HH, Shang HF, Huang XQ, Gong QY, Zhou D. MRI-negative refractory partial epilepsy: role for diffusion tensor imaging in high field MRI. Epilepsy Res 2008; 80:83-9. [PMID: 18440782 DOI: 10.1016/j.eplepsyres.2008.03.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Revised: 02/25/2008] [Accepted: 03/10/2008] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Our aim is to use the high field MR scanner (3T) to verify whether diffusion tensor imaging (DTI) could help in locating the epileptogenic zone in patients with MRI-negative refractory partial epilepsy. METHOD Fifteen patients with refractory partial epilepsy who had normal conventional MRI, and 40 healthy volunteers were recruited for the study. DTI was performed on a 3T MR scanner, individual maps of mean diffusivity (MD) and fractional anisotropy (FA) were calculated, and Voxel-Based Analysis (VBA) was performed for individual comparison between patients and controls. RESULT Voxel-based analysis revealed significant MD increase in variant regions in 13 patients. The electroclinical seizure localization was concurred to seven patients. No patient exhibited regions of significant decreased MD. Regions of significant reduced FA were observed in five patients, with two of these concurring with electroclinical seizure localization. Two patients had regions of significant increase in FA, which were distinct from electroclinical seizure localization. CONCLUSION Our study's results revealed that DTI is a responsive neuroradiologic technique that provides information about the epileptogenic areas in patients with MRI-negative refractory partial epilepsy. This technique may also helpful in pre-surgical evaluation.
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Affiliation(s)
- Qin Chen
- Department of Neurology, West China Hospital of Sichuan University, Chengdu, Sichuan, China
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Abstract
Diffusion-based imaging is an advanced MRI technique that is sensitive to the movement of water molecules, providing additional information on the micro-structural arrangement of tissue. Qualitative and quantitative analysis of peri, post and interictal diffusion images can aid the localization of seizure foci. Diffusion tensor tractography is an extension of diffusion-based imaging, and can provide additional information about white matter pathways. Both techniques are able to increase understanding of the effects of epilepsy on the structural organization of the brain, and can be used to optimize presurgical planning of patients with epilepsy. This review focuses on the basis, applications, limitations, and future directions of diffusion imaging in epilepsy. Literature search strategy: We searched Pubmed using the terms "diffusion MRI or diffusion tensor MRI or tractography and epilepsy."
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Affiliation(s)
- Mahinda Yogarajah
- Department of Clinical and Experimental Epilepsy and National Society for Epilepsy, Institute of Neurology, University College London, Queen Square, London, United Kingdom
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Abstract
PURPOSE Bilateral white matter diffusion tensor imaging (DTI) abnormalities have been reported in patients with temporal lobe epilepsy (TLE) and unilateral mesial temporal sclerosis (MTS), but it is unknown whether these are functional or structural changes. We performed a longitudinal study in patients with unilateral MTS who were seizure-free for 1 year after surgery to determine whether the observed presurgical white matter diffusion abnormalities were reversible. METHODS Eight TLE patients with unilateral MTS who were seizure-free after anterior temporal resection and 22 healthy subjects were recruited. DTI was performed before surgery and at 1-year follow-up. Tractography and region-of-interest (ROI) analyses were performed in the fornix, cingulum, genu, and splenium of the corpus callosum and external capsules. Diffusion tensor parameters were compared between groups and before and after surgery in the patient group. RESULTS The fornix, cingulum, and external capsules showed preoperative bilateral abnormal diffusion parameters (i.e., decreased diffusion anisotropy and increased mean and perpendicular diffusivities). The fornix and cingulum ipsilateral to the resected mesial temporal structures showed signs of wallerian degeneration at 1-year follow-up. The contralateral tracts of the fornix, cingulum, and external capsules, as well as the genu of the corpus callosum, failed to show a normalization of their diffusion parameters. CONCLUSIONS The irreversibility of the white matter DTI abnormalities on seizure freedom suggests underlying structural abnormalities (e.g., axonal/myelin degradation) as opposed to functional changes (e.g., fluid shifts due to seizures) in the white matter.
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Affiliation(s)
- Luis Concha
- Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada
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O'Brien TJ, David EP, Kilpatrick CJ, Desmond P, Tress B. Contrast-enhanced perfusion and diffusion MRI accurately lateralize temporal lobe epilepsy: a pilot study. J Clin Neurosci 2007; 14:841-9. [PMID: 17596947 DOI: 10.1016/j.jocn.2006.07.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2006] [Revised: 07/01/2006] [Accepted: 07/05/2006] [Indexed: 11/24/2022]
Abstract
AIMS To undertake a pilot study to assess whether magnetic resonance (MR) contrast-enhanced perfusion imaging (CEPI) and diffusion-weighted imaging (DWI) provide lateralizing information in medically refractory temporal lobe epilepsy (TLE),and to compare this to standard quantitative hippocampal assessments (volumetric measurements and T2 relaxometry). METHODS Ten patients with 'non-lesional' TLE and 10 control subjects were studied. Quantification of the relative cerebral blood flow (rCBF) and apparent diffusion coefficient (ADC) was performed for the hippocampal regions. The ratios of the ipsilateral-to-contralateral side (to the EEG lateralization) were compared with the side-to-side ratios in the controls. RESULTS Six patients (60%) had an ADC ratio outside the control range (the larger ADC ipsilateral to the EEG lateralization in all cases). The CBF ratios were outside the control range in all eight patients (100%) in whom CEPI was performed (the lower value ipsilateral to the EEG lateralization in all cases). The magnitude of the hippocampal volume (HV) ratios showed no significant correlation with the magnitude of the ADC ratios (R=-0.03, p=0.93) or CBF ratios (R=0.36, p=0.39). There was a closer relationship with the T2 relaxometry ratios, but this was also not significant (R=-0.40, p=0.32; R=0.58, p=0.08). CONCLUSIONS DWI and CEPI show potential as reliable tools for the lateralization of non-lesional TLE. Further studies with larger numbers are necessary to determine whether these techniques provide independent data to established MR quantitative measures.
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Affiliation(s)
- T J O'Brien
- Department of Neurology, The Royal Melbourne Hospital, The University of Melbourne, Victoria, Australia.
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Guye M, Ranjeva J, Bartolomei F, Confort-Gouny S, McGonigal A, Régis J, Chauvel P, Cozzone P. What is the significance of interictal water diffusion changes in frontal lobe epilepsies? Neuroimage 2007; 35:28-37. [DOI: 10.1016/j.neuroimage.2006.11.049] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2006] [Revised: 11/01/2006] [Accepted: 11/13/2006] [Indexed: 12/28/2022] Open
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Abstract
Diffusion-Weighted and Perfusion MRI Demonstrates Parenchymal Changes in Complex Partial Status Epilepticus Szabo K, Poepel A, Pohlmann-Eden B, Hirsch J, Back T, Sedlaczek O, Hennerici M, Gass A Brain 2005;128(Pt 6):1369–1376 Diffusion-weighted MRI (DWI) and perfusion MRI (PI) have been mainly applied in acute stroke, but may provide information in the peri-ictal phase in epilepsy patients. Both transient reductions of brain water diffusion, namely a low apparent diffusion coefficient (ADC), and signs of hyperperfusion have been reported in experimental and human epilepsy case studies. We studied 10 patients with complex partial status epilepticus (CPSE) with serial MRI, including DWI and PI. All patients showed regional hyperintensity on DWI, and a reduction of the ADC in (i) the hippocampal formation and the pulvinar region of the thalamus (six out of 10 patients), (ii) the pulvinar and cortical regions (two out of 10), (iii) the hippocampal formation only (one out of 10), and (iv) the hippocampal formation, the pulvinar and the cortex (one out of 10). In all patients, a close spatial correlation of focal hyperperfusion with areas of ADC/DWI change was present. In two patients, hyperperfusion was confirmed in additional SPECT (single photon emission computed tomography) studies. All patients received follow-up MRI examinations showing partial or complete resolution of diffusion and perfusion abnormalities depending on the length of the follow-up interval. The clinical course, EEG, and SPECT results all indicate that MRI detected changes related to prolonged epileptic activity. Combined PI and DWI can visualize haemodynamic and tissue changes after CPSE in the hippocampus, thalamus, and affected cortical regions.
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Burneo JG. Do Early Hippocampal Imaging Changes Predict Later Sclerosis? Epilepsy Curr 2007; 7:11-2. [PMID: 17304344 PMCID: PMC1797885 DOI: 10.1111/j.1535-7511.2007.00154.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Acute Symptomatic Seizures and Hippocampus Damage: DWI and MRS Findings. Parmar H, Lim SH, Tan NC, Lim CC. Neurology 2006;66:1732–1735. The authors describe diffusion-weighted imaging (DWI) and magnetic resonance spectroscopy (MRS) changes in the hippocampus within 48 h of acute symptomatic seizures or status epilepticus in 12 patients. DWI showed increased signal and a decreased apparent diffusion coefficient (ADC) in all patients, with corresponding lactate detected on MRS in six patients and EEG seizure activity in nine patients. On follow-up, the atrophic hippocampus had an increased ADC in six patients. DWI and MRS may predict development of hippocampal sclerosis.
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Raghavendra S, Ashalatha R, Krishnamoorthy T, Kesavadas C, Thomas SV, Radhakrishnan K. Reversible periictal MRI abnormalities: Clinical correlates and long-term outcome in 12 patients. Epilepsy Res 2007; 73:129-36. [PMID: 17125968 DOI: 10.1016/j.eplepsyres.2006.10.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2006] [Revised: 08/30/2006] [Accepted: 10/16/2006] [Indexed: 10/23/2022]
Abstract
Although a wide spectrum of reversible periictal magnetic resonance imaging (MRI) abnormalities (RPMA) are being increasingly identified, the clinicians are often in a dilemma about their localization significance. This prompted us to analyze the clinical, MRI, electroencephalographic (EEG) and follow-up data of 12 patients with RPMA seen in a tertiary referral epilepsy center. RPMA occurred after a single or a cluster of focal seizures with or without secondary generalization. The interictal and ictal EEG abnormalities were localized to the site of RPMA in nine patients. RPMA involved areas remote from the site of EEG abnormalities in four patients. We have developed a comprehensive classification to account for the wide spectrum of RPMA involving gray matter, white matter and leptomeninges with or without contrast enhancement or mass effect. Follow-up MRIs showed complete resolution of RPMA in all, except in four patients, who developed residual focal atrophy. During median follow-up period of 3 years, recurrence of RPMA was observed in two patients. Diffusion weighted MRI in two patients and histopathological finding in one patient favored causal role of hypoxia in the pathogenesis of RPMA. Our observations help to understand the electroclinical profile, radiological spectrum, localization significance and natural history of RPMA better.
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Affiliation(s)
- S Raghavendra
- Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum 695011, Kerala, India
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Abstract
OBJECTIVE Selective focal MR-Signal (diffusion-) changes in the CA-1 sector of the hippocampus have been described in transient global amnesia (TGA), but the pathophysiological substrate of these lesions is largely unknown. As several imaging and epidemiological findings point to a vascular origin an analysis of the temporal evolution of the hippocampal apparent diffusion coefficient (ADC) changes may offer new understanding of the pathomechanisms of TGA. METHODS The time course of the ADC of hippocampal DWI lesions in TGA patients was studied using serial 3 T high-resolution MR-imaging within 1-10 days as well as 4-6 months after TGA. ADC values from 76 MR-studies were analyzed and expressed as ratio ADC (rADC) in reference to the unaffected hemisphere. RESULTS Twenty-nine patients with TGA showed 34 DWI lesions with corresponding T2 lesions in the CA-1 sector of the hippocampal cornu ammonis within a time window of 24-72 h after onset. Ratio ADC decreased below 1.0 (0.66 +/- 0.08) 24 h after the acute TGA episode and did show a further significant decrease to 0.57 +/- 0.1 after 3 days (p < 0.05). After 72 h, rADC increased and normalized around day 10 with rADC values of 1.0 (p < 0.05). INTERPRETATION The temporal evolution of the rADC in hippocampal signal changes in TGA shows a time course previously described for ischemic lesions in human stroke patients. This might imply a vascular origin of diffusion changes leading to a transient perturbation of memory relevant circuits in the hippocampus.
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Affiliation(s)
- Thorsten Bartsch
- Department of Neurology, University Hospital Schleswig-Holstein, Kiel, Germany.
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Abstract
PURPOSE Our aim was to determine whether diffusion weighted imaging can detect abnormalities of diffusivity after single seizures, and investigate the localisation and time course of any changes. METHODS Twenty-one patients with intractable focal epilepsy were imaged interictally and after 23 seizures. Voxel-based statistical parametric mapping was used to detect postictal changes in mean diffusivity (MD), compared to the changes noted in 20 controls scanned twice. The time course and magnitude of the changes were evaluated by measuring MD in the areas of change identified by the voxel-based analysis. RESULTS Thirty-four focal changes in MD (24 decreases, 10 increases) were detected after 12 of 23 seizures in 11 patients, after a median interval of 53 min from the time of seizure onset. Five patients had areas of both increased and decreased diffusion after seizures. In four patients, postictal changes in diffusion corresponded with the presumed seizure focus. Repeated postictal scanning, after a further interval of a median of 46 min in eight patients, showed that postictal changes in MD, both increases and decreases, were returning towards interictal values. CONCLUSIONS Diffusion weighted imaging identified focal changes in MD after 52% of single complex partial and secondarily generalised seizures. Changes in MD corresponded to the putative seizure focus in a minority of cases suggesting that the technique is not promising as a method for localising seizure foci, but may indicate the networks involved in seizures.
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Affiliation(s)
- Tuuli M Salmenpera
- The MRI Unit, The National Society for Epilepsy and the Department of Clinical and Experimental Epilepsy, Institute of Neurology, Queen Square, University College London, London, UK
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Bauer G, Gotwald T, Dobesberger J, Embacher N, Felber S, Bauer R, Seppi K, Walser G, Trinka E, Poewe W. Transient and permanent magnetic resonance imaging abnormalities after complex partial status epilepticus. Epilepsy Behav 2006; 8:666-71. [PMID: 16503204 DOI: 10.1016/j.yebeh.2006.01.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2005] [Revised: 12/02/2005] [Accepted: 01/05/2006] [Indexed: 10/25/2022]
Abstract
Epileptic seizures, especially status epilepticus can produce MRI changes. In contrast to convulsive status epilepticus (CSE), permanent parenchymal loss is not well documented with nonconvulsive status epilepticus (NCSE) and the observed MRI changes are transient. We describe a patient with non-lesional right-sided temporal lobe epilepsy with complex partial seizures and repeated episodes of untreated complex partial status epilepticus (CPSE). Diffusion-weighted MRI exhibited marked and extended signal changes within the right temporal, frontal, insular and cingulate regions. The affected areas are considered propagation pathways of temporal lobe epilepsies. After admission, the patient was treated with i.v. antiepileptic drugs. Behavioral, EEG and MRI signal changes resolved. An atrophy of the right temporal lobe not seen in the pre-status MRI examinations was observed 6 weeks after the resolution of MRI hyperintensities. Prior episodes of CPSE had been correctly treated and remained without permanent brain damage. This case report is in favour of immediate and aggressive treatment of partial NCSE in order to avoid irreversible parenchymal loss.
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Affiliation(s)
- G Bauer
- Universitätsklinik für Neurologie, Innsbruck, Austria.
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Thivard L, Lehéricy S, Krainik A, Adam C, Dormont D, Chiras J, Baulac M, Dupont S. Diffusion tensor imaging in medial temporal lobe epilepsy with hippocampal sclerosis. Neuroimage 2005; 28:682-90. [PMID: 16084113 DOI: 10.1016/j.neuroimage.2005.06.045] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2005] [Revised: 06/06/2005] [Accepted: 06/10/2005] [Indexed: 11/26/2022] Open
Abstract
Interictal diffusion imaging studies in patients with medial temporal lobe epilepsy (MTLE) accompanied by hippocampal sclerosis (HS) have shown an increased diffusivity in the epileptogenic hippocampus. In this study, we wanted to explore the whole brain in order to determine if MTLE could have an impact on the organization and the architecture of a large cerebral network and to identify clinical factors that could mediate diffusion abnormalities. Diffusion tensor imaging (DTI) and statistical parametric mapping of the entire brain were performed in 35 well-defined MTLE patients and in 36 healthy volunteers. SPM analyses identified three abnormal areas: an increased diffusivity was detected in the epileptic hippocampus and the ipsilateral temporal structures associated with a decreased anisotropy along the temporal lobe, a decreased diffusivity was found in the contralateral non-sclerotic hippocampus, the amygdala, and the temporal pole, and finally, a decreased anisotropy was noted ipsilaterally in posterior extratemporal regions. Duration of epilepsy, age at onset, and the frequency of generalized tonic-clonic seizures or partial complex seizures did not correlate with the presence of diffusion abnormalities. Region of interest analysis in the hippocampus/parahippocampus demonstrated a correlation between lower ipsilateral diffusivity values and occurrence of epigastric aura and between higher anisotropy values in both hemispheres and history of febrile seizures. In conclusion, this study showed that diffusion abnormalities are not restricted to the pathologic hippocampus and involve a larger network. This pattern may indirectly reflect the epileptogenic network and may be interpreted as a cause or a consequence of epilepsy.
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Affiliation(s)
- Lionel Thivard
- Epileptology Unit, Hôpital de la Salpêtrière, 75013 Paris, France.
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Diehl B, Symms MR, Boulby PA, Salmenpera T, Wheeler-Kingshott CAM, Barker GJ, Duncan JS. Postictal diffusion tensor imaging. Epilepsy Res 2005; 65:137-46. [PMID: 16043327 DOI: 10.1016/j.eplepsyres.2005.05.007] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Revised: 04/29/2005] [Accepted: 05/10/2005] [Indexed: 11/29/2022]
Abstract
The objective of the study was to investigate postictal diffusion tensor imaging (DTI) in focal epilepsy. DTI and statistical parametric mapping (SPM) were used to examine objectively the diffusion properties of the brains of 18 patients with intractable focal epilepsy both postictally and interictally and to compare them with 27 normal controls scanned twice. Three sets of statistical tests were performed on each patient's fractional anisotropy and mean diffusivity data: interictal versus controls, postictal versus controls and a third "difference analysis" to test for significant changes in comparison with the differences noted between the two sets of control scans. Thirteen of the 18 patients (72%) had significant increases in mean diffusivity in the interictal scan. No decreases in mean diffusivity were detected. The difference analysis detected significant relative decreases in mean diffusivity postictally in nine patients (50%). These changes were focal in seven patients. In six of these, the site of the epileptic focus was known and co-localized with the diffusivity change in three. No significant changes in anisotropy were noted between the post- and interictal states. The postictal decrease in diffusivity probably reflects cellular swelling in the area of seizure onset and possibly areas of seizure spread. Postictal diffusivity changes appear complex and dynamic and timing after the seizure may be critical. Anisotropy measures appear less sensitive to these changes. Further systematic studies are needed and correlation with outcome after epilepsy surgery will determine the role of postictal diffusion measures in the presurgical evaluation of epilepsy patients.
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Affiliation(s)
- Beate Diehl
- NSE MRI Unit, Department of Clinical and Experimental Epilepsy, Institute of Neurology, University College, London, UK
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Abstract
Acute seizure-associated changes have been described in the animal and human literature. Controversy exists over whether seizures cause permanent damage to the brain, and whether a (prolonged) seizure can induce changes that lead to an epileptic lesion, resulting in habitual seizures and epilepsy. Current magnetic resonance imaging (MRI) offers a variety of imaging tools and is capable of detecting acute seizure-associated changes. In contrast to the histologic examination, serial MRI studies are possible and allow longitudinal observation of the fate of these changes. This report reviews the literature on acute seizure-associated effects emphasizing the MRI evidence.
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Affiliation(s)
- Regula S Briellmann
- Brain Research Institute, Austin and Repatriation Medical Centre, Victoria, Australia
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38
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Hakyemez B, Erdogan C, Yildiz H, Ercan I, Parlak M. Apparent diffusion coefficient measurements in the hippocampus and amygdala of patients with temporal lobe seizures and in healthy volunteers. Epilepsy Behav 2005; 6:250-6. [PMID: 15710312 DOI: 10.1016/j.yebeh.2004.12.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2004] [Revised: 12/07/2004] [Accepted: 12/10/2004] [Indexed: 10/25/2022]
Abstract
PURPOSE The goals of this work were to measure the apparent diffusion coefficients (ADCs) for both hippocampus and amygdala of persons diagnosed with temporal lobe epilepsy (TLE) and unilateral hippocampus pathology on magnetic resonance imaging and to evaluate the sensitivity of diffusion-weighted (DW) images in determination of the lateralization of the epileptogenic focus. METHODS Thirteen cases with a TLE diagnosis and 21 healthy subjects were evaluated. Fluid-attenuated inversion recovery and T2W images of TLE cases revealed hippocampal volume loss and signal intensity changes. DW images were obtained by spin-echo echo-planar sequences vertical to the hippocampal axis. Qualitative and quantitative ADCs for left and right hippocampus and the amygdala of the controls and the patients were determined. Hippocampal ADCs were obtained independently at the head, body, and tail levels of the hippocampus. Statistical evaluation was conducted with Kruskal-Wallis and Mann-Whitney U tests. Predictive cutoff levels of hippocampal ADCs for identifying pathologic areas were established through receiver operating characteristic (ROC) curve analysis. RESULT On conventional images, 5 of 13 cases had right hippocampal pathology, and 8 of 13 cases had left hippocampal pathology. There were no bilateral hippocampal changes in signal intensity and no cases with bilateral atrophy. The amygdala was normal in all patients except one case of hyperintense signals. No statistical differences were found between the hippocampal and amygdaloid ADCs of the control subjects (P > 0.05). However, there was a significant difference between the ADCs for the side with hippocampal pathology and the ADCs for the contralateral side, and the control group (P < 0.001). No statistical difference was detected for the amygdala (P > 0.05). Hippocampal and amygdaloid ADCs of the contralateral lesion and the values of the control group were not statistically significantly different (P > 0.05). ROC curve analysis indicated 136 as the best cutoff level for hippocampal pathology. CONCLUSION DW trace images are insensitive in lateralization of hippocampal pathology; however, lateralization can be achieved through ADC measurements of the hippocampus. An increase in ADC on the affected side should be considered as indicating pathology. On the other hand, amygdaloid ADC values remain inaccurate.
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Affiliation(s)
- Bahattin Hakyemez
- Department of Radiology, Uludag University School of Medicine, Bursa, Turkey.
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Oh JB, Lee SK, Kim KK, Song IC, Chang KH. Role of immediate postictal diffusion-weighted MRI in localizing epileptogenic foci of mesial temporal lobe epilepsy and non-lesional neocortical epilepsy. Seizure 2004; 13:509-16. [PMID: 15324831 DOI: 10.1016/j.seizure.2003.12.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
OBJECTIVE To determine whether meaningful changes in signal intensity or in the apparent diffusion coefficient of water (ADC) in the ictal onset zone can be detected through immediate postictal and interictal diffusion-weighted magnetic resonance imaging (DWMRI) in patients with localization-related epilepsy. METHOD In randomly selected 10 medial and lateral temporal lobe epilepsy (TLE) and four extratemporal epilepsy patients, DWMRI was performed immediately after a seizure and during the interictal period. All 14 patients were non-lesional except for hippocampal sclerosis detected on MRI. The mean time interval from seizure onset to postictal DWMRI was 81 min. Regions of interest (ROI) were selected in both the cortex, which was believed to be the ictal onset zone, and the corresponding anatomical region of the contralateral hemisphere in the postictal and interictal DWMRI. The mean ADC measured from all ROIs was compared. Ictal onset zones were determined by ictal electroencephalography (EEG) and seizure semiology. RESULTS On visual inspection of postictal and interictal DWMRI, signal changes in the ictal onset zone could be identified in only one patient with medial TLE. The mean ADC values from the ictal onset zones were not significantly different from those of the corresponding contralateral regions of the cortices in both postictal and interictal DWMRI. However, the postictal ADC values of the epileptogenic foci of neocortical epilepsy or neocortical temporal portion of TLE without hippocampal sclerosis were decreased compared with interictal ones in whom both interictal and postictal DWMRIs were obtained (P = 0.028). CONCLUSION Our results demonstrate that water diffusion can change even after a single seizure in non-lesional neocortical epilepsy.
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Affiliation(s)
- Jong-Bai Oh
- Department of Neurology, Seoul National University Hospital, 28 Yongon-dong, Chongno-gu, Seoul, South Korea
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40
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Abstract
Twenty percent of patients with refractory focal epilepsy have an undetermined etiologic basis for their epilepsy despite extensive investigation, including optimal MR imaging. Surgical treatment of this group is associated with a less favorable postoperative outcome. Even with improvements in imaging techniques, a proportion of these patients will remain "MR imaging-negative." It is likely, however, that some of the discrete macroscopic focal lesions that are currently occult will be identified by imaging techniques interrogating different microstructural characteristics. Furthermore, these methods may provide pathologic specificity when used in combination. The description and application of these techniques in epilepsy are the focus of this article.
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Affiliation(s)
- Fergus J Rugg-Gunn
- MRI Unit, National Society for Epilepsy and Department of Clinical and Experimental Epilepsy, Chalfont St. Peter, Gerrards Cross, Bucks SL9 0RJ, UK.
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Tatum WO, Malek A, Recio M, Orlowski J, Murtagh R. Diffusion-weighted imaging and status epilepticus during vagus nerve stimulation. Epilepsy Behav 2004; 5:411-5. [PMID: 15145313 DOI: 10.1016/j.yebeh.2004.02.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2003] [Revised: 02/18/2004] [Accepted: 02/20/2004] [Indexed: 10/26/2022]
Abstract
PURPOSE Transient abnormalities have been reported on diffusion-weighted imaging (DWI) during status epilepticus. Vagus nerve stimulation (VNS) is a therapy for epilepsy that has previously demonstrated alteration in regional cerebral blood flow on functional neuroimaging. We describe the peri-ictal DWI abnormalities in a patient with status epilepticus. METHODS A 21-year-old woman with pharmacoresistant localization-related epilepsy was treated with VNS and underwent brain magnetic resonance imaging (MRI) with DWI for clinical purposes. RESULTS Transient and reversible hyperintense signal abnormalities were noted on DWI at the site of seizure onset, in addition to the thalamus and midbrain bilaterally. A concomitant decrease in the apparent diffusion coefficient mimicked ischemia, yet complete clinical, and electrographic resolution occurred following successful termination of status. CONCLUSIONS High-energy brain MRI sequences using DWI were safely performed in our epilepsy patient with a vagus nerve stimulator who experienced status epilepticus. This case highlights the bilateral and robust involvement of subcortical structures present immediately following status epilepticus. Additionally, bilateral abnormalities in the thalamus and midbrain in addition to the region of seizure origin, were observed in our patient implanted with a vagus nerve stimulator. Modulation of regional cerebral blood flow is one potential mechanism of action for VNS in humans; therefore, these regions of involvement could reflect the effects of status epilepticus, activation or facilitation by VNS, or both.
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Affiliation(s)
- W O Tatum
- Department of Neurology, University of South Florida, Tampa, FL, USA.
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Düzel E, Kaufmann J, Guderian S, Szentkuti A, Schott B, Bodammer N, Hopf M, Kanowski M, Tempelmann C, Heinze HJ. Measures of hippocampal volumes, diffusion and 1H MRS metabolic abnormalities in temporal lobe epilepsy provide partially complementary information. Eur J Neurol 2004; 11:195-205. [PMID: 15009165 DOI: 10.1046/j.1351-5101.2003.00737.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We assessed whether interictal measures of hippocampal volume, hippocampal diffusion and metabolic abnormalities yield correlated or complementary information about hippocampal pathology in patients with temporal lobe epilepsy (TLE). Volumes, apparent diffusion coefficients (ADC) and ratios of N-acetyl-aspartate (NAA) to Creatine/Phosphocreatine (Cr) and Choline (Cho) were measured from each hippocampus during one magnetic resonance imaging (MRI) session in patients with TLE. Structural MRI showed unilateral hippocampal sclerosis (HS) in 13 patients and was normal in the remaining nine patients. Pearson's correlation (two-tailed) between ADC values and NAA/(Cr + Cho) ratios was significant (P = 0.04, r = -0.45) for the hippocampus ipsilateral to the epileptogenic zone as determined on the basis of interictal and ictal scalp EEG recordings. This finding was driven by a very high correlation between the two measures in the presence of HS (P < 0.001, r = -0.96). Furthermore, ipsilateral ADC values but not NAA/(Cr + Cho) ratios were correlated with disease duration (P = 0.001, r = 0.67). Hippocampal volumes did not correlate with either ADC values, NAA/(Cr + Cho) ratios or disease duration. These data suggest that hippocampal volumes, NAA/(Cr + Cho) ratios and ADC values capture partially complementary aspects of hippocampal pathology.
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Affiliation(s)
- E Düzel
- Department of Neurology II, Otto-von-Guericke University of Magdeburg, Magdeburg, Germany.
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Farina L, Bergqvist C, Zimmerman RA, Haselgrove J, Hunter JV, Bilaniuk LT. Acute diffusion abnormalities in the hippocampus of children with new-onset seizures: the development of mesial temporal sclerosis. Neuroradiology 2004; 46:251-7. [PMID: 14991256 DOI: 10.1007/s00234-003-1122-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2003] [Accepted: 10/13/2003] [Indexed: 11/26/2022]
Abstract
We studied the role of early diffusion-weighted imaging DWI in the investigation of children with new-onset prolonged seizures which eventually result in unilateral hippocampal sclerosis (HS). We carried out MRI on five children aged 17 months to 7 years including conventional and diffusion-weighted sequences. We calculated apparent diffusion coefficients (ADC) for the affected and the normal opposite hippocampus. Follow-up examinations were performed, including DWI and ADC measurements in four. We studied four children within 3 days of the onset of prolonged psychomotor seizures and showed increased signal on T2-weighted images, and DWI, indicating restricted diffusion, throughout the affected hippocampus. The ADC were reduced by a mean of 14.4% in the head and by 15% in the body of the hippocampus. In one child examined 15 days after the onset of seizures, the ADC were the same on both sides. All five patients showed hippocampal atrophy on follow-up 2-18 months later. In the four patients in whom ADC were obtained on follow-up, they were increased by 19% in the head and 17% in the body. DWI may represent a useful adjunct to conventional MRI for identifying acute injury to the hippocampus which results in sclerosis.
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Affiliation(s)
- L Farina
- Department of Neuroradiology, Istituto Nazionale Neurologico C. Besta, Milan, Italy
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Hasegawa D, Orima H, Fujita M, Nakamura S, Takahashi K, Ohkubo S, Igarashi H, Hashizume K. Diffusion-weighted imaging in kainic acid-induced complex partial status epilepticus in dogs. Brain Res 2003; 983:115-27. [PMID: 12914972 DOI: 10.1016/s0006-8993(03)03041-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE To investigate diffusion-weighted imaging (DWI) in status epilepticus, a canine model of kainic acid (KA)-induced complex partial status epilepticus (CPSE) was produced. In order to validate its usefulness, MR imaging was carried out at various times following onset of CPSE followed by histopathology. MATERIAL AND METHODS Six normal dogs were used in this study. In each dog, a cannula was stereotactically inserted into the left amygdala. One week after surgery, all dogs were imaged at MRI. Pre-injection imaging consisted of T2 weighted (T2W) imaging, fluid attenuated inversion recovery (FLAIR), and DWI. Two weeks after surgery, five dogs received intraamygdaloid KA microinjections. One dog was used as a control. MRI was carried out at 3, 6, 12, 24 and 48 h after onset of CPSE. Animals were euthanized immediately after MRI for histopathological evaluation. The average of each apparent diffusion coefficient (ADC) in the regions of interest was calculated from each DWI. RESULTS At 3 and 6 h, DWI hyperintensity and low ADC were found in the injected amygdala, without any T2W and FLAIR imaging changes. At 12 and 24 h, all imaging showed hyperintensity with higher ADC in the amygdala and the hippocampus. At 48 h, all imaging techniques showed continued hyperintensity, but ADC showed a trend towards normalization. This increasing hyperintensity in DWIs were in agreement with the degree of histopathology during CPSE. SUMMARY This study suggests that DWI is a useful imaging method for finding the epileptic focus or for examining potential epileptic brain damage in status epilepticus.
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Affiliation(s)
- Daisuke Hasegawa
- Department of Veterinary Radiology, Nippon Veterinary and Animal Science University, 1-7-1 Kyounanchou, Musashino-shi, 180-8602, Tokyo, Japan.
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Abstract
PURPOSE Transient increased T2 signal in the splenium of the corpus callosum after seizures has been reported and sometimes attributed to a postulated toxicity of anticonvulsant medications (AEDs). METHODS We describe two patients with bitemporal epilepsy. RESULTS Transiently increased T2 signal (in one) and decreased apparent diffusion coefficient (ADC) (in both) in the splenium appeared to be related directly to acute seizures. CONCLUSIONS These cases illustrate an unusual acute postictal imaging finding, highlight involvement of an important commissural pathway, and suggest that seizures per se, and not their treatment, are the cause of transient white-matter abnormalities in these cases.
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Affiliation(s)
- Joel Oster
- Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
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Feichtinger M, Holl A, Körner E, Schröttner O, Eder H, Unger F, Pendl G, Wurst L, Golaszewski S, Payer F, Fazekas F, Ott E. Future aspects of the presurgical evaluation in epilepsy. Acta Neurochir Suppl 2003; 84:17-26. [PMID: 12379001 DOI: 10.1007/978-3-7091-6117-3_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
Epilepsy surgery is a successful therapeutic approach in patients with medically intractable epilepsy. The presurgical evaluation aims to detect the epileptogenic brain area by use of different diagnostic techniques. In this review article the current diagnostic procedures applied for this purpose are described. The diagnostic armamentarium can be divided conceptually into three different groups: assessment of function/dysfunction, structural/morphologic imaging methods and functional neuroimaging techniques. Properties, diagnostic power and limits of all diagnostic tools used in the diagnostic evaluation are discussed. In addition, future perspectives and the diagnostic value of new technologies are mentioned. Some are increasingly gaining acceptance in the routine preoperative diagnostic procedure like MR volumetry or MR spectroscopy of the hippocampus in patients with temporal lobe epilepsy. Some, on the other hand, like MEG and 11C-flumazenil PET, still remain experimental diagnostic tools as they are technically demanding and cost intensive. Besides the refinement of established techniques, co-registration of different modalities like spike-triggered functional MRI will play an important role in the non-invasive detection of the epileptic seizure focus and may change the regimen of the preoperative diagnostic work up of epilepsy patients in the future.
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Affiliation(s)
- M Feichtinger
- Department of Neurology, Karl-Franzens University, Graz, Austria
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Konermann S, Marks S, Ludwig T, Weber J, de Greiff A, Dörfler A, Leonhardt G, Wiedemayer H, Diener HC, Hufnagel A. Presurgical evaluation of epilepsy by brain diffusion: MR-detected effects of flumazenil on the epileptogenic focus. Epilepsia 2003; 44:399-407. [PMID: 12614396 DOI: 10.1046/j.1528-1157.2003.25702.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE After focal status epilepticus, focal alterations of the apparent diffusion coefficient (ADC) have been demonstrated in the epileptogenic zone by using diffusion-weighted magnetic resonance (MR)imaging (DWI). Effects of flumazenil on an epileptogenic focus have been demonstrated by EEG recordings, but not by functional MRI. We hypothesized that dynamic spatiotemporal alterations of brain diffusion of the epileptogenic focus after application of flumazenil will be detectable by DWI and correlate with the epileptogenic zone. METHODS Twelve adult patients considered for epilepsy surgery with medically intractable temporal lobe epilepsy (TLE; n = 7), extratemporal lobe epilepsy (ETE; n = 2), and TLE+ETE (n = 3) were prospectively examined with DWI interictally (serving as baseline) and 10 min after application of 1 mg flumazenil i.v. RESULTS The baseline interictal ADC was significantly elevated in the hippocampus on the ictogenic side in the patients with TLE (p = 0.002) as compared with healthy volunteers. The following changes of the mean ADC were seen in different regions of interest (ROIs) after injection of flumazenil: decreases in the hippocampus on the seizure-onset side by 14.8% (p = 0.005); decreases in the parahippocampal gyrus on both sides by 6.8% (epileptogenic side; p = 0.044) or 7.9% (nonepileptogenic side; NS), respectively; decreases in the cortex on the nonictogenic side by 7.9% (p = 0.047); and no significant changes of the ADC in the other ROIs. CONCLUSIONS ADC decreases measured after application of flumazenil were seen in the seizure-onset zone as revealed by EEG and structural MRI and are an indicator of focus localization in patients with TLE.
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Abstract
PURPOSE Diffusion-weighted magnetic resonance imaging (DWI) after focal status epilepticus has demonstrated focal alterations of the apparent diffusion coefficient (ADC) in the epileptogenic zone. We hypothesized that localized dynamic alterations of brain diffusion during the immediate postictal state will be detectable by serial DWI and correlate with the epileptogenic zone. METHODS Nine adult patients (four men, five women) with medically intractable epilepsy were prospectively examined with a total of 25 DWI scans taken 2-210 min after a seizure. RESULTS The interictal ADC was significantly (p < 0.05) elevated in the ictogenic hippocampus in all patients with temporal lobe epilepsy. The following postictal changes of the ADC were seen: (a) decreases by maximally 25-31%, which were most pronounced in the epileptogenic zone (n = 2); (b) generalized ADC changes after generalized seizures (n = 1) or prolonged complex partial seizures (n = 2); (c) no major changes after short-lived seizures or if the time to first DWI scan was >15 min or both (n = 3); and (d) widespread bilateral ADC increases after a flumazenil-induced seizure (n = 1). CONCLUSIONS ADC changes seen during serial postictal DWI are complex and appear to reflect origin and spread of the preceding seizure. A delineation of the epileptogenic zone appears to be possible only in complex-partial seizures of >60 s duration that do not secondarily generalize.
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Ulmer S, Flemming K, Hahn A, Stephani U, Jansen O. Detection of acute cytotoxic changes in progressive neuronal degeneration of childhood with liver disease (Alpers-Huttenlocher syndrome) using diffusion-weighted MRI and MR spectroscopy. J Comput Assist Tomogr 2002; 26:641-6. [PMID: 12218835 DOI: 10.1097/00004728-200207000-00030] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Alpers-Huttenlocher syndrome (AHS) is a rare mitochondrial disorder of childhood onset that is characterized by progressive encephalopathy and hepatopathy. MRI studies are rare and have not added substantial information to the pathogenesis of the encephalopathy. Diffusion-weighted MRI (DWI) and MR spectroscopy (MRS) were used in a patient with AHS during acute clinical deterioration and after improvement. DWI detected signal hyperintensity in several brain areas not restricted to any vascular territory. MRS revealed an unequivocal lactate peak and a reduced N-acetyl-aspartate-creatinine (NAA/Crea) ratio. DWI signal hyperintensity was correlated with neurologic symptoms and decreased after clinical improvement. Potentially reversible neuronal cytotoxic edema resulting from acute impairment of mitochondrial function is strongly suggested to be an important pathogenetic mechanism in AHS encephalopathy.
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Affiliation(s)
- Stephan Ulmer
- Section of Neuroradiology, Deparment of Neurosurgery, University Hospital, Kiel, Germany.
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