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Ji Z, Song RR, Swan AR, Angeles Quinto A, Lee RR, Huang M. Magnetoencephalography Language Mapping Using Auditory Memory Retrieval and Silent Repeating Task. J Clin Neurophysiol 2024; 41:148-154. [PMID: 35512180 PMCID: PMC9633581 DOI: 10.1097/wnp.0000000000000947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE The study aims to (1) examine the spatiotemporal map of magnetoencephalography-evoked responses during an Auditory Memory Retrieval and Silent Repeating (AMRSR) task, and determine the hemispheric dominance for language, and (2) evaluate the accuracy of the AMRSR task in Wernicke and Broca area localization. METHODS In 30 patients with brain tumors and/or epilepsies, the AMRSR task was used to evoke magnetoencephalography responses. We applied Fast VEctor-based Spatial-Temporal Analyses with minimum L1-norm source imaging method to the magnetoencephalography responses for localizing the brain areas evoked by the AMRSR task. RESULTS The Fast-VEctor-based Spatial-Temporal Analysis found consistent activation in the posterior superior temporal gyrus around 300 to 500 ms, and another activation in the frontal cortex (pars opercularis and/or pars triangularis) around 600 to 900 ms, which were localized to the Wernicke area (BA 22) and Broca area (BA 44 and BA 45), respectively. The language-dominant hemispheric laterization elicited by the AMRSR task was comparable with the result from an Auditory Dichotic task result given to the same patient, with the exception that AMRSR is more sensitive on bilateral language laterization cases on finding the Wernicke and Broca areas. CONCLUSIONS For all patients who successfully finished the AMRSR task, Fast-VEctor-based Spatial-Temporal Analysis could establish accurate and robust localizations of Broca and Wernicke area and determine hemispheric dominance. For subjects with normal auditory functionality, the AMRSR paradigm evaluation showed significant promise in providing reliable assessments of cerebral language dominance and language network localization.
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Affiliation(s)
- Zhengwei Ji
- Radiology Department, University of California, San Diego, California, U.S.A
| | - Ryan R. Song
- Department of Molecular and Cell Biology, University of California, Berkeley, California, U.S.A.; and
| | - Ashley Robb Swan
- Radiology Department, University of California, San Diego, California, U.S.A
| | | | - Roland R. Lee
- Radiology Department, University of California, San Diego, California, U.S.A
- Radiology Service, San Diego VA Healthcare System, San Diego, California, U.S.A
| | - Mingxiong Huang
- Radiology Department, University of California, San Diego, California, U.S.A
- Radiology Service, San Diego VA Healthcare System, San Diego, California, U.S.A
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Pre-Operative Functional Mapping in Patients with Brain Tumors by fMRI and MEG: Advantages and Disadvantages in the Use of One Technique over the Other. Life (Basel) 2023; 13:life13030609. [PMID: 36983765 PMCID: PMC10051860 DOI: 10.3390/life13030609] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 02/17/2023] [Accepted: 02/20/2023] [Indexed: 02/24/2023] Open
Abstract
Pre-operative mapping of brain functions is crucial to plan neurosurgery and investigate potential plasticity processes. Due to its availability, functional magnetic resonance imaging (fMRI) is widely used for this purpose; on the other hand, the demanding cost and maintenance limit the use of magnetoencephalography (MEG), despite several studies reporting its accuracy in localizing brain functions of interest in patient populations. In this review paper, we discuss the strengths and weaknesses of both techniques, from a methodological perspective first; then, we scrutinized and commented on the findings from 16 studies, identified by a database search, that made pre-operative assessments using both techniques in patients with brain tumors. We commented on the results by accounting for study limitations associated with small sample sizes and variability in the used tasks. Overall, we found that, although some studies reported the superiority for MEG, the majority of them underlined the complementary use of these techniques and suggested assessment using both. Indeed, both fMRI and MEG present some disadvantages, although the development of novel devices and processing procedures has enabled ever more accurate assessments. In particular, the development of new, more feasible MEG devices will allow widespread availability of this technique and its routinely combined use with fMRI.
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3
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Soloukey S, Vincent AJPE, Smits M, De Zeeuw CI, Koekkoek SKE, Dirven CMF, Kruizinga P. Functional imaging of the exposed brain. Front Neurosci 2023; 17:1087912. [PMID: 36845427 PMCID: PMC9947297 DOI: 10.3389/fnins.2023.1087912] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 01/19/2023] [Indexed: 02/11/2023] Open
Abstract
When the brain is exposed, such as after a craniotomy in neurosurgical procedures, we are provided with the unique opportunity for real-time imaging of brain functionality. Real-time functional maps of the exposed brain are vital to ensuring safe and effective navigation during these neurosurgical procedures. However, current neurosurgical practice has yet to fully harness this potential as it pre-dominantly relies on inherently limited techniques such as electrical stimulation to provide functional feedback to guide surgical decision-making. A wealth of especially experimental imaging techniques show unique potential to improve intra-operative decision-making and neurosurgical safety, and as an added bonus, improve our fundamental neuroscientific understanding of human brain function. In this review we compare and contrast close to twenty candidate imaging techniques based on their underlying biological substrate, technical characteristics and ability to meet clinical constraints such as compatibility with surgical workflow. Our review gives insight into the interplay between technical parameters such sampling method, data rate and a technique's real-time imaging potential in the operating room. By the end of the review, the reader will understand why new, real-time volumetric imaging techniques such as functional Ultrasound (fUS) and functional Photoacoustic Computed Tomography (fPACT) hold great clinical potential for procedures in especially highly eloquent areas, despite the higher data rates involved. Finally, we will highlight the neuroscientific perspective on the exposed brain. While different neurosurgical procedures ask for different functional maps to navigate surgical territories, neuroscience potentially benefits from all these maps. In the surgical context we can uniquely combine healthy volunteer studies, lesion studies and even reversible lesion studies in in the same individual. Ultimately, individual cases will build a greater understanding of human brain function in general, which in turn will improve neurosurgeons' future navigational efforts.
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Affiliation(s)
- Sadaf Soloukey
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands,Department of Neurosurgery, Erasmus MC, Rotterdam, Netherlands
| | | | - Marion Smits
- Department of Radiology and Nuclear Medicine, Erasmus MC, Rotterdam, Netherlands
| | - Chris I. De Zeeuw
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands,Netherlands Institute for Neuroscience, Royal Dutch Academy for Arts and Sciences, Amsterdam, Netherlands
| | | | | | - Pieter Kruizinga
- Department of Neuroscience, Erasmus MC, Rotterdam, Netherlands,*Correspondence: Pieter Kruizinga,
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Fred AL, Kumar SN, Kumar Haridhas A, Ghosh S, Purushothaman Bhuvana H, Sim WKJ, Vimalan V, Givo FAS, Jousmäki V, Padmanabhan P, Gulyás B. A Brief Introduction to Magnetoencephalography (MEG) and Its Clinical Applications. Brain Sci 2022; 12:brainsci12060788. [PMID: 35741673 PMCID: PMC9221302 DOI: 10.3390/brainsci12060788] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/01/2022] [Accepted: 06/08/2022] [Indexed: 11/30/2022] Open
Abstract
Magnetoencephalography (MEG) plays a pivotal role in the diagnosis of brain disorders. In this review, we have investigated potential MEG applications for analysing brain disorders. The signal-to-noise ratio (SNRMEG = 2.2 db, SNREEG < 1 db) and spatial resolution (SRMEG = 2−3 mm, SREEG = 7−10 mm) is higher for MEG than EEG, thus MEG potentially facilitates accurate monitoring of cortical activity. We found that the direct electrophysiological MEG signals reflected the physiological status of neurological disorders and play a vital role in disease diagnosis. Single-channel connectivity, as well as brain network analysis, using MEG data acquired during resting state and a given task has been used for the diagnosis of neurological disorders such as epilepsy, Alzheimer’s, Parkinsonism, autism, and schizophrenia. The workflow of MEG and its potential applications in the diagnosis of disease and therapeutic planning are also discussed. We forecast that computer-aided algorithms will play a prominent role in the diagnosis and prediction of neurological diseases in the future. The outcome of this narrative review will aid researchers to utilise MEG in diagnostics.
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Affiliation(s)
- Alfred Lenin Fred
- Department of CSE, Mar Ephraem College of Engineering and Technology, Marthandam 629171, Tamil Nadu, India; (A.L.F.); (F.A.S.G.)
| | | | - Ajay Kumar Haridhas
- Department of ECE, Mar Ephraem College of Engineering and Technology, Marthandam 629171, Tamil Nadu, India;
| | - Sayantan Ghosh
- Department of Integrative Biology, Vellore Institute of Technology, Vellore 632014, Tamil Nadu, India;
| | - Harishita Purushothaman Bhuvana
- Cognitive Neuroimaging Centre, Nanyang Technological University, Singapore 636921, Singapore; (H.P.B.); (W.K.J.S.); (V.V.); (V.J.)
| | - Wei Khang Jeremy Sim
- Cognitive Neuroimaging Centre, Nanyang Technological University, Singapore 636921, Singapore; (H.P.B.); (W.K.J.S.); (V.V.); (V.J.)
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 636921, Singapore
| | - Vijayaragavan Vimalan
- Cognitive Neuroimaging Centre, Nanyang Technological University, Singapore 636921, Singapore; (H.P.B.); (W.K.J.S.); (V.V.); (V.J.)
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 636921, Singapore
| | - Fredin Arun Sedly Givo
- Department of CSE, Mar Ephraem College of Engineering and Technology, Marthandam 629171, Tamil Nadu, India; (A.L.F.); (F.A.S.G.)
| | - Veikko Jousmäki
- Cognitive Neuroimaging Centre, Nanyang Technological University, Singapore 636921, Singapore; (H.P.B.); (W.K.J.S.); (V.V.); (V.J.)
- Aalto NeuroImaging, Department of Neuroscience and Biomedical Engineering, Aalto University, 12200 Espoo, Finland
| | - Parasuraman Padmanabhan
- Cognitive Neuroimaging Centre, Nanyang Technological University, Singapore 636921, Singapore; (H.P.B.); (W.K.J.S.); (V.V.); (V.J.)
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 636921, Singapore
- Correspondence: (P.P.); (B.G.)
| | - Balázs Gulyás
- Cognitive Neuroimaging Centre, Nanyang Technological University, Singapore 636921, Singapore; (H.P.B.); (W.K.J.S.); (V.V.); (V.J.)
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 636921, Singapore
- Department of Clinical Neuroscience, Karolinska Institute, 17176 Stockholm, Sweden
- Correspondence: (P.P.); (B.G.)
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Nenonen J, Helle L, Jaiswal A, Bock E, Ille N, Bornfleth H. Sensitivity of a 29-Channel MEG Source Montage. Brain Sci 2022; 12:brainsci12010105. [PMID: 35053848 PMCID: PMC8773883 DOI: 10.3390/brainsci12010105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 01/08/2022] [Accepted: 01/11/2022] [Indexed: 12/04/2022] Open
Abstract
In this paper, we study the performance of a source montage corresponding to 29 brain regions reconstructed from whole-head magnetoencephalographic (MEG) recordings, with the aim of facilitating the review of MEG data containing epileptiform discharges. Test data were obtained by superposing simulated signals from 100-nAm dipolar sources to a resting state MEG recording from a healthy subject. Simulated sources were placed systematically to different cortical locations for defining the optimal regularization for the source montage reconstruction and for assessing the detectability of the source activity from the 29-channel MEG source montage. The signal-to-noise ratio (SNR), computed for each source from the sensor-level and source-montage signals, was used as the evaluation parameter. Without regularization, the SNR from the simulated sources was larger in the sensor-level signals than in the source montage reconstructions. Setting the regularization to 2% increased the source montage SNR to the same level as the sensor-level SNR, improving the detectability of the simulated events from the source montage reconstruction. Sources producing a SNR of at least 15 dB were visually detectable from the source-montage signals. Such sources are located closer than about 75 mm from the MEG sensors, in practice covering all areas in the grey matter. The 29-channel source montage creates more focal signals compared to the sensor space and can significantly shorten the detection time of epileptiform MEG discharges for focus localization.
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Affiliation(s)
- Jukka Nenonen
- Megin Oy, Keilasatama 5, FI-02150 Espoo, Finland; (L.H.); (A.J.); (E.B.)
- Correspondence: ; Tel.: +358-9-756-2400
| | - Liisa Helle
- Megin Oy, Keilasatama 5, FI-02150 Espoo, Finland; (L.H.); (A.J.); (E.B.)
- Department of Neuroscience and Biomedical Engineering, School of Science, Aalto University, FI-00076 Aalto, Finland
| | - Amit Jaiswal
- Megin Oy, Keilasatama 5, FI-02150 Espoo, Finland; (L.H.); (A.J.); (E.B.)
- Department of Neuroscience and Biomedical Engineering, School of Science, Aalto University, FI-00076 Aalto, Finland
| | - Elizabeth Bock
- Megin Oy, Keilasatama 5, FI-02150 Espoo, Finland; (L.H.); (A.J.); (E.B.)
| | - Nicole Ille
- BESA GmbH, 82166 Gräfelfing, Germany; (N.I.); (H.B.)
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Papatzalas C, Fountas K, Kapsalaki E, Papathanasiou I. The Use of Standardized Intraoperative Language Tests in Awake Craniotomies: A Scoping Review. Neuropsychol Rev 2021; 32:20-50. [PMID: 33786797 DOI: 10.1007/s11065-021-09492-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 02/22/2021] [Indexed: 12/12/2022]
Abstract
Assessment of speech and language functions is an essential part of awake craniotomies. Although standardized and validated tests have several advantages compared to homemade (or mixed) batteries, in the literature it is unclear how such tests are used or whether they are used at all. In this study, we performed a scoping review in order to locate standardized and validated intraoperative language tests. Our inquiry included two databases (PubMED and MEDLINE), gray literature, and snowball referencing. We discovered 87 studies reporting use of mixed batteries, which consist of homemade tasks and tests borrowed from other settings. The tests we found to meet the validation and standardization criteria we set were ultimately three (n = 3) and each one has its own advantages and disadvantages. We argue that tests with high sensitivity and specificity not only can lead to better outcomes postoperatively, but they can also help us to gain a better understanding of the neuroanatomy of language.
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Affiliation(s)
- Christos Papatzalas
- Department of Medicine, University of Thessaly, Larisa, Greece.
- Department of Neurosurgery, University Hospital of Larisa, Larisa, Greece.
| | - Kostas Fountas
- Department of Medicine, University of Thessaly, Larisa, Greece
- Department of Neurosurgery, University Hospital of Larisa, Larisa, Greece
| | - Eftychia Kapsalaki
- Department of Medicine, University of Thessaly, Larisa, Greece
- Department of Radiology, University Hospital of Larisa, Larisa, Greece
| | - Ilias Papathanasiou
- Department of Speech & Language Therapy, University of Patras, Patras, Greece
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Power L, Lalancette M, Bishop R, Beyea S, Taylor MJ, Dunkley BT, Bardouille T. Variability and bias between magnetoencephalography systems in localization of the primary visual cortex. Clin Neurol Neurosurg 2020; 194:105746. [PMID: 32217371 DOI: 10.1016/j.clineuro.2020.105746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 02/10/2020] [Accepted: 02/22/2020] [Indexed: 11/17/2022]
Abstract
OBJECTIVES When using MEG for pre-surgical mapping it is critically important that reliable estimates of functional locations, such as the primary visual cortex (V1) can be provided. Several different models of MEG systems exist, each with varying software and hardware configurations, and it is not currently known how the system type contributes to variability in V1 localization. PATIENTS AND METHODS In this study, participants underwent MEG sessions using two different systems (Vector View and CTF) during which they were presented with a repeating grating stimulus to the lower-left visual quadrant to generate a visual evoked field (VEF). The location, amplitude and latency of the VEF source was compared between systems for each participant. RESULTS No significant differences were found in latency and amplitude between systems, however, a significant bias in the latero-medial position of the localization was present. The median inter-system Euclidian distance between V1 localization across participants was 10.5 mm. CONCLUSIONS Overall, our results indicate that mapping of V1 can be reliably reproduced within approximately one centimetre by different MEG systems. SIGNIFICANCE This result provides knowledge of the useful limits on the reliability of localization which can be taken into consideration in clinical practice.
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Affiliation(s)
- Lindsey Power
- Biomedical Translational Imaging Centre (BIOTIC), IWK Health Centre, 5980 University Street, Halifax, NS, B3K 6R8, Canada.
| | - Marc Lalancette
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada.
| | - Ronald Bishop
- Biomedical Translational Imaging Centre (BIOTIC), IWK Health Centre, 5980 University Street, Halifax, NS, B3K 6R8, Canada.
| | - Steven Beyea
- Biomedical Translational Imaging Centre (BIOTIC), IWK Health Centre, 5980 University Street, Halifax, NS, B3K 6R8, Canada; Department of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Road, Halifax, NS, B3H 4R2, Canada; Department of Diagnostic Radiology, Dalhousie University, Room 319, Victoria Building, 1276 South Park St, Halifax, NS B3H 2Y9, Canada.
| | - Margot J Taylor
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada.
| | - Benjamin T Dunkley
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada; Neurosciences & Mental Health, The Hospital for Sick Children Research Institute, Toronto, ON, Canada; Department of Medical Imaging, University of Toronto, Toronto, ON, Canada.
| | - Timothy Bardouille
- Biomedical Translational Imaging Centre (BIOTIC), IWK Health Centre, 5980 University Street, Halifax, NS, B3K 6R8, Canada; Department of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Road, Halifax, NS, B3H 4R2, Canada; Department of Diagnostic Radiology, Dalhousie University, Room 319, Victoria Building, 1276 South Park St, Halifax, NS B3H 2Y9, Canada.
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Herbet G, Duffau H. Revisiting the Functional Anatomy of the Human Brain: Toward a Meta-Networking Theory of Cerebral Functions. Physiol Rev 2020; 100:1181-1228. [PMID: 32078778 DOI: 10.1152/physrev.00033.2019] [Citation(s) in RCA: 114] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
For more than one century, brain processing was mainly thought in a localizationist framework, in which one given function was underpinned by a discrete, isolated cortical area, and with a similar cerebral organization across individuals. However, advances in brain mapping techniques in humans have provided new insights into the organizational principles of anatomo-functional architecture. Here, we review recent findings gained from neuroimaging, electrophysiological, as well as lesion studies. Based on these recent data on brain connectome, we challenge the traditional, outdated localizationist view and propose an alternative meta-networking theory. This model holds that complex cognitions and behaviors arise from the spatiotemporal integration of distributed but relatively specialized networks underlying conation and cognition (e.g., language, spatial cognition). Dynamic interactions between such circuits result in a perpetual succession of new equilibrium states, opening the door to considerable interindividual behavioral variability and to neuroplastic phenomena. Indeed, a meta-networking organization underlies the uniquely human propensity to learn complex abilities, and also explains how postlesional reshaping can lead to some degrees of functional compensation in brain-damaged patients. We discuss the major implications of this approach in fundamental neurosciences as well as for clinical developments, especially in neurology, psychiatry, neurorehabilitation, and restorative neurosurgery.
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Affiliation(s)
- Guillaume Herbet
- Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, Montpellier, France; Team "Plasticity of Central Nervous System, Stem Cells and Glial Tumors," INSERM U1191, Institute of Functional Genomics, Montpellier, France; and University of Montpellier, Montpellier, France
| | - Hugues Duffau
- Department of Neurosurgery, Gui de Chauliac Hospital, Montpellier University Medical Center, Montpellier, France; Team "Plasticity of Central Nervous System, Stem Cells and Glial Tumors," INSERM U1191, Institute of Functional Genomics, Montpellier, France; and University of Montpellier, Montpellier, France
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Role of Functional Imaging Techniques to Assess Motor and Language Cortical Plasticity in Glioma Patients: A Systematic Review. Neural Plast 2019; 2019:4056436. [PMID: 31814822 PMCID: PMC6878806 DOI: 10.1155/2019/4056436] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 10/05/2019] [Indexed: 01/19/2023] Open
Abstract
Cerebral plasticity is the ability of the central nervous system to reorganize itself in response to different injuries. The reshaping of functional areas is a crucial mechanism to compensate for damaged function. It is acknowledged that functional remodeling of cortical areas may occur also in glioma patients. Principal limits of previous investigations on cortical plasticity of motor and language functions included scarce reports of longitudinal evaluations and limited sample sizes. This systematic review is aimed at elucidating cortical brain plasticity for motor and language functions, in adult glioma patients, by means of preoperative and intraoperative mapping techniques. We systematically reviewed the literature for prospective studies, assessing cortical plasticity of motor and language functions in low-grade and high-grade gliomas. Eight longitudinal studies investigated cortical plasticity, evaluated by motor and language task-based functional MRI (fMRI), motor navigated transcranial magnetic stimulation (n-TMS), and intraoperative mapping with cortical direct electrocortical stimulation (DES) of language and motor function. Motor function reorganization appeared relatively limited and mostly characterized by intrahemispheric functional changes, including secondary motor cortices. On the other hand, a high level of functional reshaping was found for language function in DES studies. Occurrence of cortical functional reorganization of language function was described focusing on the intrahemispheric recruitment of perilesional areas. However, the association between these functional patterns and recovery of motor and language deficits still remains partially clear. A number of relevant methodological issues possibly affecting the finding generalization emerged, such as the complexity of plasticity outcome measures and the lack of large longitudinal studies. Future studies are required to further confirm these evidences on cortical plasticity in larger samples, combining both functional imaging and intraoperative mapping techniques in longitudinally evaluations.
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Kreidenhuber R, De Tiège X, Rampp S. Presurgical Functional Cortical Mapping Using Electromagnetic Source Imaging. Front Neurol 2019; 10:628. [PMID: 31249552 PMCID: PMC6584755 DOI: 10.3389/fneur.2019.00628] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 05/28/2019] [Indexed: 02/03/2023] Open
Abstract
Preoperative localization of functionally eloquent cortex (functional cortical mapping) is common clinical practice in order to avoid or reduce postoperative morbidity. This review aims at providing a general overview of magnetoencephalography (MEG) and high-density electroencephalography (hdEEG) based methods and their clinical role as compared to common alternatives for functional cortical mapping of (1) verbal language function, (2) sensorimotor cortex, (3) memory, (4) visual, and (5) auditory cortex. We highlight strengths, weaknesses and limitations of these functional cortical mapping modalities based on findings in the recent literature. We also compare their performance relative to other non-invasive functional cortical mapping methods, such as functional Magnetic Resonance Imaging (fMRI), Transcranial Magnetic Stimulation (TMS), and to invasive methods like the intracarotid Amobarbital Test (WADA-Test) or intracranial investigations.
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Affiliation(s)
- Rudolf Kreidenhuber
- Department of Neurology, Christian-Doppler Medical Center, Paracelsus Medical University, Salzburg, Austria.,Centre for Cognitive Neuroscience, University of Salzburg, Salzburg, Austria
| | - Xavier De Tiège
- Laboratoire de Cartographie Fonctionelle du Cerveau, ULB Neuroscience Institute, Université Libre de Bruxelles, Brussels, Belgium.,Department of Functional Neuroimaging, Service of Nuclear Medicine, CUB Hôpital Erasme, Université Libre de Bruxelles, Brussels, Belgium
| | - Stefan Rampp
- Department of Neurosurgery, University Hospital Erlangen, Erlangen, Germany.,Department of Neurosurgery, University Hospital Halle, Halle, Germany
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12
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Bardouille T, Power L, Lalancette M, Bishop R, Beyea S, Taylor MJ, Dunkley BT. Variability and bias between magnetoencephalography systems in non-invasive localization of the primary somatosensory cortex. Clin Neurol Neurosurg 2018; 171:63-69. [PMID: 29843072 DOI: 10.1016/j.clineuro.2018.05.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/06/2018] [Accepted: 05/14/2018] [Indexed: 10/16/2022]
Abstract
OBJECTIVES Magnetoencephalography (MEG) provides functional neuroimaging data for pre-surgical planning in patients with epilepsy or brain tumour. For mapping the primary somatosensory cortex (S1), MEG data are acquired while a patient undergoes median nerve stimulation (MNS) to localize components of the somatosensory evoked field (SEF). In clinical settings, only one MEG imaging session is usually possible due to limited resources. As such, it is important to have an a priori estimate of the expected variability in localization. Variability in S1 localization between mapping sessions using the same MEG system has been previously measured as 8 mm. There are different types of MEG systems available with varied hardware and software, and it is not known how using a different MEG system will impact on S1 localization. PATIENTS AND METHODS In our study, healthy participants underwent the MNS procedure with two different MEG systems (Vector View and CTF). We compared the location, amplitude and latency of SEF components between data from each system to quantify variability and bias between MEG systems. RESULTS We found 8-11 mm variability in S1 localization between the two MEG systems, and no evidence for a systematic bias in location, amplitude or latency between the two systems. CONCLUSION These findings suggest that S1 localization is not biased by the type of MEG system used, and that differences between the two systems are not a major contributor to variability in localization.
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Affiliation(s)
- Timothy Bardouille
- Department of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Road, Halifax, NS, B3H 4R2, Canada; Biomedical Translational Imaging Centre (BIOTIC), IWK Health Centre, 5980 University Street, Halifax, NS, B3K 6R8, Canada; Department of Diagnostic Radiology, Dalhousie University, Room 319, Victoria Building, 1276 South Park St, Halifax, NS B3H 2Y9, Canada.
| | - Lindsey Power
- Biomedical Translational Imaging Centre (BIOTIC), IWK Health Centre, 5980 University Street, Halifax, NS, B3K 6R8, Canada.
| | - Marc Lalancette
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada.
| | - Ronald Bishop
- Biomedical Translational Imaging Centre (BIOTIC), IWK Health Centre, 5980 University Street, Halifax, NS, B3K 6R8, Canada.
| | - Steven Beyea
- Department of Physics and Atmospheric Science, Dalhousie University, 6310 Coburg Road, Halifax, NS, B3H 4R2, Canada; Biomedical Translational Imaging Centre (BIOTIC), IWK Health Centre, 5980 University Street, Halifax, NS, B3K 6R8, Canada; Department of Diagnostic Radiology, Dalhousie University, Room 319, Victoria Building, 1276 South Park St, Halifax, NS B3H 2Y9, Canada.
| | - Margot J Taylor
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada.
| | - Benjamin T Dunkley
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, ON, M5G 1X8, Canada.
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Presurgical electromagnetic functional brain mapping in refractory focal epilepsy. ZEITSCHRIFT FUR EPILEPTOLOGIE 2018. [DOI: 10.1007/s10309-018-0189-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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14
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Jandial R, Hoshide R, Waters JD, Somlo G. Operative and Therapeutic Advancements in Breast Cancer Metastases to the Brain. Clin Breast Cancer 2017; 18:e455-e467. [PMID: 29100727 DOI: 10.1016/j.clbc.2017.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 08/14/2017] [Accepted: 10/01/2017] [Indexed: 12/31/2022]
Abstract
Patients with breast cancer are surviving longer as the state of the art for care advances. Because patients are surviving longer with primary breast cancer, the incidence of secondary metastatic disease has risen. Metastatic breast cancer to the brain was once thought to be universally fatal. While it is still quite lethal, its treatment after diagnosis is increasingly safe and effective. Critical progress has been made in understanding the interaction between breast metastases and the neural niche, neuroimaging of functional anatomy, minimally invasive image-guided brain surgery, characterizing subtypes of breast cancer based on molecular and genetic profiles, and individualized pharmaceuticals and immunotherapies. In this review, we discuss recent advances that have brought us to state-of-the-art management of metastatic breast cancer to the brain.
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Affiliation(s)
- Rahul Jandial
- Department of Neurosurgery, City of Hope, Duarte, CA.
| | - Reid Hoshide
- Department of Neurosurgery, University of California, San Diego, San Diego, CA
| | - J Dawn Waters
- Department of Neurosurgery, Stanford University, Palo Alto, CA
| | - George Somlo
- Department of Medical Oncology and Therapeutics Research, City of Hope, Duarte, CA
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15
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De Tiège X, Lundqvist D, Beniczky S, Seri S, Paetau R. Current clinical magnetoencephalography practice across Europe: Are we closer to use MEG as an established clinical tool? Seizure 2017. [PMID: 28623727 DOI: 10.1016/j.seizure.2017.06.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Affiliation(s)
- Xavier De Tiège
- Department of Functional Neuroimaging, Service of Nuclear Medicine, CUB Hôpital Erasme, Université libre de Bruxelles (ULB), Brussels, Belgium; Laboratoire de Cartographie fonctionnelle du Cerveau, ULB Neuroscience Institute, Université libre de Bruxelles (ULB), Brussels, Belgium.
| | - Daniel Lundqvist
- NatMEG, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Sándor Beniczky
- Department of Clinical Neurophysiology, Danish Epilepsy Center, Dianalund, Denmark; Department of Clinical Neurophysiology, Aarhus University, Aarhus, Denmark
| | - Stefano Seri
- School of Life and Health Sciences, Aston Brain Centre, Aston University, Birmingham, United Kingdom
| | - Ritva Paetau
- Departments of Paediatric Neurology and Clinical Neurophysiology, Helsinki University Central Hospital, Helsinki, Finland
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16
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17
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Localized N20 Component of Somatosensory Evoked Magnetic Fields in Frontoparietal Brain Tumor Patients Using Noise-Normalized Approaches. Clin Neuroradiol 2017; 28:267-281. [PMID: 28116447 DOI: 10.1007/s00062-017-0557-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 01/03/2017] [Indexed: 10/20/2022]
Abstract
PURPOSE To localize sensorimotor cortical activation in 10 patients with frontoparietal tumors using quantitative magnetoencephalography (MEG) with noise-normalized approaches. MATERIAL AND METHODS Somatosensory evoked magnetic fields (SEFs) were elicited in 10 patients with somatosensory tumors and in 10 control participants using electrical stimulation of the median nerve via the right and left wrists. We localized the N20m component of the SEFs using dynamic statistical parametric mapping (dSPM) and standardized low-resolution brain electromagnetic tomography (sLORETA) combined with 3D magnetic resonance imaging (MRI). The obtained coordinates were compared between groups. Finally, we statistically evaluated the N20m parameters across hemispheres using non-parametric statistical tests. RESULTS The N20m sources were accurately localized to Brodmann area 3b in all members of the control group and in seven of the patients; however, the sources were shifted in three patients relative to locations outside the primary somatosensory cortex (SI). Compared with the affected (tumor) hemispheres in the patient group, N20m amplitudes and the strengths of the current sources were significantly lower in the unaffected hemispheres and in both hemispheres of the control group. These results were consistent for both dSPM and sLORETA approaches. CONCLUSION Tumors in the sensorimotor cortex lead to cortical functional reorganization and an increase in N20m amplitude and current-source strengths. Noise-normalized approaches for MEG analysis that are integrated with MRI show accurate and reliable localization of sensorimotor function.
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18
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Abstract
Navigated transcranial magnetic stimulation (nTMS) is employed in eloquent brain area localization prior to intraoperative direct cortical electrical stimulations and neurosurgery. No commercial archiving or file transfer protocol existed for these studies. The aim of our project was to establish a standardized protocol for the transfer of nTMS results and medical assessments to the end users in pursuance of improving data security and facilitating presurgical planning. The existing infrastructure of the hospital's Radiology Department was used. Hospital information systems and networks were configured to allow communications and archiving of the study results, and in-house software was written for file manipulations and transfers. Graphical user interface with description suggestions and user-defined text legends enabled an easy and straightforward workflow for annotations and archiving of the results. The software and configurations were implemented and have been applied in studies of ten patients. The creation of the study protocol required the involvement of various professionals and interdepartmental cooperation. The introduction of the protocol has ended previously recurrent involvement of staff in the file transfer phase and improved cost-effectiveness.
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Piitulainen H, Botter A, Bourguignon M, Jousmäki V, Hari R. Spatial variability in cortex-muscle coherence investigated with magnetoencephalography and high-density surface electromyography. J Neurophysiol 2015; 114:2843-53. [PMID: 26354317 DOI: 10.1152/jn.00574.2015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Accepted: 09/04/2015] [Indexed: 11/22/2022] Open
Abstract
Cortex-muscle coherence (CMC) reflects coupling between magnetoencephalography (MEG) and surface electromyography (sEMG), being strongest during isometric contraction but absent, for unknown reasons, in some individuals. We used a novel nonmagnetic high-density sEMG (HD-sEMG) electrode grid (36 mm × 12 mm; 60 electrodes separated by 3 mm) to study effects of sEMG recording site, electrode derivation, and rectification on the strength of CMC. Monopolar sEMG from right thenar and 306-channel whole-scalp MEG were recorded from 14 subjects during 4-min isometric thumb abduction. CMC was computed for 60 monopolar, 55 bipolar, and 32 Laplacian HD-sEMG derivations, and two derivations were computed to mimic "macroscopic" monopolar and bipolar sEMG (electrode diameter 9 mm; interelectrode distance 21 mm). With unrectified sEMG, 12 subjects showed statistically significant CMC in 91-95% of the HD-sEMG channels, with maximum coherence at ∼25 Hz. CMC was about a fifth stronger for monopolar than bipolar and Laplacian derivations. Monopolar derivations resulted in most uniform CMC distributions across the thenar and in tightest cortical source clusters in the left rolandic hand area. CMC was 19-27% stronger for HD-sEMG than for "macroscopic" monopolar or bipolar derivations. EMG rectification reduced the CMC peak by a quarter, resulted in a more uniformly distributed CMC across the thenar, and provided more tightly clustered cortical sources than unrectifed sEMGs. Moreover, it revealed CMC at ∼12 Hz. We conclude that HD-sEMG, especially with monopolar derivation, can facilitate detection of CMC and that individual muscle anatomy cannot explain the high interindividual CMC variability.
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Affiliation(s)
- Harri Piitulainen
- Brain Research Unit, Department of Neuroscience and Biomedical Engineering, and MEG Core and Advanced Magnetic Imaging (AMI) Centre, Aalto NeuroImaging, Aalto University School of Science, Aalto, Espoo, Finland; and
| | - Alberto Botter
- Laboratory of Engineering of Neuromuscular System and Motor Rehabilitation, Dipartimento di Elettronica e Telecomunicazioni, Politecnico di Torino, Turin, Italy
| | - Mathieu Bourguignon
- Brain Research Unit, Department of Neuroscience and Biomedical Engineering, and MEG Core and Advanced Magnetic Imaging (AMI) Centre, Aalto NeuroImaging, Aalto University School of Science, Aalto, Espoo, Finland; and
| | - Veikko Jousmäki
- Brain Research Unit, Department of Neuroscience and Biomedical Engineering, and MEG Core and Advanced Magnetic Imaging (AMI) Centre, Aalto NeuroImaging, Aalto University School of Science, Aalto, Espoo, Finland; and
| | - Riitta Hari
- Brain Research Unit, Department of Neuroscience and Biomedical Engineering, and MEG Core and Advanced Magnetic Imaging (AMI) Centre, Aalto NeuroImaging, Aalto University School of Science, Aalto, Espoo, Finland; and
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20
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Beniczky S, Duez L, Scherg M, Hansen PO, Tankisi H, Sidenius P, Sabers A, Pinborg LH, Uldall P, Fuglsang-Frederiksen A. Visualizing spikes in source-space: Rapid and efficient evaluation of magnetoencephalography. Clin Neurophysiol 2015; 127:1067-1072. [PMID: 26238854 DOI: 10.1016/j.clinph.2015.07.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 07/14/2015] [Accepted: 07/16/2015] [Indexed: 10/23/2022]
Abstract
OBJECTIVE Reviewing magnetoencephalography (MEG) recordings is time-consuming: signals from the 306 MEG-sensors are typically reviewed divided into six arrays of 51 sensors each, thus browsing each recording six times in order to evaluate all signals. A novel method of reconstructing the MEG signals in source-space was developed using a source-montage of 29 brain-regions and two spatial components to remove magnetocardiographic (MKG) artefacts. Our objective was to evaluate the accuracy of reviewing MEG in source-space. METHODS In 60 consecutive patients with epilepsy, we prospectively evaluated the accuracy of reviewing the MEG signals in source-space as compared to the classical method of reviewing them in sensor-space. RESULTS All 46 spike-clusters identified in sensor-space were also identified in source-space. Two additional spike-clusters were identified in source-space. As 29 source-channels can be easily displayed simultaneously, MEG recordings had to be browsed only once. Yet, this yielded a global coverage of the recorded signals and enhanced detectability of epileptiform discharges because MKG-artefacts were suppressed and did not impede evaluation in source-space. CONCLUSIONS Our results show that reviewing MEG recordings in source-space is accurate and much more rapid than the classical method of reviewing in sensor-space. SIGNIFICANCE This novel method facilitates the clinical use of MEG.
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Affiliation(s)
- Sándor Beniczky
- Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark; Department of Clinical Neurophysiology, Danish Epilepsy Centre, Dianalund, Denmark.
| | - Lene Duez
- Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Peter Orm Hansen
- Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark
| | - Hatice Tankisi
- Department of Clinical Neurophysiology, Aarhus University Hospital, Aarhus, Denmark
| | - Per Sidenius
- Department of Neurology, Aarhus University Hospital, Aarhus, Denmark
| | - Anne Sabers
- Department of Neurology and Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Lars Hageman Pinborg
- Department of Neurology and Neurobiology Research Unit, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
| | - Peter Uldall
- Department of Paediatrics, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark
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21
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Vema Krishna Murthy S, MacLellan M, Beyea S, Bardouille T. Faster and improved 3-D head digitization in MEG using Kinect. Front Neurosci 2014; 8:326. [PMID: 25389382 PMCID: PMC4211394 DOI: 10.3389/fnins.2014.00326] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 09/26/2014] [Indexed: 11/29/2022] Open
Abstract
Accuracy in localizing the brain areas that generate neuromagnetic activity in magnetoencephalography (MEG) is dependent on properly co-registering MEG data to the participant's structural magnetic resonance image (MRI). Effective MEG-MRI co-registration is, in turn, dependent on how accurately we can digitize anatomical landmarks on the surface of the head. In this study, we compared the performance of three devices—Polhemus electromagnetic system, NextEngine laser scanner and Microsoft Kinect for Windows—for source localization accuracy and MEG-MRI co-registration. A calibrated phantom was used for verifying the source localization accuracy. The Kinect improved source localization accuracy over the Polhemus and the laser scanner by 2.23 mm (137%) and 0.81 mm (50%), respectively. MEG-MRI co-registration accuracy was verified on data from five healthy human participants, who received the digitization process using all three devices. The Kinect device captured approximately 2000 times more surface points than the Polhemus in one third of the time (1 min compared to 3 min) and thrice as many points as the NextEngine laser scanner. Following automated surface matching, the calculated mean MEG-MRI co-registration error for the Kinect was improved by 2.85 mm with respect to the Polhemus device, and equivalent to the laser scanner. Importantly, the Kinect device automatically aligns 20–30 images per second in real-time, reducing the limitations on participant head movement during digitization that are implicit in the NextEngine laser scan (~1 min). We conclude that the Kinect scanner is an effective device for head digitization in MEG, providing the necessary accuracy in source localization and MEG-MRI co-registration, while reducing digitization time.
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Affiliation(s)
| | - Matthew MacLellan
- Biomedical Translational Imaging Centre (BIOTIC), IWK Health Centre Halifax, NS, Canada
| | - Steven Beyea
- Biomedical Translational Imaging Centre (BIOTIC), IWK Health Centre Halifax, NS, Canada ; Department of Diagnostic Radiology, Dalhousie University Halifax, NS, Canada
| | - Timothy Bardouille
- Biomedical Translational Imaging Centre (BIOTIC), IWK Health Centre Halifax, NS, Canada ; Faculty of Computer Science, Dalhousie University Halifax, NS, Canada
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22
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Birbilis T, Anninos P, Seimenis I, Adamopoulos A, Kotini A. MEG localization of spike sources in human patients with brain tumors. J Integr Neurosci 2014; 13:519-28. [DOI: 10.1142/s0219635214500150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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23
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Abstract
Deep brain stimulation (DBS) is a neurosurgical intervention the efficacy, safety, and utility of which are established in the treatment of Parkinson's disease. For the treatment of chronic, neuropathic pain refractory to medical therapies, many prospective case series have been reported, but few have published findings from patients treated with current standards of neuroimaging and stimulator technology over the last decade . We summarize the history, science, selection, assessment, surgery, programming, and personal clinical experience of DBS of the ventral posterior thalamus, periventricular/periaqueductal gray matter, and latterly rostral anterior cingulate cortex (Cg24) in 113 patients treated at 2 centers (John Radcliffe, Oxford, UK, and Hospital de São João, Porto, Portugal) over 13 years. Several experienced centers continue DBS for chronic pain, with success in selected patients, in particular those with pain after amputation, brachial plexus injury, stroke, and cephalalgias including anesthesia dolorosa. Other successes include pain after multiple sclerosis and spine injury. Somatotopic coverage during awake surgery is important in our technique, with cingulate DBS under general anesthesia considered for whole or hemibody pain, or after unsuccessful DBS of other targets. Findings discussed from neuroimaging modalities, invasive neurophysiological insights from local field potential recording, and autonomic assessments may translate into improved patient selection and enhanced efficacy, encouraging larger clinical trials.
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Affiliation(s)
- Erlick A C Pereira
- Oxford Functional Neurosurgery and Experimental Neurology Group, Department of Neurological Surgery and Nuffield Department of Surgical Sciences, Oxford University, John Radcliffe Hospital, Oxford, OX3 9DU, UK,
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24
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Abstract
Magnetoencephalography (MEG) is a functional modality to register magnetic brain activity with high spatiotemporal resolution. Since distortion of magnetic fields by the skin, skull and cerebrospinal fluids is negligible, the technique offers an almost undistorted view on brain activity. While MEG systems are still expensive and complex, the technique's characteristics offer promising possibilities for the investigation of epilepsy patients, for example, for focus localization and presurgical functional mapping. This review gives an overview of the method and discusses advantages and limitations in the clinical context of presurgical epilepsy diagnosis.
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Affiliation(s)
- Stefan Rampp
- Epilepsy Center (ZEE), Department of Neurology, University Hospital, Schwabachanlage 6, 91054 Erlangen, Germany.
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25
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Sommer B, Grummich P, Hamer H, Bluemcke I, Coras R, Buchfelder M, Roessler K. Frameless stereotactic functional neuronavigation combined with intraoperative magnetic resonance imaging as a strategy in highly eloquent located tumors causing epilepsy. Stereotact Funct Neurosurg 2013; 92:59-67. [PMID: 24356382 DOI: 10.1159/000355216] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 08/22/2013] [Indexed: 01/17/2023]
Abstract
BACKGROUND Intractable epilepsy due to tumors located in highly eloquent brain regions is often considered surgically inaccessible because of a high risk of postoperative neurological deterioration. Intraoperative MRI and functional navigation contribute to overcome this problem. OBJECTIVES To retrospectively investigate the long-term results and impact of functional neuronavigation and 1.5-tesla intraoperative MRI on patients who underwent surgery of tumors associated with epilepsy located close to or within eloquent brain areas. METHODS Nineteen patients (9 female, 10 male, mean age 41.4 ± 13.4 years, 11 low-grade and 8 high-grade glial tumors) were evaluated preoperatively using BOLD imaging, diffusion-tensor imaging tractography and magnetoencephalography. Functional data were implemented into neuronavigation in this multimodal approach. RESULTS In 14 of 19 patients (74%), complete resection was achieved, and in 5 patients significant tumor volume reduction was accomplished. Eight of 14 (57%) complete resections were achieved only by performing an intraoperative image update. Neurological deterioration was found permanently in 2 patients. After a mean follow-up of 43.8 ± 23.8 months, 15 patients (79%) became seizure free (Engel class Ia). CONCLUSIONS Despite the highly eloquent location of tumors causing intractable epilepsy, our multimodal approach led to complete resection in more than two-thirds of patients with an acceptable neurological morbidity and excellent long-term seizure control.
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Affiliation(s)
- Bjoern Sommer
- Department of Neurosurgery, University Hospital Erlangen, Erlangen, Germany
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26
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Dichoptic Viewing Methods for Binocular Rivalry Research: Prospects for Large-Scale Clinical and Genetic Studies. Twin Res Hum Genet 2013; 16:1033-78. [DOI: 10.1017/thg.2013.76] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Binocular rivalry (BR) is an intriguing phenomenon that occurs when two different images are presented, one to each eye, resulting in alternation orrivalrybetween the percepts. The phenomenon has been studied for nearly 200 years, with renewed and intensive investigation over recent decades. Therateof perceptual switching has long been known to vary widely between individuals but to be relatively stable within individuals. A recent twin study demonstrated that individual variation in BR rate is under substantial genetic control, a finding that also represented the first report, using a large study, of genetic contribution for any post-retinal visual processing phenomenon. The twin study had been prompted by earlier work showing BR rate was slow in the heritable psychiatric condition, bipolar disorder (BD). Together, these studies suggested that slow BR may represent an endophenotype for BD, and heralded the advent of modern clinical and genetic studies of rivalry. This new focus has coincided with rapid advances in 3D display technology, but despite such progress, specific development of technology for rivalry research has been lacking. This review therefore compares different display methods for BR research across several factors, including viewing parameters, image quality, equipment cost, compatibility with other investigative methods, subject group, and sample size, with a focus on requirements specific to large-scale clinical and genetic studies. It is intended to be a resource for investigators new to BR research, such as clinicians and geneticists, and to stimulate the development of 3D display technology for advancing interdisciplinary studies of rivalry.
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27
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Braeutigam S. Magnetoencephalography: fundamentals and established and emerging clinical applications in radiology. ISRN RADIOLOGY 2013; 2013:529463. [PMID: 24967282 PMCID: PMC4045536 DOI: 10.5402/2013/529463] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 07/03/2013] [Indexed: 12/17/2022]
Abstract
Magnetoencephalography is a noninvasive, fast, and patient friendly technique for recording brain activity. It is increasingly available and is regarded as one of the most modern imaging tools available to radiologists. The dominant clinical use of this technology currently centers on two, partly overlapping areas, namely, localizing the regions from which epileptic seizures originate, and identifying regions of normal brain function in patients preparing to undergo brain surgery. As a consequence, many radiologists may not yet be familiar with this technique. This review provides an introduction to magnetoencephalography, discusses relevant analytical techniques, and presents recent developments in established and emerging clinical applications such as pervasive developmental disorders. Although the role of magnetoencephalography in diagnosis, prognosis, and patient treatment is still limited, it is argued that this technology is exquisitely capable of contributing indispensable information about brain dynamics not easily obtained with other modalities. This, it is believed, will make this technology an important clinical tool for a wide range of disorders in the future.
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Affiliation(s)
- Sven Braeutigam
- Oxford Centre for Human Brain Activity, Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford OX3 7JX, UK
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28
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Chang WS, Kim BS, Jung HH, Kim K, Kwon HC, Lee YH, Chang JW. Decreased inhibitory neuronal activity in patients with frontal lobe brain tumors with seizure presentation: Preliminary study using magnetoencephalography. Acta Neurochir (Wien) 2013; 155:1449-57. [PMID: 23797730 DOI: 10.1007/s00701-013-1781-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 05/16/2013] [Indexed: 11/27/2022]
Abstract
BACKGROUND Although 30-50 % of patients with brain tumors experience epileptic seizure as the presenting clinical symptom, and another 10-30 % are at risk for developing epilepsy in the later stages of the disease, the mechanisms of tumor-related epileptogenesis are poorly understood. We used magnetoencephalography (MEG) to investigate sensory evoked fields (SEFs) in patients with frontal lobe brain tumors as a means of evaluating the neuronal activity of peri-tumoral cortex. METHODS Twelve patients with frontal lobe brain tumors underwent MEG. We calculated the equivalent current dipole strength of two components of the primary sensory cortical response (N20m and P35m) and compared the P35m/N20m ratio in the tumor hemisphere vs. the normal hemisphere. There were two subsets of patients: group I, in which P35m/N20m was higher in the tumor hemisphere (n= 7), and group II, in which P35m/N20m was higher in the normal hemisphere (n=5). We looked for associations between clinical factors and P35m/N20m within each group. RESULTS All patients with seizure presentation were in group I, whereas only two patients without seizure presentation were in group I (Fisher exact test, p=0.028). No other clinical factors were related to P35m/N20m. The mean ratio of P35m/N20m equivalent current dipole strength in patients with seizure presentation was 4.07 ± 2.38 in the tumor hemisphere and 2.00 ± 0.55 in the normal hemisphere. This difference was statistically significant (Mann-Whitney test, p=0.030). CONCLUSION The paradoxical increase in P35m/N20m in patients with seizure presentation suggests that decreased inhibitory neuronal activity is a potential cause of tumorrelated epilepsy.
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Affiliation(s)
- Won Seok Chang
- Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, 205 Seongsanno Seodaemun-gu, Seoul 120-752, Korea
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29
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Zhang Y, Zhang N, Han Z, Wang Y, Wang C, Chen H, Wang Y, Zhang X. Magnetoencephalography of language: new approaches to understanding the cortical organization of Chinese processing. Neurol Res 2013; 32:625-8. [DOI: 10.1179/174313209x459219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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30
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Piitulainen H, Bourguignon M, De Tiège X, Hari R, Jousmäki V. Coherence between magnetoencephalography and hand-action-related acceleration, force, pressure, and electromyogram. Neuroimage 2013; 72:83-90. [DOI: 10.1016/j.neuroimage.2013.01.029] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Revised: 01/11/2013] [Accepted: 01/17/2013] [Indexed: 10/27/2022] Open
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31
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Abstract
Deep brain stimulation (DBS) is a neurosurgical intervention whose efficacy, safety, and utility have been shown in the treatment of movement disorders. For the treatment of chronic pain refractory to medical therapies, many prospective case series have been reported, but few have published findings from patients treated during the past decade using current standards of neuroimaging and stimulator technology. We summarize the history, science, selection, assessment, surgery, and personal clinical experience of DBS of the ventral posterior thalamus, periventricular/periaqueductal gray matter, and, latterly, the rostral anterior cingulate cortex (Cg24) in 100 patients treated now at two centers (John Radcliffe Hospital, Oxford, UK, and Hospital de São João, Porto, Portugal) over 12 years. Several experienced centers continue DBS for chronic pain with success in selected patients, in particular those with pain after amputation, brachial plexus injury, stroke, and cephalalgias including anesthesia dolorosa. Other successes include pain after multiple sclerosis and spine injury. Somatotopic coverage during awake surgery is important in our technique, with cingulate DBS considered for whole-body pain or after unsuccessful DBS of other targets. Findings discussed from neuroimaging modalities, invasive neurophysiological insights from local field potential recording, and autonomic assessments may translate into improved patient selection and enhanced efficacy, encouraging larger clinical trials.
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Affiliation(s)
- Erlick A C Pereira
- Oxford Functional Neurosurgery and Experimental Neurology Group, Department of Neurological Surgery and Nuffield Department of Surgical Sciences, Oxford University, John Radcliffe Hospital, Oxford, UK
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32
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Paetau R, Mohamed IS. Magnetoencephalography (MEG) and other neurophysiological investigations. HANDBOOK OF CLINICAL NEUROLOGY 2013; 111:461-5. [DOI: 10.1016/b978-0-444-52891-9.00050-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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33
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Comprehensive Functional Mapping Scheme for Non-Invasive Primary Sensorimotor Cortex Mapping. Brain Topogr 2012; 26:511-23. [DOI: 10.1007/s10548-012-0271-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2012] [Accepted: 12/15/2012] [Indexed: 10/27/2022]
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34
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Bardouille T, Krishnamurthy SV, Hajra SG, D’Arcy RCN. Improved Localization Accuracy in Magnetic Source Imaging Using a 3-D Laser Scanner. IEEE Trans Biomed Eng 2012; 59:3491-7. [DOI: 10.1109/tbme.2012.2220356] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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35
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Burke BA, Diamond SG. Measuring cerebral hemodynamics with a modified magnetoencephalography system. Physiol Meas 2012; 33:2079-98. [PMID: 23171539 DOI: 10.1088/0967-3334/33/12/2079] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Magnetoencephalography (MEG) systems are designed to noninvasively measure magnetic fields produced by neural electrical currents. This project examines the possibility of measuring hemodynamics with an MEG system that has been modified with dc electromagnets to measure magnetic susceptibility while maintaining the capability of measuring neural dynamics. A forward model is presented that simulates the interaction of an applied magnetic field with changes in magnetic susceptibility in the brain associated with hemodynamics. Model predictions are compared with an experiment where deionized water was pumped into an inverted flask under the MEG sensor array of superconducting quantum interference device (SQUID) gradiometers (R(2) = 0.98, p < 0.001). The forward model was used to simulate the SQUID readouts from hemodynamics in the scalp and brain induced by performing the Valsalva maneuver. Experimental human subject recordings (N = 10) were made from the prefrontal region during Valsalva using concurrent measurement with the modified MEG system and near-infrared spectroscopy (NIRS). The NIRS deoxyhemoglobin signal was found to correlate significantly with the SQUID readouts (R(2) = 0.84, p < 0.01). SQUID noise was found to increase with the applied field, which will need to be mitigated in future work. These results demonstrate the potential and technical challenges of measuring cerebral hemodynamics with a modified MEG system.
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Affiliation(s)
- Broc A Burke
- Thayer School of Engineering at Dartmouth, Hanover, NH, USA
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Validation of head movement correction and spatiotemporal signal space separation in magnetoencephalography. Clin Neurophysiol 2012; 123:2180-91. [DOI: 10.1016/j.clinph.2012.03.080] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Revised: 03/19/2012] [Accepted: 03/21/2012] [Indexed: 11/23/2022]
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Vesanen PT, Nieminen JO, Zevenhoven KCJ, Dabek J, Parkkonen LT, Zhdanov AV, Luomahaara J, Hassel J, Penttilä J, Simola J, Ahonen AI, Mäkelä JP, Ilmoniemi RJ. Hybrid ultra-low-field MRI and magnetoencephalography system based on a commercial whole-head neuromagnetometer. Magn Reson Med 2012; 69:1795-804. [PMID: 22807201 DOI: 10.1002/mrm.24413] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2012] [Revised: 05/08/2012] [Accepted: 06/24/2012] [Indexed: 11/10/2022]
Abstract
Ultra-low-field MRI uses microtesla fields for signal encoding and sensitive superconducting quantum interference devices for signal detection. Similarly, modern magnetoencephalography (MEG) systems use arrays comprising hundreds of superconducting quantum interference device channels to measure the magnetic field generated by neuronal activity. In this article, hybrid MEG-MRI instrumentation based on a commercial whole-head MEG device is described. The combination of ultra-low-field MRI and MEG in a single device is expected to significantly reduce coregistration errors between the two modalities, to simplify MEG analysis, and to improve MEG localization accuracy. The sensor solutions, MRI coils (including a superconducting polarizing coil), an optimized pulse sequence, and a reconstruction method suitable for hybrid MEG-MRI measurements are described. The performance of the device is demonstrated by presenting ultra-low-field-MR images and MEG recordings that are compared with data obtained with a 3T scanner and a commercial MEG device.
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Affiliation(s)
- Panu T Vesanen
- Department of Biomedical Engineering and Computational Science, Aalto University School of Science, Espoo, Finland.
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Abstract
The insula is a functionally and anatomically complex cortical structure that can be affected by both low-grade and high-grade gliomas. This complexity often prevents many neurosurgeons from attempting to surgically manage insular gliomas. This article reviews the anatomic and functional uniqueness of the insula and the surgical outcomes and lessons learned from previously reported surgical series. Successful management of insular gliomas, defined as maximal resection of the tumor without postoperative neurologic morbidity, can be achieved through a sophisticated understanding of the neurovascular structure of the insular region and an intraoperative functional mapping using cortico-subcortical electrical stimulation.
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Affiliation(s)
- Young-Hoon Kim
- Department of Neurosurgery, Seoul National University Bundang Hospital, 166 Gumi-ro, Bundang-gu, Seongnam-si, Gyeonggi-do 463-707, Korea
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Taheri MR, Krauthamer A, Otjen J, Khanna PC, Ishak GE. Neuroimaging of Migrational Disorders in Pediatric Epilepsy. Curr Probl Diagn Radiol 2012; 41:11-9. [DOI: 10.1067/j.cpradiol.2011.06.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Affiliation(s)
- Ian F Parney
- Department of Neurological Surgery, Mayo Clinic, Rochester, MN, USA.
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Adhikary SD, Thiruvenkatarajan V, Babu KS, Tharyan P. The effects of anaesthetic agents on cortical mapping during neurosurgical procedures involving eloquent areas of the brain. Cochrane Database Syst Rev 2011:CD006679. [PMID: 22071831 DOI: 10.1002/14651858.cd006679.pub2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
BACKGROUND In patients presenting for surgical resection of lesions involving, or adjacent to, the functionally important eloquent cortical areas, it is vital to achieve complete or near complete resection of the pathology without damaging the healthy surrounding tissues.The eloquent areas that the surgeons are concerned with are the primary motor, premotor cortex, supplementary motor cortex and speech areas. If the lesions are within these regions surgeons could either take a biopsy or do a intracapsular decompression without damaging the mentioned areas to avoid postoperative dysfunction. If the lesions are adjacent to the above mentioned areas, the normal anatomy would get distorted. However, proper identification of the above mentioned areas would enable the surgeon to radically remove the tumours. Intraoperative mapping of the cortex with stimulating and recording electrodes is termed as electrophysiological (EP) mapping.The EP mapping of motor, sensory and language cortex is widely employed in the resection of lesions involving or adjacent to the eloquent areas. Both intravenous and inhalational agents are known to affect these EP mapping techniques. OBJECTIVES The aim of this review was to evaluate the effect of anaesthetic agents on intra-operative EP mapping in patients undergoing neurosurgical procedures involving, or adjacent to, the functional areas of the cortex under general anaesthesia. SEARCH METHODS We searched the Cochrane Epilepsy Group Specialized Register (7 March 2011), The Cochrane Central Register of Controlled Trials (CENTRAL issue 1 of 4, The Cochrane Library 2011), MEDLINE (Ovid, 1948 to February week 4, 2011), PsycINFO (EBSCOhost, 7 March 2011), and the National Research Register Archive and UK Clinical Research Network (7 March 2011). We also contacted other researchers in the field in an attempt to ascertain unpublished studies. SELECTION CRITERIA We planned to include randomised and quasi randomised controlled trials irrespective of blinding in patients of any age or gender undergoing neurosurgery under general anaesthesia where cortical mapping was attempted to identify eloquent areas using either somatosensory evoked potentials (SSEPs), or direct cortical stimulation (DCS) triggered muscle motor evoked potentials (mMEPs), or both. We excluded patients from trials where the anaesthetic effects were evaluated during spinal cord surgery or where MEPs were recorded from modes other than direct cortical stimulation such as transcranial electrical stimulation (TcMEPs), MEPs derived from epidural electrodes (D waves) and magnetic stimulation and trials involving awake craniotomies or the asleep-awake-asleep technique during cortical mapping. DATA COLLECTION AND ANALYSIS Two review authors planned to independently apply the inclusion criteria and extract data. MAIN RESULTS No RCTs were found for this study population. AUTHORS' CONCLUSIONS This review highlights the need for well-designed randomised controlled trials to assess the effect of anaesthetic agents on cortical mapping during neurosurgical procedures involving eloquent areas of the brain.
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Affiliation(s)
- Sanjib D Adhikary
- Department of Anaesthesia/Discipline of Acute CareMedicine, TheQueen ElizabethHospital/The University of Adelaide,Woodville,Adelaide, Australia
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Picht T, Schmidt S, Woitzik J, Suess O. Navigated Brain Stimulation for Preoperative Cortical Mapping in Paretic Patients: Case Report of a Hemiplegic Patient. Neurosurgery 2011; 68:E1475-80; discussion E1480. [DOI: 10.1227/neu.0b013e318210c7df] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Abstract
BACKGROUND AND IMPORTANCE:
Navigated brain stimulation (NBS) is an emerging technology that can be used for preoperative mapping of the motor cortex. It combines conventional transcranial magnetic stimulation with neuronavigation and achieves high precision by taking into account all relevant physical factors. In contrast to functional imaging technologies, NBS does not rely on voluntary patient movements for cortical mapping. Thus, NBS can be used even on patients with severe motor impairment.
CLINICAL PRESENTATION:
This article presents the case of a hemiplegic elderly woman with a brain tumor in the motor cortex. Preoperative NBS surprisingly demonstrated intact corticospinal tracts in the hemiplegic patient. The results modified the surgical strategy. Direct cortical stimulation was performed intraoperatively. The direct cortical stimulation results were in agreement with the preoperative NBS findings, and the clinical success of the surgery exceeded expectations.
CONCLUSION:
NBS can be used for preoperative mapping in plegic patients. Even more important, this case report discusses why tumor resection surgery based on NBS may sometimes lead to substantially better clinical outcomes than surgery planned according to functional imaging technologies.
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Affiliation(s)
- Thomas Picht
- Department of Neurosurgery, Charité-Universitaetsmedizin, Berlin, Germany
| | - Sein Schmidt
- Department of Neurology, Charité-Universitaetsmedizin, Berlin, Germany
| | - Johannes Woitzik
- Department of Neurosurgery, Charité-Universitaetsmedizin, Berlin, Germany
| | - Olaf Suess
- Department of Neurosurgery, Charité-Universitaetsmedizin, Berlin, Germany
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Shiraishi H. Source localization in magnetoencephalography to identify epileptogenic foci. Brain Dev 2011; 33:276-81. [PMID: 21075573 DOI: 10.1016/j.braindev.2010.10.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2010] [Revised: 10/21/2010] [Accepted: 10/22/2010] [Indexed: 10/18/2022]
Abstract
RATIONALE Magnetoencephalography (MEG) is useful to localize epileptic foci in epilepsy as MEG has higher spatio-temporal resolution than conventional diagnostic imaging studies; positron emission computed tomography, single photon emission computed tomography and magnetic resonance imaging (MRI). METHODS We use 204-channel helmet-shaped MEG with a sampling rate of 600 Hz. A single dipole method calculates equivalent current dipoles to localize epileptic sources. The equivalent current dipoles are superimposed onto MRI as magnetic source imaging (MSI). Ictal MEG data are analyzed using time-frequency analysis. The power spectrum density is calculated using short-time Fourier transform and superimposed onto MRI results. RESULTS Clustered equivalent current dipoles represent epileptogenic zones in patients with localization-related epilepsy. The surgical plan is reliably developed from source localizations of dipoles and power spectrum of interictal spike discharges, and ictal frequency. CONCLUSION MEG is indispensable in diagnosis and surgical resection for epilepsy to accurately localize the epileptogenic zone.
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Affiliation(s)
- Hideaki Shiraishi
- Department of Pediatrics, Hokkaido University, Graduate School of Medicine, Hokkaido, Japan.
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González-Darder J, González-López P, Talamantes-Escribá F, García-March G, Roldán-Badía P, Quilis-Quesada V, Verdú-López F, Bordes-García V, Botella-Maciá L, Masbout G, Cortés-Doñate V, Belloch-Ugarte V. Tratamiento de los tumores cerebrales intrínsecos de áreas motoras elocuentes. Resultados de un protocolo basado en la navegación, tractografía y monitorización neurofisiológica de estructuras corticales y subcorticales. Neurocirugia (Astur) 2011. [DOI: 10.1016/s1130-1473(11)70002-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Prabhu VC, Khaldi A, Barton KP, Melian E, Schneck MJ, Primeau MJ, Lee JM. Management of Diffuse Low-Grade Cerebral Gliomas. Neurol Clin 2010; 28:1037-59. [DOI: 10.1016/j.ncl.2010.03.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Placantonakis DG, Shariff S, Lafaille F, Labar D, Harden C, Hosain S, Kandula P, Schaul N, Kolesnik D, Schwartz TH. Bilateral intracranial electrodes for lateralizing intractable epilepsy: efficacy, risk, and outcome. Neurosurgery 2010; 66:274-83. [PMID: 20087126 DOI: 10.1227/01.neu.0000363184.43723.94] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Medically refractory epilepsy is amenable to neurosurgical intervention if the epileptogenic focus is accurately localized. If the scalp video-electroencephalography (EEG) and magnetic resonance imaging are nonlateralizing, yet a single focus is suspected, video-EEG monitoring with bilateral intracranial electrode placement is helpful to lateralize the ictal onset zone. We describe the indications, risks, and utility of such bilateral surveys at our institution. METHODS We retrospectively reviewed 26 patients with medically refractory seizures who were treated over a 5-year period and underwent bilateral placement of intracranial electrodes. Subdural strips were used in all cases, and additional stereotactic implantation of depth electrodes into mesial temporal lobes occurred in 50%. The mean patient age was 37.7 years, and 65.4% of patients were male. RESULTS The most common indication for bilateral invasive monitoring was bilateral ictal onsets on surface video-EEG (76.9%), followed by frequent interictal spikes contralateral to a single ictal focus (7.7%). Intracranial monitoring lasted an average of 8.2 days, with ictal events recorded in all cases. Ten patients (38.5%) subsequently underwent more extensive unilateral monitoring via implantation of subdural and depth electrodes through a craniotomy. A therapeutic procedure was performed in 17 patients (65.4%), whereas 1 patient underwent a palliative corpus callosotomy (3.8%). Nine patients underwent a resection without unilateral invasive mapping. Reasons for no therapeutic surgery (n = 8) included multifocal onsets, failing the Wada test, refusal of further treatment, and negative intraoperative electrocorticogram. There was 1 surgical complication, involving a retained electrode fragment that was removed in a separate minor procedure. Of the 26 patients, 15 (57.7%) are now seizure-free or have seizure disorders that have substantially improved (modified Engel classes I and II). Of the 17 patients who underwent a potentially curative surgery, 13 (76.5%) were Engel classes I and II. CONCLUSION Bilateral placement of subdural strip and depth electrodes for epilepsy monitoring in patients with nonlateralizing scalp EEG and/or discordant imaging studies but clinical suspicion for focal seizure origin is both safe and effective. Given the safety and efficacy of this procedure, epileptologists should have a low threshold to consider bilateral implants for suitable patients.
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Affiliation(s)
- Dimitris G Placantonakis
- Department of Neurological Surgery, Weill Cornell Medical College, New York-Presbyterian Hospital, New York, New York 10065, USA
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González-Darder JM, González-López P, Talamantes F, Quilis V, Cortés V, García-March G, Roldán P. Multimodal navigation in the functional microsurgical resection of intrinsic brain tumors located in eloquent motor areas: role of tractography. Neurosurg Focus 2010; 28:E5. [PMID: 20121440 DOI: 10.3171/2009.11.focus09234] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT Nowadays the role of microsurgical management of intrinsic brain tumors is to maximize the volumetric resection of the tumoral tissue, minimizing the postoperative morbidity. The purpose of this paper was to study the benefits of an original protocol developed for the microsurgical treatment of tumors located in eloquent motor areas where the navigation and electrical stimulation of motor subcortical pathways have been implemented. METHODS A total of 17 patients who underwent resection of cortical or subcortical tumors in motor areas have been included in the series. The preoperative planning for multimodal navigation was done by integrating anatomical studies, motor functional MR (fMR) imaging, and subcortical pathway volumes generated by diffusion tensor (DT) imaging. Intraoperative neuromonitoring included motor mapping by direct cortical stimulation (CS) and subcortical stimulation (sCS), and localization of the central sulcus by using cortical multipolar electrodes and the N20 wave inversion technique. The location of all cortically and subcortically stimulated points with positive motor response was stored in the navigator and correlated with the cortical and subcortical motor functional structures defined preoperatively. RESULTS The mean tumoral volumetric resection was 89.1 +/- 14.2% of the preoperative volume, with a total resection (> or = 100%) in 8 patients. Preoperatively a total of 58.8% of the patients had some kind of motor neurological deficit, increasing 24 hours after surgery to 70.6% and decreasing to 47.1% at 1 month later. There was a great correlation between anatomical and functional data, both cortically and subcortically. A total of 52 cortical points submitted to CS had positive motor response, with a positive correlation of 83.7%. Also, a total of 55 subcortical points had positive motor response; in these cases the mean distance from the stimulated point to the subcortical tract was 7.3 +/- 3.1 mm. CONCLUSIONS The integration of anatomical and functional studies allows a safe functional resection of the brain tumors located in eloquent areas. Multimodal navigation allows integration and correlation among preoperative and intraoperative anatomical and functional data. Cortical motor functional areas are anatomically and functionally located preoperatively thanks to MR and fMR imaging and subcortical motor pathways with DT imaging and tractography. Intraoperative confirmation is done with CS and N20 inversion wave for cortical structures and with sCS for subcortical pathways. With this protocol the authors achieved a good volumetric resection in cortical and subcortical tumors located in eloquent motor areas, with an increase in the incidence of neurological deficits in the immediate postoperative period that significantly decreased 1 month later. Ongoing studies must define the safe limits for functional resection, taking into account the intraoperative brain shift. Finally, it must be demonstrated whether this protocol has any long-term benefit for patients by prolonging the disease-free interval, the time to recurrence, or the survival time.
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Affiliation(s)
- José M González-Darder
- Department of Neurosurgery, Hospital Clínico Universitario, Servicio Valenciano de Salud, 46010 Valencia, Spain.
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Signal space separation algorithm and its application on suppressing artifacts caused by vagus nerve stimulation for magnetoencephalography recordings. J Clin Neurophysiol 2010; 26:392-400. [PMID: 19952563 DOI: 10.1097/wnp.0b013e3181c29896] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Magnetoencephalography (MEG) has been successfully applied to presurgical epilepsy foci localization and brain functional mapping. Because the neuronal magnetic signals from the brain are extremely weak, MEG measurement requires both low environment noise and the subject/patient being free of artifact-generating metal objects. This strict requirement makes it hard for patients with vagus nerve stimulator, or other similar medical devices, to benefit from the presurgical MEG examinations. Therefore, an approach that can effectively reduce the environmental noise and faithfully recover the brain signals is highly desirable. We applied spatiotemporal signal space separation method, an advanced signal processing approach that can recover bio-magnetic signal from inside the MEG sensor helmet and suppress external disturbance from outside the helmet in empirical MEG measurements, on MEG recordings from normal control subjects and patients who has vagus nerve stimulator. The original MEG recordings were heavily contaminated, and the data could not be assessed. After applying temporal signal space separation, the strong external artifacts from outside the brain were successfully removed, and the neuronal signal from the human brain was faithfully recovered. Both of the goodness-of-fit and 95% confident limit volume confirmed the significant improvement after temporal signal space separation. Hence, temporal signal space separation makes presurgical MEG examinations possible for patients with implanted vagus nerve stimulator or similar medical devices.
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Signorelli F, Guyotat J, Elisevich K, Barbagallo GMV. Review of current microsurgical management of insular gliomas. Acta Neurochir (Wien) 2010; 152:19-26. [PMID: 19603136 DOI: 10.1007/s00701-009-0450-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2009] [Accepted: 06/22/2009] [Indexed: 10/20/2022]
Abstract
The insular lobe is a functionally complex structure, harbouring peculiar anatomical and vascular features and specific neuronal connectivity with surrounding cerebral structures. It is situated in the depth of the Sylvian fissure and can be affected by either low-grade or high-grade gliomas. Because of its complexity, surgery of insular tumours has been traditionally regarded as hazardous. Nonetheless, currently improved diagnostic, neurophysiological and surgical tools allow the neurosurgeon to perform surgery of insular gliomas in a safer way, thus bringing forward the pioneering work performed by neurosurgeons in the past two decades.The aim of this paper is to provide the reader with an updated review of the anatomy, the clinical picture, diagnosis and surgical management of insular gliomas.
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