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López-Caballero F, Curtis M, Coffman BA, Salisbury DF. Is source-resolved magnetoencephalographic mismatch negativity a viable biomarker for early psychosis? Eur J Neurosci 2024; 59:1889-1906. [PMID: 37537883 PMCID: PMC10837325 DOI: 10.1111/ejn.16107] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/04/2023] [Accepted: 07/20/2023] [Indexed: 08/05/2023]
Abstract
Mismatch negativity (MMN) is an auditory event-related response reflecting the pre-attentive detection of novel stimuli and is a biomarker of cortical dysfunction in schizophrenia (SZ). MMN to pitch (pMMN) and to duration (dMMN) deviant stimuli are impaired in chronic SZ, but it is less clear if MMN is reduced in first-episode SZ, with inconsistent findings in scalp-level EEG studies. Here, we investigated the neural generators of pMMN and dMMN with MEG recordings in 26 first-episode schizophrenia spectrum (FEsz) and 26 matched healthy controls (C). We projected MEG inverse solutions into precise functionally meaningful auditory cortex areas. MEG-derived MMN sources were in bilateral primary auditory cortex (A1) and belt areas. In A1, pMMN FEsz reduction showed a trend towards statistical significance (F(1,50) = 3.31; p = .07), and dMMN was reduced in FEsz (F(1,50) = 4.11; p = .04). Hypothesis-driven comparisons at each hemisphere revealed dMMN reduction in FEsz occurred in the left (t(56) = 2.23; p = .03; d = .61) but not right (t(56) = 1.02; p = .31; d = .28) hemisphere, with a moderate effect size. The added precision of MEG source solution with high-resolution MRI and parcellation of A1 may be requisite to detect the emerging pathophysiology and indicates a critical role for left hemisphere pathology at psychosis onset. However, the moderate effect size in left A1, albeit larger than reported in scalp MMN meta-analyses, casts doubt on the clinical utility of MMN for differential diagnosis, as a majority of patients will overlap with the healthy individual's distribution.
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Affiliation(s)
- Fran López-Caballero
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Hospital, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Mark Curtis
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Hospital, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Brian A Coffman
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Hospital, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Dean F Salisbury
- Clinical Neurophysiology Research Laboratory, Western Psychiatric Hospital, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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2
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Noorizadeh N, Varner JA, Birg L, Williard T, Rezaie R, Wheless J, Narayana S. Comparing the efficacy of awake and sedated MEG to TMS in mapping hand sensorimotor cortex in a clinical cohort. Neuroimage Clin 2024; 41:103562. [PMID: 38215622 PMCID: PMC10821581 DOI: 10.1016/j.nicl.2024.103562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 11/19/2023] [Accepted: 01/07/2024] [Indexed: 01/14/2024]
Abstract
Non-invasive methods such as Transcranial Magnetic Stimulation (TMS) and magnetoencephalography (MEG) aid in the pre-surgical evaluation of patients with epilepsy or brain tumor to identify sensorimotor cortices. MEG requires sedation in children or patients with developmental delay. However, TMS can be applied to awake patients of all ages with any cognitive abilities. In this study, we compared the efficacy of TMS with MEG (in awake and sedated states) in identifying the hand sensorimotor areas in patients with epilepsy or brain tumors. We identified 153 patients who underwent awake- (n = 98) or sedated-MEG (n = 55), along with awake TMS for hand sensorimotor mapping as part of their pre-surgical evaluation. TMS involved stimulating the precentral gyrus and recording electromyography responses, while MEG identified the somatosensory cortex during median nerve stimulation. Awake-MEG had a success rate of 92.35 % and TMS had 99.49 % (p-value = 0.5517). However, in the sedated-MEG cohort, TMS success rate of 95.61 % was significantly higher compared to MEG's 58.77 % (p-value = 0.0001). Factors affecting mapping success were analyzed. Logistic regression across the entire cohort identified patient sedation as the lone significant predictor, contrary to age, lesion, metal, and number of antiseizure medications (ASMs). A subsequent analysis replaced sedation with anesthetic drug dosage, revealing no significant predictors impacting somatosensory mapping success under sedation. This study yields insights into the utility of TMS and MEG in mapping hand sensorimotor cortices and underscores the importance of considering factors that influence eloquent cortex mapping limitations during sedation.
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Affiliation(s)
- Negar Noorizadeh
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States; Neuroscience Institute, Le Bonheur Children's Hospital, Memphis, TN, United States
| | - Jackie Austin Varner
- Neuroscience Institute, Le Bonheur Children's Hospital, Memphis, TN, United States
| | - Liliya Birg
- Neuroscience Institute, Le Bonheur Children's Hospital, Memphis, TN, United States
| | - Theresa Williard
- Neuroscience Institute, Le Bonheur Children's Hospital, Memphis, TN, United States
| | - Roozbeh Rezaie
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States; Neuroscience Institute, Le Bonheur Children's Hospital, Memphis, TN, United States
| | - James Wheless
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States; Neuroscience Institute, Le Bonheur Children's Hospital, Memphis, TN, United States
| | - Shalini Narayana
- Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, United States; Neuroscience Institute, Le Bonheur Children's Hospital, Memphis, TN, United States; Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, TN, United States.
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3
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Iannotti GR, Nadin I, Ivanova V, Tourdot Q, Lascano AM, Momjian S, Schaller KL, Lovblad KO, Grouiller F. Specificity of Quantitative Functional Brain Mapping with Arterial Spin-Labeling for Preoperative Assessment. AJNR Am J Neuroradiol 2023; 44:1302-1308. [PMID: 37857448 PMCID: PMC10631521 DOI: 10.3174/ajnr.a8006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 08/28/2023] [Indexed: 10/21/2023]
Abstract
BACKGROUND AND PURPOSE Arterial spin-labeling is a noninvasive MR imaging technique allowing direct and quantitative measurement of brain perfusion. Arterial spin-labeling is well-established in clinics for investigating the overall cerebral perfusion, but it is still occasionally employed during tasks. The typical contrast for functional MR imaging is blood oxygen level-dependent (BOLD) imaging, whose specificity could be biased in neurologic patients due to altered neurovascular coupling. This work aimed to validate the use of functional ASL as a noninvasive tool for presurgical functional brain mapping. This is achieved by comparing the spatial accuracy of functional ASL with transcranial magnetic stimulation as the criterion standard. MATERIALS AND METHODS Twenty-eight healthy participants executed a motor task and received a somatosensory stimulation, while BOLD imaging and arterial spin-labeling were acquired simultaneously. Transcranial magnetic stimulation was subsequently used to define hand somatotopy. RESULTS Functional ASL was found more adjacent to transcranial magnetic stimulation than BOLD imaging, with a significant shift along the inferior-to-superior direction. With respect to BOLD imaging, functional ASL was localized significantly more laterally, anteriorly, and inferiorly during motor tasks and pneumatic stimulation. CONCLUSIONS Our results confirm the specificity of functional ASL in targeting the regional neuronal excitability. Functional ASL could be considered as a valid supplementary technique to BOLD imaging for presurgical mapping when spatial accuracy is crucial for delineating eloquent cortex.
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Affiliation(s)
- Giannina R Iannotti
- From the Division of Neuroradiology, Diagnostic Department (G.R.I., K.O.L.), Geneva University Hospitals and University of Geneva, Geneva, Switzerland
- Department of Neurosurgery (G.R.I., I.N., V.I., S.M., K.L.S.), Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Isaure Nadin
- Department of Neurosurgery (G.R.I., I.N., V.I., S.M., K.L.S.), Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Vladimira Ivanova
- Department of Neurosurgery (G.R.I., I.N., V.I., S.M., K.L.S.), Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Quentin Tourdot
- Faculty of Pharmacy (Q.T.), University of Montpellier, Montpellier, France
| | - Agustina M Lascano
- Division of Neurology (A.M.L.), Department of Clinical Neuroscience, Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Shahan Momjian
- Department of Neurosurgery (G.R.I., I.N., V.I., S.M., K.L.S.), Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Karl L Schaller
- Department of Neurosurgery (G.R.I., I.N., V.I., S.M., K.L.S.), Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Karl O Lovblad
- From the Division of Neuroradiology, Diagnostic Department (G.R.I., K.O.L.), Geneva University Hospitals and University of Geneva, Geneva, Switzerland
| | - Frederic Grouiller
- Swiss Centre for Affective Sciences (F.G.), University of Geneva, Geneva, Switzerland
- Center for Biomedical Imaging (F.G.), MRI University of Geneva Cognitive and Affective Neuroimaging Section, Geneva, Switzerland
- Laboratory of Neurology and Imaging of Cognition (F.G.), Department of Basic Neurosciences, University of Geneva, Geneva, Switzerland
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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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Bakhaidar M, Bokhari R, Hall JA, Mirza FA. The Central Sulcus of the Insula: A Highly Reliable Radiographic Landmark for Identification of the Rolandic Sulcus. World Neurosurg 2022; 167:e165-e171. [PMID: 35940504 DOI: 10.1016/j.wneu.2022.07.110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/24/2022] [Accepted: 07/25/2022] [Indexed: 11/16/2022]
Abstract
BACKGROUND Anatomic studies have suggested that the central insular sulcus (CIS) runs in line with the Rolandic sulcus (RS). The radiographic relationship between the RS and CIS has not been systematically studied. This study aims to evaluate the applicability of using the CIS as a radiologic landmark to identify the RS. METHODS We retrospectively reviewed 100 consecutive normal magnetic resonance imaging (MRI) scans (200 hemispheres) performed at a single institution. MRI scans with any intracranial pathology or finding were excluded. Sagittal and axial fluid-attenuated inversion recovery sequences were used in this study. Two evaluators independently evaluated the relationship of the CIS and RS in all MRI scans. A predefined 3-step method was then used to identify the CIS, RS, and hand motor area in sagittal and axial images. RESULTS The CIS was found to be correlated with the RS in 191 hemispheres (95.5%). In the remaining 9 hemispheres, the postcentral sulcus represented the most correlated sulcus with the CIS (7 hemispheres). The interrater agreement was 0.673 (P < 0.05), indicating a substantial agreement. The hand motor area was identified in the same section as the CIS in 175 hemispheres (87.5%). CONCLUSIONS The CIS is a highly reliable radiographic landmark for the identification of the RS. The hand motor area can also be identified reliably using this method.
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Affiliation(s)
- Mohamad Bakhaidar
- Departments of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Neurosurgical Simulation and Artificial Intelligence Learning Centre, Department of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Surgery, Division of Neurosurgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia.
| | - Rakan Bokhari
- Departments of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada; Department of Surgery, Division of Neurosurgery, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Jeffery Alan Hall
- Departments of Neurology and Neurosurgery, Montreal Neurological Hospital and Institute, McGill University, Montreal, Quebec, Canada
| | - Farhan A Mirza
- Department of Neurosurgery, Kentucky Neuroscience Institute, University of Kentucky, Lexington, Kentucky, USA
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Current Status of Neuromodulation-Induced Cortical Prehabilitation and Considerations for Treatment Pathways in Lower-Grade Glioma Surgery. LIFE (BASEL, SWITZERLAND) 2022; 12:life12040466. [PMID: 35454957 PMCID: PMC9024440 DOI: 10.3390/life12040466] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 03/19/2022] [Accepted: 03/19/2022] [Indexed: 12/15/2022]
Abstract
The infiltrative character of supratentorial lower grade glioma makes it possible for eloquent neural pathways to remain within tumoural tissue, which renders complete surgical resection challenging. Neuromodulation-Induced Cortical Prehabilitation (NICP) is intended to reduce the likelihood of premeditated neurologic sequelae that otherwise would have resulted in extensive rehabilitation or permanent injury following surgery. This review aims to conceptualise current approaches involving Repetitive Transcranial Magnetic Stimulation (rTMS-NICP) and extraoperative Direct Cortical Stimulation (eDCS-NICP) for the purposes of inducing cortical reorganisation prior to surgery, with considerations derived from psychiatric, rehabilitative and electrophysiologic findings related to previous reports of prehabilitation. Despite the promise of reduced risk and incidence of neurologic injury in glioma surgery, the current data indicates a broad but compelling possibility of effective cortical prehabilitation relating to perisylvian cortex, though it remains an under-explored investigational tool. Preliminary findings may prove sufficient for the continued investigation of prehabilitation in small-volume lower-grade tumour or epilepsy patients. However, considering the very low number of peer-reviewed case reports, optimal stimulation parameters and duration of therapy necessary to catalyse functional reorganisation remain equivocal. The non-invasive nature and low risk profile of rTMS-NICP may permit larger sample sizes and control groups until such time that eDCS-NICP protocols can be further elucidated.
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Yu S, Guo J, Li Y, Zhang K, Li J, Liu P, Ming H, Guo Y. Advanced modalities and surgical theories in glioma resection: A narrative review. GLIOMA 2022. [DOI: 10.4103/glioma.glioma_14_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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8
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Low-frequency oscillations in cortical level to help diagnose task-specific dystonia. Neurobiol Dis 2021; 157:105444. [PMID: 34265424 DOI: 10.1016/j.nbd.2021.105444] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 06/20/2021] [Accepted: 07/07/2021] [Indexed: 11/23/2022] Open
Abstract
Task-specific dystonia is a neurological movement disorder that abnormal contractions of muscles result in the twisting of fixed postures or muscle spasm during specific tasks. Due to the rareness and the pathophysiology of the disease, there is no test to confirm the diagnosis of task-specific dystonia, except comprehensive observations by the experts. Evidence from neural electrophysiological data suggests that enhanced low frequency (4-12 Hz) oscillations in the subcortical structure of the globus pallidus were associated with the pathological abnormalities concerning β and γ rhythms in motor areas and motor cortical network in patients with task-specific dystonia. However, whether patients with task-specific dystonia have any low-frequency abnormalities in motor cortical areas remains unclear. In this study, we hypothesized that low-frequency abnormalities are present in core motor areas and motor cortical networks in patients with task-specific dystonia during performing the non-symptomatic movements and those low-frequency abnormalities can help the diagnosis of this disease. We tested this hypothesis by using EEG, effective connectivity analysis, and a machine learning method. Fifteen patients with task-specific dystonia and 15 healthy controls were recruited. The machine learning method identified 8 aberrant movement-related network connections concerning low frequency, β and γ frequencies, which enabled the separation of the data of patients from those of controls with an accuracy of 90%. Importantly, 7 of the 8 aberrant connections engaged the premotor area contralateral to the affected hand, suggesting an important role of the premotor area in the pathological abnormities. The patients exhibited significantly lower low frequency activities during the movement preparation and significantly lower β rhythms during movements compared with healthy controls in the core motor areas. Our findings of low frequency- and β-related abnormalities at the cortical level and aberrant motor network could help diagnose task-specific dystonia in the clinical setting, and the importance of the contralesional premotor area suggests its diagnostic potential for task-specific dystonia.
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Asman P, Prabhu S, Bastos D, Tummala S, Bhavsar S, McHugh TM, Ince NF. Unsupervised machine learning can delineate central sulcus by using the spatiotemporal characteristic of somatosensory evoked potentials. J Neural Eng 2021; 18. [PMID: 33836520 PMCID: PMC8718352 DOI: 10.1088/1741-2552/abf68a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 04/09/2021] [Indexed: 11/16/2022]
Abstract
Objective. Somatosensory evoked potentials (SSEPs) recorded with electrocorticography (ECoG) for central sulcus (CS) identification is a widely accepted procedure in routine intraoperative neurophysiological monitoring. Clinical practices test the short-latency SSEPs for the phase reversal over strip electrodes. However, assessments based on waveform morphology are susceptible to variations in interpretations due to the hand area’s localized nature and usually require multiple electrode placements or electrode relocation. We investigated the feasibility of unsupervised delineation of the CS by using the spatiotemporal patterns of the SSEP captured with the ECoG grid. Approach. Intraoperatively, SSEPs were recorded from eight patients using ECoG grids placed over the sensorimotor cortex. Neurosurgeons blinded to the electrophysiology identified the sensory and motor gyri using neuronavigation based on sulcal anatomy. We quantified the most discriminatory time points in SSEPs temporal profile between the primary motor (M1) and somatosensory (S1) cortex using the Fisher discrimination criterion. We visualized the amplitude gradient of the SSEP over a 2D heat map to provide visual feedback for the delineation of the CS based on electrophysiology. Subsequently, we employed spectral clustering using the entire the SSEP waveform without selecting any time points and grouped ECoG channels in an unsupervised fashion. Main results. Consistently in all patients, two different time points provided almost equal discrimination between anterior and posterior channels, which vividly outlined the CS when we viewed the SSEP amplitude distribution as a spatial 2D heat map. The first discriminative time point was in proximity to the conventionally favored ~20 ms peak (N20), and the second time point was slightly later than the markedly high ~30 ms peak (P30). Still, the location of these time points varied noticeably across subjects. Unsupervised clustering approach separated the anterior and posterior channels with an accuracy of 96.3% based on the time derivative of the SSEP trace without the need for a subject-specific time point selection. In contrast, the raw trace resulted in an accuracy of 88.0%. Significance. We show that the unsupervised clustering of the SSEP trace assessed with subdural electrode grids can delineate the CS automatically with high precision, and the constructed heat maps can localize the motor cortex. We anticipate that the spatiotemporal patterns of SSEP fused with machine learning can serve as a useful tool to assist in surgical planning.
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Affiliation(s)
- Priscella Asman
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States of America
| | - Sujit Prabhu
- Department of Neurosurgery, UT MD Anderson Cancer Center, Houston, TX, United States of America
| | - Dhiego Bastos
- Department of Neurosurgery, UT MD Anderson Cancer Center, Houston, TX, United States of America
| | - Sudhakar Tummala
- Department of Neurosurgery, UT MD Anderson Cancer Center, Houston, TX, United States of America
| | - Shreyas Bhavsar
- Department of Anesthesiology, UT MD Anderson Cancer Center, Houston, TX, United States of America
| | - Thomas Michael McHugh
- Department of Anesthesiology, UT MD Anderson Cancer Center, Houston, TX, United States of America
| | - Nuri Firat Ince
- Department of Biomedical Engineering, University of Houston, Houston, TX, United States of America
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10
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Brahimaj BC, Kochanski RB, Pearce JJ, Guryildirim M, Gerard CS, Kocak M, Sani S, Byrne RW. Structural and Functional Imaging in Glioma Management. Neurosurgery 2021; 88:211-221. [PMID: 33313852 DOI: 10.1093/neuros/nyaa360] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 04/26/2020] [Indexed: 01/08/2023] Open
Abstract
The goal of glioma surgery is maximal safe resection in order to provide optimal tumor control and survival benefit to the patient. There are multiple imaging modalities beyond traditional contrast-enhanced magnetic resonance imaging (MRI) that have been incorporated into the preoperative workup of patients presenting with gliomas. The aim of these imaging modalities is to identify cortical and subcortical areas of eloquence, and their relationship to the lesion. In this article, multiple modalities are described with an emphasis on the underlying technology, clinical utilization, advantages, and disadvantages of each. functional MRI and its role in identifying hemispheric dominance and areas of language and motor are discussed. The nuances of magnetoencephalography and transcranial magnetic stimulation in localization of eloquent cortex are examined, as well as the role of diffusion tensor imaging in defining normal white matter tracts in glioma surgery. Lastly, we highlight the role of stimulated Raman spectroscopy in intraoperative histopathological diagnosis of tissue to guide tumor resection. Tumors may shift the normal arrangement of functional anatomy in the brain; thus, utilization of multiple modalities may be helpful in operative planning and patient counseling for successful surgery.
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Affiliation(s)
- Bledi C Brahimaj
- Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois
| | - Ryan B Kochanski
- Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois
| | - John J Pearce
- Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois
| | - Melike Guryildirim
- Department of Radiology and Radiological Science, Johns Hopkins Hospital, Baltimore, Maryland
| | - Carter S Gerard
- Swedish Neuroscience Institute, Swedish Medical Center, Seattle, Washington
| | - Mehmet Kocak
- Department of Diagnostic Radiology and Nuclear Medicine, Rush University Medical Center, Chicago, Illinois
| | - Sepehr Sani
- Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois
| | - Richard W Byrne
- Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois
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11
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Otsubo H, Ogawa H, Pang E, Wong SM, Ibrahim GM, Widjaja E. A review of magnetoencephalography use in pediatric epilepsy: an update on best practice. Expert Rev Neurother 2021; 21:1225-1240. [PMID: 33780318 DOI: 10.1080/14737175.2021.1910024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Introduction: Magnetoencephalography (MEG) is a noninvasive technique that is used for presurgical evaluation of children with drug-resistant epilepsy (DRE).Areas covered: The contributions of MEG for localizing the epileptogenic zone are discussed, in particular in extra-temporal lobe epilepsy and focal cortical dysplasia, which are common in children, as well as in difficult to localize epilepsy such as operculo-insular epilepsy. Further, the authors review current evidence on MEG for mapping eloquent cortex, its performance, application in clinical practice, and potential challenges.Expert opinion: MEG could change the clinical management of children with DRE by directing placement of intracranial electrodes thereby enhancing their yield. With improved identification of a circumscribed epileptogenic zone, MEG could render more patients as suitable candidates for epilepsy surgery and increase utilization of surgery.
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Affiliation(s)
- Hiroshi Otsubo
- Diagnostic Imaging, Hospital for Sick Children, Toronto, Canada
| | - Hiroshi Ogawa
- Diagnostic Imaging, Hospital for Sick Children, Toronto, Canada
| | - Elizabeth Pang
- Diagnostic Imaging, Hospital for Sick Children, Toronto, Canada.,Neuroscience and Mental Health, Hospital for Sick Children, Toronto, Canada
| | - Simeon M Wong
- Neuroscience and Mental Health, Hospital for Sick Children, Toronto, Canada
| | - George M Ibrahim
- Division of Neurosurgery, Hospital for Sick Children, Toronto, Canada.,Diagnostic Imaging, Hospital for Sick Children, Toronto, Canada
| | - Elysa Widjaja
- Diagnostic Imaging, Hospital for Sick Children, Toronto, Canada.,Neuroscience and Mental Health, Hospital for Sick Children, Toronto, Canada.,Diagnostic Imaging, Hospital for Sick Children, Toronto, Canada
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12
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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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13
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Sensorimotor Mapping With MEG: An Update on the Current State of Clinical Research and Practice With Considerations for Clinical Practice Guidelines. J Clin Neurophysiol 2021; 37:564-573. [PMID: 33165229 DOI: 10.1097/wnp.0000000000000481] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In this article, we present the clinical indications and advances in the use of magnetoencephalography to map the primary sensorimotor (SM1) cortex in neurosurgical patients noninvasively. We emphasize the advantages of magnetoencephalography over sensorimotor mapping using functional magnetic resonance imaging. Recommendations to the referring physicians and the clinical magnetoencephalographers to achieve appropriate sensorimotor cortex mapping using magnetoencephalography are proposed. We finally provide some practical advice for the use of corticomuscular coherence, cortico-kinematic coherence, and mu rhythm suppression in this indication. Magnetoencephalography should now be considered as a method of reference for presurgical functional mapping of the sensorimotor cortex.
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14
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Ellis DG, White ML, Hayasaka S, Warren DE, Wilson TW, Aizenberg MR. Accuracy analysis of fMRI and MEG activations determined by intraoperative mapping. Neurosurg Focus 2021; 48:E13. [PMID: 32006951 DOI: 10.3171/2019.11.focus19784] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 11/13/2019] [Indexed: 11/06/2022]
Abstract
OBJECTIVE By looking at how the accuracy of preoperative brain mapping methods vary according to differences in the distance from the activation clusters used for the analysis, the present study aimed to elucidate how preoperative functional neuroimaging may be used in such a way that maximizes the mapping accuracy. METHODS The eloquent function of 19 patients with a brain tumor or cavernoma was mapped prior to resection with both functional MRI (fMRI) and magnetoencephalography (MEG). The mapping results were then validated using direct cortical stimulation mapping performed immediately after craniotomy and prior to resection. The subset of patients with equivalent MEG and fMRI tasks performed for motor (n = 14) and language (n = 12) were evaluated as both individual and combined predictions. Furthermore, the distance resulting in the maximum accuracy, as evaluated by the J statistic, was determined by plotting the sensitivities and specificities against a linearly increasing distance threshold. RESULTS fMRI showed a maximum mapping accuracy at 5 mm for both motor and language mapping. MEG showed a maximum mapping accuracy at 40 mm for motor and 15 mm for language mapping. At the standard 10-mm distance used in the literature, MEG showed a greater specificity than fMRI for both motor and language mapping but a lower sensitivity for motor mapping. Combining MEG and fMRI showed a maximum accuracy at 15 mm and 5 mm-MEG and fMRI distances, respectively-for motor mapping and at a 10-mm distance for both MEG and fMRI for language mapping. For motor mapping, combining MEG and fMRI at the optimal distances resulted in a greater accuracy than the maximum accuracy of the individual predictions. CONCLUSIONS This study demonstrates that the accuracy of language and motor mapping for both fMRI and MEG is heavily dependent on the distance threshold used in the analysis. Furthermore, combining MEG and fMRI showed the potential for increased motor mapping accuracy compared to when using the modalities separately.Clinical trial registration no.: NCT01535430 (clinicaltrials.gov).
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Affiliation(s)
| | - Matthew L White
- 2Radiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Satoru Hayasaka
- 3Department of Psychology, University of Texas at Austin, Texas; and
| | - David E Warren
- 4Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, Nebraska
| | - Tony W Wilson
- 4Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, Nebraska
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15
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Golosheykin SA, Blagoveschenskiy ED, Agranovich OE, Nazarova MA, Nikulin VV, Moiseenko OE, Chan RW, Shestakova AN. Feasibility and Challenges of Performing Magnetoencephalography Experiments in Children With Arthrogryposis Multiplex Congenita. Front Pediatr 2021; 9:626734. [PMID: 34671580 PMCID: PMC8521161 DOI: 10.3389/fped.2021.626734] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 08/31/2021] [Indexed: 12/02/2022] Open
Abstract
Arthrogryposis multiplex congenita (AMC) has recently drawn substantial attention from researchers and clinicians. New effective surgical and physiotherapeutic methods have been developed to improve the quality of life of patients with AMC. While it is clear that all these interventions should strongly rely on the plastic reorganization of the central nervous system, almost no studies have investigated this topic. The present study demonstrates the feasibility of using magnetoencephalography (MEG) to investigate brain activity in young AMC patients. We also outlined the general challenges and limitations of electrophysiological investigations on patients with arthrogryposis. We conducted MEG recordings using a 306-channel Elekta Neuromag VectorView system during a cued motor task performance in four patients with arthrogryposis, five normally developed children, and five control adults. Following the voice command of the experimenter, each subject was asked to bring their hand toward their mouth to imitate the self-feeding process. Two patients had latissimus dorsi transferred to the biceps brachii position, one patient had a pectoralis major transferred to the biceps brachii position, and one patient had no elbow flexion restoration surgery before the MEG investigation. Three patients who had undergone autotransplantation prior to the MEG investigation demonstrated activation in the sensorimotor area contralateral to the elbow flexion movement similar to the healthy controls. One patient who was recorded before the surgery demonstrated subjectively weak distributed bilateral activation during both left and right elbow flexion. Visual inspection of MEG data suggested that neural activity associated with motor performance was less pronounced and more widely distributed across the cortical areas of patients than of healthy control subjects. In general, our results could serve as a proof of principle in terms of the application of MEG in studies on cortical activity in patients with AMC. Reported trends might be consistent with the idea that prolonged motor deficits are associated with more difficult neuronal recruitment and the spatial heterogeneity of neuronal sources, most likely reflecting compensatory neuronal mechanisms. On the practical side, MEG could be a valuable technique for investigating the neurodynamics of patients with AMC as a function of postoperative abilitation.
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Affiliation(s)
- Semyon A Golosheykin
- Center for Cognition and Decision Making, National Research University Higher School of Economics, Moscow, Russia
| | - Evgueni D Blagoveschenskiy
- Center for Cognition and Decision Making, National Research University Higher School of Economics, Moscow, Russia.,G.I. Turner Scientific Research Institute for Children's Orthopaedics, Ministry of Health of Russia, Saint Petersburg, Russia
| | - Olga E Agranovich
- G.I. Turner Scientific Research Institute for Children's Orthopaedics, Ministry of Health of Russia, Saint Petersburg, Russia
| | - Maria A Nazarova
- Center for Cognition and Decision Making, National Research University Higher School of Economics, Moscow, Russia.,Federal State Budgetary Institution ≪Federal Center of Brain Research and Neurotechnologies≫ of the Federal Medical Biological Agency, Moscow, Russia
| | - Vadim V Nikulin
- Center for Cognition and Decision Making, National Research University Higher School of Economics, Moscow, Russia.,Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Olesya E Moiseenko
- Center for Cognition and Decision Making, National Research University Higher School of Economics, Moscow, Russia
| | - Russell W Chan
- Center for Cognition and Decision Making, National Research University Higher School of Economics, Moscow, Russia.,Department of Cognitive Psychology and Ergonomics, University of Twente, Enschede, Netherlands
| | - Anna N Shestakova
- Center for Cognition and Decision Making, National Research University Higher School of Economics, Moscow, Russia
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16
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Ille S, Krieg SM. Functional Mapping for Glioma Surgery, Part 1: Preoperative Mapping Tools. Neurosurg Clin N Am 2020; 32:65-74. [PMID: 33223027 DOI: 10.1016/j.nec.2020.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Although intraoperative mapping of brain areas was shown to promote greater extent of resection and reduce functional deficits, this was shown only recently for some noninvasive techniques. Yet, proper surgical planning, indication, and patient consultation require reliable noninvasive techniques. Because functional magnetic resonance imaging, tractography, and neurophysiologic methods like navigated transcranial magnetic stimulation and magnetoencephalography allow identifying eloquent areas prior to resective surgery and tailor the surgical approach, this article provides an overview on the individual strengths and limitations of each modality.
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Affiliation(s)
- Sebastian Ille
- Department of Neurosurgery, Technical University of Munich, Germany, School of Medicine, Klinikum rechts der Isar, Ismaninger Strasse 22, Munich 81675, Germany
| | - Sandro M Krieg
- Department of Neurosurgery, Technical University of Munich, Germany, School of Medicine, Klinikum rechts der Isar, Ismaninger Strasse 22, Munich 81675, Germany.
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17
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Verburg N, de Witt Hamer PC. State-of-the-art imaging for glioma surgery. Neurosurg Rev 2020; 44:1331-1343. [PMID: 32607869 PMCID: PMC8121714 DOI: 10.1007/s10143-020-01337-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 05/25/2020] [Accepted: 06/15/2020] [Indexed: 11/29/2022]
Abstract
Diffuse gliomas are infiltrative primary brain tumors with a poor prognosis despite multimodal treatment. Maximum safe resection is recommended whenever feasible. The extent of resection (EOR) is positively correlated with survival. Identification of glioma tissue during surgery is difficult due to its diffuse nature. Therefore, glioma resection is imaging-guided, making the choice for imaging technique an important aspect of glioma surgery. The current standard for resection guidance in non-enhancing gliomas is T2 weighted or T2w-fluid attenuation inversion recovery magnetic resonance imaging (MRI), and in enhancing gliomas T1-weighted MRI with a gadolinium-based contrast agent. Other MRI sequences, like magnetic resonance spectroscopy, imaging modalities, such as positron emission tomography, as well as intraoperative imaging techniques, including the use of fluorescence, are also available for the guidance of glioma resection. The neurosurgeon’s goal is to find the balance between maximizing the EOR and preserving brain functions since surgery-induced neurological deficits result in lower quality of life and shortened survival. This requires localization of important brain functions and white matter tracts to aid the pre-operative planning and surgical decision-making. Visualization of brain functions and white matter tracts is possible with functional MRI, diffusion tensor imaging, magnetoencephalography, and navigated transcranial magnetic stimulation. In this review, we discuss the current available imaging techniques for the guidance of glioma resection and the localization of brain functions and white matter tracts.
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Affiliation(s)
- Niels Verburg
- Department of Neurosurgery and Cancer Center Amsterdam, Amsterdam UMC location VU University Medical Center, Amsterdam, The Netherlands. .,Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge Brain Tumor Imaging Laboratory, University of Cambridge, Addenbrooke's Hospital, Hill Rd, Cambridge, CB2 0QQ, UK.
| | - Philip C de Witt Hamer
- Department of Neurosurgery and Cancer Center Amsterdam, Amsterdam UMC location VU University Medical Center, Amsterdam, The Netherlands
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18
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Weiss Lucas C, Nettekoven C, Neuschmelting V, Oros-Peusquens AM, Stoffels G, Viswanathan S, Rehme AK, Faymonville AM, Shah NJ, Langen KJ, Goldbrunner R, Grefkes C. Invasive versus non-invasive mapping of the motor cortex. Hum Brain Mapp 2020; 41:3970-3983. [PMID: 32588936 PMCID: PMC7469817 DOI: 10.1002/hbm.25101] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 05/05/2020] [Accepted: 06/08/2020] [Indexed: 11/26/2022] Open
Abstract
Precise and comprehensive mapping of somatotopic representations in the motor cortex is clinically essential to achieve maximum resection of brain tumours whilst preserving motor function, especially since the current gold standard, that is, intraoperative direct cortical stimulation (DCS), holds limitations linked to the intraoperative setting such as time constraints or anatomical restrictions. Non‐invasive techniques are increasingly relevant with regard to pre‐operative risk‐assessment. Here, we assessed the congruency of neuronavigated transcranial magnetic stimulation (nTMS) and functional magnetic resonance imaging (fMRI) with DCS. The motor representations of the hand, the foot and the tongue regions of 36 patients with intracranial tumours were mapped pre‐operatively using nTMS and fMRI and by intraoperative DCS. Euclidean distances (ED) between hotspots/centres of gravity and (relative) overlaps of the maps were compared. We found significantly smaller EDs (11.4 ± 8.3 vs. 16.8 ± 7.0 mm) and better spatial overlaps (64 ± 38% vs. 37 ± 37%) between DCS and nTMS compared with DCS and fMRI. In contrast to DCS, fMRI and nTMS mappings were feasible for all regions and patients without complications. In summary, nTMS seems to be the more promising non‐invasive motor cortex mapping technique to approximate the gold standard DCS results.
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Affiliation(s)
- Carolin Weiss Lucas
- Medical Faculty and University Hospital, Center for Neurosurgery, University of Cologne, Cologne, Germany
| | - Charlotte Nettekoven
- Medical Faculty and University Hospital, Center for Neurosurgery, University of Cologne, Cologne, Germany
| | - Volker Neuschmelting
- Medical Faculty and University Hospital, Center for Neurosurgery, University of Cologne, Cologne, Germany
| | | | - Gabriele Stoffels
- Research Centre Jülich, Institute of Neuroscience and Medicine, Jülich, Germany
| | | | - Anne K Rehme
- Research Centre Jülich, Institute of Neuroscience and Medicine, Jülich, Germany.,Medical Faculty and University Hospital, Department of Neurology, University of Cologne, Cologne, Germany
| | - Andrea Maria Faymonville
- Medical Faculty and University Hospital, Center for Neurosurgery, University of Cologne, Cologne, Germany
| | - N Jon Shah
- Research Centre Jülich, Institute of Neuroscience and Medicine, Jülich, Germany.,Department of Neurology, RWTH Aachen University, University Clinic Aachen, Aachen, Germany
| | - Karl Josef Langen
- Research Centre Jülich, Institute of Neuroscience and Medicine, Jülich, Germany
| | - Roland Goldbrunner
- Medical Faculty and University Hospital, Center for Neurosurgery, University of Cologne, Cologne, Germany
| | - Christian Grefkes
- Research Centre Jülich, Institute of Neuroscience and Medicine, Jülich, Germany.,Medical Faculty and University Hospital, Department of Neurology, University of Cologne, Cologne, Germany
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19
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Bowyer SM, Pang EW, Huang M, Papanicolaou AC, Lee RR. Presurgical Functional Mapping with Magnetoencephalography. Neuroimaging Clin N Am 2020; 30:159-174. [DOI: 10.1016/j.nic.2020.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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20
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Appliance of Navigated Transcranial Magnetic Stimulation in Radiosurgery for Brain Metastases. J Clin Neurophysiol 2020; 37:50-55. [PMID: 31335563 DOI: 10.1097/wnp.0000000000000621] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
PURPOSE Navigated transcranial magnetic stimulation (nTMS) provides noninvasive visualization of eloquent brain areas. The nTMS is usually applied in presurgical planning to minimize the risk of surgery-related neurological deterioration. The aim of this study was to evaluate the usefulness of nTMS data for GammaKnife treatment planning for patients suffering from brain metastases. METHODS Motor cortex mapping with nTMS was performed in eight patients with brain metastases within or adjacent to the precentral gyrus. The nTMS data set was imported into the planning software and fused with anatomical MRI. Then contouring of the target and critical structures was performed. Treatment plans with and without visualization of the functional structures by nTMS were analyzed and compared by neurosurgeon and medical physicist. RESULTS The primary motor cortex was successfully delineated even in all cases despite significant peritumoral edema. Beam shaping and combined isocenters were used for conformal dose distribution and steeper dose fall-off near the identified eloquent zone. Compared with plans without nTMS data, treatment plans with integration of cortical nTMS mapping data showed a 2% to 78% (mean, 35.2% ± 22.7%) lower 12-Gy volume within the motor cortex without reduction of the dose applied to the tumor. CONCLUSIONS The presented approach allows the easy and reliable integration of neurophysiological mapping data into GammaKnife treatment plans by the standard GammaPlan software. Diminishing the dose to critical structures might help to minimize side effects and therefore improve quality of life for brain metastasis patients.
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21
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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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22
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Roland JL, Hacker CD, Snyder AZ, Shimony JS, Zempel JM, Limbrick DD, Smyth MD, Leuthardt EC. A comparison of resting state functional magnetic resonance imaging to invasive electrocortical stimulation for sensorimotor mapping in pediatric patients. Neuroimage Clin 2019; 23:101850. [PMID: 31077983 PMCID: PMC6514367 DOI: 10.1016/j.nicl.2019.101850] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 04/21/2019] [Accepted: 05/02/2019] [Indexed: 01/11/2023]
Abstract
Localizing neurologic function within the brain remains a significant challenge in clinical neurosurgery. Invasive mapping with direct electrocortical stimulation currently is the clinical gold standard but is impractical in young or cognitively delayed patients who are unable to reliably perform tasks. Resting state functional magnetic resonance imaging non-invasively identifies resting state networks without the need for task performance, hence, is well suited to pediatric patients. We compared sensorimotor network localization by resting state fMRI to cortical stimulation sensory and motor mapping in 16 pediatric patients aged 3.1 to 18.6 years. All had medically refractory epilepsy that required invasive electrographic monitoring and stimulation mapping. The resting state fMRI data were analyzed using a previously trained machine learning classifier that has previously been evaluated in adults. We report comparable functional localization by resting state fMRI compared to stimulation mapping. These results provide strong evidence for the utility of resting state functional imaging in the localization of sensorimotor cortex across a wide range of pediatric patients.
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Affiliation(s)
- Jarod L Roland
- Department of Neurological Surgery, Washington University in St. Louis, St. Louis, MO, United States of America.
| | - Carl D Hacker
- Department of Neurological Surgery, Washington University in St. Louis, St. Louis, MO, United States of America
| | - Abraham Z Snyder
- Mallinckrodt Institute Radiology, Washington University in St. Louis, St. Louis, MO, United States of America; Neurology, Washington University in St. Louis, St. Louis, MO, United States of America
| | - Joshua S Shimony
- Mallinckrodt Institute Radiology, Washington University in St. Louis, St. Louis, MO, United States of America
| | - John M Zempel
- Neurology, Washington University in St. Louis, St. Louis, MO, United States of America
| | - David D Limbrick
- Department of Neurological Surgery, Washington University in St. Louis, St. Louis, MO, United States of America
| | - Matthew D Smyth
- Department of Neurological Surgery, Washington University in St. Louis, St. Louis, MO, United States of America
| | - Eric C Leuthardt
- Department of Neurological Surgery, Washington University in St. Louis, St. Louis, MO, United States of America; Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, United States of America; Neuroscience, Washington University in St. Louis, St. Louis, MO, United States of America; Mechanical Engineering and Materials Science, Washington University in St. Louis, St. Louis, MO, United States of America; Center for Innovation in Neuroscience and Technology, Washington University in St. Louis, St. Louis, MO, United States of America; Brain Laser Center, Washington University in St. Louis, St. Louis, MO, United States of America
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23
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Chen CC, Kuo JC, Wang WJ. Distinguishing the Visual Working Memory Training and Practice Effects by the Effective Connectivity During n-back Tasks: A DCM of ERP Study. Front Behav Neurosci 2019; 13:84. [PMID: 31057376 PMCID: PMC6478890 DOI: 10.3389/fnbeh.2019.00084] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 04/05/2019] [Indexed: 11/25/2022] Open
Abstract
Visual working memory (WM) training and practice can result in improved task performance and increased P300 amplitude; however, only training can yield N160 enhancements. N160 amplitudes are related to the spatial attention, the detection of novelty and the inhibitory control, while P300 amplitudes are related to the selective attention. Therefore, it could be speculated that the mechanisms underlying N160 and P300 production may differ to accommodate to their functions. Based on the different N160 engagements and different functional roles of N160 and P300, we hypothesized that the effects of visual WM training and practice can be dissociated by their brain effective connectivity patterns. We compared different neural connectivity configurations for the main task-related brain activities including N160 and P300 during the visual three-back task in subjects after visual WM training (the WM group) and after repetitive task practice (the control group). The behavioral result shows significantly greater improvement in accuracy after training and suggests that visual WM training can boost the learning process of this simple task. The N160 peak amplitude increased significantly after training over the anterior and posterior brain areas but decreased after practice over the posterior areas, indicating different mechanisms for mediating the training and practice effects. In support of our hypothesis, we observed that visual WM training alters the frontal-parietal connections, which comprise the executive control network (ECN) and the dorsal attention network (DAN), whereas practice modulates the parietal-frontal connections underpinning P300 production for selective attention. It should be noted that the analytic results in this study are conditional on the plausible models being tested and the experimental settings. Studies that employ different tasks, devices and plausible models may lead to different results. Nevertheless, our findings provide a reference for distinguishing the visual WM training and practice effects by the underlying neuroplasticity.
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Affiliation(s)
- Chun-Chuan Chen
- Department of Biomedical Sciences and Engineering, National Central University, Taoyuan, Taiwan.,Institute of Cognitive Neuroscience, National Central University, Taoyuan, Taiwan
| | - Ju-Che Kuo
- Department of Biomedical Sciences and Engineering, National Central University, Taoyuan, Taiwan
| | - Wei-Jen Wang
- Department of Computer Science and Information Engineering, National Central University, Taoyuan, Taiwan
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24
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Zimmermann M, Rössler K, Kaltenhäuser M, Grummich P, Brandner N, Buchfelder M, Dörfler A, Kölble K, Stadlbauer A. Comparative fMRI and MEG localization of cortical sensorimotor function: Bimodal mapping supports motor area reorganization in glioma patients. PLoS One 2019; 14:e0213371. [PMID: 30845241 PMCID: PMC6405066 DOI: 10.1371/journal.pone.0213371] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 02/19/2019] [Indexed: 12/31/2022] Open
Abstract
INTRODUCTION Preoperative functional mapping in the vicinity of brain lesion is of high importance for avoiding complications in surgical management. However, space-occupying lesions may lead to functional reorganization or decreased BOLD activity. METHODS Therefore in 13 patients with cerebral gliomas or brain arterio-venous malformations/ hemangioma fMRI- and MEG-based cortical localizations of motor and somatosensory cortical activation pattern were compared in order to investigate their congruency. RESULTS Localization of cortical sensorimotor areas with fMRI and MEG showed good congruency with a mean spatial distance of around 10 mm, with differences depending on the localization method. The smallest mean differences for the centroids were found for MEF with MNE 8 mm and SEF with sLORETA 8 mm. Primary motor area (M1) reorganization was found in 5 of 12 patients in fMRI and confirmed with MEG data. In these 5 patients with M1-reorganization the distance between the border of the fMRI-based cortical M1-localization and the tumor border on T1w MR images varied between 0-4 mm, which was significant (P = 0.025) different to the distance in glioma patients without M1-reorganization (5-26 mm). CONCLUSION Our multimodal preoperative mapping approach combining fMRI and MEG reveals a high degree of spatial congruence and provided high evidence for the presence of motor cortex reorganization.
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Affiliation(s)
- Max Zimmermann
- Department of Neurosurgery, University of Erlangen-Nürnberg, Erlangen, Germany
- * E-mail:
| | - Karl Rössler
- Department of Neurosurgery, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Martin Kaltenhäuser
- Department of Neurosurgery, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Peter Grummich
- Department of Neurosurgery, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Nadja Brandner
- Department of Neurosurgery, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Michael Buchfelder
- Department of Neurosurgery, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Arnd Dörfler
- Department of Neuroradiology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Konrad Kölble
- Department of Neuropathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Andreas Stadlbauer
- Department of Neurosurgery, University of Erlangen-Nürnberg, Erlangen, Germany
- Institute of Medical Radiology, University Clinic of St. Pölten, St. Pölten, Austria
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25
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Mortazavi MM, Ahmadi Jazi G, Sadati M, Zakowicz K, Sheikh S, Khalili K, Adl FH, Taqi MA, Nguyen HS, Tubbs RS. Modern operative nuances for the management of eloquent high-grade gliomas. J Neurosurg Sci 2019; 63:135-161. [DOI: 10.23736/s0390-5616.18.04594-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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26
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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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De Martin E, Duran D, Ghielmetti F, Visani E, Aquino D, Marchetti M, Sebastiano DR, Cusumano D, Bruzzone MG, Panzica F, Fariselli L. Integration of Functional Magnetic Resonance Imaging and Magnetoencephalography Functional Maps Into a CyberKnife Planning System: Feasibility Study for Motor Activity Localization and Dose Planning. World Neurosurg 2017; 108:756-762. [DOI: 10.1016/j.wneu.2017.08.187] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 08/28/2017] [Accepted: 08/30/2017] [Indexed: 12/31/2022]
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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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Abstract
Maximal safe resection is the cornerstone of treatment for low-grade and high-grade gliomas. In addition to high-resolution anatomic MRI studies that highlight tumor architecture, it is important to determine the relationship of the tumor to the eloquent cortical and subcortical areas to avoid introducing or exacerbating a neurologic deficit. The goal of this review was to highlight imaging modalities that provide functional information and can be integrated with intraoperative MRI navigation to maximize the extent of resection while preserving a patient's neurologic function.
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Burks JD, Bonney PA, Conner AK, Glenn CA, Briggs RG, Battiste JD, McCoy T, O'Donoghue DL, Wu DH, Sughrue ME. A method for safely resecting anterior butterfly gliomas: the surgical anatomy of the default mode network and the relevance of its preservation. J Neurosurg 2016; 126:1795-1811. [DOI: 10.3171/2016.5.jns153006] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVEGliomas invading the anterior corpus callosum are commonly deemed unresectable due to an unacceptable risk/benefit ratio, including the risk of abulia. In this study, the authors investigated the anatomy of the cingulum and its connectivity within the default mode network (DMN). A technique is described involving awake subcortical mapping with higher attention tasks to preserve the cingulum and reduce the incidence of postoperative abulia for patients with so-called butterfly gliomas.METHODSThe authors reviewed clinical data on all patients undergoing glioma surgery performed by the senior author during a 4-year period at the University of Oklahoma Health Sciences Center. Forty patients were identified who underwent surgery for butterfly gliomas. Each patient was designated as having undergone surgery either with or without the use of awake subcortical mapping and preservation of the cingulum. Data recorded on these patients included the incidence of abulia/akinetic mutism. In the context of the study findings, the authors conducted a detailed anatomical study of the cingulum and its role within the DMN using postmortem fiber tract dissections of 10 cerebral hemispheres and in vivo diffusion tractography of 10 healthy subjects.RESULTSForty patients with butterfly gliomas were treated, 25 (62%) with standard surgical methods and 15 (38%) with awake subcortical mapping and preservation of the cingulum. One patient (1/15, 7%) experienced postoperative abulia following surgery with the cingulum-sparing technique. Greater than 90% resection was achieved in 13/15 (87%) of these patients.CONCLUSIONSThis study presents evidence that anterior butterfly gliomas can be safely removed using a novel, attention-task based, awake brain surgery technique that focuses on preserving the anatomical connectivity of the cingulum and relevant aspects of the cingulate gyrus.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Dee H. Wu
- 4Radiological Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma
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Fargier P, Collet C, Moran A, Massarelli R. Inter-disciplinarity in sport sciences: The neuroscience example. Eur J Sport Sci 2016; 17:42-50. [PMID: 27485177 DOI: 10.1080/17461391.2016.1207710] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Sport science is a relatively recent domain of research born from the interactions of different disciplines related to sport. According to the European College of sport science ( http://sport-science.org ): "scientific excellence in sport science is based on disciplinary competence embedded in the understanding that its essence lies in its multi- and interdisciplinary character". In this respect, the scientific domain of neuroscience has been developed within such a framework. Influenced by the apparent homogeneity of this scientific domain, the present paper reviews three important research topics in sport from a neuroscientific perspective. These topics concern the relationship between mind and motor action, the effects of cognition on motor performance, and the study of certain mental states (such as the "flow" effect, see below) and motor control issues to understand, for example, the neural substrates of the vertical squat jump. Based on the few extensive examples shown in this review, we argue that by adopting an interdisciplinary paradigm, sport science can emulate neuroscience in becoming a mono-discipline.
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Affiliation(s)
- Patrick Fargier
- a University of Lyon, University Claude Bernard Lyon 1, Inter-University Laboratory on Human Movement Biology, Federative Centre for Interdisciplinary Research in Sport , Villeurbanne , France
| | - Christian Collet
- a University of Lyon, University Claude Bernard Lyon 1, Inter-University Laboratory on Human Movement Biology, Federative Centre for Interdisciplinary Research in Sport , Villeurbanne , France
| | - Aidan Moran
- b School of Psychology , University College Dublin , Dublin 4 , Ireland
| | - Raphaël Massarelli
- a University of Lyon, University Claude Bernard Lyon 1, Inter-University Laboratory on Human Movement Biology, Federative Centre for Interdisciplinary Research in Sport , Villeurbanne , France
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Technical principles in glioma surgery and preoperative considerations. J Neurooncol 2016; 130:243-252. [DOI: 10.1007/s11060-016-2171-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2016] [Accepted: 06/01/2016] [Indexed: 01/16/2023]
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Fully automated quality assurance and localization of volumetric MEG for single-subject mapping. J Neurosci Methods 2016; 266:21-31. [PMID: 26993819 DOI: 10.1016/j.jneumeth.2016.03.008] [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: 09/17/2015] [Revised: 03/10/2016] [Accepted: 03/11/2016] [Indexed: 11/20/2022]
Abstract
BACKGROUND Robust and reproducible source mapping with magnetoencephalography is particularly challenging at the individual level. We evaluated a receiver-operating characteristic reliability (ROC-r) method for automated production of volumetric MEG maps in single-subjects. ROC-r provides quality assurance comparable to that offered by goodness-of-fit (GoF) and confidence volume (CV) for equivalent current dipole (ECD) modeling. NEW METHOD ROC-r utilizes within-session reproducibility for quality assurance, latency identification, and thresholding of volumetric source maps. We tested ROC-r on simulated and real MEG with a strongly focal source, using somatosensory evoked fields (SEFs) elicited by bilateral median nerve stimulation (MNS). For quality assurance, the ROC-r reliable fraction (FR) was compared to the ECD GoF and CV. Peak beamformer locations and latencies identified by ROC-r were compared to the ECD for co-localization accuracy. RESULTS The predominant component of the SEF response occurred around 35ms, contralateral to the MNS. COMPARISON WITH EXISTING METHODS FR and 1/CV were more strongly correlated (mean Pearson's correlation: 0.76; 95% CI 0.60-0.87) than FR and GoF (0.65; 95% CI 0.32-0.85). There was no difference in the latency of the peak GoF (35.0+/-0.6ms), CV (34.8+/-0.7ms) and FR (35.5+/-0.8ms). The ECD fits and ROC-r peaks co-localized to within a mean (median) distance of 8.3+/-5.9mm (6.2mm). CONCLUSION ROC-r volumetric mapping co-localized closely with the standard ECD approach. This analysis can be added to any whole-brain MEG source imaging protocol, and is especially useful for single-subject mapping. Additionally, the development of FR as an analogue to GoF or CV for volumetric mapping is a critical improvement for clinical applications.
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Reliable recording and analysis of MEG-based corticokinematic coherence in the presence of strong magnetic artifacts. Clin Neurophysiol 2016; 127:1460-1469. [DOI: 10.1016/j.clinph.2015.07.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 07/08/2015] [Accepted: 07/25/2015] [Indexed: 11/21/2022]
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Reliability for non-invasive somatosensory cortex localization: Implications for pre-surgical mapping. Clin Neurol Neurosurg 2015; 139:224-9. [DOI: 10.1016/j.clineuro.2015.10.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 08/21/2015] [Accepted: 10/05/2015] [Indexed: 11/24/2022]
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Willemse RB, Hillebrand A, Ronner HE, Vandertop WP, Stam CJ. Magnetoencephalographic study of hand and foot sensorimotor organization in 325 consecutive patients evaluated for tumor or epilepsy surgery. NEUROIMAGE-CLINICAL 2015; 10:46-53. [PMID: 26693401 PMCID: PMC4660376 DOI: 10.1016/j.nicl.2015.11.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 10/30/2015] [Accepted: 11/04/2015] [Indexed: 01/27/2023]
Abstract
Objectives The presence of intracranial lesions or epilepsy may lead to functional reorganization and hemispheric lateralization. We applied a clinical magnetoencephalography (MEG) protocol for the localization of the contralateral and ipsilateral S1 and M1 of the foot and hand in patients with non-lesional epilepsy, stroke, developmental brain injury, traumatic brain injury and brain tumors. We investigated whether differences in activation patterns could be related to underlying pathology. Methods Using dipole fitting, we localized the sources underlying sensory and motor evoked magnetic fields (SEFs and MEFs) of both hands and feet following unilateral stimulation of the median nerve (MN) and posterior tibial nerve (PTN) in 325 consecutive patients. The primary motor cortex was localized using beamforming following a self-paced repetitive motor task for each hand and foot. Results The success rate for motor and sensory localization for the feet was significantly lower than for the hands (motor_hand 94.6% versus motor_feet 81.8%, p < 0.001; sensory_hand 95.3% versus sensory_feet 76.0%, p < 0.001). MN and PTN stimulation activated 86.6% in the contralateral S1, with ipsilateral activation < 0.5%. Motor cortex activation localized contralaterally in 76.1% (5.2% ipsilateral, 7.6% bilateral and 11.1% failures) of all motor MEG recordings. The ipsilateral motor responses were found in 43 (14%) out of 308 patients with motor recordings (range: 8.3–50%, depending on the underlying pathology), and had a higher occurrence in the foot than in the hand (motor_foot 44.8% versus motor_hand 29.6%, p = 0.031). Ipsilateral motor responses tended to be more frequent in patients with a history of stroke, traumatic brain injury (TBI) or developmental brain lesions (p = 0.063). Conclusions MEG localization of sensorimotor cortex activation was more successful for the hand compared to the foot. In patients with neural lesions, there were signs of brain reorganization as measured by more frequent ipsilateral motor cortical activation of the foot in addition to the traditional sensory and motor activation patterns in the contralateral hemisphere. The presence of ipsilateral neural reorganization, especially around the foot motor area, suggests that careful mapping of the hand and foot in both contralateral and ipsilateral hemispheres prior to surgery might minimize postoperative deficits. Using MEG, S1 and M1 responses of the hand and foot were mapped in patients with brain tumors or epilepsy. Localization of the hand was more successful than of the foot. Ipsilateral S1 responses were rarely seen but ipsilateral M1 responses differed by underlying pathology and limb. Results indicate that differential sensorimotor re-organization can occur in the presence of pathology. Ipsilateral and contralateral mapping of the hand and foot should be done to minimize postsurgical dysfunction.
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Affiliation(s)
- Ronald B Willemse
- Neurosurgical Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
| | - Arjan Hillebrand
- Department of Clinical Neurophysiology and MEG Center, VU University Medical Center, Amsterdam, The Netherlands
| | - Hanneke E Ronner
- Department of Clinical Neurophysiology and MEG Center, VU University Medical Center, Amsterdam, The Netherlands
| | - W Peter Vandertop
- Neurosurgical Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands
| | - Cornelis J Stam
- Department of Clinical Neurophysiology and MEG Center, VU University Medical Center, Amsterdam, The Netherlands
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Ottenhausen M, Krieg SM, Meyer B, Ringel F. Functional preoperative and intraoperative mapping and monitoring: increasing safety and efficacy in glioma surgery. Neurosurg Focus 2015; 38:E3. [PMID: 25552283 DOI: 10.3171/2014.10.focus14611] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Greater extent of resection (EOR) of low-grade gliomas is associated with improved survival. Proximity to eloquent cortical regions often limits resectability and elevates the risk of surgery-related deficits. Therefore, functional localization of eloquent cortex or subcortical fiber tracts can enhance the EOR and functional outcome. Imaging techniques such as functional MRI and diffusion tensor imaging fiber tracking, and neurophysiological methods like navigated transcranial magnetic stimulation and magnetoencephalography, make it possible to identify eloquent areas prior to resective surgery and to tailor indication and surgical approach but also to assess the surgical risk. Intraoperative monitoring with direct cortical stimulation and subcortical stimulation enables surgeons to preserve essential functional tissue during surgery. Through tailored pre- and intraoperative mapping and monitoring the EOR can be maximized, with reduced rates of surgery-related deficits.
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Affiliation(s)
- Malte Ottenhausen
- Department of Neurosurgery, Klinikum rechts der Isar, Technische Universität München, Munich, Germany
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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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Idris Z, Kandasamy R, Reza F, Abdullah JM. Neural oscillation, network, eloquent cortex and epileptogenic zone revealed by magnetoencephalography and awake craniotomy. Asian J Neurosurg 2015; 9:144-52. [PMID: 25685205 PMCID: PMC4323898 DOI: 10.4103/1793-5482.142734] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Magnetoencephalography (MEG) is a method of functional neuroimaging. The concomitant use of MEG and electrocorticography has been found to be useful in elucidating neural oscillation and network, and to localize epileptogenic zone and functional cortex. We describe our early experience using MEG in neurosurgical patients, emphasizing on its impact on patient management as well as the enrichment of our knowledge in neurosciences. MATERIALS AND METHODS A total of 10 subjects were included; five patients had intraaxial tumors, one with an extraaxial tumor and brain compression, two with arteriovenous malformations, one with cerebral peduncle hemorrhage and one with sensorimotor cortical dysplasia. All patients underwent evoked and spontaneous MEG recordings. MEG data was processed at band-pass filtering frequency of between 0.1 and 300 Hz with a sampling rate of 1 kHz. MEG source localization was performed using either overdetermined equivalent current dipoles or underdetermined inversed solution. Neuromag collection of events software was used to study brain network and epileptogenic zone. The studied data were analyzed for neural oscillation in three patients; brain network and clinical manifestation in five patients; and for the location of epileptogenic zone and eloquent cortex in two patients. RESULTS We elucidated neural oscillation in three patients. One demonstrated oscillatory phenomenon on stimulation of the motor-cortex during awake surgery, and two had improvement in neural oscillatory parameters after surgery. Brain networks corresponding to clinico-anatomical relationships were depicted in five patients, and two networks were illustrated here. Finally, we demonstrated epilepsy cases in which MEG data was found to be useful in localizing the epileptogenic zones and functional cortices. CONCLUSION The application of MEG while enhancing our knowledge in neurosciences also has a useful role in epilepsy and awake surgery.
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Affiliation(s)
- Zamzuri Idris
- Center for Neuroscience Service and Research, School of Medical Sciences, Center for Neuroscience Service and Research, Universiti Sains Malaysia, Kubang Kerian, 16150 Kota Bharu, Kelantan, Malaysia ; Department of Neurosciences, School of Medical Sciences, Center for Neuroscience Service and Research, Universiti Sains Malaysia, Kubang Kerian, 16150 Kota Bharu, Kelantan, Malaysia
| | - Regunath Kandasamy
- Department of Neurosciences, School of Medical Sciences, Center for Neuroscience Service and Research, Universiti Sains Malaysia, Kubang Kerian, 16150 Kota Bharu, Kelantan, Malaysia
| | - Faruque Reza
- Department of Neurosciences, School of Medical Sciences, Center for Neuroscience Service and Research, Universiti Sains Malaysia, Kubang Kerian, 16150 Kota Bharu, Kelantan, Malaysia
| | - Jafri M Abdullah
- Center for Neuroscience Service and Research, School of Medical Sciences, Center for Neuroscience Service and Research, Universiti Sains Malaysia, Kubang Kerian, 16150 Kota Bharu, Kelantan, Malaysia ; Department of Neurosciences, School of Medical Sciences, Center for Neuroscience Service and Research, Universiti Sains Malaysia, Kubang Kerian, 16150 Kota Bharu, Kelantan, Malaysia
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Lascano AM, Grouiller F, Genetti M, Spinelli L, Seeck M, Schaller K, Michel CM. Surgically relevant localization of the central sulcus with high-density somatosensory-evoked potentials compared with functional magnetic resonance imaging. Neurosurgery 2014; 74:517-26. [PMID: 24463494 DOI: 10.1227/neu.0000000000000298] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Resection of abnormal brain tissue lying near the sensorimotor cortex entails precise localization of the central sulcus. Mapping of this area is achieved by applying invasive direct cortical electrical stimulation. However, noninvasive methods, particularly functional magnetic resonance imaging (fMRI), are also used. As a supplement to fMRI, localization of somatosensory-evoked potentials (SEPs) recorded with an electroencephalogram (EEG) has been proposed, but has not found its place in clinical practice. OBJECTIVE To assess localization accuracy of the hand somatosensory cortex with SEP source imaging. METHODS We applied electrical source imaging in 49 subjects, recorded with high-density EEG (256 channels). We compared it with fMRI in 18 participants and with direct cortical electrical stimulation in 6 epileptic patients. RESULTS Comparison of SEP source imaging with fMRI indicated differences of 3 to 8 mm, with the exception of the mesial-distal orientation, where variances of up to 20 mm were found. This discrepancy is explained by the fact that the source maximum of the first SEP peak is localized deep in the central sulcus (area 3b), where information initially arrives. Conversely, fMRI showed maximal signal change on the lateral surface of the postcentral gyrus (area 1), where sensory information is integrated later in time. Electrical source imaging and fMRI showed mean Euclidean distances of 13 and 14 mm, respectively, from the contacts where electrocorticography elicited sensory phenomena of the contralateral upper limb. CONCLUSION SEP source imaging, based on high-density EEG, reliably identifies the depth of the central sulcus. Moreover, it is a simple, flexible, and relatively inexpensive alternative to fMRI.
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Affiliation(s)
- Agustina M Lascano
- *Department of Neurology, University Hospital of Geneva, Geneva, Switzerland; ‡Functional Brain Mapping Laboratory, Department of Neurology, University Hospital of Geneva and University Medical Centre, Geneva, Switzerland; §Department of Radiology and Medical Informatics, University Hospital of Geneva, Geneva, Switzerland; ¶Department of Neurosurgery, University Hospitals of Geneva, Geneva, Switzerland
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Gabriel M, Brennan NP, Peck KK, Holodny AI. Blood oxygen level dependent functional magnetic resonance imaging for presurgical planning. Neuroimaging Clin N Am 2014; 24:557-71. [PMID: 25441500 DOI: 10.1016/j.nic.2014.07.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Functional magnetic resonance imaging (fMRI) has become a common tool for presurgical sensorimotor mapping, and is a significant preoperative asset for tumors located adjacent to the central sulcus. fMRI has changed surgical options for many patients. This noninvasive tool allows for easy display and integration with other neuroimaging techniques. Although fMRI is a useful preoperative tool, it is not perfect. Tumors that affect the normal vascular coupling of neuronal activity will affect fMRI measurements. This article discusses the usefulness of blood oxygen level dependent (BOLD) fMRI with regard to preoperative motor mapping.
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Affiliation(s)
- Meredith Gabriel
- Functional MRI Laboratory, Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Nicole P Brennan
- Functional MRI Laboratory, Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Kyung K Peck
- Functional MRI Laboratory, Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Andrei I Holodny
- Functional MRI Laboratory, Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA.
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Jensen RL. Navigated transcranial magnetic stimulation: another tool for preoperative planning for patients with motor-eloquent brain tumors. Neuro Oncol 2014; 16:1299-300. [PMID: 25150252 DOI: 10.1093/neuonc/nou213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Simon MV, Sheth SA, Eckhardt CA, Kilbride RD, Braver D, Williams Z, Curry W, Cahill D, Eskandar EN. Phase reversal technique decreases cortical stimulation time during motor mapping. J Clin Neurosci 2014; 21:1011-7. [DOI: 10.1016/j.jocn.2013.12.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 12/18/2013] [Indexed: 10/25/2022]
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Picht T, Schilt S, Frey D, Vajkoczy P, Kufeld M. Integration of navigated brain stimulation data into radiosurgical planning: potential benefits and dangers. Acta Neurochir (Wien) 2014; 156:1125-33. [PMID: 24744010 DOI: 10.1007/s00701-014-2079-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 03/25/2014] [Indexed: 02/03/2023]
Abstract
BACKGROUND Radiosurgical treatment of brain lesions near motor or language eloquent areas requires careful planning to achieve the optimal balance between effective dose prescription and preservation of function. Navigated brain stimulation (NBS) is the only non-invasive modality that allows the identification of functionally essential areas by electrical stimulation or inhibition of cortical neurons analogous to the gold-standard of intraoperative electrical mapping. OBJECTIVE To evaluate the feasibility of NBS data integration into the radiosurgical environment, and to analyze the influence of NBS data on the radiosurgical treatment planning for lesions near or within motor or language eloquent areas of the brain. METHODS Eleven consecutive patients with brain lesions in presumed motor or language eloquent locations eligible for radiosurgical treatment were mapped with NBS. The radiosurgical team prospectively analyzed the data transfer and classified the influence of the functional NBS information on the radiosurgical treatment planning using a standardized questionnaire. RESULTS The semi-automatized data transfer to the radiosurgical planning workstation was flawless in all cases. The NBS data influenced the radiosurgical treatment planning procedure as follows: improved risk-benefit balancing in all cases, target contouring in 0 %, dose plan modification in 81.9 %, reduction of radiation dosage in 72.7 % and treatment indication in 63.7 % of the cases. CONCLUSIONS NBS data integration into radiosurgical treatment planning is feasible. By mapping the spatial relationship between the lesion and functionally essential areas, NBS has the potential to improve radiosurgical planning safety for eloquently located lesions.
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Affiliation(s)
- Thomas Picht
- Department of Neurosurgery, Charité University Hospital, Augustenburger Platz 1, 13353, Berlin, Germany,
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Functional brain mapping of patients with arteriovenous malformations using navigated transcranial magnetic stimulation: first experience in ten patients. Acta Neurochir (Wien) 2014; 156:885-95. [PMID: 24639144 DOI: 10.1007/s00701-014-2043-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Accepted: 02/16/2014] [Indexed: 10/25/2022]
Abstract
BACKGROUND Intracranial arteriovenous malformations (AVM) are known to be potent inductors of functional plasticity, and their vasculature makes standard functional imaging difficult. Here we conducted functional mapping of both primary motor cortex and speech related areas in patients with AVM using navigated transcranial magnetic stimulation (nTMS), which has been recently proven as a reliable noninvasive modality of preoperative functional brain mapping. METHOD nTMS mapping was performed in ten patients with unruptured intracranial AVMs located in or near eloquent areas. Motor mapping was conducted for six patients with AVMs near the rolandic region, and speech mapping was performed for four patients with left perisylvian AVMs. After the examination, all patients were treated with surgery, radiosurgery or observed with best medical treatment on case-by-case basis. RESULTS Motor mapping allowed for delineation of the primary motor cortex, even if the anatomy was severely obscured by the AVM in all cases with rolandic AVMs. No plastic relocation of the primary motor cortex was observed. Repetitive stimulation of the left ventral precentral gyrus led to speech impairments in all four cases that underwent speech mapping. Right hemispheric involvement was observed in one out of four cases and potentially indicated plastic changes. No side effects were observed. CONCLUSION nTMS allowed for detailed delineation of eloquent areas even within hypervascularized cortical areas. Our observations indicate that nTMS functional mapping is feasible not only in tumorous brain lesions, but also in AVMs.
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Comparison of high gamma electrocorticography and fMRI with electrocortical stimulation for localization of somatosensory and language cortex. Clin Neurophysiol 2014; 126:121-30. [PMID: 24845600 DOI: 10.1016/j.clinph.2014.04.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2014] [Revised: 03/17/2014] [Accepted: 04/16/2014] [Indexed: 11/23/2022]
Abstract
OBJECTIVE We investigated the contribution of electrocortical stimulation (ECS), induced high gamma electrocorticography (hgECoG) and functional magnetic resonance imaging (fMRI) for the localization of somatosensory and language cortex. METHODS 23 Epileptic patients with subdural electrodes underwent a protocol of somatosensory stimulation and/or an auditory semantic decision task. 14 Patients did the same protocol with fMRI prior to implantation. RESULTS ECS resulted in the identification of thumb somatosensory cortex in 12/16 patients. Taking ECS as a gold standard, hgECoG and fMRI identified 53.6/33% of true positive and 4/12% of false positive contacts, respectively. The hgECoG false positive sites were all found in the hand area of the post-central gyrus. ECS localized language-related sites in 7/12 patients with hgECoG and fMRI showing 50/64% of true positive and 8/23% of false positive contacts, respectively. All but one of the hgECoG/fMRI false positive contacts were located in plausible language areas. Four patients showed post-surgical impairments: the resection included the sites positively indicated by ECS, hgECoG and fMRI in 3 patients and a positive hgECoG site in one patient. CONCLUSIONS HgECoG and fMRI provide additional localization information in patients who cannot sufficiently collaborate during ECS. SIGNIFICANCE HgECoG and fMRI make the cortical mapping procedure more flexible not only by identifying priority cortical sites for ECS or when ECS is not feasible, but also when ECS does not provide any result.
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Magnetoencephalography in the Preoperative Evaluation for Epilepsy Surgery. Curr Neurol Neurosci Rep 2014; 14:446. [DOI: 10.1007/s11910-014-0446-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Motor cortex activation by H-coil and figure-8 coil at different depths. Combined motor threshold and electric field distribution study. Clin Neurophysiol 2014; 125:336-43. [DOI: 10.1016/j.clinph.2013.07.013] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 07/24/2013] [Accepted: 07/28/2013] [Indexed: 11/19/2022]
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