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Mishra R, Mariyappa N, Rao Malla B, Arivazhagan A, Mishra B, Gautham B, Chowdary Mundlamuri R, Jayabal V, Raghavendra K, Asranna A, Viswanathan LG, Sadashiva N, Bharath RD, Saini J, Nagaraj C, Mangalore S, Karthik K, Rajeswaran J, Kumar K, Mahadevan A, Sinha S. Localisation of eloquent cortex using magnetoencephalography and its clinical implications. Int J Neurosci 2023:1-13. [PMID: 37824719 DOI: 10.1080/00207454.2023.2270684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 10/09/2023] [Indexed: 10/14/2023]
Abstract
OBJECTIVES This study aimed to localise the eloquent cortex and measure evoked field (EF) parameters using magnetoencephalography in patients with epilepsy and tumours near the eloquent cortex. METHODS A total of 41 patients (26 with drug-refractory epilepsy and 15 with tumours), with a mean age of 33 years, were recruited. Visual evoked field (VEF), auditory evoked field (AEF), sensory evoked field (SSEF), and motor-evoked field (MEF) latencies, amplitudes, and localisation were compared with those of a control population. Subgroup analyses were performed based on lobar involvement. Evoked Field parameters on the affected side were compared with those on the opposite side. The effect of distance from the lesion on nearby and distant evoked fields was evaluated. RESULTS AEF and VEF amplitudes and latencies were reduced bilaterally (p < 0.05). Amplitude in the ipsilateral SSEF was reduced by 29.27% and 2.16% in the AEF group compared to the contralateral side (p = 0.02). In patients with temporal lobe lesions, the SSEF amplitude was reduced bilaterally (p < 0.02), and latency was prolonged compared with controls. The MEF amplitude was reduced and latency was prolonged in patients with frontal lobe lesions (p = 0.01). EF displacement was 32%, 57%, 21%, and 16% for AEF, MEF, VEF, and SSEF respectively. Patients in the epilepsy group had distant EF abnormalities. CONCLUSIONS EF amplitude was reduced and latency was prolonged in the involved hemisphere. Distant EF amplitudes were more affected than latencies in epilepsy. Amplitude and distance from the lesion had negative correlation for all EF. EF changes indicated eloquent cortical displacement which may not be apparent on MRI.
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Affiliation(s)
- Rakesh Mishra
- Department of Neurosurgery, NIMHANS, Bangalore, India
| | - N Mariyappa
- MEG Research Centre, NIMHANS, Bangalore, India
- Department of Neurology, NIMHANS, Bangalore, India
| | | | - A Arivazhagan
- Department of Neurosurgery, NIMHANS, Bangalore, India
| | - Bhupendra Mishra
- Department of Computer Science Engineering, IIT Kharagpur, Kharagpur, India
| | - Bhargava Gautham
- MEG Research Centre, NIMHANS, Bangalore, India
- Department of Neurology, NIMHANS, Bangalore, India
| | | | - Velmurugan Jayabal
- MEG Research Centre, NIMHANS, Bangalore, India
- Department of Neurology, NIMHANS, Bangalore, India
| | | | - Ajay Asranna
- Department of Neurology, NIMHANS, Bangalore, India
| | | | | | - Rose Dawn Bharath
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Bangalore, India
| | - Jitender Saini
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Bangalore, India
| | - Chandana Nagaraj
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Bangalore, India
| | - Sandhya Mangalore
- Department of Neuroimaging and Interventional Radiology, NIMHANS, Bangalore, India
| | | | | | - Keshav Kumar
- Department of Clinical Psychology, NIMHANS, Bangalore, India
| | | | - Sanjib Sinha
- MEG Research Centre, NIMHANS, Bangalore, India
- Department of Neurology, NIMHANS, Bangalore, India
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Niimi M, Ohira T, Akiyama T, Hiraga K, Kaneko Y, Ochiai M, Fukunaga A, Kobayashi M, Kawase T. Source analysis of the magnetic field evoked during self-paced finger movements. Neurol Res 2013; 30:239-43. [PMID: 17848207 DOI: 10.1179/016164107x230801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
OBJECTIVE The aim of this study is to investigate a source of cortical magnetic fields evoked by index finger movements. METHODS We analysed both movement-related cortical fields (MRCFs) and somatosensory-evoked fields (SEFs) by single equivalent current dipole (ECD) method in six healthy subjects. Dipole locations were superimposed on MR images of each individual subject. RESULTS The first component after finger movement (movement-evoked field I, MEFI) was observed in all subjects. The dipole of MEFI was oriented posteriorly, and was located on the posterior wall of the central sulcus of the hemisphere contralateral to the movement. The SEFs showed three major components: N20m, P30m and P60m. The dipoles of P30m and P60m were orientated posteriorly, similarly to the MEFI dipole, while that of N20m was orientated anteriorly. The dipole location of MEFI was closely located to P60m, not to N20m and P30m. The mean location of the MEFI dipole was significantly (p<0.05) superior to N20m. CONCLUSION These findings suggest that MEFI would be generated in the sensory area (area 3b) affected by multiple afferents and activities, and that the source of the MEFI is not identical to that of the N20m component.
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Affiliation(s)
- Maki Niimi
- Department of Neurosurgery, School of Medicine, Keio University, 35 Shinano-machi, Shinjuku-ku, Tokyo 160-8582, Japan.
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Ganslandt O, Fahlbusch R, Nimsky C, Kober H, Möller M, Steinmeier R, Romstöck J, Vieth J. Functional neuronavigation with magnetoencephalography: outcome in 50 patients with lesions around the motor cortex. J Neurosurg 1999; 91:73-9. [PMID: 10389883 DOI: 10.3171/jns.1999.91.1.0073] [Citation(s) in RCA: 165] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT The authors conducted a study to evaluate the clinical outcome in 50 patients with lesions around the motor cortex who underwent surgery in which functional neuronavigation was performed. METHODS The sensorimotor cortex was identified in all patients with the use of magnetoencephalography (MEG). The MEG-source localizations were superimposed onto a three-dimensional magnetic resonance image and the image data set was implemented into a neuronavigation system. Based on this setup, the surgeon chose the best surgical strategy. During surgery, the pre- and postcentral gyri were identified by neuronavigation and, in addition, the central sulcus was localized using intraoperative recording of somatosensory evoked potentials. In all cases MEG localizations of the sensory or motor cortex were correct. In 30% of the patients preoperative paresis improved, in 66% no additional deficits occurred, and in only 4% (two patients) deterioration of neurological function occurred. In one of these patients the deterioration was not related to the procedure. CONCLUSIONS The method of incorporating functional data into neuronavigation systems is a promising tool that can be used in more radical surgery to lessen morbidity around eloquent brain areas.
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Affiliation(s)
- O Ganslandt
- Department of Neurosurgery, University of Erlangen-Nürnberg, Erlangen, Germany
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Ganslandt O, Fahlbusch R, Nimsky C, Kober H, Moller M, Steinmeier R, Romstock J, Vieth J. Functional neuronavigation with magnetoencephalography: outcome in 50 patients with lesions around the motor cortex. Neurosurg Focus 1999; 6:e3. [PMID: 17031915 DOI: 10.3171/foc.1999.6.3.6] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The authors conducted a study to evaluate the clinical outcome in 50 patients with lesions around the motor cortex who underwent surgery in which functional neuronavigation was performed.
The sensorimotor cortex was identified in all patients with the use of magnetoencephalography (MEG). The MEG-source localizations were superimposed onto a three-dimensional magnetic resonance image, and the image data set was then implemented into a neuronavigation system. Based on this setup, the surgeon chose the best surgical strategy. During surgery, the pre- and postcentral gyrus were identified by neuronavigation, and in addition, the central sulcus was localized using intraoperative recording of somatosensory evoked potentials. In all cases MEG localizations of the sensory or motor cortex were correct. In 30% of the patients preoperative paresis improved, in 66% no additional deficits occurred, and in only 4% (two patients) deterioration of neurological function occurred. In one of these patients the deterioration was not related to the method.
The method of incorporating functional data into neuronavigation systems is a promising tool that can be used in more radical surgery to cause less morbidity around eloquent brain areas.
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Affiliation(s)
- O Ganslandt
- Department of Neurosurgery and Division of Experimental Neuropsychiatry, and Department of Neurology, University of Erlangen-Nurnberg, Erlangen, Germany
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