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CC BY-NC-ND 4.0 · International Journal of Epilepsy 2018; 05(02): S12
DOI: 10.1055/s-0039-1694889
Abstracts of 20th Joint Annual Conference of Indian Epilepsy Society and Indian Epilepsy Association (ECON 2019)
Indian Epilepsy Society

Magnetic Source Imaging of Eloquent Cortex: Novel Findings and Implications

Authors

  • Rakesh Kumar Mishra‡

    1   Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India

  • N. Mariyappa‡

    2   MEG Research Centre, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India

  • Sanjib Sinha‡

    3   Department of Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India

  • A. Arivazhagan‡

    1   Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India

  • Malla Bhaskara Rao‡

    1   Department of Neurosurgery, National Institute of Mental Health and Neurosciences, Bengaluru, Karnataka, India

Subject Editor:
Further Information

Publication History

Publication Date:
31 July 2019 (online)

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Objective: Aim of this study is to localize eloquent cortex including vision, language, motor, and sensory area using MEG, study the efficacy of MEG in the localization of eloquent cortex, and to assess the changes in evoked responses due to a lesion in the eloquent cortex.

Methods: This study was performed at the department of neurosurgery, NIMHANS, from March 2016 to July 2019. Detailed clinical examination, multimodal evoked fields, and magnetic source imaging were recorded and analyzed. Patient underwent surgery and data obtained were correlated. Statistical analysis was performed using SPSS 2.0 and R statistical software. Mathematical models included linear regression, logistic regression, state vector machine, confusion matrix, and Wilcoxon's sign rank test to predict the nature of pathology.

Results: A total of 41 patients were recruited with a mean age of 33 years. The 196 evoked fields were analyzed. Amplitude was reduced in the evoked field in affected hemisphere and latency was prolonged. Amplitude of distant evoked field was affected more than latency in the epilepsy group than tumor group. Displacement of evoked field found was 33% in AEF, 57% in MEF, 9% in VEF, and 16% in SSEF. More patients in the epilepsy group had abnormality in the distant evoked fields.

Conclusion: MEG helped in localizing the eloquent cortex and presurgical MEG mapping of eloquent cortex would help in computing the distance between the lesion and eloquent cortex. Being a functional imaging tool, it can help in understanding the pathophysiology of the lesions and its effect on the eloquent cortex.