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Hoshino T1,2, Oguchi K1, Hoshiyama M2,3
1Kariya Toyota General Hospital, Rehabilitation, Kariya, Japan, 2Graduate School of Medicine, Nagoya University, Rehabilitation Sciences, Nagoya, Japan, 3Brain & Mind Research Center, Nagoya University, Nagoya, Japan
Background: The neural connectivity (NC) among cortical regions has been investigated as a biomarker to assess brain function. For prediction of motor recovery after stroke, changes in intra- and inter-hemispheric NC among motor related areas have been reported. Clinical application of NC analysis with a convenient method should be considered in the field of rehabilitation. Since the latest analytical method of electroencephalography (EEG) has recently enabled us to use the EEG signals for NC analysis, we applied the NC analysis to patients after stroke to predict their functional recovery.
Purpose: The present study investigated relationship between NC and the upper limb function in patients after stroke, using EEG signals recorded at motor related areas selected.
Methods: The participants were 24 patients (mean age: 62 ±12 (SD)) in recovery stage after stroke. Fugl-Meyer Assessment (FMA) was used to assess upper limb motor function. The EEG signals were obtained from 5 electrodes placed on the motor-related areas; C3, C4 (primary motor cortex, M1), FC3, FC4 (premotor cortex, PMC), and FCz (supplementary motor area, SMA) in the International 10-10 system. The EEG was recorded at supine position with eyes-closed for 60 seconds at rest. Physical assessments and the EEG recordings were performed at 4th week (4W) and 8th week (8W) after stroke. The EEG data were analyzed with a software, Brainstorm (Ver. 3.4.). Amplitude envelope correlations (AEC) between electrodes were calculated in beta frequency band (13-30Hz) for NC between the electrodes. Pairs of electrodes, which showed high correlation between the NC and FMA values, were selected by multiple linear regression analysis.
Results: The FMA scores evaluated at 4W (33±24 (SD)) were improved by 8W (42±23) (p .001). At 4W, the NC value between the central and FC electrodes in the ipsilateral hemisphere to the lesion correlated positively with the FMA value. The NC value between the contralateral central and FC electrodes correlated negatively with FMA. On the other hand at 8W, no significant correlation was found between the NC and FMA values. The NC value between the contralateral central and FC electrodes at 4W correlated with the FMA at 8W.
Conclusion(s): The NC values corresponded with the upper limb function at 4W, and the NC values also predicted the recovery at 8W. Effects of inter-hemispheric inhibition (IHI) from unaffected to affected hemisphere on motor recovery were considered during the recovery stage (Volz et al., 2015; Silasi et al., 2014). We considered that a NC value in the hemisphere affected by stroke suggested a facilitating activity in the hemisphere affected, while that in the unaffected hemisphere corresponded to the inhibitory activity to the affected hemisphere (Wu et al., 2015). The reason why the NC values did not correlated with the FMA at 8W might be that the neural network was differently reconstructed in each participant.
Implications: The present study suggested a possibility of the NC recorded by EEG to be a biomarker for motor recovery after stroke.
Keywords: neural connectivity, stroke, EEG
Funding acknowledgements: This research did not any specific grants from funding agencies in the public, commercial, or not-for-profit sectors.
Purpose: The present study investigated relationship between NC and the upper limb function in patients after stroke, using EEG signals recorded at motor related areas selected.
Methods: The participants were 24 patients (mean age: 62 ±12 (SD)) in recovery stage after stroke. Fugl-Meyer Assessment (FMA) was used to assess upper limb motor function. The EEG signals were obtained from 5 electrodes placed on the motor-related areas; C3, C4 (primary motor cortex, M1), FC3, FC4 (premotor cortex, PMC), and FCz (supplementary motor area, SMA) in the International 10-10 system. The EEG was recorded at supine position with eyes-closed for 60 seconds at rest. Physical assessments and the EEG recordings were performed at 4th week (4W) and 8th week (8W) after stroke. The EEG data were analyzed with a software, Brainstorm (Ver. 3.4.). Amplitude envelope correlations (AEC) between electrodes were calculated in beta frequency band (13-30Hz) for NC between the electrodes. Pairs of electrodes, which showed high correlation between the NC and FMA values, were selected by multiple linear regression analysis.
Results: The FMA scores evaluated at 4W (33±24 (SD)) were improved by 8W (42±23) (p .001). At 4W, the NC value between the central and FC electrodes in the ipsilateral hemisphere to the lesion correlated positively with the FMA value. The NC value between the contralateral central and FC electrodes correlated negatively with FMA. On the other hand at 8W, no significant correlation was found between the NC and FMA values. The NC value between the contralateral central and FC electrodes at 4W correlated with the FMA at 8W.
Conclusion(s): The NC values corresponded with the upper limb function at 4W, and the NC values also predicted the recovery at 8W. Effects of inter-hemispheric inhibition (IHI) from unaffected to affected hemisphere on motor recovery were considered during the recovery stage (Volz et al., 2015; Silasi et al., 2014). We considered that a NC value in the hemisphere affected by stroke suggested a facilitating activity in the hemisphere affected, while that in the unaffected hemisphere corresponded to the inhibitory activity to the affected hemisphere (Wu et al., 2015). The reason why the NC values did not correlated with the FMA at 8W might be that the neural network was differently reconstructed in each participant.
Implications: The present study suggested a possibility of the NC recorded by EEG to be a biomarker for motor recovery after stroke.
Keywords: neural connectivity, stroke, EEG
Funding acknowledgements: This research did not any specific grants from funding agencies in the public, commercial, or not-for-profit sectors.
Topic: Neurology: stroke; Neurology
Ethics approval required: Yes
Institution: Nagoya University, School of Health Sciences
Ethics committee: Nagoya University, School of Health Sciences
Ethics number: No. 17-602
All authors, affiliations and abstracts have been published as submitted.
