Abstract
ObjectiveA minimally conscious state (MCS) is characterized by discernible behavioral evidence of consciousness that cannot be reproduced consistently. This condition is highly challenging to treat. Recent studies have demonstrated the potential therapeutic effect of non-invasive brain stimulation in patients with MCS. In one patient in an MCS, we delivered simultaneous transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) based on an individual brain network analysis and evaluated the therapeutic effect.MethodsThe directional transfer function (DTF) was calculated based on electroencephalograph (EEG) analysis. Global brain connectivity was calculated based on functional magnetic resonance imaging (fMRI) analysis. By referring to the EEG and fMRI results, we identified inferior parietal lobes (IPLs) as targets. In the 2-week treatment period, 14 sessions were applied to the identified bilateral parietal regions. Simultaneous 1.5-mA anodal tDCS and 5-Hz rTMS were delivered for 20 min per hemisphere in each session. Clinical evaluation scores were recorded weekly throughout the treatment. A second patient given the routine treatment was evaluated as a control.ResultsThe clinical scores of patient 1 with MCS improved after 2 weeks of stimulation treatment, and the effect lasted for up to 1 month. EEG analysis showed a significant increase (p < 0.001) in the DTF value in the gamma band in a bilateral set of posterior regions, and fMRI showed a trend toward normalized activity in the IPLs. The clinical scores of patient 2 with coma did not improve much after 2 weeks of routine treatment. The EEG analysis showed a significant increase (p = 0.021) in the DTF value in the gamma band in a bilateral set of posterior regions.ConclusionThe application of EEG and fMRI to characterize the functional connectivity features of the network in an MCS patient provided a reasonable and accurate stimulation target and verified the changes in functional connectivity resulting from stimulation.
Highlights
MATERIALS AND METHODSA minimally conscious state (MCS) is characterized by discernible behavioral evidence of consciousness that cannot be reproduced consistently (Giacino et al, 2002)
We identified stimulation targets and evaluated therapeutic effects by analyzing functional connections based on scalp electroencephalography (EEG) and functional magnetic resonance imaging
Further analysis of subscales of the Coma Recovery Scale-Revised (CRS-R) score in patient 1 showed that the arousal and auditory functions were the first to show improvement during stimulation (Figure 4B)
Summary
MATERIALS AND METHODSA minimally conscious state (MCS) is characterized by discernible behavioral evidence of consciousness that cannot be reproduced consistently (Giacino et al, 2002). An MCS may result from degenerative nervous system disorders or evolve from a coma or vegetative state (VS). In MCS patients, integrated cortical functions are retained but undersustained. Recent studies have demonstrated the potential therapeutic effect of non-invasive brain stimulation (NIBS) in patients with MCS. Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) are two NIBS techniques that have been developed in the past decades. Anodal tDCS can change the resting membrane potential by influencing ion channels and gradients, increasing cortical excitability (Lefaucheur et al, 2017). These techniques have recently been employed independently in the treatment of MCS and have shown some inspiring beneficial results
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