Effects of Long-Lasting High-Definition Transcranial Direct Current Stimulation in Chronic Disorders of Consciousness: A Pilot Study.

Yongkun Guo,Yiwu Dai,Yuanyuan Dang,Jianghong He,Yang Bai,Xiaoli Wang,Jinju Li,Xiaoyu Xia,Chunying Liu,Hui Zhang

doi:10.3389/fnins.2019.00412

Abstract

Transcranial direct current stimulation (tDCS) recently was shown to benefit rehabilitation of patients with disorders of consciousness (DOC). However, high-Definition tDCS (HD-tDCS) has not been applied in DOC. In this study, we tried to use HD-tDCS protocol (2 mA, 20 min, the precuneus, and sustaining 14 days) to rehabilitate 11 patients with DOC. Electroencephalography (EEG) and Coma Recovery Scale–Revised (CRS-R) scores were recorded at before (T0), after a single session (T1), after 7 days’ (T2), and 14 days’ HD-tDCS (T3) to assess the modulation effects. EEG coherence was measured to evaluate functional connectivity during the experiment. It showed that 9 patients’ scores increased compared with the baseline. The central-parietal coherence significantly decreased in the delta band in patients with DOC. EEG coherence might be useful for assessing the effect of HD-tDCS in patients with DOC. Long-lasting HD-tDCS over the precuneus is promising for the treatment of patients with DOC.

Highlights

Chronic disorders of consciousness (DOC) consist of vegetative state/ unresponsive wakefulness syndrome (VS/ UWS) and minimally conscious state (MCS) (Giacino et al, 2014)
Eleven (6 MCS and 5 VS) patients with chronic DOC completed the treatment, with no specific side effects, such as redness of the skin, signs of discomfort or epilepsy. 9/11 (72%) patients (54% of responders, 6 MCS and 3 VS) showed the Coma Recovery Scale–Revised (CRS-R) scores increased after 14 days of stimulation (Table 2)
It demonstrated that long-lasting HD-Transcranial direct current stimulation (tDCS) treatment can improve the recovery of consciousness in patients with DOC, whereas behavioral changes were not observed at just one session of stimulation

Summary

Introduction

Chronic disorders of consciousness (DOC) consist of vegetative state/ unresponsive wakefulness syndrome (VS/ UWS) and minimally conscious state (MCS) (Giacino et al, 2014). TDCS modulates cortical excitability at stimulation sites via weak current which flows through the brain from the anode to the cathode. Our group showed that tDCS can effectively modulate the cortical excitability of patients with DOC, especially in patients with MCS (Bai et al, 2017a,c). Several studies have showed that patients with MCS can benefit from tDCS over the left dorsolateral prefrontal cortex (DLPFC) (Angelakis et al, 2014; Thibaut et al, 2014, 2015, 2017; Dimitri et al, 2017). Except the treatment effect of tDCS in patients with DOC, tDCS induced changes in cortical connectivity and excitability is useful in differentiating MCS from UWS patients (Naro et al, 2015). Researchers found tDCS of the posterior parietal cortex improves the recovery of clinical signs of consciousness in some patients with MCS (Huang et al, 2017). It is difficult to interpret whether produced effects are due to stimulation of the targeted cortical region or neighboring anatomical area (Bai et al, 2014; To et al, 2016)

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