Efficacy of Transcranial Direct Current Stimulation Over Dorsolateral Prefrontal Cortex in Patients With Minimally Conscious State

Yuan Peng; Jingpu Zhao; Xiao Lu; Juntao Dong; Shunxi Zhang; Jin Zhang; Huihua Liu; Xiuyuan Zheng; Xin Wang; Yue Lan; Tiebin Yan

doi:10.3389/fneur.2022.821286

Efficacy of Transcranial Direct Current Stimulation Over Dorsolateral Prefrontal Cortex in Patients With Minimally Conscious State

Front Neurol. 2022 Feb 18:13:821286. doi: 10.3389/fneur.2022.821286. eCollection 2022.

Authors

Yuan Peng¹, Jingpu Zhao^{2

3}, Xiao Lu⁴, Juntao Dong⁵, Shunxi Zhang¹, Jin Zhang¹, Huihua Liu², Xiuyuan Zheng², Xin Wang⁶, Yue Lan¹, Tiebin Yan²

Affiliations

¹ Department of Rehabilitation Medicine, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, China.
² Department of Rehabilitation Medicine, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China.
³ Department of Rehabilitation, Shenzhen Second People's Hospital, The First Affiliated Hospital of Shenzhen University, Shenzhen, China.
⁴ Department of Rehabilitation Medicine, Guangdong 999 Brain Hospital, Guangzhou, China.
⁵ Huazhong University of Science and Technology Union Shenzhen Hospital, Shenzhen, China.
⁶ Department of Rehabilitation Medicine, Clinical Medical College, Yangzhou University, Yangzhou, China.

Abstract

Background: The treatment of patients in a minimally conscious state (MCS) remains challenging. Transcranial direct current stimulation (tDCS) is a non-invasive therapeutic method in treating neurologic diseases by regulating the cortical excitability. The aim is to investigate the effect of tDCS in patients with MCS in this study.

Methods: Eleven patients in MCS were enrolled in the study. All the patients received 5 daily sessions of 20-min sham tDCS, followed by 10 sessions of 20-min real tDCS. The anodal electrode and cathodal electrodes were placed over the left dorsolateral prefrontal cortex (DLPFC) and the right eyebrow, respectively. Assessment of Coma Recovery Scale-Revised (CRS-R) scores and resting-state functional MRI (rs-fMRI) scans was conducted three times in each patient: before tDCS (baseline, T0), post-sham tDCS at week 1 (T1), and post-real tDCS at week 2 (T2). The whole-brain functional connectivity (FC) was obtained by bilaterally computing FC from six seed regions: precuneus, middle frontal gyrus, supplemental motor area, angular gyrus, superior temporal gyrus, and occipital lobe. One-way repeated measure ANOVA was used to compare the differences of CRS-R scores and FC at T0, T1, and T2. The false discovery rate correction of p < 0.001 was adopted for controlling multiple comparisons in FC analysis.

Results: Five patients with MCS showed obvious clinical improvement represented by increased CRS-R scores post- 2-week real tDCS. The CRS-R scores did not change post- 1-week sham treatment. No side effects were reported during the study. The FC of the bilateral supplementary motor area, right angular gyrus, and right superior temporal gyrus were significantly enhanced after 2-week real tDCS compared with that after 1-week sham-tDCS. In addition, FC of bilateral occipital lobe and right precuneus were significantly enhanced post- 2-week real tDCS compared with the baseline.

Conclusion: Our findings indicated that tDCS over DLPFC could serve as a potentially effective therapy for improving the consciousness state in patients with MCS. The FC in rs-fMRI can be modulated by tDCS at both the stimulation site (left DLPFC) and the distant regions.

Keywords: coma recovery scale-revised score; functional connectivity; left dorsolateral prefrontal cortex; minimally conscious state; transcranial direct current stimulation.