Deep Cerebellar Transcranial Direct Current Stimulation of the Dentate Nucleus to Facilitate Standing Balance in Chronic Stroke Survivors-A Pilot Study.

Zeynab Rezaee,Surbhi Kaura,Anirban Dutta,Uttama Lahiri,M V Padma Srivastava,Dhaval Solanki,Adyasha Dash

doi:10.3390/brainsci10020094

Abstract

Objective: Cerebrovascular accidents are the second leading cause of death and the third leading cause of disability worldwide. We hypothesized that cerebellar transcranial direct current stimulation (ctDCS) of the dentate nuclei and the lower-limb representations in the cerebellum can improve functional reach during standing balance in chronic (>6 months’ post-stroke) stroke survivors. Materials and Methods: Magnetic resonance imaging (MRI) based subject-specific electric field was computed across a convenience sample of 10 male chronic (>6 months) stroke survivors and one healthy MRI template to find an optimal bipolar bilateral ctDCS montage to target dentate nuclei and lower-limb representations (lobules VII–IX). Then, in a repeated-measure crossover study on a subset of 5 stroke survivors, we compared 15 min of 2 mA ctDCS based on the effects on successful functional reach (%) during standing balance task. Three-way ANOVA investigated the factors of interest– brain regions, montages, stroke participants, and their interactions. Results: “One-size-fits-all” bipolar ctDCS montage for the clinical study was found to be PO9h–PO10h for dentate nuclei and Exx7–Exx8 for lobules VII–IX with the contralesional anode. PO9h–PO10h ctDCS performed significantly (alpha = 0.05) better in facilitating successful functional reach (%) when compared to Exx7–Exx8 ctDCS. Furthermore, a linear relationship between successful functional reach (%) and electric field strength was found where PO9h–PO10h montage resulted in a significantly (alpha = 0.05) higher electric field strength when compared to Exx7–Exx8 montage for the same 2 mA current. Conclusion: We presented a rational neuroimaging based approach to optimize deep ctDCS of the dentate nuclei and lower limb representations in the cerebellum for post-stroke balance rehabilitation. However, this promising pilot study was limited by “one-size-fits-all” bipolar ctDCS montage as well as a small sample size.

Highlights

Cerebrovascular accidents are the second leading cause of death and the third leading cause of disability worldwide
Based on Van de Winckel [22], the capacity building for the clinical study included: (1) cerebellar transcranial direct current stimulation (ctDCS) treatment design and supervision of ctDCS to facilitate virtual reality (VR)-based functional reach tasks (FRT); (2) assessment of the stroke survivor’s capability to participate in VR-based FRT; (3) ongoing training procedures and materials including assessments of the stroke survivor using VR-based FRT; (4) simple and fail-safe electrode placement technique using a neoprene cap; (5) dose estimation based on computational modeling; (6) quantifying compliance by the rehabilitation specialist at the site, with corresponding corrective steps as required; (7) monitoring for treatment-emergent adverse effects; (8) procedures for discontinuation of a session or study participation including emergency failsafe procedures tailored to the treatment population’s level of need
The reduced set of 87 electrode locations to optimize bipolar ctDCS montage were selected for high L1 norm of the columns of the transfer matrices related to cerebellar brain, namely, “E145”, “E146”, “E156”, “E165”, “Ex1”, “Ex2”, “Ex3”, “Ex4”, “Ex5”, “Ex6”, “Ex7”, “Ex8”, “Exx10”, “Exx11”, “Exx12”, “Exx1”, “Exx2”, “Exx3”, “Exx4”, “Exx5”, “Exx6”, “Exx7”, “Exx8”, “Exx9”, “Exxz”, “Exz”, “I1h”, “I2h”, “Iz”, “NkB”, “NkL”, “NkR”, “O1”, “O1h”, “O2”, “O2h”, “OI1”, “OI1h”, “OI2”, “OI2h”, “OIz”, “Oz”, “P10”, “P10h”, “P7”, “P7h”, “P8”, “P8h”, “P9”, “P9h”, “PO10”, “PO10h”, “PO7”, “PO7h”, “PO8”, “PO8h”, “PO9”, “PO9h”, “POO10”, “POO10h”, “POO1h”, “POO2”, “POO2h”, “POO3h”, “POO8”, “POO9”, “POO9h”, “POOz”, “PPO10”, “PPO10h”, “PPO7”, “PPO7h”, “PPO8”, “PPO8h”, “PPO9”, “PPO9h”, “T5”, “T6”, “TPP10h”, “TPP7”, “TPP8”, “TPP8h”, “TPP9h”, “Z1”, “Z2”, “Z7”, “Z9”

Summary

Introduction

Cerebrovascular accidents (stroke) are the second leading cause of death and the third leading cause of disability worldwide 70% of strokes and 87% of both stroke-related deaths and disability-adjusted life years occur in low- and middle-income countries (LMIC) [1]. Brain Sci. 2020, 10, 94 in the developed world [1], the incidence is increasing in India, an LMIC, due to demographic transition and a rapid shift in the socio-economic milieu. The estimated adjusted prevalence rate of stroke ranges from 84–262/100,000 in rural and 334–424/100,000 in urban India, and the incidence rate is 119–145/100,000 based on the recent population-based studies [2]. Given the high prevalence and incidence of stroke in India, there is a need to investigate low-cost neurotechnologies to facilitate early post-stroke rehabilitation

Methods

Results

Conclusion