The Effects of Non-Invasive Brain Stimulation on Quantitative EEG in Patients With Parkinson's Disease: A Systematic Scoping Review.

Thaísa Dias De Carvalho Costa,Suellen Marinho Andrade,Silmara Freitas Dos Santos,Daniel Gomes Da Silva Machado,Rodrigo Alencar E Silva,Clécio Godeiro Júnior

doi:10.3389/fneur.2022.758452

Abstract

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by motor and non-motor symptoms, aside from alterations in the electroencephalogram (EEG) already registered. Non-invasive brain stimulation (NIBS) techniques have been suggested as an alternative rehabilitative therapy, but the neurophysiological changes associated with these techniques are still unclear. We aimed to identify the nature and extent of research evidence on the effects of NIBS techniques in the cortical activity measured by EEG in patients with PD. A systematic scoping review was configured by gathering evidence on the following bases: PubMed (MEDLINE), PsycINFO, ScienceDirect, Web of Science, and cumulative index to nursing & allied health (CINAHL). We included clinical trials with patients with PD treated with NIBS and evaluated by EEG pre-intervention and post-intervention. We used the criteria of Downs and Black to evaluate the quality of the studies. Repetitive transcranial magnetic stimulation (TMS), transcranial electrical stimulation (tES), electrical vestibular stimulation, and binaural beats (BBs) are non-invasive stimulation techniques used to treat cognitive and motor impairment in PD. This systematic scoping review found that the current evidence suggests that NIBS could change quantitative EEG in patients with PD. However, considering that the quality of the studies varied from poor to excellent, the low number of studies, variability in NIBS intervention, and quantitative EEG measures, we are not yet able to use the EEG outcomes to predict the cognitive and motor treatment response after brain stimulation. Based on our findings, we recommend additional research efforts to validate EEG as a biomarker in non-invasive brain stimulation trials in PD.

Highlights

Parkinson’s disease (PD) is a progressive neurodegenerative disorder caused by the degeneration of the dopaminergic neurons of the substance nigra pars compacta and involvement of other neural circuits, resulting in motor and non-motor symptoms [1, 2]
Despite the benefits associated with the use of Non-invasive brain stimulation (NIBS) in the treatment of patients with PD, such as the improvement of motor [3, 5, 8] and non-motor [9–11], the neurophysiological changes associated with these techniques are still unclear
The following search terms, with the Boolean operators AND/OR, were used: “Parkinson disease”; “Parkinson’s disease; “electroencephalography”; “electroencephalogram”; “EEG”; “transcranial direct current stimulation”; “transcranial direct stimulation (tDCS)”; “transcranial magnetic stimulation”; “TMS”; “non-invasive brain stimulation”; “NIBS”; “transcranial electrical stimulation”; “binaural beats (BBs)”; “galvanic vestibular stimulation (GVS)”; “transcranial alternating current stimulation”; and “tACS.” The strategy was adjusted for each database following the example of PsycINFO (Table 1)

Summary

Introduction

Parkinson’s disease (PD) is a progressive neurodegenerative disorder caused by the degeneration of the dopaminergic neurons of the substance nigra pars compacta and involvement of other neural circuits, resulting in motor and non-motor symptoms [1, 2]. Despite the benefits associated with the use of NIBS in the treatment of patients with PD, such as the improvement of motor [3, 5, 8] and non-motor [9–11], the neurophysiological changes associated with these techniques are still unclear In this regard, the electroencephalogram (EEG) is a tool of interest due to the possibility of identifying the changes in bioelectrical brain activity, which presents as a potential neurophysiological biomarker and prognosis for clinical management of PD [12, 13]. NIBS can modify the cerebral oscillations and their associated functions, such as increased synchronization of the frequency bands of the EEG [17], decrease the spectral power of low or high frequencies [18, 19], suggesting a possible link between beta and gamma frequencies with the anti-kinetic and prokinetic effects, respectively [20]. A review concluded that the modulation of beta frequency may be a consolidated marker of the success of NIBS in PD, it presented only preliminary results from TMS and tACS [21]

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