MANAGEMENT OF FATIGUE USING TRANSCRANIAL DIRECT CURRENT STIMULATION IN NEUROLOGICAL CONDITIONS: A SYSTEMATIC SCOPING REVIEW

A. Jagadish^1,2, A.M. Shankaranarayana^1,2, M. Natarajan^1,2, J.M. Solomon^1,2

¹Department of Physiotherapy, Manipal College of Health Professions, Manipal Academy of Higher Education, Manipal, India, ²Centre for Comprehensive Stroke Rehabilitation and Research, Manipal Academy of Higher Education, Manipal, India

Background: Perception of fatigue in neurological conditions is caused due to the interaction of homeostatic, psychological, peripheral, and central factors. These factors imply directly or indirectly that the symptoms are central nervous system driven. Despite fatigue being one of the most typical symptoms reported, the management for the same is still in its infancy. Treatment strategies that target the altered cortical excitability mechanism through neuromodulation could play a role in effective recovery. Hence, transcranial direct current stimulation (tDCS) could be a valuable therapeutic approach for the management of fatigue in people with neurological disorders.

Purpose: To identify and summarize the current literature on tDCS interventions for fatigue in neurological conditions.

Methods: A comprehensive literature search was conducted using the following databases; PubMed, Scopus, CINAHL, Web of Science, Embase, ProQuest, and Cochrane Library. Grey literature was manually searched from Google Scholar and clinicaltrials.gov. The review included all the study designs restricted to English language and Human studies. All the relevant studies that implemented tDCS as a management technique for alleviating fatigue in any neurological condition were included. Quality assessment was carried out using Physiotherapy Evidence Database (PEDro) scale for Randomized Control Trials (RCT) and Joanna Briggs Institute (JBI) checklist for Non- RCTs. A data extraction template was formed based on the review objectives, finalized, and charted by two reviewers individually.

Results: A total of 1478 articles were obtained, out of which data from 29 interventional studies are summarized. The PEDro scores ranged from 6-8 (good) for all studies except one (fair). JBI reported a score of 5/9 (moderate). Multiple Sclerosis (n=22, 77%), Parkinson’s disease (n=3, 10%), Post-polio syndrome (n=2, 7%), Stroke (n=1, 3%) and Traumatic Brain Injury (n=1, 3%) implemented tDCS for fatigue management. All the studies primarily used anodal stimulation with the left dorsolateral prefrontal cortex (n=12) commonly stimulated in MS. Stimulation intensity of 1.0mA to 2.5mA with duration ranging from 15 to 30 minutes in 1 to 20 sessions was commonly reported. Fatigue Severity Scale (n=16, 55%) and Modified Fatigue Impact Scale (n=13, 45%) were the frequently implemented outcome measures. Among 29 studies, 7 (24%) showed a positive outcome between groups. The common adverse events noted were tingling (n=5, 17%) and headache (n=4, 14%).

Conclusions: Multiple Sclerosis, Parkinson's disease, Post-polio syndrome, Stroke, and Traumatic Brain Injury were the neurological conditions that have trialed tDCS for fatigue management. Despite differences in stimulation site, treatment parameters, and outcome measures across studies, tDCS positively reduced fatigue symptoms.

Implications: Transcranial direct current stimulation can be a promising tool to alleviate fatigue among neurological populations due to its direct impact on altered cortical excitability. Its applicability can be further investigated in other neurological conditions experiencing fatigue. More primary research is warranted to address the uncertainty noted in the stimulation area and treatment parameters.

Funding acknowledgements: This study is not funded by any agencies in the public, commercial, or not-for-profit sectors.

Keywords:
Nervous system diseases
Transcranial direct current stimulation
Fatigue

Topics:
Neurology: stroke
Neurology: stroke
Neurology

Did this work require ethics approval? No

Reason: This scoping review did not have the direct involvement of the participants. Hence ethical approval was not required.