Comparing the effects of multi-session anodal trans-cranial direct current stimulation of primary motor and dorsolateral prefrontal cortices on fatigue and quality of life in patients with multiple sclerosis: a double-blind, randomized, sham-controlled trial

Abstract

Objective: To compare the effects of anodal trans-cranial direct current stimulation (a-tDCS) over primary motor and dorsolateral prefrontal cortices on Fatigue Severity Scale and its lasting effect on fatigue reduction and improvement in quality of life in patients with multiple sclerosis. Design: A randomized, double-blinded, sham-controlled parallel clinical trial study. Setting: Neurological physiotherapy clinics. Subjects: Thirty-nine participants were randomly assigned to three groups: dorsolateral prefrontal cortex a-tDCS, primary motor a-tDCS (experimental groups) and sham a-tDCS. Finally, 36 participants completed the whole study ( n = 12 in each group). Interventions: Participants in the experimental groups received six-session a-tDCS (1.5 mA, 20 minutes) during two weeks (three sessions per week). The sham group received six sessions of 20-minute sham stimulation. Main measures: The Fatigue Severity Scale and quality of life were assessed before, immediately and four weeks after the intervention. Results: Findings indicated a significant reduction in the Fatigue Severity Scale and a significant increase in the quality of life in both experimental groups, immediately after the intervention ( P < 0.001), while Fatigue Severity Scale and quality of life changes were not significant in the sham a-tDCS group ( P > 0.05). In addition, improvement of the variables remained four weeks after the intervention in dorsolateral prefrontal cortex a-tDCS (mean differences (95% confidence interval): 0.03 (−0.63 to 0.68) as compared to primary motor (−0.62 (−0.11 to −1.14) and sham a-tDCS groups (−0.47 (−1.37 to 0.43)). Conclusion: Both primary motor and dorsolateral prefrontal cortex a-tDCS as compared to sham intervention can immediately improve fatigue and quality of life. However, the effects last up to four weeks only by the dorsolateral prefrontal cortex a-tDCS.

Effects of Transcranial Direct Current Stimulation on Cognition, Mood, Pain, and Fatigue in Multiple Sclerosis: A Systematic Review and Meta-Analysis

“…For cognition and mood, one of the studies contributed more than one trial, due to different stimulation sites (24). For fatigue, four articles contributed more than one trial because they applied the stimulation over different brain regions (24,32,33) or employed two studies with different design (34). For pain, SD was calculated from standard error of mean (SEM) in one study (23).…”

“…One of the studies did not report the M and SD of their outcome measures and the data were extracted from the figures (30). The SD was calculated from SEM (32,35) and data range (36) based on the range rule of thumb (37,38) in three of the studies. All the extracted data were carefully checked by another author (C.-H. C.) and disagreements were resolved by discussion.…”

“…The standardized effect sizes and 95% confidence interval (CI) were calculated to test the results of different trials. The effect sizes were calculated based on differences between the post-treatment evaluations (22,24,25,32,33,36,(39)(40)(41)(42), changes relative to the baseline (23), or the mean changes between pre-and post-treatments (20,21,26,30,34,35) in the experimental and control groups, divided by the pooled SD. Because the effect sizes from each study may be influenced by the sample sizes, a weighting factor was applied to give more weight to the studies with larger samples.…”

“…Two studies were designed as single session trials (26,35). Ten studies applied the stimulation at an intensity lower than 2 mA (20,25,26,30,32,33,35,36,39,41). Target stimulation regions included motor cortex (23,25,32,42), dorsolateral prefrontal cortex (20-22, 24, 30, 32, 34, 35, 40), primary somatosensory cortex (33,36,39,41), sensorimotor cortex (33) and parietal cortex (24,26).…”

“…Eight studies reported adverse events. These included skin reaction, insomnia, tingling, itching, phosphene, burning sensation, head pain or pressure, difficulty concentrating, facial muscle twitching, nausea, fatigue, and iron taste (21,22,24,25,30,32,34,40). One study (23) reported no adverse events.…”