Impact of transcranial direct current stimulation on fatigue in multiple sclerosis

Fatigue is a frequent and difficult to treat symptom affecting patients with multiple sclerosis (MS) with a profound negative impact on quality of life. Fatigue has been associated with functional and structural abnormalities of the frontal cortex, including frontal hypo-activation. The aim of this exploratory study was to assess whether fatigue symptoms can be reduced by excitability-enhancing anodal transcranial direct current stimulation (tDCS).

In this sham-controlled, double-blind intervention study, tDCS was applied over the left prefrontal cortex of MS patients with fatigue for five consecutive days. Symptoms were tracked for 1 month via questionnaires. Lesion load at baseline was calculated for each patient and correlated with fatigue levels and responsiveness to stimulation.

In the whole group analysis the scores of the fatigue scales were not altered by tDCS. However, in an exploratory analysis we found a correlation between response to the stimulation regarding subjectively perceived fatigue and lesion load in the left frontal cortex: patients responding positively to anodal tDCS had higher lesion load, compared to non-responding patients.

We conclude that in patient subgroups discernible by specific morphological alterations, tDCS may be a tool for MS fatigue management.