Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system that is considered one of the most frequent causes of disability in the young adult.
Fatigue in MS may affect up to 80 % of the people with MS. It tends to persist over time once it appears. However, despite high frequency, fatigue remains poorly understood. Fatigue in MS is neither consistently linked to disease severity nor disease duration, although it is found to be worse in individuals with the secondary progressive subtype.
Fatigue is distinct from sleepiness, and fails to improve with adequate sleep. Multiple factors are thought to contribute to fatigue\[7 , 8\] with no specific biomarker or etiology yet confirmed.
A wide variety of therapies have been tested to reduce fatigue in MS, but unfortunately, none have been consistently effective. Transcranial direct current stimulation (tDCS) is a relatively recent therapeutic development that utilizes low-amplitude direct currents to induce changes in cortical excitability. Although various non-invasive neuromodulation technologies are available , tDCS has unique advantages compared to other stimulation methods such as its ease of use, lower cost, and greater safety and tolerability.
Small preliminary studies have observed that tDCS may be a promising treatment for MS fatigue, using sham-controlled crossover designs, with five tDCS sessions, using either a motor, sensory, or dorsolateral prefrontal cortex (DLPFC). Recently Chalah et al.\[12\] study demonstrated that DLPFC (left anodal) when compared the posterior parietal cortex led to the most fatigue specific improvements.
Thus, tDCS can reduce fatigue burden for people with MS, it may be possible to implement a tDCS therapy for symptomatic management of fatigue.
