The majority of the patients with
multiple sclerosis (MS) experience
fatigue. Some observations indicate that
fatigue and related manifestations concomitant with MS could be associated with an intracellular mild
thiamine deficiency. We recruited 15 patients with MS who also experience
fatigue and assessed the severity of the
fatigue using the
Fatigue Severity Scale. Although blood
thiamine and
thiamine pyrophosphate levels were within normal limit in all the patients, high-dose
thiamine therapy administered orally or parenterally led to an appreciable improvement of the
fatigue. The absence of apparent decrease in blood
thiamine despite the presence of symptoms referable to a mild
thiamine deficiency suggests that these patients may have a dysfunction of the mechanisms of intracellular transport or structural enzymatic abnormalities. The administration of large quantities of
thiamine was effective in reversing the
fatigue in MS, suggesting that the abnormalities in
thiamine-dependent processes could be overcome by diffusion-mediated transport at supranormal
thiamine concentrations.