Severe transient myopathy in a patient with progressive multiple sclerosis and high-dose biotin

Daily high-dose biotin has been suggested to improve disability in patients with progressive multiple sclerosis (P-MS) in a small controlled trial conducted in France.(1) The supposed mechanisms of action supporting high-dose biotin are (1) the support of myelin repair through acetyl-CoA carboxylase activation by enhancing fatty acid synthesis and (2) the protection against axonal degeneration related to hypoxia through enhanced energy production. 2 In the trial, safety was good, with incidence of adverse events similar in both groups, and few serious adverse events (SAE).(1) Here, we report a detailed SAE: a transient myopathy resembling multiple acyl-coenzyme A dehydrogenase deficiency (MADD) or riboflavin transporter defects, reversible upon biotin withdrawal.