Background: Riboflavin (RFV) deficiency is the most common reported dietary vitamin deficiency leading to multisystem dysfunction. Essential steps for successful RFV function include its transport via RFV transporter (RFVT) and the synthesis of its active derivates, flavoprotein coenzymes. Genetic conditions related to the former affect the CNS function primarily, with the clinical presentation of Brown Vialetto Van Laere syndrome and Fazio-Londe disease. The later one results in mitochondrial dysfunction, Multiple Acyl-CoA Dehydrogenase Deficiency syndrome, leading to CNS dysfunction in severe cases and restricted to RFV responsive myopathy in milder cases.
Case presentation: A 29-year-old female with severe alcohol use disorder developed balance problems and weakness. Neuroexam revealed proximal limb muscle weakness and severe sensory ataxia necessitating wheelchair for ambulation. Laboratory findings included hyperCKemia (1200-3000 U/L) and elevated transaminases, abnormal acylcarnitine profile suggestive for RFV metabolism disorder, normal genetic testing for metabolic myopathies/rhabdomyolysis, B1, B6, B12 vitamin levels and autoimmune myopathy panel; but low serum RFV (<1mcg/L) and folate (5.2ng/mL). Electrodiagnostic study revealed a mild myopathy without muscle membrane irritability and no evidence for large fiber polyneuropathy. Muscle biopsy was consistent with lipid storage myopathy. MRI spine showed increased T2 signal in the posterior columns. Ataxia did not improve with folate supplementation. After the oral RFV supplementation she had significant improvement of sensory ataxia and resolution of muscle strength and hyperCKemia and was able to ambulate unassisted. Conclusion: We report a unique case of a myopathy combined with myelopathy as a result of dietary RFV deficiency secondary to severe alcohol use and with favorable outcome after the RFV supplementation.