ADEM Mimic with Thiamine Transporter Deficiency

Abstract

Thiamine transporter-2 (ThTR2) deficiency is a rare autosomal recessive disorder with childhood onset that results from mutations in the SLC19A3 gene. We present a case of a 16-month-old girl with ThTR2 deficiency who presented with encephalopathy and recurrent episodes of developmental regression triggered by acute illness. The clinical features and diagnostic work-up of ThTR2 deficiency are discussed with emphasis on distinguishing this disorder from acute disseminated encephalomyelitis (ADEM) and other mimics including mitochondrial DNA (mtDNA)-associated Leigh syndrome. The chapter highlights the importance of early treatment with high-dose thiamine and biotin to reverse symptoms and prevent the progression of disease and the consideration of empiric treatment in any patient presenting with acute encephalopathy, bilateral basal ganglia lesions, and elevated lactate levels in the brain or blood.