Reversible myelopathy in a 34-year-old man with vitamin B₁₂ deficiency

Vitamin B₁₂ deficiency is common, with most patients lacking classic features of advanced severe deficiency. Early diagnosis and treatment prevent severe anemia and irreversible damage to the nervous system. We describe a 34-year-old man with pernicious anemia who presented with clinical and radiologic features of early myelopathy and borderline low serum levels of vitamin B₁₂. Prompt diagnosis based on the measurement of serum methylmalonic acid and treatment with cyanocobalamin injections led to rapid resolution of clinical manifestations and magnetic resonance imaging abnormalities. We review the literature of magnetic resonance imaging in vitamin B₁₂ deficiency myelopathy and discuss the issues relating to diagnosis and early treatment of this potentially reversible condition.