Neurological Consequences of Vitamin B12 Deficiency and Its Treatment

In developed countries, the vitamin B₁₂ deficiency usually occurs in children exclusively breast-fed, whose mothers are vegetarians, causing low stores of vitamin B₁₂. Symptoms of vitamin B₁₂ deficiency appear during the second trimester of life and include failure to thrive, lethargy, hypotonia, and arrest or regression of developmental skills. A megaloblastic anemia can be present. One half of the infants exhibit abnormal movements before the start of treatment with intramuscular cobalamin, which disappear 1 or 2 days after. More rarely, movement disorders appear a few days after treatment, whereas neurological symptoms are improving. These abnormal movements can last for 2 to 6 weeks. If not treated, vitamin B₁₂ deficiency can cause lasting neurodisability. Therefore, efforts should be directed to preventing deficiency in pregnant and breast-feeding women on vegan diets and their infants by giving them vitamin B₁₂ supplements. When preventive supplementation has failed, one should recognize and treat quickly an infant presenting with failure to thrive and delayed development.