Abstract

Introduction: Vitamin B12 deficiency affects not only the bone marrow but also the nervous system. Usually, B12 hypovitaminosis develops slowly to over several years, although infants may also have this disorder.

Patients and Methods: We performed a retrospective analysis of clinical symptoms and results of routine laboratory testing in patients with vitamin B12 deficiency anemia. Our sample included 19 children from 3 - 24 months of age. All patients were treated at Krasnoyarsk Regional Clinical Center for Maternal and Child Health from 2012 to 2019. All participants had serum levels of vitamin B12 < 83 pg/mL.

Results: All patients were found to have nervous system disorders, including muscular hypotonia (100%), hypo- or adynamia and neurodevelopmental retardation (63%), and hyporeflexia (42%). One-third of children (32%) developed involuntary movements during treatment with cyanocobalamin.

A case is reported of an 8 month old boy with developmental regression and brain atrophy secondary to severe vitamin B12 deficiency. Timely cyanocobalamin treatment can prevent irreversible neurological injury.

Conclusion: Vitamin B12 deficiency in infants may manifest itself with neurological disorders that do not correlate with the degree of anemia. Children with muscular hypotonia and delayed psychomotor development should be tested for their serum level of vitamin B12 if all other potential causes of these disorders have been excluded. It is also important to perform differential diagnoses with paroxysmal conditions, including those induced by cobalamin therapy.

Keywords: Infants; Vitamin B12 Deficiency Anemia; Involuntary Movements; Neurological Findings; Cyanocobalamin

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