Neurological Consequences of Infantile Vitamin B12 Deficiency - A Prospective Cohort Study

The purpose of this research is to study the neurological consequences of infantile vitamin B12 deficiency on the developing brain.

A prospective cohort study was done in consecutive children with Infantile B12 deficiency. Clinical evaluation, developmental assessment, blood investigations, and a magnetic resonance imaging (MRI) of the brain were performed at baseline and after therapy with injectable vitamin B12.

Among 141 children (median age-13 months), developmental delay was observed in 131 (93%), and 79 (56%) had regression. Eighty (57%) babies had head circumference of < -2 Z score. At baseline, the MRI of the brain was abnormal in 137 (97.2%), showing thinning of corpus callosum (n = 133, 94.3%), cerebral cortical atrophy (n = 128, 90.8%), cerebellar atrophy (n = 126, 89.4%), atrophy of midbrain (n = 81, 57.4%) and pons (n = 78, 55.3%). A follow-up MRI done in 98 (69.5%) showed 66 (67%) had one or more residual abnormalities. The baseline full-scale developmental quotient was 22 (interquartile range: 13-30), while the follow-up full-scale developmental quotient score was 47.5 (interquartile range: 42.5-55). Seventy-nine (67.5%) had a follow-up developmental quotient of less than 50, implying moderate to severe developmental retardation.

Despite therapy, children affected by the infantile B12 deficiency syndrome have significant lasting effects on the brain, evident as poor head growth, developmental deficits, and residual brain imaging changes.