Vitamin B12 Deficiency Can Lead to Reversible Basal Ganglia Changes in Infants: A Case Study

A 9-month-old girl, born to non-consanguineous parents, experienced developmental delays and loss of previously achieved milestones from 7 months of age. 

At 6 months, she could roll over, had good hand coordination, and recognized her parents. However, she had difficulty with complementary feeds, leading to exclusive breastfeeding. Her mother followed a vegetarian diet with dairy restrictions during pregnancy and lactation. Over the next 2 months, she developed knuckle hyperpigmentation, sparse hypopigmented hair, and weight and head circumference below average. She also exhibited glossitis, pallor, and irritable behavior with decreased reflexes, hypotonia, and dystonia.

Medical tests revealed megaloblastic anemia, low vitamin B12 levels, and elevated serum homocysteine. Brain MRI showed cortical atrophy and signal changes in the basal ganglia. Her mother had similar issues with anemia and vitamin B12 levels. 

The child was administered intravenous (IV) vitamin B12. After three days, the baby showed tremors, and her condition improved. Thereafter, she regained head control, partial rolling, and parent recognition and exhibited stranger anxiety. She also started oral vitamin B12 supplementation and nutritional rehabilitation. Her hair and skin issues were resolved, and she made developmental progress. 

A follow-up MRI showed reversed signal changes in the basal ganglia, although cortical atrophy persisted. Genetic tests found no pathogenic variants.

The diagnosis considered other metabolic disorders affecting the basal ganglia due to symmetric brain lesions. 

This case differs from previous reports, with bilateral putamen findings and negative genetic testing. It was suggested that methylmalonic acid accumulation, impacting mitochondrial oxygen utilization, could cause basal ganglia lesions. These lesions were reversed with cobalamin (vitamin B12) supplementation. 

This case highlights the importance of considering vitamin B12 deficiency in cases with reversible basal ganglia lesions in brain MRI when clinical features suggest such a deficiency.

Source: Gowda VK, Bylappa AY, Kinhal U, Srinivasan VM. Indian pediatrics. 2023 Sep 15;60(9):770-1.