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The neurological syndrome of infantile cobalamin deficiency: developmental regression and involuntary movements
P J Grattan-Smith1, B Wilcken, P G Procopis
1Department of Paediatric Neurology, Westmead Hospital, Sydney, Australia.
Insights
Infants with Vitamin B12 deficiency can develop movement disorders, often presenting as tremor and myoclonus. This neurological sign, particularly in breast-fed infants of vegetarian mothers, may signal early deficiency before severe developmental regression.
Area of Science:
- Neurology
- Pediatrics
- Nutritional Science
Background:
- Cobalamin (Vitamin B12) deficiency is a critical concern in exclusively breast-fed infants, particularly those born to vegetarian mothers.
- Developmental regression is the most common initial symptom, often masking other potential neurological deficits.
Observation:
- This case series reports three infants with Vitamin B12 deficiency who exhibited movement disorders.
- Two infants developed a distinct movement disorder (tremor and myoclonus) affecting the face, tongue, and pharynx within 48 hours of cobalamin treatment initiation.
- One infant presented with a persistent focal tremor prior to treatment.
Findings:
- The movement disorder in two infants coincided with improved plasma amino acid levels and paradoxical neurological improvement.
- The movements observed in the third infant gradually resolved over 3-6 weeks.
- The precise etiology of the post-treatment movement disorder remains unknown.
Implications:
- Movement disorders, though less commonly recognized, may serve as an early indicator of cobalamin deficiency in infants.
- Prompt diagnosis and treatment are crucial to prevent severe neurological deterioration.
- Further research is needed to elucidate the pathophysiology of treatment-emergent movement disorders in cobalamin deficiency.
Abstract:
Developmental regression is the presenting symptom of most infants with cobalamin (Vitamin B12) deficiency. We present a report of three infants with cobalamin deficiency in which the infants also developed a movement disorder. In each case the mother was a vegetarian and the infant was exclusively breast-fed. In two of the infants, a striking movement disorder consisting of a combination of tremor and myoclonus particularly involving face, tongue, and pharynx appeared 48 h after the initiation of treatment with intramuscular cobalamin. This was associated with marked changes in plasma amino acid levels. Paradoxically, the onset of the movement disorder coincided with overall neurological improvement. The third infant had a persistent focal tremor, which appeared before the commencement of treatment. The movements slowly abated during a 3-6 week period. The presence of a movement disorder in cobalamin deficiency has received less attention than other features, but in a mild form is probably common. It may offer an early clue to the diagnosis before the onset of profound neurological deterioration. The cause of the severe movement disorder that can appear after treatment is not known.