THE NEUROLOGICAL SYNDROME OF INFANTILE COBALAMIN DEFICIENCY - DEVELOPMENTAL REGRESSION AND INVOLUNTARY MOVEMENTS

Developmental regression is the presenting symptom of most infants wit h cobalamin (vitamin B-12) deficiency. We present a report of three in fants with cobalamin deficiency in which the infants also developed a movement disorder. In each case the mother was a vegetarian and the in fant was exclusively breast-fed. In two of the infants, a striking mov ement disorder consisting of a combination of tremor and myoclonus par ticularly involving face, tongue, and pharynx appeared 48 h after the initiation of treatment with intramuscular cobalamin. This was associa ted with marked changes in plasma amino acid levels. Paradoxically, th e onset of the movement disorder coincided with overall neurological i mprovement. The third infant had a persistent focal tremor, which appe ared before the commencement of treatment. The movements slowly abated during a 3-6-week period. The presence of a movement disorder in coba lamin deficiency has received less attention than other features, but in a mild form is probably common. It may offer an early clue to the d iagnosis before the onset of profound neurological deterioration. The cause of the severe movement disorder that can appear after treatment is not known.