Psychomotor regression due to vitamin B12 deficiency

A vitamin B12 deficiency in infants is rare, but may sometimes be seen in breastfed babies of strict vegetarian mothers. Vitamin B12, also known as cobalamin, is only found in meat and other animal products. Most babies have a sufficient supply as long as the mother was not deficient herself. Symptoms and signs of vitamin B12 deficiency appear between the ages of 2 to 12 months and include vomiting, lethargy, failure to thrive, hypotonia, and arrest or regression of developmental skills. Urinary concentrations of methylmalonic acid and homocystine are characteristically elevated in vitamin B12 deficiency. Early treatment for a vitamin B12 deficiency in an infant involves immediate administration of vitamin B12 to the baby and the breastfeeding mother. The infant and mother will each receive an injection of vitamin B12 containing 1,000 mcg or more of the vitamin, and the mother will continue to receive injections every month to raise her own stores. After the initial injection, the baby will often receive future vitamin B12 through food sources. We present a case of vitamin B12 deficiency in a 9-month-old girl presented with psychomotor regression, hypotonia and lethargy. The child was exclusively breast-fed from birth by a mother who was on strict vegetarian diet and belong to a low socio-economic status. Laboratory data revealed bicytopenia with macrocytic anemia and methylmalonic acid in the urine, consistent with vitamin B12 deficient anemia. The Brain CT revealed a cerebral atrophy and delayed myelination. Vitamin B12 supply was effective on anaemia and psychomotor delay. This case figures out the importance of an early diagnosis in front of psychomoteur regression and hypotonia, given the risk of incomplete neurologic recovery due to vitamin B12 deficiency mainly in the setting of maternal nutritional deficiency.


Introduction
Vitamin B12 deficiency (<148 pmol/L) is a major public health problem worldwide [1]. Maternal vitamin B12 deficiency has been associated with increased risk of common pregnancy complications [2] and impaired growth and brain development in offspring [3].
Maternal and fetal vitamin B12 concentrations are thought to be closely associated throughout pregnancy [4]. Previous cross sectional studies in Norway, Turkey, and Brazil have noted correlations between maternal and infant vitamin B12 status at delivery [5]. In developed countries, manifestation is restricted to breast-fed infants of either vegetarian or vegan mothers or mothers with pre-existing malabsorption [6], and to rare cases of genetic defects of vitamin B12 metabolism [7]. Vitamin B12 is found primarily in animal source foods and functions as essential cofactor for methylation of homocysteine to methionine and conversion of methylmalonyl-CoA [7]. Adult hepatic stores of 1-4 mg balance a vitamin B12 devoid diet for several years. In contrast, infantile vitamin B12 body stores comprise about 25µg and may be much lower, if the infant's mother is vitamin B12 deficient [7]. The clinical features of vitamin B12 deficiency include hematologic and neurologic alterations. Hematologically, in about 70% megaloblastic anemia is present. Neurological symptoms comprise muscle weakness, paresthesia and atactic paraplegia in adults. Typical neurological symptoms in infancy are irritability, weakness, developmental delay and failure to thrive, finally apathy and coma [8].
The biochemical mechanisms underlying the neurological symptoms of vitamin B12 deficiency are poorly understood. Impaired myelination, demyelination, axonal degeneration and general cerebral atrophy display morphological correlates [8]. Altered myelin formation and integrity due to dysregulated incorporation of fatty acids have been hypothesized as well as an accumulation of lactate or neurotoxic cytokines [8,9]. With myelination being most active in the first 6 months of life, infantile vitamin B12 deficiency may cause substantial neurological damage [8]. Initial improvement upon therapy might not immediately affect morphological changes, but might be due to a resolution of neurotransmitter imbalance [8].
Thus, treatment does not necessarily result in appropriate psychomotor long-term development. We report a case of vitamin B12 deficiency in a 9-month-old girl presented with psychomotor regression, hypotonia and lethargy.

Patient and observation
We report the 9-month-old exclusively breast-fed girl who had been referred due to progressive hyptonia and apathy. Pregnancy and birth history were unremarkable. The girl had been born full-term Anti-intrinsic factor were not found. This mothers was on strict vegetarian diet (excluded all animal products from her diet) belong to a low socio-economic status explaining this vitamin B12 deficiency and she was also treated with intramuscular cyanocobalamin.

Discussion
From one population to another and among age groups, the prevalence of vitamin B12 deficiency varies considerably. In the US, a prevalence of 1-3% has been reported in children less than 4 years [7][8][9], whereas a high prevalence of up to 40% has been described in children of developing countries due to malnutrition [10]. Vitamin B12 is found primarily in animal source foods and functions as essential cofactor for methylation of homocysteine to methionine and conversion of methylmalonyl-CoA [11]. Adult  [17]. Although it is known that the placenta produces TC, which may be released into the maternal and fetal circuit, the mechanisms and pathways of vitamin B12 transport from the maternal to the fetal circuit are largely unknown [18]. Few data exist on the ability of the placenta to modify vitamin B12 transport in response to maternal vitamin B12 status.
Pregnant adolescents, which represent over 5% of the U.S obstetric population [19], are at an even greater risk for micronutrient deficiencies and pregnancy complications [20].  [21]. This contrasts with Vitamin B12 deficiency in infants who undergo extensive growth and development of the brain: Vitamin B12 deficiency may cause severe impairment in only a few weeks. The most common symptoms include failure to thrive, hypotonia, irritability or lethargy, developmental delay and even regression, [22,23] epilepsy or movement disorder [13,14]. Brain atrophy, delayed myelination [24], polyneuropathy and abnormal evoked responses 9 were

Competing interests
The authors declare no competing interests.