Infantile tremor syndrome associated with cobalamin therapy: a case report

Biochemical, Nutritional, and Clinical Parameters of Vitamin B12 Deficiency in Infants: A Systematic Review and Analysis of 292 Cases Published between 1962 and 2022

Pooled data from published reports on infants with clinically diagnosed vitamin B12 (B12) deficiency were analyzed with the purpose of describing the presentation, diagnostic approaches, and risk factors for the condition to inform prevention strategies. An electronic (PubMed database) and manual literature search following the PRISMA approach was conducted (preregistration with the Open Science Framework, accessed on 15 February 2023). Data were described and analyzed using correlation analyses, Chi-square tests, ANOVAs, and regression analyses, and 102 publications (292 cases) were analyzed. The mean age at first symptoms (anemia, various neurological symptoms) was four months; the mean time to diagnosis was 2.6 months. Maternal B12 at diagnosis, exclusive breastfeeding, and a maternal diet low in B12 predicted infant B12, methylmalonic acid, and total homocysteine. Infant B12 deficiency is still not easily diagnosed. Methylmalonic acid and total homocysteine are useful diagnostic parameters in addition to B12 levels. Since maternal B12 status predicts infant B12 status, it would probably be advantageous to target women in early pregnancy or even preconceptionally to prevent infant B12 deficiency, rather than to rely on newborn screening that often does not reliably identify high-risk children.

Development of infantile tremor syndrome after initiation of hydroxycobalamin treatment in an infant with a late diagnosis of cobalamin C disorder

Combined methylmalonic aciduria and homocystinuria (cobalamin C deficiency, cblC) is a well-described disorder of vitamin B12 metabolism caused by mutations in the MMACHC gene with multisystemic manifestations. While there is no cure, combined treatment with intramuscular hydroxycobalamin and oral betaine may reduce the severity of symptoms and improve clinical outcome. We report a female patient diagnosed with late-onset cobalamin C deficiency at the age of 8 months who presented with developmental regression and severe dermatitis. She developed a movement disorder after initiation of hydroxycobalamin treatment. Similar movement disorders have been described in patients with nutritional vitamin B12 deficiencies following cobalamin supplementation but have not previously been reported in patients with cobalamin C disorder. The movement disorder in our patient gradually resolved with clonazepam treatment, despite no seizure activity detected on EEG. She was eventually weaned off the clonazepam and the abnormal movements have not recurred. The patient remains developmentally delayed but is showing no other symptoms related to cobalamin C deficiency. The patient has a younger affected sibling who was treated from birth and who is physically and developmentally entirely normal; she did not have abnormal movements after treatment with hydroxycobalamin was initiated. There is no clear consensus on the cause of movement disorders that develop following initiation of intramuscular vitamin B12 treatment.

A variety of abnormal movements in 13 cases with nutritional cobalamin deficiency in infants

HYPOTHESIS

Abnormal movements such as tremor, myoclonus, and choreoathetosis due to infantile nutritional vitamin B12 (Cbl, cobalamin) deficiency or after Cbl injection have been recognized for many years. However, nutritional Cbl deficiency may be more common than recognized and a variety of the abnormal movements may be beyond our estimates.

OBJECTIVE

To define the relationship between a large variety of abnormal movements in infants and vitamin B12 deficiency even if serum vitamin B12 levels and/or examination are normal.

MATERIALS AND METHODS

This study analyzed a variety of abnormal movements such as involuntary eye movements, limb and body contractions, and gasping as well as clinical, metabolic, radiologic, and treatment results in 13 infants with nutritional Cbl deficiency. This is a retrospective study based on observation and experience.

RESULTS

This study included 13 infants (11 boys and 2 girls) with a large spectrum of abnormal movements, the mean age at admission was 8.3 months with a range of 3-22 months. All patients were breastfeeding. In seven cases and their mothers serum vitamin B12 levels were below 200 pg/ml. About one-third of cases serum vitamin B12 levels were over 200 pg/ml. Clinically, mild hypotonia was present in 5 cases, inadequate social interactions in 2 cases, and sensorineural hearing loss in one case. Brain MRI showed frontotemporal enlarged subarachnoid spaces and thinning of the corpus callosum in two cases. EEG examinations were normal in all cases at admission. All cases recovered rapidly within one month with treatment.

CONCLUSION

Nutritional Cbl deficiency is a treatable disease that should be considered in the etiology of a variety of movement abnormalities in infants even if serum vitamin B12 values and neurological development are normal.

Growth retardation, general hypotonia, and loss of acquired neuromotor skills in the infants of mothers with cobalamin deficiency and the possible role of succinyl-CoA and glycine in the pathogenesis

Vitamin B12 (cobalamin, Cbl) deficiency can cause metabolic, hematological, and neurological abnormalities. Adequate levels of succinyl-coenzyme A (CoA) cannot be synthesized from methylmalonyl-CoA because of the decreased activity of the methylmalonyl-CoA mutase enzyme that uses Cbl as the cofactor. Succinyl-CoA synthesis deficiency leads to decreased heme synthesis and gluconeogenesis. The reason of growth retardation can be gluconeogenesis deficiency together with heme synthesis deficiency whereas the reason of the neurological abnormalities can be glycine increase in the tissue due to decreased heme synthesis. We present 7 infants diagnosed with severe nutritional Cbl deficiency and discuss the role of succinyl-CoA and glycine in the possible pathogenesis in this article. Patients brought to our clinic with a complaint of growth retardation and diagnosed with nutritional Cbl deficiency were included in the study. There were 5 females and 2 males. The mean age was 11 ± 2.30 (range 6-13) months. All patients had general muscular hypotonia and 4 had growth retardation. Neuromotor growth retardation was found in 4 of the children who had previously shown normal neuromotor development for age. The mean Cbl level was 83.8 ± 27.6 (45.6-114) pg/mL. The mean Cbl level of the mothers was 155 ± 56.6 (88-258) pg/mL. Six of the patients had anemia and 1 had thrombocytopenia. Mean corpuscular volume value was 91.5 ± 12.2 fL. Following treatment, the muscle tonus of the patients improved, the anemia and growth retardation decreased, and the lost neuromotor abilities were recovered. Severe nutritional Cbl deficiency is an important nutritional disease where complications can be prevented with early treatment. When evaluating the pathogenesis, it should be noted that nutritional Cbl deficiency is a succinyl-CoA synthesis deficiency.