Progressive neurological deterioration and MRI changes in cblC methylmalonic acidaemia treated with hydroxocobalamin

Cobalamin C (cblC) defects result in decreased activity of both methylmalonyl-CoA mutase and N5-methyltetrahydrofolate:homocysteine methyltransferase (methionine synthase), with subsequent methylmalonic acid-uria and homocystinuria. Patients typically show failure to thrive, developmental delay and megaloblastic anaemia. Vitamin B12 therapy has been beneficial in some cases. We report a now 4-year-old Hispanic girl with cblC disease documented by complementation analysis, with progressive neurological deterioration and worsening head MRI changes while on intramuscular hydroxocobalamin begun at age 3 weeks. Oral carnitine and folic acid were added at age 1 year. Blood levels of methylmalonic acid were reduced to treatment ranges. In the absence of acute metabolic crises, she developed microcephaly, progressive hypotonia and decreased interactiveness. Funduscopic examination was normal at age 13 months. At age 19 months, she developed nystagmus, and darkly pigmented fundi and sclerotic retinal vessels were observed on examination. Her neonatal head MRI was normal. By age 1 year, the MRI showed diffuse white-matter loss with secondary third and lateral ventricle enlargement, a thin corpus callosum, and normal basal ganglia. At age 15 months, progression of the white-matter loss, as well as hyperintense globi pallidi, were present. Interval progression of both grey- and white-matter loss was seen at age 27 months. We therefore caution that progressive neurological deterioration and head MRI abnormalities may still occur in cblC disease, despite early initiation of hydroxocobalamin therapy and improvement in toxic metabolite concentrations in physiological fluids.

Long-term outcome in treated combined methylmalonic acidemia and homocystinemia

PURPOSE

To describe the clinical and biochemical features and long-term outcome of a cohort of eight patients with methylmalonic acidemia and homocystinuria (cblC).

METHODS

Documentation of clinical features at birth and longitudinal follow-up of the biochemical and clinical response to treatment with daily oral carnitine and intramuscular hydroxocobalamin observed during continuous follow-up for an average of 5.7 years.

RESULTS

Our patients had an increased incidence of congenital malformations including microcephaly (<5%) at birth (2 of 8), congenital heart disease (2 of 8), dysmorphic facial features (1 of 8), and thyroglossal duct cyst (1 of 8). Postnatal hydrocephalus (2 of 8) and hip dislocation caused by ligament laxity (1 of 8) were also noted. One patient had profound visual impairment before 6 months of age secondary to cblC retinopathy, and two patients had abnormal retinal pigmentation with normal visual function. All patients presented with poor growth, feeding problems, and/or seizures. No patients had acute acidotic crises before or after treatment. All patients had dramatic reduction of plasma free homocystine and urine methylmalonic acid excretion after initiation of therapy with carnitine, intramuscular (IM) hydroxocobalamin (OHcbl) and, in two cases, oral betaine. Growth was significantly improved in most cases after the initiation of therapy, and microcephaly was resolved in one patient. All patients were developmentally delayed regardless of age of treatment onset, although two patients had relatively mild developmental delay.

CONCLUSION

cblC patients may have an increased incidence of congenital malformations suggesting prenatal effects of abnormal cbl metabolism. Treatment with IM OHcbl and carnitine successfully corrects the biochemical abnormalities and improves growth. Developmental delay of variable severity is always present regardless of age at diagnosis or treatment onset.

MRI of the spinal cord in myelopathy complicating vitamin B12 deficiency: two additional cases and a review of the literature

Focal spinal cord lesions have been present in all previously reported cases of MRI appearances in myelopathy complicating vitamin B12 deficiency. We describe two further cases showing mild atrophy only and review the salient features of the previous 11 publications. MRI findings reflect quite closely the known pathological changes in this condition.

[Polyneuropathy caused by vitamin B12 deficiency secondary to chronic atrophic gastritis and giardiasis]

INTRODUCTION

In chronic atrophic gastritis atrophy of the stomach glands leads to intrinsic factor deficit, with consequent failure to absorb vitamin B12 and gastric achylia, which predisposes to Giardia infection which in itself leads to depletion of vitamin B12. We describe the case of a patient with peripheral and central nervous system pathology due to lack of vitamin B12 secondary to the combined effect of these two disorders.

CLINICAL CASE

A 54 year old woman consulted us for paraesthesia and weakness of the legs which had been progressive for the previous two years. She presented with tactile hypoaesthesia, hypoparaesthesia, distal hyperreflexia and dysymmetry of the legs, ataxic-spastic gait and a positive Romberg sign. The investigations carried out showed the serum vitamin B12 level to be 3 pg/ml (N: 180-900), hemoglobin 13 g/dl and MCV 111 fl with MCHC 348/dl; neurophysiological studies: compatible with demyelinating motor polyneuropathy. Schilling test: deficit of absorption of vitamin B12 which was corrected on administration of intrinsic factor; gastroscopy; atrophic gastritis which confirmed the morbid anatomy findings. There was also flora containing Helicobacter and massive Giardia infection. Replacement and antibiotic therapy was followed by complete remission of the clinical picture.

CONCLUSION

We emphasize the excellent clinical response to treatment in spite of the time elapsed since onset of symptoms.

Vitamin supplementation reduces blood homocysteine levels: a controlled trial in patients with venous thrombosis and healthy volunteers

Hyperhomocysteinemia is a risk factor for atherosclerosis and thrombosis and is inversely related to plasma folate and vitamin B12 levels. We assessed the effects of vitamin supplementation on plasma homocysteine levels in 89 patients with a history of recurrent venous thrombosis and 227 healthy volunteers. Patients and hyperhomocysteinemic (homocysteine level >16 micromol/L) volunteers were randomized to placebo or high-dose multivitamin supplements containing 5 mg folic acid, 0.4 mg hydroxycobalamin, and 50 mg pyridoxine. A subgroup of volunteers without hyperhomocysteinemia was also randomized into three additional regimens of 5 mg folic acid, 0.5 mg folic acid, or 0.4 mg hydroxycobalamin. Before and after the intervention period, blood samples were taken for measurements of homocysteine, folate, cobalamin, and pyridoxal-5'-phosphate levels. Supplementation with high-dose multivitamin preparations normalized plasma homocysteine levels (< or = 16 micromol/L) in 26 of 30 individuals compared with 7 of 30 in the placebo group. Also in normohomocysteinemic subjects, multivitamin supplementation strongly reduced homocysteine levels (median reduction, 30%; range, -22% to 55%). In this subgroup the effect of folic acid alone was similar to that of multivitamin: median reduction, 26%; range, -2% to 52% for 5 mg folic acid and 25%; range, -54% to 40% for 0.5 mg folic acid. Cobalamin supplementation had only a slight effect on homocysteine lowering (median reduction, 10%; range, -21% to 41%). Our study shows that combined vitamin supplementation reduces homocysteine levels effectively in patients with venous thrombosis and in healthy volunteers, either with or without hyperhomocysteinemia. Even supplementation with 0.5 mg of folic acid led to a substantial reduction of blood homocysteine levels.

Biochemical and clinical response to hydroxocobalamin versus cyanocobalamin treatment in patients with methylmalonic acidemia and homocystinuria (cblC)

OBJECTIVE

To compare the therapeutic effectiveness of hydroxocobalamin and cyanocobalamin in patients with combined methylmalonic acidemia and homocystinuria.

STUDY DESIGN

Analysis of urine methylmalonic acid, plasma homocystine, and growth of two unrelated patients with cobalamin C disease who were initially receiving cyanocobalamin and were subsequently switched to hydroxocobalamin.

RESULTS

Each patient had a significant decrease in urine methylmalonic acid excretion while receiving cyanocobalamin, but levels remained at least 10 times normal. Cyanocobalamin treatment resulted in a decrease of plasma homocystine to near normal in one patient but had no effect on plasma homocystine in the second patient. Each patient was switched to hydroxocobalamin and urine methylmalonic acid levels decreased to the limit of detection. Plasma homocystine values while taking hydroxocobalamin remained < 5 nmol/ml in both patients. In patient 1, who continued to receive cyanocobalamin therapy for more than 1 year, growth rates (height, weight, and head circumference) were very poor. After initiation of hydroxocobalamin, growth parameters normalized with growth rates above normal.

CONCLUSION

Intramuscular cyanocobalamin treatment is inadequate in the treatment of patients with cobalamin C disease. Appropriate management of cobalamin C disease should include only the hydroxocobalamin form of cobalamin.

Normalization of plasma vitamin B12 concentration by intranasal hydroxocobalamin in vitamin B12-deficient patients

BACKGROUND & AIMS

Patients with previous stomach and terminal ileum resections are often treated with intramuscular vitamin B12 injections. Disadvantages are, on a worldwide scale, the frequent need for medical personnel to administer injections and the sometimes painful way of application. This study was designed to investigate the feasibility of intranasal hydroxocobalamin suppletion in cobalamin-deficient patients and to assess whether intranasal hydroxocobalamin application could be an alternative for intramuscular injection.

METHODS

Six patients with plasma cobalamin concentrations of < 200 ng/L were recruited. A dose of 1500 micrograms hydroxocobalamin was applied intranasally at days 0, 14, and 21. Plasma cobalamin concentrations were determined 1 hour after hydroxocobalamin application and on days 0, 7, 21, 28, and 35.

RESULTS

All patients showed substantial increase of cobalamin concentrations 1 hour after intranasal application. In these 6 patients, there was an eightfold increase of mean baseline cobalamin concentrations. All patients showed a sustained increase of baseline cobalamin concentrations 1 week after prior intranasal application of hydroxocobalamin. No side effects were noted.

CONCLUSIONS

Intranasal application of hydroxocobalamin in cobalamin-deficient patients results in fast nasal absorption and leads to sustained increase of baseline cobalamin concentrations.

Clinical applications of commonly used contemporary antidotes. A US perspective

Poisonings are a common problem. In 1995, over 2 million exposures were reported to American poison information centres alone. The majority of poisoning exposures can be treated without major therapeutic intervention. If therapy is indicated, it is usually in the form of gastrointestinal decontamination with activated charcoal, to prevent absorption of the toxin and the subsequent toxicity that may occur. In a limited number of cases, more aggressive life-support measures may be necessary to treat the adverse effects of poisons. Occasionally, that intervention may include the use of pharmacological antagonists, more commonly referred to as antidotes. According to the American Association of Poison Control Centers, the most commonly used antidotes are acetylcysteine, naloxone, atropine, deferoxamine (desferrioxamine) and antivenins. Overall, 17 antidotes account for 99% of all antidote use and those agents are reviewed in this article. With the exception of naloxone, most antidotes have pharmacological effects that are independent of their inherent antidotal properties. Therefore, antidotes should be used judiciously because their pharmacological properties may exacerbate pre-existing toxicity and only in rare circumstances are they used prophylactically. Some antidotes, such as digoxin-specific antigen binding fragments (digoxin immune Fab), are very expensive, and both the risk: benefit ratio and the associated cost should be considered before the antidote is administered. The principle aims are to "treat the patient, not the poison' and to do no harm to the patient. Antidotes should be used only when they are indicated and may help a patient.

[Effect of the Nucleus CMP forte in 46 patients with progressive spastic paraparesis. Randomized and blind study]

BACKGROUND

Idiopatic or HTLV-1 associated progressive spastic paraparesis does not have a clear etiology or treatment.

AIM

To assess the effects of a medication containing cytidinmonophosphate, uridintriphosphate and vitamin B 12 in the treatment of progressive spastic.

PATIENTS AND METHODS

Patients with the disease were randomly assigned to receive the Nucleus CMP forte (containing dysodic cytidinmonophosphate 5 mg, trisodic uridintriphosphate 3 mg and hydroxicobalamin 2 Mg) tid or placebo during six months. Gait, spasticity, degree of neurogenic bladder and somatosensitive evoked potentials were assessed during treatment.

RESULTS

Forty six patients aged 25 to 79 years old were studied, 24 were female and 29 HTLV-1 positive. Twenty two were treated with the drug and the rest with placebo. Gait and spasticity improved in 7 of 22 patients receiving the drug and 1 of 24 receiving placebo (p < 0.05). Neurogenic bladder improved in 10 of 22 receiving the drug and 4 of 24 receiving placebo (NS) Somatosensitive evoked potentials improved in four of seven patients treated with the drug and in two of seven treated with placebo.

CONCLUSIONS

The medication caused a modest improvement in patients with progressive spastic paraparesis and was free of side effects.

Recovery patterns of motor and somatosensory evoked potentials following treatment of vitamin B12 deficiency

Motor and somatosensory pathway functions were studied using motor evoked potentials (MEPs), somatosensory evoked potentials (SEPs) and F-wave responses in a woman with vitamin B12 deficiency. Initial evaluation before treatment revealed: 1) prolongation of central motor conduction to both the upper and lower limbs, and prolongation of peripheral conduction to the lower limbs; 2) prolongation of central conduction time to median nerve stimulation and absence of cortical SEPs to tibial nerve stimulation; and 3) prolongation of F-wave responses to tibial and peroneal nerve stimulation. After 11 months of treatment with hydroxocobalamin, follow-up studies disclosed: 1) normalization of central motor conduction to the upper limbs, peripheral motor conduction to the lower limbs and improvement of central motor conduction to the lower limbs; 2) normalization of central conduction time to median nerve stimulation but persistent absence of cortical SEPs to tibial nerve stimulation; and 3) normalization of F-wave responses. These data suggest that both central and peripheral conductions of motor and somatosensory pathways may respond to hydroxocobalamin therapy, and that MEPs are useful in the early detection of central and peripheral motor pathway function recovery following treatment with vitamin B12 deficiency.

Pharmacokinetics of hydroxocobalamin in smoke inhalation victims

OBJECTIVE

Hydroxocobalamin has been proposed as a cyanide antidote. Little is known, however, about its pharmacokinetics in human cyanide poisoning.

METHODS

We prospectively studied the pharmacokinetics of hydroxocobalamin in 11 smoke inhalation victims of whom all but one had objective evidence of cyanide exposure. Serum hydroxocobalamin levels were followed from just before drug administration to six days after a single 5 g dose of hydroxocobalamin.

RESULTS

The results (mean +/- standard error) suggest a two compartment model. Distribution half-life is on the order of 1.86 +/- 0.34 h and the elimination half-life 26.2 +/- 2.7 h. The apparent volume of distribution is 0.45 +/- 0.03 L/kg. Renal and total body clearance are 0.31 +/- 0.06 and 0.83 +/- 0.07 L/h, respectively.

CONCLUSION

The apparent volume of distribution suggests a predominantly extracellular partitioning of the antidote, even in the presence of cyanide, an important factor in terms of its antidotal effect. Hydroxocobalamin's elimination half-life in these cyanide-exposed patients far exceeds those found in previous studies of dogs and minimally-exposed humans. If confirmed, this half-life suggests that a single dose of hydroxocobalamin, sufficiently large enough to bind the cyanide present, should be adequate.

Relation of blood cyanide to plasma cyanocobalamin concentration after a fixed dose of hydroxocobalamin in cyanide poisoning

Hydroxocobalamin combines with cyanide to form cyanocobalamin. We hypothesised that the amount of cyanocobalamin formed after a fixed dose of hydroxocobalamin given for cyanide poisoning would correlate with initial blood cyanide concentration. We determined blood cyanide concentration in 12 patients exposed to residential fires, and compared this with markers of the amount of cyanocobalamin formed after treatment with 5 g intravenous hydroxocobalamin. All relationships were highly correlated (r2 0.79-0.95), for the whole group, and there appeared to be an almost linear relationship for the 9 patients with initial cyanide concentration below 40 mumol/L. Above this concentration, no further cyanocobalamin was formed from a single 5 g dose of hydroxocobalamin. In one patient with initial blood cyanide concentration of 96 mumol/L, however, plasma cyanocobalamin concentration approximately doubled after a second 5 g dose of hydroxocobalamin. 5 g of hydroxocobalamin appears capable of binding all available cyanide ions for blood cyanide concentrations up to about 40 mumol/L. Beyond this, more hydroxocobalamin must be given for remaining cyanide ions to be bound. This information will allow clinicians to use rapidly measurable plasma cyanocobalamin concentrations to gauge severity of exposure and evaluate adequacy of treatment.

Effect of the cyanide antidote hydroxocobalamin on commonly ordered serum chemistry studies

STUDY HYPOTHESIS

Concentrated aqueous solutions of hydroxocobalamin (OHCob) are given intravenously for the treatment of cyanide poisoning. Because OHCob solutions are intensely red and have peak light absorptions at 352 nm and 525 nm, we investigated whether the presence of OHCob in serum would interfere with various automated, colorimetric chemistry measurements.

DESIGN

Selected serum chemistry colorimetric measurements were compared in seven patients, using their own serum as control, with serum containing OHCob at the following concentrations: 100 mg/L, 500 mg/L, and 1,000 mg/L. These concentrations are in the range achieved with therapeutic doses of OHCob when given for cyanide poisoning.

MEASUREMENTS AND MAIN RESULTS

Statistically significant alterations in serum values for aspartate aminotransferase, total bilirubin, creatinine, magnesium, and iron were seen in the presence of OHCob.

CONCLUSION

The presence of OHCob in serum interferes with several chemistry methodologies, and such interference should be anticipated when this antidote is used.

Use of vitamin B12 in the treatment and prevention of nitroprusside-induced cyanide toxicity

OBJECTIVE

To review the mechanism of action, safety, and efficacy of hydroxocobalamin in the treatment and prevention of nitroprusside-induced cyanide toxicity.

DATA SOURCES

English and foreign-language journal articles and reference texts identified from Index Medicus. Both animal and human studies were included.

DATA SYNTHESIS

High-dose or prolonged therapy with nitroprusside in patients with hepatic or renal dysfunction increases the risk for nitroprusside-induced cyanide or thiocyanate toxicity, respectively. Hydroxocobalamin has been shown to significantly reduce RBC and plasma cyanide concentrations in animals and surgical patients without producing clinically important adverse effects or toxic metabolites. Thiosulfate infusions also decrease cyanide toxicity but can cause accumulation of thiocyanate resulting in clinical toxicity. Cyanocobalamin cannot effectively remove cyanide due to poor binding.

CONCLUSIONS

Hydroxocobalamin is a safe and effective agent in the prevention and treatment of nitroprusside-induced cyanide toxicity. Prolonged or high-dose infusions of nitroprusside should be minimized in critically ill patients, especially if hepatic and/or renal dysfunction is present.

Biochemical diagnosis and outcome of 2 years treatment in a patient with combined methylmalonic aciduria and homocystinuria

We describe a patient with methylmalonic aciduria and homocystinuria due to a defect in cobalamin metabolism of the Cbl-C type mutant (McKusick 277400). Our case was diagnosed within the first 2 months of life by amino acid analysis (ion-exchange chromatography) and by biochemical studies in cultured fibroblasts ([14C]propionate incorporation, methionine and serine formation). We discuss the clinical course and the biochemical evolution after 2 years of hydroxycobalamin treatment that led to an improvement in general clinical condition and neurological performance.