Peripheral Neuropathy Due to Cobalamin Deficiency

Ramen noodle neuropathy: an atypical case of partial paralysis from malnutrition

INTRODUCTION

Due to a COVID-related job loss resulting in financial and food insecurity, a 28-year-old woman initiated a diet consisting solely of one cup of ramen noodles daily for twenty-two months, leading to 27 kg of weight loss. Ramen noodles are low in calories and lack key nutrients, including potassium, chloride, and vitamin B12.

CASE DESCRIPTION

The patient presented to the emergency department with acute, worsening weakness and paresthesias in her left wrist and hand. Exam revealed no other abnormalities aside from a cachectic appearance. Labs revealed marked hypokalemia, hypochloremia, lactic acidosis, a mixed metabolic alkalosis with respiratory acidosis, and low levels of zinc and copper. An EKG revealed a prolonged QT interval. After a neurology and psychiatry consult, the patient was admitted for failure to thrive with malnutrition, peripheral neuropathy, hypokalemia, and an acid-base disorder. An MRI of the brain was unremarkable. Studies of other nutritional deficiencies, autoimmune conditions, and sexually transmitted infections were unremarkable. The patient received food and vitamin supplementation, was monitored for re-feeding syndrome, and had a significant recovery.

DISCUSSION

After stroke, spinal injury, multiple sclerosis, and the most common focal mononeuropathies were ruled out, the clinical focus turned to nutritional deficiencies, the most significant of which was hypokalemia. Prior research has shown that severe hypokalemia can lead to weakness. It has also shown that chronically insufficient dietary intake is a common cause of hypokalemia. This case, with its partial paralysis of a unilateral upper extremity, may add to the known clinical manifestations of hypokalemia. We review the role of hypokalemia and hypochloremia in acid-base dynamics. Etiologies and clinical manifestations of cobalamin, thiamine, pyridoxine, and copper deficiencies, along with lead toxicity, are also discussed. Diagnostic clarity of mononeuropathies in the context of malnutrition and hypokalemia can be aided by urine potassium levels prior to repletion, neuroimaging that includes the cervical spine, and follow-up electromyography.

Impact of Vitamin B12 Insufficiency on the Incidence of Sarcopenia in Korean Community-Dwelling Older Adults: A Two-Year Longitudinal Study

The longitudinal effect of B12 insufficiency on sarcopenia has not yet been investigated in older adults. We aimed to study the impact of B12 levels on alterations in muscle mass, function and strength over two years. Non-sarcopenic older adults (n = 926) aged 70-84 were included. Using the Korean Frailty and Aging Cohort Study, this two-year longitudinal study used data across South Korea. The tools used for assessing muscle criteria were based on the Asian Working Group for Sarcopenia guidelines. Participants were divided into the insufficiency (initial serum B12 concentration < 350 pg/mL) and sufficiency groups (≥350 pg/mL). Logistic regression analyses were performed to evaluate the effect of initial B12 concentration on sarcopenia parameters over a two-year period. In women, multivariate analysis showed that the B12 insufficiency group had a significantly higher incidence of low SPPB scores (odds ratio [OR] = 3.28, 95% confidence interval [CI] = 1.59-6.76) and sarcopenia (OR = 3.72, 95% CI = 1.10-12.62). However, the B12 insufficiency group did not have a greater incidence of sarcopenia or other parameters in men. Our findings suggest B12 insufficiency negatively impacts physical performance and increases the incidence of sarcopenia only in women.

Nutritional neuropathies

Neuropathies associated with nutritional deficiencies are routinely encountered by the practicing neurologist. Although these neuropathies assume different patterns, most are length-dependent, sensory axonopathies. Cobalamin deficiency neuropathy is the exception, often presenting with a non-length-dependent sensory neuropathy. Patients with cobalamin and copper deficiency neuropathy characteristically have concomitant myelopathy, whereas vitamin E deficiency is uniquely associated with a spinocerebellar syndrome. In contrast to those nutrients for which deficiencies produce neuropathies, pyridoxine toxicity results in a non-length-dependent sensory neuronopathy. Deficiencies occur in the context of malnutrition, malabsorption, increased nutrient loss (such as with dialysis), autoimmune conditions such as pernicious anemia, and with certain drugs that inhibit nutrient absorption. When promptly identified, therapeutic nutrient supplementation may result in stabilization or improvement of these neuropathies.

Homocysteine as a potential predictive factor for high major adverse cardiovascular events risk in female patients with premature acute coronary syndrome

We aimed to investigate the correlation of homocysteine (Hcy) level with clinical characteristics, and explore its predictive value for major adverse cardiovascular events (MACE) risk in female patients with premature acute coronary syndrome (ACS).The serum Hcy level was detected from 1299 female patients with premature ACS. According to the tertile of Hcy level, patients were divided into 3 groups: lowest tertile group (≤9.1 μmol/L), middle tertile group (9.2-11.6 μmol/L) and highest tertile group (>11.6 μmol/L). MACE incidence was recorded and MACE-free survival was caculated with the median follow-up duration of 28.3 months.Increased Hcy correlated with older age (P < .001), higher creatinine level (P < .001), and enhanced uric acid level (P = .001), while reduced fasting glucose concentration (P < .001). MACE incidence was 10.7% and it was highest in highest tertile group (22.1%), followed by middle tertile group (7.7%) and lowest tertile group (2.4%) (P < .001). Receiver operating characteristic curve showed that Hcy distinguished MACE patients from non-MACE patients with the area under the curve of 0.789 (95% CI: 0.742-0.835). Kaplan-Meier curves revealed that MACE-free survival was shortest in Hcy highest tertile group, followed by middle tertile group and lowest tertile group (P < .001). Multivariate Cox analyses further showed that higher Hcy level was an independent predictive factor for poor MACE-free survival (middle tertile vs lowest tertile (P = .001, HR: 3.615, 95% CI: 1.661-7.864); highest tertile vs lowest tertile (P < .001, HR: 11.023, 95% CI: 5.356-22.684)).Hcy serves as a potential predictive factor for increased MACE risk in female patients with premature ACS.

Long-term treatment with metformin in type 2 diabetes and methylmalonic acid: Post hoc analysis of a randomized controlled 4.3year trial

AIMS

Metformin treatment is associated with a decrease of serum vitamin B12, but whether this reflects tissue B12 deficiency is controversial. We studied the effects of metformin on serum levels of methylmalonic acid (MMA), a biomarker for tissue B12 deficiency, and on onset or progression of neuropathy.

METHODS

In the HOME trial, 390 insulin-treated patients with type 2 diabetes were treated with metformin or placebo for 52months. In a post hoc analysis, we analyzed the association between metformin, MMA and a validated Neuropathy Score (NPS).

RESULTS

Metformin vs placebo increased MMA at the end of the study (95%CI: 0.019 to 0.055, p=0.001). Mediation analysis showed that the effect of metformin on the NPS consisted of a beneficial effect through lowering HbA1c (-0.020 per gram year) and an adverse effect through increasing MMA (0.042 per gram year), resulting in a non-significant net effect (0.032 per gram year, 95% CI: -0.121 to 0.182, p=0.34).

CONCLUSION

Metformin not only reduces serum levels of B12, but also progressively increases serum MMA. The increase of MMA in metformin users was associated with significant worsening of the NPS. These results provide further support that metformin-related B12 deficiency is clinically relevant. Monitoring of B12 in users of metformin should be considered.

Autoimmune atrophic gastritis: current perspectives

At present there is no universally accepted classification for gastritis. The first successful classification (The Sydney System) that is still commonly used by medical professionals was first introduced by Misiewicz et al in Sydney in 1990. In fact, it was the first detailed classification after the discovery of Helicobacter pylori by Warren and Marshall in 1982. In 1994, the Updated Sydney System was proposed during the International Workshop on the Histopathology of Gastritis followed by the publication in The American Journal of Surgical Pathology by Dixon et al. Using the new classification, distinction between atrophic and nonatrophic gastritis was revised, and the visual scale grading was incorporated. According to the Updated Sydney System Classification, atrophic gastritis is categorized into multifocal (H. pylori, environmental factors, specific diet) and corpus-predominant (autoimmune). Since metaplasia is a key histological characteristic in patients with atrophic gastritis, it has been recommended to use the word “metaplastic” in both variants of atrophic gastritis: autoimmune metaplastic atrophic gastritis (AMAG) and environmental metaplastic atrophic gastritis. Although there are many overlaps in the course of the disease and distinction between those two entities may be challenging, the aim of this review article was to describe the etiology, epidemiology, pathogenesis, diagnosis, clinical manifestations and treatment in patients with AMAG. However, it is important to mention that H. pylori is the most common etiologic factor for the development of gastritis in the world.

Vitamin B12 and Homocysteine Associations with Gait Speed in Older Adults: The Baltimore Longitudinal Study of Aging

OBJECTIVES

This study aimed to assess the independent associations of serum levels of vitamin B12 and plasma concentrations of homocysteine with gait speed decline.

DESIGN, SETTING, PARTICIPANTS

This study utilized longitudinal analysis of participants 50 years or older from The Baltimore Longitudinal Study of Aging, N=774.

MEASUREMENTS

Gait speed (m/s) was assessed using the 6-meter usual pace test. Vitamin B12 and homocysteine concentrations were collected using standard clinical protocols. Linear mixed effects regression was stratified by baseline age category (50-69, 70-79, and ≥80 years old).

RESULTS

Mean follow-up time for the total study sample was 5.4 ± 2.0 years. No association between vitamin B12 and gait speed decline over the follow-up time for any age group was found. Elevated homocysteine concentrations were associated with decline in gait speed after adjustment for covariates (50-69: β= -0.005, p=.057; 70-79: β= -0.013, p<.001, ≥80: β= -0.007, p=.054).

CONCLUSION

Homocysteine and vitamin B12 are inversely related, yet only homocysteine was associated with gait speed decline in this population of healthy older adults. Given these results, future research should be directed towards investigating the relationship in populations with greater variation in vitamin B12 concentrations and other mechanisms influencing homocysteine concentrations.

Cervical Spondylotic Myelopathy: What the Neurologist Should Know

Cervical spondylotic myelopathy is a well-known cause of disability among older people. A significant amount of these patients is asymptomatic. Once the symptoms start, the worsening may follow a progressive manner. We should suspect of spondylotic myelopathy in any individual over 55 years presenting progressive changes in gait or losing fine motor control of the upper limbs. Despite its frequent prevalence, this condition is still neglected and many times confused with other supratentorial lesions regarding diagnostic. Here we address some of most important aspects of this disease, calling attention to pathophysiology, the natural history, presentation, differential diagnosis, clinical assessment, and treatment.

Pseudo-Foster Kennedy Syndrome as a Rare Presentation of Vitamin B12 Deficiency

Introduction

Pseudo-Foster Kennedy syndrome is a triad consisting of ipsilateral optic atrophy, contralateral optic disc edema, and ipsilateral anosmia in the absence of an intracranial mass. Vitamin B12 plays an important role in DNA synthesis, and its deficiency causes peripheral neuropathy, myeloneuropathy, and, very rarely, optic neuropathy.

Case Presentation

In this study, we describe a 34-year-old male who presented with progressive loss of visual acuity and field. Fundoscopy showed optic disc edema with telangiectasia in the right eye, while the left eye had optic disc atrophy. We ruled out nearly all possible and common causes of optic neuropathy, and vitamin B12 deficiency was finally diagnosed. After treatment with vitamin B12, the patient improved.

Conclusions

Demyelinating disease, anterior ischemic optic neuropathy, non-arteritic anterior ischemic optic neuropathy, autoimmune disease, and hereditary optic neuropathy could cause optic neuropathy. Normal CBC parameters and the absence of clinical manifestations of vitamin B12 deficiency could not rule out its diagnosis. Careful physical examinations and history-taking with a classical approach led us to the diagnosis of vitamin B12 deficiency and its treatment.

The role of metformin on vitamin B12 deficiency: a meta-analysis review

Metformin is the only biguanide oral hypoglycemic drug, that is used to treat patients with type-2 diabetes mellitus. There are some reports of metformin being associated with decreased serum levels of vitamin B12 (VB12). The objective of this study is to systematically analyze the impact of metformin on the frequency of VB12 deficiency and serum levels of VB12. A search of various databases provided 18 retrospective cohort studies and 11 randomized controlled trials. Pooled estimates of odds ratio with 95% confidence interval using random effect model were conducted. Studies were examined for heterogeneity, publication bias and sensitivity analysis. Separate analysis of randomized control trials (RCTs) including both low-risk and high-risk bias was also conducted. 29 studies were selected with a total of 8,089 patients. 19 studies were rated intermediate or high quality. Primary outcome suggested increased incidence of VB12 deficiency in metformin group (OR = 2.45, 95% CI 1.74-3.44, P < 0.0001.) Heterogeneity was relatively high (I(2) = 53%), with minor publication bias. Secondary outcome suggested lower serum VB12 concentrations in metformin group (Mean difference = -65.8, 95% CI -78.1 to -53.6 pmol/L, P < 0.00001) with high heterogeneity (I(2) = 98%,) and low publication bias. RCTs analysis of low-and high-risk group revealed similar trends. We conclude that metformin treatment is significantly associated with an increase in incidence of VB12 deficiency and reduced serum VB12 levels.

Relationships between cobalamin, epidermal growth factor, and normal prions in the myelin maintenance of central nervous system

Cobalamin (Cbl), epidermal growth factor (EGF), and prions (PrPs) are key molecules for myelin maintenance in the central and peripheral nervous systems. Cbl and EGF increase normal prion (PrP(C)) synthesis and PrP(C) levels in rat spinal cord (SC) and elsewhere. Cbl deficiency increases PrP(C) levels in rat SC and cerebrospinal fluid (CSF), and decreases PrP(C)-mRNA levels in rat SC. The administration of anti-octapeptide repeat PrP(C) region antibodies (Abs) to Cbl-deficient (Cbl-D) rats prevents SC myelin lesions and a local increase in tumor necrosis factor (TNF)-α levels, whereas anti-TNF-α Abs prevent SC myelin lesions and the increase in SC and CSF PrP(C) levels. As it is known that both Cbl and EGF regulate SC PrP(C) synthesis independently, and that Cbl regulates SC EGF synthesis, EGF may play both Cbl-independent and Cbl-dependent roles. When Cbl-D rats undergo Cbl replacement therapy, SC PrP(C) levels are similar to those observed in Cbl-D rats. In rat frontal cortex (which is marginally affected by Cbl deficiency in histological terms), Cbl deficiency decreases PrP(C) levels and the increase induced by Cbl replacement leads to their normalization. Increased nerve PrP(C) levels are detected in the myelin lesions of the peripheral neuropathy of Cbl-D rats, and CSF PrP(C) levels are also increased in Cbl-D patients (but not in patients with Cbl-unrelated neurological diseases). Various common steps in the downstream signaling pathway of Cbl, EGF, and PrP(C) underlines the close relationship between the three molecules in keeping myelin normal.

Perturbation of neuronal cobalamin transport by lysosomal enzyme inhibition

Cbl (cobalamin) utilization as an enzyme cofactor is dependent on its efficient transit through lysosomes to the cytosol and mitochondria. We have previously proposed that pathophysiological perturbations in lysosomal function may inhibit intracellular Cbl transport with consequences for down-stream metabolic pathways. In the current study, we used both HT1080 fibroblasts and SH-SY5Y neurons to assess the impact that protease inhibitors, chloroquine and leupeptin (N-acetyl-L-leucyl-L-leucyl-L-argininal), have on the distribution of [⁵⁷Co]Cbl in lysosomes, mitochondria and cytosol. Under standard cell culture conditions the distribution of [⁵⁷Co]Cbl in both neurons and fibroblasts was ~5% in lysosomes, 14% in mitochondria and 81% in cytosol. Treatment of cells with either 25 μM chloroquine or 40 μM leupeptin for 48 h significantly increased the lysosomal [⁵⁷Co]Cbl levels, by 4-fold in fibroblasts and 10-fold in neurons, and this was associated with reduced cytosolic and mitochondrial [⁵⁷Co]Cbl concentrations. Based on Western blotting of LAMP2 in fractions recovered from an OptiPrep density gradient, lysosomal Cbl trapping was associated with an expansion of the lysosomal compartment and an increase in a subpopulation of lysosomes with increased size and density. Moreover, the decreased mitochondrial Cbl that was associated with lysosomal Cbl trapping was correlated with decreased incorporation of [¹⁴C] propionate into cellular proteins/macromolecules, indicating an inhibition of Cbl-dependent Mm-CoA (methylmalonyl-coenzyme A) mutase activity. These results add support to the idea that lysosomal dysfunction may significantly impact upon Cbl transport and utilization.

Pattern-recognition approach to neuropathy and neuronopathy

Neuropathic disorders encompass those that affect the neuron's cell body or neuronopathies, those affecting the peripheral process, or peripheral neuropathies. The peripheral neuropathies can be broadly subdivided into the myelinopathies and axonopathies, conditions which can be hereditary or acquired. Each of these disorders has distinct clinical features that enable neurologists to recognize the various patterns of presentation. Once a particular pattern is established, further laboratory studies can be performed to support the clinical impression.

Nutritional neuropathies

Neuropathies due to nutritional problems can affect certain patient populations and have a varied presentation because of multiple coexistent nutritional deficiencies. Clinicians should consider nutritional neuropathies in patients presenting with neuropathies. Clinicians should be alert for signs and symptoms of neuropathy in patients who have had bariatric surgery.

Cobalamin and normal prions: a new horizon for cobalamin neurotrophism

It is known that cobalamin (Cbl) deficiency damages myelin by increasing tumor necrosis factor (TNF)-α and decreasing epidermal growth factor (EGF) levels in rat central nervous system (CNS), and affects the peripheral nervous system (PNS) morphologically and functionally. It is also known that some polyneuropathies not due to Cbl deficiency are connected with increased TNF-α levels, and that various cytokines (including TNF-α) and growth factors regulate the in vitro synthesis of normal prions (PrP(C)s). Given that there is extensive evidence that PrP(C)s play a key role in the maintenance of CNS and PNS myelin, we investigated whether the PrP(C) octapeptide repeat (OR) region is involved in the pathogenesis of rat Cbl-deficient (Cbl-D) polyneuropathy. After intracerebroventricularly administering antibodies (Abs) against the OR region (OR-Abs) to Cbl-D rats to prevent myelin damage and maximum nerve conduction velocity (MNCV) abnormalities, and PrP(C)s to otherwise normal rats to reproduce PNS Cbl-D-like lesions, we measured PrP(C) levels and MNCV of the sciatic and tibial nerves. PrP(C) and TNF-α levels were increased in sciatic and tibial nerves of Cbl-D and saline-treated rats, and the OR-Abs normalized the myelin ultrastructure, TNF-α levels, and MNCV values of the sciatic and tibial nerves of Cbl-D rats. The same peripheral nerves of the otherwise normal PrP(C)-treated rats showed typical Cbl-D myelin lesions, significantly increased TNF-α levels, and significantly decreased MNCV values. These findings demonstrate that Cbl deficiency induces excess PrP(C)s and thereby excess OR regions, which seem to be responsible for the PNS myelin damage, as has recently been found in the case of CNS myelin damage [66]. Furthermore, excess TNF-α is also involved in the pathogenesis of Cbl-D polyneuropathy. In conclusion, we have extended the list of prion diseases by adding one caused by excess PrP(C)s and the polyneuropathies related to excess TNF-α.

A rational diagnostic approach to peripheral neuropathy

Peripheral neuropathies are among the most common disorders encountered by neuromuscular specialists and their evaluation can be challenging. The first part of this review outlined an algorithm based on anatomy, pathology, electrodiagnosis, and clinical localization that leads to a full characterization of the peripheral neuropathy. In the second part, we apply this approach, emphasizing recognition of atypical features and formulation of a focused differential diagnosis, thus reducing the number of uninformative tests. We review evidence supporting the routine use of commonly ordered laboratory tests and recommend a panel of tests that should be performed in patients with symmetric, distal, sensory-predominant peripheral neuropathy. Using this diagnostic approach, a diagnosis could be made in two thirds of patients.

Alcoholic neuropathy: possible mechanisms and future treatment possibilities

Chronic alcohol consumption produces painful peripheral neuropathy for which there is no reliable successful therapy, mainly due to lack of understanding of its pathobiology. Alcoholic neuropathy involves coasting caused by damage to nerves that results from long term excessive drinking of alcohol and is characterized by spontaneous burning pain, hyperalgesia and allodynia. The mechanism behind alcoholic neuropathy is not well understood, but several explanations have been proposed. These include activation of spinal cord microglia after chronic alcohol consumption, oxidative stress leading to free radical damage to nerves, activation of mGlu5 receptors in the spinal cord and activation of the sympathoadrenal and hypothalamo-pituitary-adrenal (HPA) axis. Nutritional deficiency (especially thiamine deficiency) and/or the direct toxic effect of alcohol or both have also been implicated in alcohol-induced neuropathic pain. Treatment is directed towards halting further damage to the peripheral nerves and restoring their normal functioning. This can be achieved by alcohol abstinence and a nutritionally balanced diet supplemented by all B vitamins. However, in the setting of ongoing alcohol use, vitamin supplementation alone has not been convincingly shown to be sufficient for improvement in most patients. The present review is focused around the multiple pathways involved in the development of peripheral neuropathy associated with chronic alcohol intake and the different therapeutic agents which may find a place in the therapeutic armamentarium for both prevention and management of alcoholic neuropathy.

Relationship between vitamin B12 and sensory and motor peripheral nerve function in older adults

OBJECTIVES

To examine whether deficient B12 status or low serum B12 levels are associated with worse sensory and motor peripheral nerve function in older adults.

DESIGN

Cross-sectional.

SETTING

Health, Aging and Body Composition Study.

PARTICIPANTS

Two thousand two hundred and eighty-seven adults aged 72 to 83 (mean 76.5 ± 2.9; 51.4% female; 38.3% black).

MEASUREMENTS

Low serum B12 was defined as serum B12 less than 260 pmol/L, and deficient B12 status was defined as B12 less than 260 pmol/L, methylmalonic acid (MMA) greater than 271 nmol/L, and MMA greater than 2-methylcitrate. Peripheral nerve function was assessed according to peroneal nerve conduction amplitude and velocity (NCV) (motor), 1.4 g/10 g monofilament detection, average vibration threshold detection, and peripheral neuropathy symptoms (numbness, aching or burning pain, or both) (sensory).

RESULTS

B12-deficient status was found in 7.0% of participants, and an additional 10.1% had low serum B12 levels. B12 deficient status was associated with greater insensitivity to light (1.4 g) touch (odds ratio = 1.50, 95% confidence interval = 1.06-2.13) and worse NCV (42.3 vs 43.5 m/s) (β = -1.16, P = .01) after multivariable adjustment for demographics, lifestyle factors, and health conditions. Associations were consistent for the alternative definition using low serum B12 only. No significant associations were found for deficient B12 status or the alternative low serum B12 definition and vibration detection, nerve conduction amplitude, or peripheral neuropathy symptoms.

CONCLUSION

Poor B12 (deficient B12 status and low serum B12) is associated with worse sensory and motor peripheral nerve function. Nerve function impairments may lead to physical function declines and disability in older adults, suggesting that prevention and treatment of low B12 levels may be important to evaluate.

Vitamin B12 and homocysteine levels and 6-year change in peripheral nerve function and neurological signs

BACKGROUND

Low vitamin B12 and high homocysteine (Hcy) levels are common in older adults and may be associated with worse neurological function. The aim of this study is to determine whether changes in B12 or Hcy levels are associated with longitudinal changes in peripheral nerve function and clinical neurological signs and symptoms.

METHODS

Participants aged 60 years and older at baseline (n = 678; 72.2 ± 6.2 years; 43.5% male) were from the InCHIANTI Study. Low B12 (<260 pmol/L) and high Hcy (≥13 μmol/L) were measured at baseline and 3-year follow-up. Neurological function was assessed by peroneal nerve conduction amplitude (compound motor action potential) and velocity, neurological examination, and peripheral neuropathy symptoms at baseline, 3-year, and 6-year follow-up.

RESULTS

At baseline, 43.8% had low B12 levels and 58.6% had high Hcy levels. Over 6 years, 12.4% declined to poor compound motor action potential (<1 mV) and 42.1% declined to poor nerve conduction velocity (<40 m/s). In mixed models analyses, sustained high Hcy was associated with worse compound motor action potential compared with sustained normal Hcy (p = .04), adjusting for demographics, diabetes, and folate level. Participants whose Hcy level became high at follow-up were more likely to become unable to detect monofilament at 6-year follow-up compared with those with sustained normal Hcy (odds ratio: 5.4; 95% CI: 1.5-19.0), adjusting for demographics, diabetes, body mass index, and peripheral arterial disease. There was no association with vitamin B12 level or with symptoms.

CONCLUSIONS

High Hcy may be associated with worse sensory and motor peripheral nerve function. Because poor nerve function has been associated with lower strength and physical performance, these results have important implications for disability in older adults.

Levodopa, methylmalonic acid, and neuropathy in idiopathic Parkinson disease

OBJECTIVE

Peripheral neuropathy (PN) is thought to be coincidental in patients with idiopathic Parkinson disease (IPD). We sought to examine the prevalence of PN in a population of IPD patients and a potential relationship to levodopa use and fasting methylmalonic acid (MMA) levels.

METHODS

In a prospective cohort study, IPD patients randomly selected from a comprehensive database were compared to control subjects regarding the presence and severity of PN using clinical and electrophysiological measures. IPD severity was determined using the Unified Parkinson's Disease Rating Scale (UPDRS). We determined the relation of levodopa use with serum levels of cobalamin, MMA, and homocysteine (Hcy). We also explored the association between presence and severity of PN and age, duration of IPD, cumulative levodopa dosing, cobalamin, MMA, and Hcy levels.

RESULTS

Fifty-eight randomly selected IPD patients were compared to 58 age- and sex-matched controls. PN was present in 55% of IPD patients and 9% of controls. Patients with IPD had greater prevalence of PN and fasting MMA/Hcy levels than controls. IPD patients with PN were older and exhibited higher UPDRS scores, fasting MMA/Hcy levels, and cumulative levodopa exposure. PN severity in IPD subjects positively correlated with both levodopa exposure and MMA levels.

INTERPRETATION

IPD patients have a higher prevalence of PN than controls. Although causality is not established, levodopa exposure is associated with MMA elevation and sensorimotor neuropathy in IPD patients. Cobalamin replacement concurrent with levodopa therapy should be considered to protect against development of PN in IPD patients.

Unexplained decline in the prevalence of anemia among US children and women between 1988-1994 and 1999-2002

BACKGROUND

The current anemia burden among US preschool children and women of childbearing age has not been documented.

OBJECTIVE

We used data from National Health and Nutrition Examination Surveys 1988-1994 and 1999-2002 to examine recent anemia changes.

DESIGN

We calculated the prevalence of anemia (hemoglobin < 11.0 g/dL at <24 mo, <11.1 g/dL at 24-59 mo, and <12.0 g/dL for women), iron deficiency anemia (anemia plus abnormal value >or=2: serum ferritin, transferrin saturation, and erythrocyte protoporphyrin), and high blood lead (>or=10 microg/dL) with anemia among children 12-59 mo and women 20-49 y in both surveys. Among women, we also calculated the prevalence of folate deficiency (erythrocyte folate < 317.2 nmol/L) with anemia and high C-reactive protein (>10 mg/L) with anemia. Multiple logistic regression was used to compare anemia prevalence between surveys, with control for race and age.

RESULTS

Anemia declined significantly in children (from 8.0% to 3.6%; OR: 0.4; 95% CI: 0.3, 0.7) and women (10.8% to 6.9%; OR: 0.6; CI: 0.4, 0.7), but the prevalence of iron deficiency anemia did not change significantly in children (1.5% compared with 1.2%; OR: 0.7; 95% CI: 0.4, 1.5) or women (4.9% compared with 4.1%; OR: 0.8; 95% CI: 0.6, 1.1). Folate deficiency with anemia declined significantly in women (from 4.1% to 0.5%; OR: 0.1; 95% CI: 0.1, 0.2), but logistic regression models and standardization indicated that none of the known possible anemia causes could account for the decline in total anemia in children or women.

CONCLUSIONS

The prevalence of anemia declined significantly among US women and children between 1988-1994 and 1999-2002, but this decline was not associated with changes in iron or folate deficiency, inflammation, or high blood lead.

Peak bone mass in patients with phenylketonuria

OBJECTIVE

Several studies have suggested a compromised bone mass in phenylketonuria patients but most reported on heterogeneous or small patient groups. Our aim was to evaluate peak bone mass in adult PKU patients and to relate BMD to nutritional parameters.

PATIENTS AND METHODS

BMD was measured by dual-energy x-ray absorptiometry in 31 adult PKU patients (18 female), mean age 25 +/- 5.3 years. Nutritional intake was calculated based on food diaries. Diet adherence was determined based on patients' report.

RESULTS

Mean blood phenylalanine (Phe) concentration was 968 +/- 526 micromol/L (16 +/- 8.7 mg/dl). Eight patients (32.2%) met the recommended blood Phe concentration of <726 micromol/L (<12 mg/dl), and there was no significant difference in Phe concentrations between diet-adherent and non-adherent patients. Osteopenia was detected in 11 patients (38.7%), while osteoporosis was detected in 2 patients (6.5%). No correlation was found between BMD and age, blood minerals, Phe, vitamin D and alkaline phosphatase levels, calcium and protein intake, body mass index, and body fat percentage.

CONCLUSIONS

Peak bone mass is decreased in PKU patients. Possible explanations include long-standing dietary deficiency in protein, calcium, vitamin D or trace elements, or a primary defect in bone turnover inherent to the disease itself. Our data do not favour any of these hypotheses. Further studies are needed to elucidate the cause of low bone density in PKU patients.

Neuroprotection during chemotherapy: a systematic review

The development of neurotoxicity during antineoplastic therapy is one of the most common reasons for termination or modification of cancer treatment. A number of different agents have been proposed to provide neuroprotection without affecting antitumor efficacy. This review provides an evidence-based summary of neuroprotective medicines, an overview of the literature relating to neuroprotection during cancer treatment and a Neurologist perspective risk assessment and management. Through a systematic review the authors identified 49 papers published to date that report human clinical trials involving potential neuroprotectants in adults. Case reports and series completed in a prospective fashion were also included. Sensory neuropathies were the most prevalent subtype in the literature, and most were at least partially reversible with or without neuroprotective treatment. The majority of study medications had minimal side effects, though 2 trials were prematurely terminated because of adverse patient outcomes. No study reported an effect on antitumor efficacy. Because of the variability in study design, cancer type, outcome measures, and clinical confirmation of neuropathy, meta-analysis could not be appropriately performed. We highlight risk factors and discuss neuropathy screening. Descriptive analysis is provided which reveals that many of the agents studied were likely to confer some at least some neuroprotective benefit.

Neuropathie périphérique réversible liée au déficit en vitamine B12

OBJECTIVE

To describe an electroclinical presentation of a peripheral neuropathy in a patient who suffered from vitamin B12 deficiency.

PATIENT AND METHODS

We report the case of a 56-year-old man who, 17 years after a subtotal gastrectomy, presented with a diffuse sensory-motor demyelinating peripheral neuropathy with multifocal alteration of conduction confirmed by electromyography. Its causal relationship with vitamin B12 deficiency was biologically demonstrated. This neuropathy improved within a few days after intramuscular hydroxocobalamin treatment. Both clinical and electrophysiological signs had totally disappeared 3 months later on.

CONCLUSION

This observation demonstrates that, in spite of its poor outcome reported by several authors, peripheral neuropathy induced by vitamin B12 deficiency can recover completely with substitutive treatment.