Elevated Biomarkers of Inflammation and Vascular Dysfunction Are Associated with Distal Sensory Polyneuropathy in People with HIV

Distal sensory polyneuropathy (DSP) is a disabling, chronic condition in people with HIV (PWH), even those with viral suppression of antiretroviral therapy (ART), and with a wide range of complications, such as reduced quality of life. Previous studies demonstrated that DSP is associated with inflammatory cytokines in PWH. Adhesion molecules, essential for normal vascular function, are perturbed in HIV and other conditions linked to DSP, but the link between adhesion molecules and DSP in PWH is unknown. This study aimed to determine whether DSP signs and symptoms were associated with a panel of plasma biomarkers of inflammation (d-dimer, sTNFRII, MCP-1, IL-6, IL-8, IP-10, sCD14) and vascular I integrity (ICAM-1, VCAM-1, uPAR, MMP-2, VEGF, uPAR, TIMP-1, TIMP-2) and differed between PWH and people without HIV (PWoH). A cross-sectional study was conducted among 143 participants (69 PWH and 74 PWoH) assessed by studies at the UC San Diego HIV Neurobehavioral Research Program. DSP signs and symptoms were clinically assessed for all participants. DSP was defined as two or more DSP signs: bilateral symmetrically reduced distal vibration, sharp sensation, and ankle reflexes. Participant-reported symptoms were neuropathic pain, paresthesias, and loss of sensation. Factor analyses reduced the dimensionality of the 15 biomarkers among all participants, yielding six factors. Logistic regression was used to assess the associations between biomarkers and DSP signs and symptoms, controlling for relevant demographic and clinical covariates. The 143 participants were 48.3% PWH, 47 (32.9%) women, and 47 (33.6%) Hispanics, with a mean age of 44.3 ± 12.9 years. Among PWH, the median (IQR) nadir and current CD4+ T-cells were 300 (178-448) and 643 (502-839), respectively. Participants with DSP were older but had similar distributions of gender and ethnicity to those without DSP. Multiple logistic regression showed that Factor 2 (sTNFRII and VCAM-1) and Factor 4 (MMP-2) were independently associated with DSP signs in both PWH and PWoH (OR [95% CI]: 5.45 [1.42-21.00], and 15.16 [1.07-215.22]), respectively. These findings suggest that inflammation and vascular integrity alterations may contribute to DSP pathogenesis in PWH, but not PWoH, possibly through endothelial dysfunction and axonal degeneration.

Deficits in systemic biomarkers of neuroinflammation and growth factors promoting nerve regeneration in patients with type 2 diabetes and polyneuropathy

INTRODUCTION

The determinants and mechanisms contributing to diabetic sensorimotor polyneuropathy (DSPN) remain unclear. Since neuroinflammation and altered nerve regeneration have been implicated in the pathogenesis of both DSPN and neuropathic pain, we hypothesized that the corresponding biomarkers could be associated with DSPN in general and could have the potential to discriminate between the painful and painless DSPN entities.

METHODS

In a cross-sectional study using multimarker proximity extension assay technology we assessed 71 serum biomarkers including cytokines, chemokines, growth factors, receptors, and others in patients with type 2 diabetes with DSPN (DSPN+) (n=304) or without DSPN (DSPN-) (n=158) and persons with normal glucose tolerance (NGT) without polyneuropathy (n=354).

RESULTS

After adjustment for multiple testing and sex, age, body mass index, HbA1c, and smoking, the serum levels of 17 biomarkers (four cytokines, five chemokines, four growth factors, two receptors, two miscellaneous) were lower in DSPN+ than in DSPN- and NGT. In DSPN+, six of these biomarkers were associated with peripheral nerve function. The concentrations of 15 other biomarkers differed between NGT and both DSPN+ and DSPN-, but not between DSPN+ and DSPN-. No differences in biomarker levels were found between patients with painful (n=164) and painless DSPN (n=140).

CONCLUSIONS

Deficits in systemic cytokines, chemokines, and growth factors promoting nerve regeneration in patients with type 2 diabetes are linked to polyneuropathy in general but not specifically to the painful or painless entity.

TRIAL REGISTRATION NUMBER

NCT02243475.

A Systemic Inflammatory Signature Reflecting Cross Talk Between Innate and Adaptive Immunity Is Associated With Incident Polyneuropathy: KORA F4/FF4 Study

Prospective analyses of biomarkers of inflammation and distal sensorimotor polyneuropathy (DSPN) are scarce and limited to innate immunity. We therefore aimed to assess associations between biomarkers reflecting multiple aspects of immune activation and DSPN. The study was based on 127 case subjects with incident DSPN and 386 noncase subjects from the population-based Cooperative Health Research in the Region of Augsburg (KORA) F4/FF4 cohort (follow-up 6.5 years). Proximity extension assay technology was used to measure serum levels of biomarkers of inflammation. Of 71 biomarkers assessed, 26 were associated with incident DSPN. After adjustment for multiple testing, higher levels of six biomarkers remained related to incident DSPN. Three of these proteins (MCP-3/CCL7, MIG/CXCL9, IP-10/CXCL10) were chemokines, and the other three (DNER, CD40, TNFRSF9) were soluble forms of transmembrane receptors. The chemokines had neurotoxic effects on neuroblastoma cells in vitro. Addition of all six biomarkers improved the C statistic of a clinical risk model from 0.748 to 0.783 (P = 0.011). Pathway analyses indicated that multiple cell types from innate and adaptive immunity are involved in the development of DSPN. We thus identified novel associations between biomarkers of inflammation and incident DSPN pointing to a complex cross talk between innate and adaptive immunity in the pathogenesis of the disease.

Myeloperoxidase, superoxide dismutase-3, cardiometabolic risk factors, and distal sensorimotor polyneuropathy: The KORA F4/FF4 study

BACKGROUND

Oxidative stress has been proposed as important pathomechanism of cardiometabolic diseases and distal sensorimotor polyneuropathy (DSPN). However, the relevance of biomarkers of oxidative stress has not been investigated in this context. Therefore, this study aimed to assess the association of the prooxidant myeloperoxidase (MPO) and the antioxidant extracellular superoxide dismutase (SOD3) with cardiometabolic risk factors and with prevalence and incidence of DSPN.

METHODS

Cross-sectional analyses comprised 1069 participants (40.3% with prediabetes and 20.5% with type 2 diabetes) of the population-based Cooperative Health Research in the Region of Augsburg (KORA) F4 study (2006-2008), 181 of whom had DSPN at baseline. Prospective analyses included 524 individuals without DSPN at baseline who also participated in the KORA FF4 study (2013-2014), 132 of whom developed DSPN during the 6.5-year follow-up. Serum MPO and SOD3 were measured by ELISA, and their association with cardiometabolic risk factors and DSPN were estimated by using linear and logistic regression analyses.

RESULTS

Higher MPO and SOD levels showed multiple positive associations with cardiometabolic risk factors including age, indices of obesity, insulin resistance, serum lipids, renal dysfunction, and biomarkers of inflammation. Higher MPO levels were associated with prevalent DSPN (fully adjusted OR 1.38 [95% CI 1.10; 1.72] per doubling of MPO). Higher baseline SOD3 levels were related to incident DSPN (age and sex-adjusted OR 2.14 [1.02; 4.48] per doubling of SOD3), which was partially explained by cardiometabolic risk factors.

CONCLUSIONS

Systemic levels of both pro- and antioxidant enzymes appear involved in cardiometabolic risk and development of DSPN.

An Adult with Polyneuropathy and Hypogonadism due to Poems Syndrome

POEMS (acronym for polyneuropathy, organomegaly, endocrinopathy, M protein myeloma and skin changes), is a rare disease which occurs in the setting of plasma cell dyscrasias. We describe a case of an adult lady who presented with gradual onset weakness of all four limbs and multisystem involvement characterized by pedal edema, ascites, hyperpigmentation and hypogonadism. Nerve conduction study showed severe sensorimotor polyneuropathy. Serum immunofixation showed lambda light chain restricted monoclonal gammopathy. Bone marrow biopsy consistent with plasma cell dyscrasia. Hormonal assay showed decreased FSH, LH and estradiol levels which led us to diagnosis of hypogonadotrophic hypogonadism. The patient responded well to combination therapy of thalidomide, melphalan and dexamethasone. Eight months after the therapy, she noted decreased paresthesias and increased strength. She had reduced edema and ascites.

Uric acid levels correlate with the severity of diabetic sensorimotor polyneuropathy

INTRODUCTION

Diabetic sensorimotor polyneuropathy (DSP) is the most frequent complication in patients with diabetes mellitus (DM), and is associated with age, DM duration, and HbA1c levels. In addition, higher uric acid (UA) levels are reported in patients with DSP.

OBJECTIVES

To explore whether UA levels correlate with DSP severity.

METHODS

We extracted the demographic data, clinical history, neurological and electrophysiological examinations and laboratory findings of 115 patients diagnosed with DSP from January 2012 to December 2015.

RESULTS

The mean age of the total cohort was 62±13years, with 61% men. A positive correlation was demonstrated between uric acid levels and increasing sensory symptoms, and more abnormal electrophysiological findings and vibration perception thresholds. In addition, correlations with gait abnormality, the presence of paraproteinemia and creatine kinase levels were found.

DISCUSSION

Our study results show that uric acid levels correlate with clinical and electrophysiological severity of DSP, providing additional evidence for the relationship between the two, and a potential therapeutic target for DSP.

Low serum omentin levels in the elderly population with Type 2 diabetes and polyneuropathy

AIMS

To investigate the hypothesis that high serum levels of omentin, an adipokine with anti-inflammatory, insulin-sensitizing and cardioprotective properties, may be related to a lower risk of diabetic sensorimotor polyneuropathy.

METHODS

The association between serum omentin level and polyneuropathy was estimated in people aged 61-82 years with Type 2 diabetes (47 with and 168 without polyneuropathy) from the population-based KORA F4 study. The presence of clinical diabetic sensorimotor polyneuropathy was defined as bilateral impairment of foot vibration perception and/or foot pressure sensation. Omentin levels were determined by enzyme-linked immunosorbent assay.

RESULTS

Serum omentin level was inversely associated with polyneuropathy after adjustment for age, sex, height, waist circumference, hypertension, total cholesterol, smoking, alcohol intake and physical activity [odds ratio 0.45 (95% CI 0.21-0.98); P = 0.043]. Although omentin was positively correlated with adiponectin (r = 0.55, P < 0.0001) and inversely with tumour necrosis factor-α (r = -0.30, P = 0.019), additional adjustment for adiponectin and tumour necrosis factor-α had little impact on the association.

CONCLUSIONS

Serum levels of omentin are reduced in people with Type 2 diabetes and diabetic sensorimotor polyneuropathy, independently of established risk factors of polyneuropathy. This association is only partially explained by biomarkers of subclinical inflammation.

Near-normoglycaemia and development of neuropathy: a 24-year prospective study from diagnosis of type 1 diabetes

OBJECTIVE

Complete prevention of diabetic neuropathies has not been previously demonstrated. We sought to determine whether long-term near-normoglycaemia maintained from the diagnosis of type 1 diabetes is associated with polyneuropathy and cardiac autonomic dysfunction.

DESIGN

Prospective observational study over 24 years.

SETTING

Ambulatory care.

PARTICIPANTS

32 newly diagnosed patients with type 1 diabetes aged 20.3 ± 1.0 years, duration of diabetes 2.7 ± 0.3 weeks.

INTERVENTION

Insulin therapy according to standards of care.

PRIMARY AND SECONDARY OUTCOME MEASURES

Motor and sensory nerve conduction velocity (MNCV and SNCV), heart rate variability (HRV), and confirmed clinical polyneuropathy measured at 15 time points over 24 years and quantitative sensory testing (QST) determined over 20-22 years.

RESULTS

11 patients were well controlled over 24 years with mean glycated haemoglobin (HbA1c) <7.0% (6.5 ± 0.1%; group 1), whereas 21 patients were poorly controlled (mean HbA1c ≥ 7.0%: 8.3 ± 0.2%; group 2). After 24 years, MNCV was faster in group 1 versus group 2 in the median (55.5 ± 1.6 vs 48.9 ± 1.6 m/s), ulnar (56.5 ± 1.5 vs 49.3 ± 1.7 m/s) and peroneal nerve (44.7 ± 1.6 vs 36.8 ± 2.5 m/s), while SNCV was faster in the median (53.6 ± 1.6 vs 45.5 ± 2.8 m/s), ulnar (54.7 ± 1.8 vs 43.0 ± 3.9 m/s), and sural nerve (44.5 ± 1.8 vs 35.5 ± 2.6 m/s; all p<0.05). The annual decline in peroneal MNCV and sural SNCV in group 1 was sixfold and threefold faster in group 2 than in group 1, respectively. Likewise, impairment in QST and HRV developed at faster rates in group 2. After 24 years, 64% of patients in group 2, but none in group 1, developed confirmed clinical polyneuropathy.

CONCLUSIONS

Near-normoglycaemia maintained from the diagnosis of type 1 diabetes over 24 years was associated with a complete prevention of the decline in hyperglycaemia-related peripheral and autonomic nerve function, and development of confirmed clinical polyneuropathy.

Demonstration of ameliorative effect of lacosamide: in a rat model of sepsis-induced critical illness polyneuropathy

OBJECTIVES

Critical illness neuropathy (CIN) is a condition that may occur in diseases with severe systemic response, particularly in sepsis. The aim of this study is to investigate the potential anti-inflammatory and lipid-peroxidation inhibiting activities of lacosamide by measuring tumour necrotizing factor-alpha (TNF-alpha), C-reactive protein (CRP), malondialdehyde (MDA) and white blood cells (WBC) using electroneuromyography (ENMG) in rats with sepsis-induced critical illness neuropathy (SICIN).

METHODS

Cecal ligation and puncture (CLP) procedure was performed on 39 rats to induce a sepsis model. The study groups were designed as follows: Group 1: normal (nonoperative); Group 2: (sham-operated); Group 3: CLP (untreated group); Group 4: CLP and lacosamide 20 mg/kg; Group 5: CLP and lacosamide 40 mg/kg. TNF-alpha, C reactive protein, MDA and WBC levels was measured and compound muscle action potential (CMAP) distal latans, amplitudes were measured by using ENMG in rats with SICIN.

RESULTS

When untreated sepsis group was compared with both control and sham groups, CMAP amplitudes and latans were significantly lower (P < 000.1). When CLP, CLP+lacosamide 20 mg/kg and CLP+lacosamide 40 mg/kg groups were compared, plasma levels of TNF-alpha and MDA were significantly higher in the untreated CLP group (F = 12.74, P < 0.0001), (F = 19.43, P < 0.05). In the CLP+lacosamide 40 mg/kg group, CRP levels were significantly lower only compared to the CLP group (P < 0.001).

DISCUSSION

We have showed that lacosamide may have beneficial effects on early SICIN by its potential anti-inflammatory and lipid peroxidation inhibiting activities; however, further comprehensive studies are required to clarify these effects.

Autoantibodies to neurofascin-186 and gliomedin in multifocal motor neuropathy

We tested autoantibodies to neurofascin-186 (NF186) and gliomedin in sera from patients with multifocal motor neuropathy (MMN, n=53) and chronic inflammatory demyelinating polyneuropathy (CIDP, n=95) by ELISA. IgG antibodies to NF186 or gliomedin were found in 62% of MMN and 1% of CIDP sera, and IgM antibodies to the same antigens in 12% of MMN and 1% of CIDP sera. These autoantibodies activated complement. Ten percent of the MMN sera without IgM anti-GM1 reactivity had anti-NF186 antibodies. Because NF186 and gliomedin play a crucial role for salutatory conduction, the autoantibodies may contribute to produce motor nerve conduction block and muscle weakness in MMN.

[The role of neurotrophic factors in formation of vibration disease]

The authors studied serum levels of neurotrophic factors (brain-derived neurotrophic factor BDNF and ciliary neurotrophic factor CNTF) in workers exposed to vibration (workers with long length of service and without health disorders caused by vibration, patients with occupational limbs polyneuropathy, and vibration disease patients). Findings are that occupational vibration induces increased BDNF and CNTF serum levels in all groups examined. Increased levels of neurotrophic factors at early stages of pathologic process indicate their protective action, action of compensatory protective mechanisms. However, high levels of BDNF and CNTF in vibration disease may point to neurodestructive processes in nervous system.

Glucose control and diabetic neuropathy: lessons from recent large clinical trials

Diabetic peripheral and autonomic neuropathies are common complications of diabetes with broad spectrums of clinical manifestations and high morbidity. Studies using various agents to target the pathways implicated in the development and progression of diabetic neuropathy were promising in animal models. In humans, however, randomized controlled studies have failed to show efficacy on objective measures of neuropathy. The complex anatomy of the peripheral and autonomic nervous systems, the multitude of pathogenic mechanisms involved, and the lack of uniformity of neuropathy measures have likely contributed to these failures. To date, tight glycemic control is the only strategy convincingly shown to prevent or delay the development of neuropathy in patients with type 1 diabetes and to slow the progression of neuropathy in some patients with type 2 diabetes. Lessons learned about the role of glycemic control on distal symmetrical polyneuropathy and cardiovascular autonomic neuropathy are discussed in this review.

Urinary methylmalonic acid as an indicator of early vitamin B12 deficiency and its role in polyneuropathy in type 2 diabetes

The rising incidence of diabetes and its negative impact on quality of life highlights the urgent need to develop biomarkers of early nerve damage. Measurement of total vitamin B12 has some limitations. We want to determine the levels of urinary methylmalonic acid and its relationships with serum vitamin B12 and polyneuropathy. The 176 Chinese patients with Type 2 diabetes mellitus were divided into 3 groups according to the levels of vitamin B12. A gas chromatography mass spectrometric technique was used to determine blood methylmalonic acid and urinary methylmalonic acid. The diagnosis of distal diabetic polyneuropathy was based on the determination of bilateral limb sensory and motor nerve conduction velocity and amplitude with electromyogram. Multiple regression analysis revealed that urinary methylmalonic acid/creatinine, blood methylmalonic acid, and so forth were variables that influenced diabetic polyneuropathy significantly. Nerve sensory conduction velocity and nerve amplitude in the group of urinary methylmalonic acid/creatinine >3.5 mmol/mol decreased significantly. Superficial peroneal nerve sensory and motor conduction velocity and ulnar nerve compound motor active potential amplitude were inversely correlated with urinary methylmalonic acid/creatinine. Urinary methylmalonic acid correlates with serum vitamin B12 levels in person with diabetes and is a sensitive marker of early polyneuropathy.

Neuropathy in prediabetes: does the clock start ticking early?

Between 25% and 62% of patients with idiopathic peripheral neuropathy are reported to have prediabetes, and among individuals with prediabetes 11-25% are thought to have peripheral neuropathy, and 13-21% have neuropathic pain. Population-based studies suggest a gradient for the prevalence of neuropathy, being highest in patients with manifest diabetes mellitus, followed by individuals with impaired glucose tolerance then impaired fasting glucose and least in those with normoglycemia. The most sensitive test to assess glucose metabolism status is the oral glucose tolerance test. Pathogenesis involves hyperglycemia, microvascular abnormalities, dyslipidemia and the metabolic syndrome. Individuals with prediabetes have less severe neuropathy than those with manifest diabetes mellitus. Sensory modalities are more frequently affected than motor modalities, but impairment of small nerve fibers could be the earliest detectable sign. Diagnosis should rely on careful clinical examination, with emphasis on the evaluation of small fibers. An oral glucose tolerance test should be performed in patients with idiopathic neuropathy. The only treatment with any efficacy is lifestyle modification to improve control of hyperglycemia and cardiovascular risk factors, but long-term efficacy of this approach has not been established. This Review summarizes the current evidence on the association between prediabetes and neuropathy.

[Dynamics of blood concentration of neurospecific proteins and risk of neuropathy development in the conditions of 105-day confinement]

Six male volunteers (aged 25 to 40 years) were subjects in all-round psychophysiological, hormonal and immunological studies before, in and after 105-day isolation and confinement. Blood was drawn and the 16-factorial Cattell personality inventory was filled out every 30 days. Concentrations of blood hormones, neurospecific proteins and cytokines point to a close interrelation between antibody titers to myelin-associated glycoprotein and changes in the parameters of metabolism and reproduction-related hormones, as well as cytokines and individual psychophysiology (extra-introversion, dominance, intropunitiveness, social contact selectivity, etc.), and suggest a minimum risk of demyelinizing neuropathy due to exposure to the conditions of isolation and confinement.

Sensory-motor polyneuropathy occurring in variant maple syrup urine disease

Maple syrup urine disease (MSUD; OMIM 248600) results from an inherited deficiency of the branched-chain ketoacid dehydrogenase (BCKD) complex. Approximately 20% of patients with BCKD deficiency are non-classic variants of MSUD with differing clinical severity. Outcomes for this cohort are generally favourable; episodes of metabolic decompensation do not appear to correlate with adverse events if acute management is promptly provided. A case of predominantly axonal sensory-motor neuropathy following metabolic decompensation which persisted for a number of months is presented in an adolescent girl with variant (intermediate type) MSUD. EMG and nerve conduction studies suggested a pre-existent asymptomatic chronic neuropathy, exacerbated by the acute decompensation. Peak leucine concentration at decompensation was 1083 μmol/L. The patient had laboratory signs of secondary mitochondrial respiratory chain dysfunction at presentation. She had been on a moderate dose of thiamine prior to decompensation; thiamine and pyridoxine blood concentrations were normal. This, to our knowledge, is the first report of a neuropathy presenting in a patient with a decompensation of variant MSUD. We propose that this presentation resembles the intermittent neuropathy observed in pyruvate dehydrogenase deficiency and may reflect secondary inhibition of pyruvate dehydrogenase activity by MSUD metabolites.

Antibodies against GM1 in demented patients

The aim of this study was to evaluate the levels of anti-GM1 in demented patients, correlating them with the type and severity of dementia as well as with the eventually coexistent polyneuropathy. Anti-GM1 concentrations were measured in the sera of 33 demented patients with a male-to-female ratio of 1:2.7 (the mean age was 69.7 years for males and 70.1 years for females). Eighty-two percent of the patients revealed increased values of anti-GM1, but only 18.2% demonstrated polyneuropathies. Fifty-nine percent of the patients suffered from vascular dementia. The most severely demented patients demonstrated a Mini-Mental State Examination score of 5 to 23 out of 30 and revealed the most increased levels of anti-GM1 (>40 EU/mL). The findings of this study are indicative of a possible correlation between the levels of anti-GM1 and the severity of dementia, mainly of the vascular type.

Vitamin B(12) and methylmalonic acid levels in patients presenting with polyneuropathy

This study was designed to determine the prevalence of definite vitamin B(12) deficiency (defined as < or =240 pg/ml) and possible vitamin B(12) deficiency (defined as >240 pg/ml and a methylmalonic acid [MMA] level >243 nmol/L) in patients with polyneuropathy and to determine whether patients in both groups respond to vitamin B(12) repletion. We performed a retrospective cohort study of 581 patients presenting with polyneuropathy over a 2-year period; 4% had definite vitamin B(12) deficiency and 32% had possible deficiency as the sole or contributing cause for their polyneuropathy. For those who received treatment with vitamin B(12), subjective improvement was seen in 87% with definite and in 43% with possible deficiency. Possible vitamin B(12) deficiency, defined as an elevated MMA level, is a common finding in patients with polyneuropathy and treatment of these patients with vitamin B(12) may lead to clinical improvement.

Restless legs syndrome is frequently overlooked in patients being evaluated for polyneuropathies

Restless legs syndrome (RLS) often presents with paresthesias and dysesthesisas. We have investigated the prevalence and clinical features of RLS in a cohort of patients referred for clinical suspicion of peripheral neuropathy (PN). Sixty-four patients with sensory symptoms, and 101 age-matched controls were prospectively evaluated for RLS, PN and causes of both conditions. In the 64 patients (60 +/- 14 years), none were referred with a suspicion of RLS. Forty-one had a sensori-motor PN of which 22 had a definite RLS (54%). When excluding other causes of RLS, 8 of 41 patients had a RLS associated with a neuropathy (20%). The proportion of RLS in the healthy controls was 10%, lower than in the cohort of patients. In patients without PN, 57% had a RLS, and 55% in the whole cohort, a higher proportion than in the healthy controls (P < 0.0001). Patients with PN and RLS had more sleep disorders (P < 0.04), and legs and calves symptoms (P = 0.09) than patients with PN without RLS. Toes symptoms were more frequently observed in patients with PN but without RLS (P < 0.02). We conclude that RLS frequently presents with symptoms suggestive of peripheral neuropathy, and therefore, is often overlooked.

Neurologic and hematologic response to fludarabine treatment in IgM MGUS polyneuropathy

We studied the efficacy of fludarabine in 16 patients with immunoglobulin M monoclonal gammopathy of unknown significance polyneuropathy in a prospective uncontrolled trial. The modified Rankin scale improved in 5/16 patients, all of whom had a demyelinating polyneuropathy. The motor conduction velocity improved by more than 10% in two or more nerves for four of five of these patients. Hematologic response in bone marrow occurred in three of five of these patients, whereas two of five already had small polyclonal B cell populations. There were no serious side effects.

Value of the oral glucose tolerance test in the evaluation of chronic idiopathic axonal polyneuropathy

BACKGROUND

An underlying cause is found in only 7% to 30% of patients with chronic idiopathic axonal polyneuropathy (CIAP). Diabetes mellitus, inherited disorders, toxin exposure, and primary amyloidosis are the most common identified causes of sensory neuropathies affecting both large and small myelinated fibers. Undiagnosed impaired fasting glucose metabolism has been associated with CIAP at a higher frequency rate than in the general population. This increased prevalence rate was identified using the 2-hour oral glucose tolerance test (2h-OGTT) and a previous version of the American Diabetes Association (ADA) guidelines.

OBJECTIVES

To determine the prevalence of abnormal fasting glucose metabolism in patients with CIAP and to compare the value of determining fasting plasma glucose levels using revised (2003) ADA criteria with the 2h-OGTT for predicting abnormal fasting glucose metabolism.

PATIENTS

In this 24-month retrospective study, 100 consecutive patients were identified with no known cause for CIAP, including diabetes mellitus, between January 2003 and January 2005. All had both a fasting plasma glucose test and a 2h-OGTT in addition to a complete neurological examination. Neurophysiological studies, computer-assisted sensory examination, and quantitative sudomotor axonal reflex testing were used to classify CIAP into subtypes according to nerve fiber involvement.

RESULTS

The prevalence of undiagnosed abnormal fasting glucose metabolism was found to be nearly 2-fold higher (62%) in patients with CIAP than in similar age-matched general population groups (33%). Using the 2003 revised ADA criteria, 39 patients (39%) had abnormal fasting plasma glucose metabolism (36 with impaired fasting glucose, 3 with diabetes mellitus), while the 2h-OGTT provided an even higher diagnostic rate of 62% (62 patients; P<.001) of impaired fasting glucose metabolism (38 with impaired glucose tolerance, 24 with diabetes mellitus). The abnormal glucose metabolism rates were found to be similar across the 3 subtypes (sensorimotor, pure sensory, and small-fiber neuropathy) of CIAP (P = .60, .72, and .61).

CONCLUSIONS

This study adds to emerging evidence that abnormal glucose metabolism may be a risk factor for CIAP. Even with revised (2003) ADA criteria, the 2h-OGTT provides additional diagnostic information to the health care professional in the evaluation of CIAP. Subtypes of CIAP are equally likely to have abnormal glucose metabolism.

Circulating levels of cytokines and their modulation by intravenous immunoglobulin in multifocal motor neuropathy

We found comparable levels of tumor necrosis factor (TNF)-alpha, interferon-gamma, interleukin (IL)-2, IL-4, IL-10, and IL-12 in the sera of 22 patients with multifocal motor neuropathy (MMN), 12 with amyotrophic lateral sclerosis (ALS), 12 multiple sclerosis, seven chronic inflammatory demyelinating polyneuropathy, five myasthenia gravis, and 13 healthy controls (NS). TNF-alpha levels, however, were higher in 15 (68%) MMN patients than in any NS. In all but one MMN patient tested, TNF-alpha levels repeatedly, albeit slightly, increased after each intravenous immunoglobulin infusion in parallel with clinical improvement and decreased 3-4 weeks after therapy, while in both ALS patients tested, they decreased or remained unchanged. The possible pathogenetic relevance of serum TNF-alpha modification in MMN remains to be clarified.

Recurrent Crow-Fukase Syndrome Associated with Increased Serum Levels of Vascular Endothelial Growth Factor: A Case Report and Review of the Literature

Crow-Fukase syndrome (CFS) is a rare multi-system disorder, characterized by polyneuropathy, organomegaly, endocrinopathy, M-proteins, skin changes and anasarca, with or without myeloma. The pathophysiology, diagnosis, and treatment of CFS are controversial. CFS may be associated with the overproduction of vascular endothelial growth factor (VEGF). However, there have been no reports of monitoring the serum VEGF level after recurrence, to the best of our knowledge. We report a 54-year-old man with CFS presenting with a 3-year history of ascites, anasarca, weakness of the lower extremities, and plasmacytoma in the scapula. At the initial examination, the VEGF level was 1,590 pg/ml (the VEGF level of a healthy control, 78.4 +/- 75.2 pg/ml). After initial treatment with chemotherapy and irradiation of the affected shoulder, the VEGF level decreased to 154 pg/ml and the symptoms disappeared. Twenty one months later, gate disturbance and anasarca recurred, and the VEGF level was over 2,000 pg/dl. After total scaplectomy, the VEGF level decreased to 730 pg/dl and the symptoms disappeared. The serum level of VEGF well correlated to the clinical course of the patient. In conclusion, measurement of the VEGF level is useful for diagnosing CFS and for monitoring its clinical course.

Monotonicity of nerve tests in diabetes: subclinical nerve dysfunction precedes diagnosis of polyneuropathy

OBJECTIVE

The objective of this study was to test whether monotone worsening of nerve function, attributable to diabetes, can be demonstrated before criteria for diabetic sensorimotor polyneuropathy (DSPN) have been met. Which nerve tests are best?

RESEARCH DESIGN AND METHODS

From a prevalence cohort of 504 individuals in the Rochester Diabetic Neuropathy study (RDNS), we identified 238 individuals (group 1) who at first examination were without polyneuropathy (DSPN) by a sum score of the normal deviates (from percentiles) of five attributes of nerve conduction of the legs (i.e., their five nerve conduction normal deviate values were <97.5th percentile) and were followed longitudinally two or more times. Of these 238, 90 (group 2) were followed six or more times at yearly or bi-yearly intervals. We compared different nerve tests for the ones most sensitive and reliable in showing latent nerve dysfunction and monotone (the extent to which a variable measured repeatedly over time reveals a significant trend of worsening or improvement).

RESULTS

In group 1 patients, the mean sum score of five attributes of nerve conduction (sigma 5 NC nds) at baseline was 1.08 and at the last examination (only patients with Sigma 5 NC nds <97.5th percentile) was 3.63, markedly higher than that in healthy subjects (only of individuals with Sigma 5 NC nds <97.5th percentile) (-0.12), indicating a subtle latent shift of nerve conduction tests toward abnormality. Serial evaluations of many individual and especially sum scores of nerve conduction tests in group 2 patients showed statistically significant worsening with time, even when nerve conduction tests were still well within normal limits. Neurologic signs also worsened but barely to significant levels; however, symptoms and quantitative sensation tests did not. Considering the composite score sigma 5 NC nds, 42 (of 90 group 2 patients) showed significant worsening, 22 were still without DSPN by nerve conduction test criteria, and some were even below the 50th percentile at the last evaluation.

CONCLUSIONS

Subtle and latent functional worsening of nerve conduction can be demonstrated even before nerve conduction test criteria for DSPN have been met. For demonstrating monotone worsening, the order (from best to worst) of tests was: some composite scores of nerve conduction and individual attributes of nerve conduction. We did not show monotone worsening of symptoms or of quantitative sensation test results. In multivariate analysis of risk factors and their association with worsening sigma 5 NC nds, 24-h microalbuminuria (a marker of microvessel disease) was found to be a significant covariate, an indication that the asymptomatic alterations of nerve conduction are meaningful.

Topical 2% amitriptyline and 1% ketamine in neuropathic pain syndromes: a randomized, double-blind, placebo-controlled trial

BACKGROUND

A double-blind, randomized, placebo-controlled 3-week study evaluated the efficacy of topical 2% amitriptyline, 1% ketamine, and a combination of both in treating patients with neuropathic pain.

METHODS

Ninety-two patients with diabetic neuropathy, postherpetic neuralgia, or postsurgical/posttraumatic neuropathic pain with allodynia, hyperalgesia, or pinprick hypesthesia were randomly assigned to receive one of four creams (placebo, 2% amitriptyline, 1% ketamine, or 2% amitriptyline-1% ketamine combined). The primary outcome measure was change in average daily pain intensity (baseline week vs. final week) using an 11-point numerical pain rating scale. Secondary outcomes included the McGill Pain Questionnaire, measures of allodynia and hyperalgesia, and patient satisfaction.

RESULTS

A reduction in pain scores of 1.1-1.5 units was observed in all groups, and there was no difference between groups. Blood concentrations revealed no significant systemic absorption. Minimal side effects were encountered.

CONCLUSION

This randomized, placebo-controlled trial examining topical 2% amitriptyline, 1% ketamine, and a combination in the treatment of neuropathic pain revealed no difference between groups. Optimization of doses may be required, because another study has revealed that higher concentrations of these agents combined do produce significant analgesia.

Critical illness polyneuropathy and myopathy in patients with acute respiratory distress syndrome

OBJECTIVE

Critical illness polyneuropathy/myopathy (CIP/CIM) is frequently described in critically ill patients who survive severe sepsis. Clinically relevant paresis is major symptom of CIP/CIM. We aimed at determining risk factors and diagnostic value of electrophysiologic testing for CIP/CIM in patients with acute respiratory distress syndrome (ARDS).

DESIGN

Single-center, retrospective analysis, using charts.

SETTING

University medical center.

PATIENTS

Fifty consecutive ARDS patients in our intensive care unit.

INTERVENTIONS

Patient characteristics and clinical course were analyzed. All patients received early electrophysiologic testing. CIP/CIM was diagnosed by the presence of clinical relevant paresis.

MEASUREMENTS AND MAIN RESULTS

Clinically relevant paresis was confirmed in 27 ARDS patients (60%), whereas in 18 patients no paresis was determined (controls); five patients died before clinical assessment of paresis was feasible. Patients with paresis were older, had more days on mechanical ventilation, and had increased intensive care unit length of stay compared with controls. Patients who developed paresis had elevated daily peak blood glucose levels during 28 days of intensive care unit treatment: 166 (134, 200) mg/dL in CIP/CIM patients vs. 144 (132, 161) mg/dL in controls (median, quartiles). Twenty-five of 27 patients with paresis revealed reduced motor unit potentials, fibrillation potentials, or positive sharp waves on early electrophysiologic testing indicating CIP/CIM, whereas 16 of 18 control patients did not.

CONCLUSIONS

In ARDS patients, paresis is a frequent complication causing prolonged mechanical ventilation and intensive care unit length of stay. An association between hyperglycemia and CIP/CIM has been found. However, since this is a retrospective survey, a causal relation is not clearly supported. In this study, the use of early electrophysiologic testing in ARDS patients was a valuable diagnostic tool for detecting CIP/CIM.

IgG Neuropathy: An Immunoelectron Microscopic Study

There are many potential mechanisms of peripheral nerve impairment by a monoclonal IgG dysglobulinemia. In this study, using electron microscopy, we observed widening of the myelin lamellae comparable to that commonly described in IgM neuropathies with antimyelin-associated glycoprotein activity. Such features have yet to be described in IgG neuropathies. In addition, we observed deposits of a granular material in the interstitial tissue of the nerve. By immunoelectron microscopy, we demonstrated the presence of the IgG in the lesions of myelin and the endoneurial space. A direct link between monoclonal dysglobulinemia (regardless of type) and polyneuropathy should be confirmed by nerve biopsy, because the result may influence treatment.

[Hormonal mechanisms of peripheral neuropathy in vibration disease]

Studies of peripheral limb nerves through stimulation electroneuromyography, evaluation of hormonal levels via radioimmune assay were performed in 59 patients having vibration disease caused by local vibration. Findings are obligatory signs of peripheral neuropathy and hypothyroid state without thyroid disease manifestations. Statistic analysis revealed reliable dependence between degree of motor axons functional deficit and level of serum triiodothyronine and thyroxin decrease--that could point to participation of thyroid hormones in peripheral neuropathy progression in vibration disease.

Polineuropatía paraneoplásica con anticuerpos anti-anfifisina

Paraneoplastic neurological syndromes consist of a dysfunction of any part of the nervous system, in isolation or in combination, caused by a malign neoplasia, but not by the direct tissular or metastasic invasion of the tumour. Their pathogeny is explained by immunological mechanisms and they are characterised by the presence of high rates of antibodies in serum and cerebrospinal fluid. We present the case of a patient with a sensitive neuropathy that produced ataxia, and who suffered from a poorly differentiated adenocarcinoma of the lung, in whom the search for antineuronal antibodies was positive for antiamphiphysin antibodies, supporting the diagnosis of paraneoplastic polyneuropathy.

Treatment of IgM antibody associated polyneuropathies using rituximab

OBJECTIVES

Polyneuropathies with associated serum IgM antibodies are often difficult to treat. Rituximab is a monoclonal antibody directed against the B cell surface membrane marker CD20. Rituximab eliminates B cells from the circulation, and, over time, could reduce cells producing autoantibodies. This study tested the ability of rituximab to produce changes in serum antibody titres, and improvement in strength, in patients with neuromuscular disorders and IgM autoantibodies.

METHODS

Over a period of two years, the authors evaluated changes in strength, measured by quantitative dynamometry, and concentrations of several types of serum antibodies in patients with polyneuropathies and serum IgM autoantibodies. Twenty one patients treated with rituximab were compared with 13 untreated controls.

RESULTS

Treatment with rituximab was followed by improved strength (an increase of mean (SEM) 23% (2%)of normal levels of strength), a reduction in serum IgM autoantibodies (to 43% (4%) of initial values), and a reduction in total levels of IgM (to 55% (4%) of initial values). There was no change in levels of serum IgG antibodies. There were no major side effects, even though B cells were virtually eliminated from the circulation for periods up to two years.

CONCLUSIONS

In patients with IgM autoantibody associated peripheral neuropathies, rituximab treatment is followed by reduced serum concentrations of IgM, but not IgG, antibodies, and by improvement in strength. Additional studies, with placebo controls and blinded outcome measures, are warranted to further test the efficacy of rituximab treatment of IgM associated polyneuropathies.

Can electrophysiology differentiate polyneuropathy with anti-MAG/SGPG antibodies from chronic inflammatory demyelinating polyneuropathy?

OBJECTIVES

Patients with polyneuropathy and antibodies to myelin-associated glycoprotein (MAG) and sulphated glucuronyl paragloboside (SGPG) differ from chronic inflammatory demyelinating polyneuropathy (CIDP) because of a slower, progressive course, symmetrical and predominantly sensory involvement of legs, predominantly distal slowing of motor conductions, and poorer response to therapy. We studied whether a wide set of electrophysiologic parameters may differentiate these two neuropathies.

METHODS

We reviewed the electrophysiological studies of 10 patients with anti-MAG/SGPG antibodies and 22 with CIDP examining: (1) motor conduction velocity and distal compound muscle action potential amplitude; (2) conduction block (CB) and temporal dispersion; (3) distal motor latency and terminal latency index (TLI); (4) F wave and proximal conduction time; and (5) sensory conduction and occurrence of abnormal median with normal sural sensory potential.

RESULTS

Anti-MAG/SGPG neuropathies showed: (1) more severe involvement of peroneal nerves; (2) more frequent disproportionate distal slowing of motor conductions (TLI< or =0.25) and absent sural potential, and (3) no CB. However 3/22 CIDP patients also had at least two nerves with TLI< or =0.25 and no CB.

CONCLUSIONS

Electrophysiologic findings suggest in anti-MAG/SGPG neuropathy a length-dependent process with a likely centripetal evolution. A disproportionate slowing of conduction in distal segments of motor nerves suggests the diagnosis of anti-MAG/SGPG neuropathy, although it is not pathognomonic.

[A case of polyneuropathy associated with increased levels of vascular endotherial growth factor (VEGF) insera]

A 54-year-old woman began to notice numbness and motor weakness in the lower extremities in July 1999. These symptoms rapidly progressed and she could not walk any more. When she admitted to our hospital, she showed peripherally dominant, moderate motor weakness, drop foot and loss of superficial and deep sensation in the lower extremities, but only slight weakness in the hands. Cranial nerves were intact. Deep tendon reflexes were all absent. Nerve conduction velocities were reduced and cerebrospinal fluid protein was elevated. VEGF was greatly increased in serum (1,850 pg/ml), which has been found to be increased exclusively in patients with Crow-Fukase syndrome. Many characteristic manifestations of the syndrome except polyneuropathy are well explained to be resulted from the abnormal production of VEGF. She did not, however, exhibit any constellation of Crow-Fukase syndrome such as edema, skin change, organomegaly, bone lesions or M-proteinemia. Steroid therapy improved her symptoms and lessened the levels of serum VEGF and cerebrospinal fluid protein. This case indicated that overproduction of VEGF could induce polyneuropathy rather than the other symptoms of Crow-Fukase syndrome, and that a polyneuropathy associated with increased VEGF might exist.

Postgastrectomy polyneuropathy with thiamine deficiency

OBJECTIVE

Polyneuropathy has been reported after gastrectomy performed to treat various lesions. Although thiamine deficiency is a possible cause of this neuropathy, the pathogenesis still remains to be clarified. Seventeen patients with peripheral neuropathy with thiamine deficiency after gastrectomy are described.

METHODS

Seventeen patients with polyneuropathy after gastrectomy accompanied by thiamine deficiency were selected. Patients were restricted to those with total or subtotal gastric resection to treat ulcer or neoplasm. Patients who had undergone operations to treat morbid obesity were excluded.

RESULTS

Intervals between the operation and onset of neuropathy varied from 2 months to 39 years. Most patients did not seem malnourished. Serum concentrations of B vitamins other than thiamine were nearly normal. Symmetric motor-sensory polyneuropathy, predominantly involving the lower limbs, had progressed over intervals varying from 3 days to 8 years. Relative degrees of motor and sensory impairment also varied extensively. Some cases that progressed rapidly mimicked Guillain-Barré syndrome. Electrophysiological and pathological findings were those of axonal neuropathy. Substantial functional recovery from polyneuropathy was seen in most patients by 3 to 6 months after initiating thiamine supplementation. Motor recovery was better than sensory recovery.

CONCLUSIONS

Various symptoms were seen in patients with postgastrectomy neuropathy. Thiamine deficiency should be considered in the differential diagnosis of motor-sensory polyneuropathy after gastrectomy.

[Multiple symmetrical lipomatosis with familial polineuropathy]

INTRODUCTION

Multiple symmetrical lipomatosis (LSM) is characterized by the development of symmetrical lipomas and is often associated with axonal polyneuropathy (PNP). Presentation is usually sporadic. Familial cases have been reported infrequently, with variable modes of inheritance. The pathogenesis is unknown. It has been related to mitochondrial cytopathy and alterations in lipid metabolism.

OBJECTIVES

To establish clinico pathological correlation in our cases of familial presentation. Patients and methods. We report seven patients, from three families, teetotalers with LSM. Clinical assessment included lipidogram, neurophysiological study of nerve and muscle, sural nerve biopsy in two of them and muscle biopsy in one member of each family for morphological assessment, respiratory chain biochemistry and study of molecular genetics.

RESULTS

LSM was associated with axonal PNP and hyperlipidemia in the seven members of the three families, with an apparent pattern of autosomal recessive inheritance. No conclusive data of mitochondrial cytopathy, in the form of significant morphological changes, biochemistry of the mitochondrial respiratory chain or micochondrial DNA were found.

CONCLUSION

Although mitochondrial cytopathy has been described as part of the syndromes in which LSM occurs, there may be other undefined aspects, such as disorders of lipid metabolism which form part of the pathogenesis.

Glycemic control is related to the morphological severity of diabetic sensorimotor polyneuropathy

OBJECTIVE

The aim of the current study was to determine the independent clinical risk factors for predicting morphological severity of distal diabetic sensorimotor polynecuropathy (DSP) as determined by fiber density (FD) on sural nerve biopsy.

RESEARCH DESIGN AND METHODS

A total of 89 patients with both type 1 and type 2 diabetes, ascertained from a large therapeutic randomized clinical trial, were included in this observational cohort study. Morphological severity of DSP was expressed as the myelinated FD in the sural nerve biopsy General linear models were used to assess the relationship between the morphological severity of DSP and various clinical risk factors.

RESULTS

Glycated hemoglobin (GHb) was significantly related to FD in univariate and multivariate regression analyses. This relationship was present in models in which GHb was handled either as a continuous variable or as a categorical variable with the highest significance level, with a GHb cutoff level of 9%. After dividing patients into groups with optimal to moderate GHb < or = 9%) and suboptimal (GHb >9%) glycemic control, the difference in FD between the two groups ranged between 3,461 and 2,334 per mm2. FD was also significantly related to duration of diabetes and age of the patient.

CONCLUSIONS

The severity of peripheral DSP expressed by morphological criteria was significantly related to glycemic control in type 1 and type 2 diabetic patients. Inconsistent with previously published electrophysiological data demonstrating a correlation between height and conduction velocity, increasing height is not associated with morphological severity. Based on the results of the present study, it might be hypothesized that improving glycemic control will lessen severity of DSP in terms of FD loss in subjects with diabetes.

[Autoimmune peripheral neuropathies with anti-MAG antibodies and hematological disorders. Five cases]

OBJECTIVE

The aim of this study was to report our experience with autoimmune neuropathies associated with hematological disorders and to describe their etiological and clinical polymorphism.

PATIENTS AND METHODS

A retrospective study was conducted in five patients with autoimmune peripheral neuropathies with anti-MAG (myelin-associated glycoprotein) antibodies.

RESULTS

Autoimmune neuropathies were associated with Waldenström's macroglobulinemia (n=2), Hodgkin disease (n=1), chronic lymphocytic leukemia (n=1) and idiopathic polyclonal B lymphoproliferation (n=1). Most of the patients had a sensorial polyneuropathy, predominant in the legs, exhibiting slow progress. Our patients showed a disappointing response to chemotherapy with stabilization or short response.

Vitamin B6 deficiency in elderly patients on chronic peritoneal dialysis

Polyneuropathy is one of the most frequent manifestations in chronic uremia. Among the factors related to polyneuropathy, vitamin B6 deficiency is well known. The exact prevalence of vitamin B6 deficiency related to neurological manifestations has not been previously reported. We studied vitamin B6 status, collected self-reported symptoms, and carried out full neurological examinations in 66 patients on chronic peritoneal dialysis. Vitamin B6 status was estimated by direct measurement of pyridoxal phosphate. In general, symptoms related to vitamin B6 deficiency are peripheral neuropathies, such as paresthesia, burning and painful dysesthesias, and thermal sensations. These symptoms were reported and assigned one of five grade scores. Of our 66 patients, 12 patients complained at least one sensory abnormality. The levels of vitamin B6 in the patients varied between 1.0 ng/mL and 30 ng/mL. Patients who complained of neurological symptoms owing to vitamin B6 deficiency were significantly older than the other patients. In analyzing the symptomatic cases before and after vitamin B6 supplementation, a significant correlation was seen between the level of vitamin B6 and symptoms. Within one month after initiation of oral vitamin B6 supplementations (30 mg daily), levels of pyridoxal phosphate rose, and sensory abnormalities improved in 8 of 12 patients. When peripheral neuropathy is suspected in elderly patients on chronic peritoneal dialysis, vitamin B6 deficiency should be taken into consideration as the cause. If vitamin B6 deficiency is appropriately treated by oral supplementation, sensory abnormalities can be eliminated.

Vitamin B6 supplementation can improve peripheral polyneuropathy in patients with chronic renal failure on high-flux haemodialysis and human recombinant erythropoietin

BACKGROUND

High-flux haemodialysis (HD) has recently been vigorously promoted as a novel standard, and it can indeed efficiently reduce the occurrence of most uraemic symptoms due to middle molecular toxins and/or underdialysis. However, some symptoms remain problematical, particularly peripheral polyneuropathy (PPN). One of the possible reasons for this is that the patients may have low concentrations of some nutrients, e.g. vitamin B(6), necessary for normal peripheral neuron function.

METHODS

Predialysis serum pyridoxal-5'-phosphate (P5P) level was determined in 36 chronic HD patients who were undergoing high-flux HD and receiving human recombinant erythropoietin. Among them, 26 patients suffered from PPN. Prior to supplementation, these 26 patients were examined and their neurological symptoms were ranked according to our PPN symptom score. Vitamin B(6) (60 mg/day) was randomly prescribed to 14 of them, and vitamin B(12) (500 microg/day) was prescribed to the others. After 4 weeks, all the patients were re-examined.

RESULTS

We found that predialysis serum P5P levels of HD patients with PPN were not significantly lower than those of matched HD patients without PPN. Nonetheless, it was demonstrated that supplementation with vitamin B(6) for 4 weeks significantly increased the predialysis level of P5P and dramatically attenuated PPN symptoms compared with initial symptoms. No improvement was observed in response to vitamin B(12) supplementation.

CONCLUSION

This result suggests that although vitamin B(6) deficiency could not be demonstrated in patients with chronic renal failure on high-flux HD, vitamin B(6) supplementation was effective in improving PPN symptoms of various aetiologies, possibly because of vitamin B(6) resistance to PPN in these patients.

Enhancement of AA-amyloid formation in mice by transthyretin amyloid fragments and polyethylene glycol

The mechanism behind amyloid formation is unknown in all types of amyloidosis. Several substances can enhance amyloid formation in animal experiments. To induce secondary systemic amyloid (AA-type amyloid) formation, we injected silver nitrate into mice together with either amyloid fibrils obtained from patients with familial polyneuropathy (FAP) type I or polyethylene glycol (PEG). Mice injected with silver nitrate only served as controls. Amyloid deposits were detectable at day 3 in animals injected with amyloid fibrils and in those injected with PEG, whereas in control mice, deposits were not noted before day 12. Our results indicate that amyloid fibrils from FAP patients and even a non-sulfate containing polysaccharide (PEG) have the potential to act as amyloid-enhancing factors.

The effect of tramadol in painful polyneuropathy in relation to serum drug and metabolite levels

BACKGROUND AND OBJECTIVE

Tramadol is a racemic drug that may act through a monoaminergic effect of (+)- and (-)-tramadol and through an opioid effect of its metabolite (+)-Ml. The objective of this study was to investigate the relationship between relief of pain and serum concentrations of tramadol and Ml in tramadol treatment of painful polyneuropathy.

METHODS

In a randomized, double-blind, placebo-controlled trial of 200 to 400 mg/day tramadol, serum concentrations of (+)- and (-)-tramadol and (+)- and (-)-Ml were determined in 28 of 34 patients. Ongoing and touch-evoked pain was rated daily by the patients by use of 0- to 10-point numeric rating scales during two 4-week treatment periods.

RESULTS

Tramadol significantly reduced both on-going (P = .002) and touch-evoked pain (P < .001). There was no relation between relief of on-going and touch-evoked pain and serum concentrations of (+)-tramadol, (-)-tramadol, (+)-M1, or (-)-M1 (P = .11 to P = .89). Seventeen of the patients were categorized as responders for on-going pain and 16 for touch-evoked pain. Responders for on-going pain tended to have higher serum concentrations of (+)-Ml than nonresponders (median, 27 nmol/L versus 16 nmol/L; P = .08). Isobolograms showed that the fraction of nonresponders was higher among patients with low concentrations of both tramadol and (+)-Ml both for on-going (P = .009) and touch-evoked (P = .02) pain.

CONCLUSION

The opioid effect of (+)-Ml may be of importance for tramadol relief of on-going neuropathic pain but, in general, relief of neuropathic pain seems to depend on both the monoaminergic effect of (+)- and (-)-tramadol and the opioid effect of (+)-Ml.

[Effect of diabetic control on the progression of neuropathy]

We investigated the relationship between blood levels of HbA1, an indicator of diabetic control, and the polyneuropathy index (PNI), an indicator of diabetic polyneuropathy. A total of 175 patients with non-insulin-dependent diabetes mellitus were followed for more than 3 years and were subjected to a series of motor conduction studies every 1 to 3 years. The PNI was calculated as a mean percentage of normal values for 12 indices derived from the conduction velocity and long-distance latency in motor conduction studies of 4 nerves. The mean follow-up period was 5.0 years, and during that time the mean decrease in the PNI was 2.7%. There was a significant negative correlation between mean HbA1 levels (X) and the percent changes in PNI per year (Y), and the equation for the regression line was Y = -0.102X + 0.37 (r = 0.283, p < 0.001). The higher the HbA1 level during this period, the larger the decline in PNI was. In patients with low initial PNI levels the change in PNI tended to be small in spite of high HbA1 levels. Likewise, in patients with high initial PNI levels the decrease in PNI tended to be large despite relatively good control of their HbA1 levels. However, since there were many patients whose HbA1 levels were not correlated with the reduction in PNI, there may be some unknown factors, possibly genetic, that play a role in the progression of polyneuropathy in diabetic patients.