Obesity and peripheral neuropathy risk: a dangerous liaison

Associations between Obesity and Spinal Diseases: A Medical Expenditure Panel Study Analysis

Background: The link between body weight status and spinal diseases has been suggested by a number of cross-sectional and cohort studies with a limited range of patient populations. No population-representative samples have been used to examine the link between obesity and spinal diseases. The present study is based on a nationally representative sample drawn from the Medical Expenditure Panel Survey. Methods: Using the cross-sectional sample of the 2014 Medical Expenditure Panel Study, we built four weighted logistic regression analyses of the associations between body weight status and the following four spinal diseases: low back pain, spondylosis, other cervical disorders and intervertebral disc disorder (IDD). Each respondent's body weight status was used as the key independent variable with three categories: normal/underweight, overweight, and obese. We controlled for marital status, gender, age, smoking status, household income, health insurance coverage, educational attainment and the use of health services for other major categories of diseases. Results: A total sample of 23,048 respondents was used in our analysis. Overweight and obese respondents, as compared to normal/underweight respondents, were more likely to develop lower back problems (Overweight: logged odds = 0.218, p < 0.01; Obese: logged odds = 0.395, p < 0.001) and IDD (Overweight: logged odds = 0.441, p < 0.05; Obese: logged odds = 0.528, p < 0.001). The associations between bodyweight status and spondylitis were statistically insignificant (Overweight: logged odds = 0.281, p = 0.442; Obese: logged odds = 0.680, p = 0.104). The associations between body weight status and other cervical disorders (Overweight: logged odds = -0.116, p = 0.304; Obese: logged odds = -0.160, p = 0.865) were statistically insignificant. Conclusions: As the first study using a national sample to study bodyweight and spinal diseases, our paper supports the hypothesis that obesity adds to the burden of low back pain and IDD. Longitudinal and interventional studies are needed to understand the specific mechanisms behind these positive associations.

Somatic neural alterations in non-diabetic obesity: a cross-sectional study

BACKGROUND

Reports on alterations in somatic neural functions due to non-diabetic obesity, a major risk factor for diabetes, are few and still a matter of debate. Nevertheless, to our knowledge, reports lack any comments on the type of somatic nerve fibers affected in non-diabetic obesity. Therefore, this study aimed to find out the alteration in somatic neural functions in non-diabetic obese persons if any.

METHODS

The study was conducted on 30 adult non-diabetic obese persons (mean age 32.07 ± 7.25 years) with BMI > 30 Kg/m2 (mean BMI 30.02 ± 2.89 Kg/m2) and 29 age- and sex-matched normal weight controls (mean age 30.48 ± 8.01 years) with BMI: 18-24Kg/m2 (mean BMI 21.87 ± 2.40 Kg/m2). Nerve conduction study (NCS) variables of median, tibial and sural nerves were assessed in each subject using standard protocol. The data were compared by Mann Whitney 'U' test.

RESULTS

In comparison to normal weight persons, obese had lower compound muscle action potential (CMAP) amplitudes of right median [9.09(7.62-10.20) Vs 10.75(8.71-12.2) mV, p = 0.025] and bilateral tibial nerves [Right: 8.5(7.04-11.18) Vs 12.1(10.55-15) mV, p < 0.001 and left 9.08(6.58-11.65) Vs 13.05(10.2-15.6) mV, p = 0.002]. Furthermore, obese persons had prolonged CMAP durations of right and left median [10.5(9.62-12) Vs 10(8.4-10.3) ms, p = 0.02 and 10.85(10-11.88) Vs 10(9-10.57) ms, p = 0.019] and right tibial [10(9-11) 8.5(7.92-10) ms, p = 0.032] nerves. Sensory NCS (sural nerve) also showed diminished sensory nerve action potential (SNAP) amplitude [16(12.08-18.21) vs 22.8(18.3-31.08) μV, p < 0.001] and prolonged duration. However, onset latencies and conduction velocities for all nerves were comparable between the groups.

CONCLUSION

This study documents subclinical peripheral nerve damage in non-diabetic obese with abnormal NCS parameters; shorter amplitudes and prolonged CMAP and SNAP durations. The reduced amplitudes of mixed and sensory nerves might be due to decreased axonal number stimulation or actual decrease in number of axonal fibers, or defect at NMJ in non-diabetic obese. Prolonged durations but normal onset latencies and conduction velocities strongly suggest involvement of slow conducting fibers.

Association of nerve conduction impairment and insulin resistance in children with obesity

AIM

The objective of our study was to investigate nerve conduction in normoglycemic obese children.

METHODS

A total of 60 children with obesity (30 female and 30 male) and 30 healthy children (15 female and 15 male) were enrolled in the study. Insulin resistance (IR) and other metabolic disturbances were investigated and nerve conduction was measured in all participants. Obese children were divided into groups according to the presence of IR. All results were compared between these subgroups.

RESULTS

The nerve conduction velocity (NCV) of motor median nerves in the IR+ group was significantly higher than that in the IR- group and lower than that in the control group. The NCV of the motor peroneal nerve in the IR+ group was significantly lower than that in the IR- group. The sensory nerve action potential (SNAP) of the sensory median nerve was significantly lower in the IR+ group compared to that in the IR- group. The sensory sural nerve's SNAP was significantly lower in the IR+ group than that in the control group.

CONCLUSION

Nerve conduction tests may help to detect early pathologies in peripheral nerves and to decrease morbidities in obese children.

Pain Experience and Perception in the Obese Subject Systematic Review (Revised Version)

Pain is an integral part of life and has an important protective function. Pain perception has been shown to differ between subjects and changes with gender, race, and culture. In addition, it has been suggested that obesity influences pain perception and that obesity can be a risk factor for increased pain thresholds. The aim of this systematic review was to examine pain thresholds in obese subjects compared to non-obese subjects. The electronic databases of the Cochrane Central Register of Controlled Trials (CENTRAL), PubMed, and EMBASE were searched using combinations of terms for obese, pain measurement, visual analog scale, quantitative sensory testing, and pain perception. Studies without comparison as well as cross-sectional studies, case series, and case reports were excluded. The search was conducted without restrictions on language or date of publication. From a total of 1818 identified studies, seven studies fulfilled the inclusion criteria, whereby only one study tested the pain threshold difference between obese and non-obese and also before and after body weight loss surgery. Two studies showed a lower pain threshold and four studies a higher pain threshold in obese subjects compared to non-obese subjects. Two studies showed no difference in pain threshold before and after substantial body weight loss due to surgery. Weight loss after surgery was not identified as a factor for higher pain thresholds in obese subjects. In view of the heterogeneity of the studies, the variability of the subjects and differences in methodological quality, a meta-analysis could not be performed. From the available literature, there is a tendency towards higher pain thresholds in obese subjects. Neither substantial weight loss, nor gender, were factors explaining difference in threshold. Future randomized, controlled trials should explore demographic variables that could influence pain perception or pain thresholds in obese individuals, and multimodal pain testing is necessary for better understanding of the apparent differences in pain thresholds in obese individuals.

Higher body fat percentage is associated with enhanced temperature perception in NAFLD: results from the randomised Wessex Evaluation of fatty Liver and Cardiovascular markers in NAFLD with OMacor thErapy trial (WELCOME) trial

AIMS/HYPOTHESIS

The effect of n-3 fatty acid treatment on temperature perception as a sensory nerve function modality is uncertain. In patients with non-alcoholic fatty liver disease (NAFLD) both with and without type 2 diabetes, we: (1) tested whether 15-18 months' treatment with 4 g/day of docosahexaenoic plus eicosapentaenoic acid (DHA+EPA) improved hot (HPT) and cold (CPT) temperature perception thresholds and (2) explored factors associated with HPT and CPT, in a randomised, double-blind, placebo-controlled trial.

METHODS

The effect of treatment (n = 44) on HPT, CPT and temperature perception index (TPI: difference between HPT and CPT) was measured at the big toe in 90 individuals without neuropathy (type 2 diabetes; n = 30). Participants were randomised 1:1, using sequential numbering, by personnel independent from the trial team. All participants and all members of the research team were blinded to group assignment. Data were collected in the Southampton National Institute for Health Research Biomedical Research Centre. Treatment effects and the independence of associations were testing by regression modelling.

RESULTS

Mean ± SD age was 50.9 ± 10.6 years. In men (n = 53) and women (n = 37), HPTs (°C) were 46.1 ± 5.1 and 43.1 ± 6.4 (p = 0.02), CPTs (°C) were 22.7 ± 3.4 and 24.5 ± 3.6 (p = 0.07) and TPIs (°C) were 23.4 ± 7.4 and 18.7 ± 9.5 (p = 0.008), respectively. In univariate analyses, total body fat percentage (measured by dual-energy x-ray absorptiometry [DXA]) was associated with HPT (r = -0.36 p = 0.001), CPT (r = 0.35 p = 0.001) and TPI (r = 0.39 p = 0.0001). In multivariable-adjusted regression models, adjusting for age, sex and other potential confounders, only body fat percentage was independently associated with HPT, CPT or TPI (p = 0.006, p = 0.006 and p = 0.002, respectively). DHA+EPA treatment did not modify HPT, CPT or TPI (p = 0.93, p = 0.44 and p = 0.67, respectively). There were no important adverse effects or side effects reported.

CONCLUSIONS/INTERPRETATION

Higher body fat percentage is associated with enhanced temperature perception. There was no benefit of treatment with high-dose n-3 fatty acids on the thresholds to detect hot or cold stimuli.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00760513 FUNDING: This work was supported by the National Institute for Health Research through the NIHR Southampton Biomedical Research Unit grant and by a Diabetes UK allied health research training fellowship awarded to KMcC (Diabetes UK. BDA 09/0003937).

Altered multisensory temporal integration in obesity

Eating is a multisensory behavior. The act of placing food in the mouth provides us with a variety of sensory information, including gustatory, olfactory, somatosensory, visual, and auditory. Evidence suggests altered eating behavior in obesity. Nonetheless, multisensory integration in obesity has been scantily investigated so far. Starting from this gap in the literature, we seek to provide the first comprehensive investigation of multisensory integration in obesity. Twenty male obese participants and twenty male healthy-weight participants took part in the study aimed at describing the multisensory temporal binding window (TBW). The TBW is defined as the range of stimulus onset asynchrony in which multiple sensory inputs have a high probability of being integrated. To investigate possible multisensory temporal processing deficits in obesity, we investigated performance in two multisensory audiovisual temporal tasks, namely simultaneity judgment and temporal order judgment. Results showed a wider TBW in obese participants as compared to healthy-weight controls. This holds true for both the simultaneity judgment and the temporal order judgment tasks. An explanatory hypothesis would regard the effect of metabolic alterations and low-grade inflammatory state, clinically observed in obesity, on the temporal organization of brain ongoing activity, which one of the neural mechanisms enabling multisensory integration.

Associations between anthropometric factors and peripheral neuropathy defined by vibrotactile perception threshold among industrial vibrating tool operators in Japan

OBJECTIVES

The effect of anthropometric factors on the fingertip vibrotactile perception threshold (VPT) of industrial vibrating tool operators (IVTOs) is not well known. The purpose of this study was to investigate the associations between anthropometric factors and fingertip VPT.

METHODS

We included for analysis two groups of IVTOs: Group 1, predominantly forestry workers (n=325); and Group 2, public servants (n=68). These IVTOs regularly received medical examinations to evaluate hand-arm vibration syndrome. In the examination, measurements of their fingertip VPTs were taken before and after cold-water immersion (10 minutes at 10°C for Group 1 and 5 minutes at 12°C for Group 2). Their body height and weight were measured to calculate the body mass index (BMI). The presence of peripheral neuropathy (PN) was defined as a VPT ≥17.5 dB at 10 minutes after finishing immersion.

RESULTS

In the univariate analysis, weight and BMI were associated with a decreased risk of PN in both Groups 1 and 2. The negative association between BMI and PN remained in the multivariate analysis consistently, but weight reached marginal significance only in the multivariate analysis without BMI in both the groups. Age was positively associated with PN consistently in Group 1 but not in Group 2. Years exposed to vibration showed positive association with PN only in the univariate analysis of Group 1.

CONCLUSIONS

Among IVTOs, factors reflecting body heat production, such as weight and BMI, were associated with a decreased risk of VPT-defined PN, regardless of the task engaged.

Relationship between Neuropathic Pain and Obesity

Objectives. Overweight negatively affects musculoskeletal health; hence obesity is considered a risk factor for osteoarthritis and chronic low back pain. This was conducted to determine if obesity affects neuropathic pain, usually considered unrelated to the weight-load on the musculoskeletal system. Methods. Using a cut-off body mass index value of 25, 44 patients with neuropathic pain were grouped into a "high-BMI" group and a "normal-BMI" group. Results. The numeric rating scale of the high-BMI group was significantly higher than that of the normal-weight group (P < 0.05). The total NPSI scores were significantly higher (P < 0.01), and the paroxysmal pain and the negative symptoms were more serious in the high-BMI group than in the normal-BMI group. The high-BMI subjects also had significantly higher SF-MPQ scores (P < 0.05). However, both physical and mental health status on the SF-36 were comparable between the groups. Discussion. Neuropathic pain that did not arise from musculoskeletal damage was higher in the high-BMI patients. Paroxysmal pain was more severe, suggesting that neural damage might be aggravated by obesity-associated inflammation. These findings should have needed to be confirmed in future studies.

Critical care of obese patients during and after spine surgery

Obesity is one of the most prevalent health problems facing the United States today, with a recent JAMA article published in 2014 estimating the prevalence of one third of all adults in the United States being obese. Also, due to technological advancements, the incidence of spine surgeries is growing. Considering these overall increases in both obesity and the performance of spinal surgeries, it can be inferred that more spinal surgery candidates will be obese. Due to this, certain factors must be taken into consideration when dealing with spine surgeries in the obese. Obesity is closely correlated with additional medical comorbidities, including hypertension, coronary artery disease, congestive heart failure, and diabetes mellitus. The pre-operative evaluation may be more difficult, as a more extensive medical evaluation may be needed. Also, adequate radiographic images can be difficult to obtain due to patient size and equipment limitations. Administering anesthesia becomes more difficult, as does proper patient positioning. Post-operatively, the obese patient is at greater risk for reintubation, difficulty with pain control, wound infection and deep vein thrombosis. However, despite these concerns, appropriate clinical outcomes can still be achieved in the obese spine surgical candidate. Obesity, therefore, is not a contraindication to spine surgery, and appropriate patient selection remains the key to obtaining favorable clinical outcomes.

BMI, HOMA-IR, and Fasting Blood Glucose Are Significant Predictors of Peripheral Nerve Dysfunction in Adult Overweight and Obese Nondiabetic Nepalese Individuals: A Study from Central Nepal

Objective. Nondiabetic obese individuals have subclinical involvement of peripheral nerves. We report the factors predicting peripheral nerve function in overweight and obese nondiabetic Nepalese individuals. Methodology. In this cross-sectional study, we included 50 adult overweight and obese nondiabetic volunteers without features of peripheral neuropathy and 50 healthy volunteers to determine the normative nerve conduction data. In cases of abnormal function, the study population was classified on the basis of the number of nerves involved, namely, “<2” or “≥2.” Multivariable logistic regression analysis was carried out to predict outcomes. Results. Fasting blood glucose (FBG) was the significant predictor of motor nerve dysfunction (P = 0.039, 95% confidence interval (CI) = 1.003–1.127). Homeostatic model assessment of insulin resistance (HOMA-IR) was the significant predictor (P = 0.019, 96% CI = 1.420–49.322) of sensory nerve dysfunction. Body mass index (BMI) was the significant predictor (P = 0.034, 95% CI = 1.018–1.577) in case of ≥2 mixed nerves' involvement. Conclusion. FBG, HOMA-IR, and BMI were significant predictors of peripheral nerve dysfunction in overweight and obese Nepalese individuals.

Predictive Value of Glycated Hemoglobin and Body Mass Index for Pretreatment Neuropathy in Patients With Multiple Myeloma

BACKGROUND

Peripheral neuropathy (PN) is detected in up to 62% patients with multiple myeloma (MM) at diagnosis. No specific risk factor for pretreatment neuropathy has been identified.

PATIENTS AND METHODS

We evaluated 29 sequential patients with MM attending our tertiary care center for peripheral neuropathy at diagnosis using symptoms, clinical examination, and nerve conduction studies (NCSs). Total Neuropathy Score, reduced (TNSr) and Total Neuropathy Score, clinical (TNSc) were calculated, and a score of ≥ 2 in each scale was considered diagnostic of PN. The study was approved by our institutional review board.

RESULTS

We found that 51.7% (n = 15) and 17.2% (n = 5) of patients had pretreatment neuropathy by TNSr and TNSc scales, respectively. Higher glycated hemoglobin (HbA1C) (P = .022), higher body mass index (BMI) (P = .008), higher serum creatinine levels (P = .023), and higher blood urea levels (P = .006) were associated with neuropathy by TNSr in univariate analysis. Higher blood urea levels (P = .023), higher serum creatinine levels (P = .003), and higher serum β2-microglobulin levels (P = .013) were associated with neuropathy by TNSc in univariate analysis. Higher HbA1c levels (P = .036; odds ratio [OR], 9.46) and BMI (P = .028; OR, 1.78) were associated with neuropathy by TNSr on binomial logistic regression analysis. Cutoffs of 5.6% (sensitivity, 60%; specificity, 71.4%) and 23.7 kg/m(2) (sensitivity, 80%; specificity, 71.4%) were obtained for HbA1c (area under the curve [AUC], 0.75) and BMI (AUC, 0.79), respectively, on receiver operating characteristic (ROC) curve analysis to predict neuropathy. The combination of HbA1c ≥ 5.6% and BMI ≥ 23.7 kg/m(2) had higher odds of neuropathy by TNSr (OR, 27.0; 95% confidence interval [CI], 2.0-368.4) when compared with either factor alone.

CONCLUSION

Use of TNSr, which incorporates electrophysiological abnormalities in addition to clinical manifestations, improves the detection rate of neuropathy. We found that high HbA1c and high BMI together are risk factors for neuropathy at diagnosis in patients with MM.

Obesity and chronic pain: systematic review of prevalence and implications for pain practice

The combination of obesity and pain may worsen a patient's functional status and quality of life more than each condition in isolation. We systematically searched PubMed/MEDLINE and the Cochrane databases for all reports published on obesity and pain. The prevalence of combined obesity and pain was substantial. Good evidence shows that weight reduction can alleviate pain and diminish pain-related functional impairment. However, inadequate pain control can be a barrier to effective lifestyle modification and rehabilitation. This article examines specific pain management approaches for obese patients and reviews novel interventional techniques for treatment of obesity. The infrastructure for simultaneous treatment of obesity and pain already exists in pain medicine (eg, patient education, behavioral medicine approaches, physical rehabilitation, medications, and interventional treatment). Screening for obesity, pain-related disability, and behavioral disorders as well as monitoring of functional performance should become routine in pain medicine practices. Such an approach requires additional physician and staff training. Further research should focus on better understanding the interplay between these 2 very common conditions and the development of effective treatment strategies.

The association between chronic pain and obesity

Obesity and pain present serious public health concerns in our society. Evidence strongly suggests that comorbid obesity is common in chronic pain conditions, and pain complaints are common in obese individuals. In this paper, we review the association between obesity and pain in the general population as well as chronic pain patients. We also review the relationship between obesity and pain response to noxious stimulation in animals and humans. Based upon the existing research, we present several potential mechanisms that may link the two phenomena, including mechanical/structural factors, chemical mediators, depression, sleep, and lifestyle. We discuss the clinical implications of obesity and pain, focusing on the effect of weight loss, both surgical and noninvasive, on pain. The literature suggests that the two conditions are significant comorbidities, adversely impacting each other. The nature of the relationship however is not likely to be direct, but many interacting factors appear to contribute. Weight loss for obese pain patients appears to be an important aspect of overall pain rehabilitation, although more efforts are needed to determine strategies to maintain long-term benefit.

Relations between metabolic homeostasis, diet, and peripheral afferent neuron biology

It is well established that food intake behavior and energy balance are regulated by crosstalk between peripheral organ systems and the central nervous system (CNS), for instance, through the actions of peripherally derived leptin on hindbrain and hypothalamic loci. Diet- or obesity-associated disturbances in metabolic and hormonal signals to the CNS can perturb metabolic homeostasis bodywide. Although interrelations between metabolic status and diet with CNS biology are well characterized, afferent networks (those sending information to the CNS from the periphery) have received far less attention. It is increasingly appreciated that afferent neurons in adipose tissue, the intestines, liver, and other tissues are important controllers of energy balance and feeding behavior. Disruption in their signaling may have consequences for cardiovascular, pancreatic, adipose, and immune function. This review discusses the diverse ways that afferent neurons participate in metabolic homeostasis and highlights how changes in their function associate with dysmetabolic states, such as obesity and insulin resistance.

Challenges in the optimisation of post-operative pain management with opioids in obese patients: a literature review

An increasing number of obese patients are undergoing surgery, particularly bariatric and orthopaedic surgery. The physiological differences between obese and normal-weight subjects may modify not only anaesthetic requirements during surgery but also post-operative analgesic management, raising a number of challenges in a critical period. In this review, we analyse studies of post-operative pain management with opioids in obese subjects. We discuss the genetic factors common to pain and obesity and the factors potentially modifying opioid pharmacokinetics and pharmacodynamics in obese patients, and we analyse the overall efficacy and safety of opioids for pain management during the post-operative period in obese patients. Both modifications to surgical methods and additional analgesic treatments to decrease the requirement for opioids may improve early rehabilitation and quality of care and reduce adverse effects in obese patients.

Effects of high fat diet induced obesity on peripheral nerve regeneration and levels of GAP 43 and TGF-β in rats

The increasing frequency of obesity is important because of its accompanying related health problems. The effects of obesity on peripheral nerves have not been elucidated. We investigated the effects of obesity on sciatic nerve regeneration using electrophysiology, stereology, immunohistochemistry, histopathology and functional tests. We used control, obese, control injured and obese injured groups of rats. Electrophysiological results showed that nerve conduction velocity and EMG were same in the experimental groups, but the amplitude of the compound action potential of the control group was significantly higher than that of the obese group. Examination of the nerves showed that the control and obese groups had both larger axon diameters and thicker myelin sheaths. The number of myelinated axons was decreased in both of the injured groups. Axon diameters and myelin sheath thicknesses of the control injured group were significantly greater those of the obese injured group. There were no significant differences in functional tests among the groups. Although growth associated protein 43 immunostaining in the control injured group was significantly greater than that of the obese injured group, no significant difference was observed between the control and obese groups. There was no significant difference in immunohistochemical staining for transforming growth factor beta 3 between the control injured and obese injured groups. Our results suggest that obesity may affect peripheral nerve regeneration negatively after crush injury.

Effect of high-fat diet on peripheral neuropathy in C57BL/6 mice

Objective. Dyslipidemia may contribute to the development of peripheral neuropathy, even in prediabetics; however, few studies have evaluated vascular dysfunction and oxidative stress in patients with peripheral neuropathy. Methods. Using high-fat diet- (HFD-) induced prediabetic C57BL/6 mice, we assessed motor and sensory nerve conduction velocity (NCV) using a BIOPAC System and thermal algesia with a Plantar Test (Hargreaves' method) Analgesia Meter. Intraepidermal nerve fiber density and mean dendrite length were tested following standard protocols. Vascular endothelial growth factor-A (VEGF-A) and 12/15-lipoxygenase (12/15-LOX) were evaluated by immunohistochemistry and Western blot, respectively. Results. HFD-fed mice showed deficits in motor and sensory NCV, thermal hyperalgesia, reduced mean dendrite length, and VEGF-A expression in the plantar skin and increased 12/15-LOX in the sciatic nerve (P < 0.05 compared with controls). Conclusion. HFD may cause large myelinated nerve and small sensory nerve fiber damage, thus leading to neuropathy. The mean dendrite length may be a more sensitive marker for early detection of peripheral neuropathy. Reduced blood supply to the nerves and increased oxidative stress may contribute to the development and severity of peripheral neuropathy.

Identification of risk factors for new-onset sciatica in Japanese workers: findings from the Japan epidemiological research of Occupation-related Back pain study

STUDY DESIGN

Two-year, prospective cohort data collected for the Japan epidemiological research of Occupation-related Back pain study were used for the analysis.

OBJECTIVE

To identify potential risk factors for the development of new-onset sciatica in initially symptom-free Japanese workers with no history of sciatica.

SUMMARY OF BACKGROUND DATA

Although the associations between individual and occupational factors and cases of new-onset sciatica are established, the effect of psychosocial factors on the development of sciatica has still not been adequately clarified.

METHODS

In total, 5310 participants responded to a self-administered baseline questionnaire (response rate: 86.5%). Furthermore, 3194 (60.2%) completed both 1- and 2-year follow-up questionnaires. The baseline questionnaire assessed individual characteristics, ergonomic work demands, and work-related psychosocial factors. The outcome of interest was new-onset sciatica with or without low back pain during the 2-year follow-up period. Incidence was calculated for participants who reported no low back pain in the preceding year and no history of lumbar radicular pain (sciatica) at baseline. Logistical regression assessed risk factors associated with new-onset sciatica.

RESULTS

Of 765 eligible participants, 141 (18.4%) reported a new episode of sciatica during the 2-year follow-up. In crude analysis, significant associations were found between new-onset sciatica and age and obesity. In adjusted analysis, significant associations were found for obesity and mental workload in a qualitative aspect after controlling for age and sex. Consequently, in multivariate analysis with all the potential risk factors, age and obesity remained statistically significant (odds ratios: 1.59, 95% confidence interval: 1.01-2.52; odds ratios: 1.77, 95% confidence interval: 1.17-2.68, respectively).

CONCLUSION

In previously asymptomatic Japanese workers, the risk of developing new-onset sciatica is mediated by individual factors. Our findings suggest that the management of obesity may prevent new-onset sciatica.

LEVEL OF EVIDENCE

3.

Increased autophagy in peripheral nerves may protect Wistar Ottawa Karlsburg W rats against neuropathy

OBJECTIVE

Wistar Ottawa Karlsburg W (RT1(u)) rats (WOKW) develop obesity, dyslipidemia, moderate hypertension, hyperinsulinemia and impaired glucose tolerance prone to induce peripheral neuropathy (PN). Autophagy has been shown to prevent neurodegeneration in the central and peripheral nervous system. We analyzed the potential protective role of autophagy in an established rat model in preventing PN.

METHODS

We examined electrophysiology (motor-and sensory/mixed afferent conduction velocities and the minimal F-wave latency) and morphology, including ultrathin sections, myelin sheath thickness (g-ratio) and immunohistochemical markers of autophagy and inflammation in the sciatic nerve of five-month-old, male WOKW as compared to Wistar derived, congenic LEW.1W control rats, characterized by the same major histocompatibility complex as WOKW rats (RT1(u)). Moreover, the expression of axonal and synaptic proteins (NF68, GAP43, MP0), autophagy- (Atg5, Atg7, LC3), and apoptosis (cleaved caspase-3)-related markers was measured using Western blot.

RESULTS

No abnormalities in nerve electrophysiology and morphology were found in WOKW compared to LEW.1W rats. However, autophagosomes were more frequently apparent in sciatic nerves of WOKW rats. In Western blot analyses no significant differences in expression of neuronal structural proteins were found, but autophagy markers were up-regulated in WOKW compared to LEW.1W sciatic nerves. Immunostaining revealed a greater infiltration of Iba1/ED-1-positive macrophages, CD-3-positive T-cells and LC3-expression in sciatic nerves of WOKW rats.

CONCLUSIONS

Our results indicate that WOKW rats show an up-regulated autophagy and a mild inflammatory response but do not develop overt neuropathy. We suggest that autophagy and inflammatory cells may exert a protective role in preventing neuropathy in this rat model of the metabolic syndrome but the mechanism of action is still unclear.

Neuroprotective effects of Vitis vinifera extract on prediabetic mice induced by a high-fat diet

BACKGROUND/AIMS

Vitis vinifera grape seed extract (VVE) contains oligomeric proanthocyanidins that show antioxidant and free radical-scavenging activities. We evaluated VVE for its neuroprotective effect in prediabetic mice induce by a high-fat diet (HD).

METHODS

Mice were divided into four groups according to VVE dose: those fed a normal diet (ND; n = 10), HD (n = 10), HD with 100 mg/kg VVE (n = 10), and HD with 250 mg/kg VVE (n = 10). After 12 weeks, immunohistochemical analyses were carried out using a polyclonal antibody against antiprotein gene product 9.5 (protein-gene-product, 9.5), and intraepidermal innervation was subsequently quantified as nerve fiber abundance per unit length of epidermis (intraepidermal nerve fiber, IENF/mm).

RESULTS

Daily administration of VVE at doses of 100 or 250 mg/kg for 12 weeks protected HD mice from nerve fiber loss compared to untreated mice, as follows (IENF/mm): controls (40.95 ± 5.40), HD (28.70 ± 6.37), HD with 100 mg/kg (41.14 ± 1.12), and HD with 250 mg/kg (48.98 ± 7.01; p < 0.05, HD with VVE vs. HD).

CONCLUSIONS

This study provides scientific support for the therapeutic potential of VVE in peripheral neuropathy in an HD mouse model. Our results suggest that VVE could play a role in the management of peripheral neuropathy, similar to other antioxidants known to be beneficial for diabetic peripheral neuropathy.

Sensory impairment in obese patients? Sensitivity and pain detection thresholds for electrical stimulation after surgery-induced weight loss, and comparison with a nonobese population

INTRODUCTION

Obese patients have a high prevalence of painful musculoskeletal disorders that may decrease after massive weight loss. Pain thresholds may be different in obese participants.

OBJECTIVES

To assess the sensitivity and pain detection thresholds, through the application of an electrical sensitivity, before and after massive weight loss, and to compare the thresholds obtained with those in a control population.

METHODS

The sensitivity and pain detection thresholds obtained in participants subjected to electrical stimulation were determined in 31 obese individuals (age: 40.3 ± 10.5 y) before (body mass index: 45.7 ± 6.8 kg/m) and 6 months after a mean weight loss of 32 kg induced by gastric bypass. The results obtained were compared with those for 49 nonobese control participants (38.5 ± 11.2 y; body mass index: 22.6 ± 2.6 kg/m). Body composition and metabolic biomarkers, such as leptin, adiponectin, insulin, and interleukin 6, were assessed and single-nucleotide polymorphisms of the mu opioid receptor [OPRM1 (c.118A > G) and COMT (p.Val158Met)] were genotyped in obese patients.

RESULTS

Sensitivity and pain detection thresholds (3.9 ± 1.1; 11.6 ± 6.0) were significantly higher in obese than in nonobese participants (3.1 ± 1.1; 6.0 ± 3.0), respectively (P < 0.0001), and were not affected by drastic weight loss (mean change: 32 kg). Pain thresholds in obese participants were not correlated with any of the clinical and biological variables studied. The obese participants in the highest quartile for both sensitivity and pain detection thresholds were significantly older than those in the lowest quartile.

CONCLUSIONS

Further studies are required to explore sensory dysfunction in obese individuals and to investigate the implications of this dysfunction for pain management.

Obesity is associated with inferior results after surgery for lumbar spinal stenosis: a study of 2633 patients from the Swedish spine register

STUDY DESIGN

A cohort study based on the Swedish Spine Register.

OBJECTIVE

To determine the association between body mass index (BMI) and outcome of lumbar spine surgery for spinal stenosis.

SUMMARY OF BACKGROUND DATA

Several small studies have sought to evaluate the importance of obesity in relation to results after surgery for lumbar spinal stenosis (LSS), but the findings are inconsistent and relatively weak.

METHODS

All patients who underwent surgery for LSS from January 1, 2006, to June 30, 2008, with a completed 2-year follow-up in the Swedish Spine Register were included. Logistic regression was used to assess the association between BMI and different outcomes.

RESULTS

Of the 2633 patients enrolled, 819 (31%) had normal weight, 1208 (46%) were overweight, and 606 (23%) were obese. On average, all 3 BMI groups achieved significant improvements after surgery. A higher BMI, however, was associated with greater odds of dissatisfaction after surgery and inferior results at the 2-year follow-up. After adjusting for differences in baseline characteristics, the obese group demonstrated inferior function and quality of life as measured by the Oswestry Disability Index (ODI) and the EuroQol Group Index (EQ-5D), respectively. At the 2-year follow-up, obese patients had a mean ODI of 33 (95% confidence interval [CI], 31-34) and mean EQ-5D of 0.56 (95% CI, 0.54-0.59) compared with a mean ODI of 25 (95% CI, 24-26) and mean EQ-5D of 0.64 (95% CI, 0.62-0.66) in the normal weight group. When compared with the normal weight patients, the adjusted odds ratio for dissatisfaction was 1.73 in the obese group (95% CI, 1.36-2.19). Differences between the normal weight and overweight groups were modest and therefore could not be considered clinically relevant.

CONCLUSION

Obese patients achieved significant pain reduction, better walking ability, and improved quality of life after surgical treatment of LSS. Nevertheless, obesity was associated with a higher degree of dissatisfaction and poorer outcomes after surgery for LSS.

Serial anthropometry predicts peripheral nerve dysfunction in a community cohort

BACKGROUND

Obesity is a risk factor for glucose intolerance, but the independent role of obesity in the development of peripheral neuropathy is unclear. This study assessed the impact of body size trajectories on prevalent nerve dysfunction in community-dwelling women with and without glucose intolerance.

METHODS

Annual (1996-2008) anthropometric measures of weight, height, waist circumference and body mass index [BMI, weight (kg)/height (m(2) )] were assessed in the Study of Women's Health Across the Nation - Michigan site. Glucose intolerance was defined annually on the basis of current use of diabetes medications, self-reported diabetes diagnosis and, when available, fasting glucose. Peripheral nerve dysfunction in 2008 was defined as abnormal monofilament testing or ≥4 symptoms or signs. Linear mixed models were used to determine trajectories of anthropometry by subsequently identified nerve dysfunction status.

RESULTS

Mean BMI was 32.4 kg/m(2) at baseline, and 27.8% of the women had nerve dysfunction in 2008. BMI, weight and waist circumference increased over time. Women who would have nerve dysfunction were significantly larger than women without dysfunction, independent of glucose intolerance. At mean baseline age of 46, BMI, weight and waist circumference differed significantly (p-value < 0.01) by subsequent nerve dysfunction status, independent of glucose intolerance and hypertension. These body size differences were maintained but not exacerbated over time.

CONCLUSIONS

Peripheral nerve dysfunction is prevalent among community-dwelling women. Twelve years before the nerve assessment, anthropometry differed between women who would and would not have nerve dysfunction, differences that were maintained over time. Obesity deserves attention as an important and potentially modifiable risk factor for peripheral nerve dysfunction.

"The more pain I have, the more I want to eat": obesity in the context of chronic pain

Providers frequently report pain as a barrier to weight loss, and initial evidence suggests individuals with chronic pain and obesity experience reduced treatment success. However, scant evidence informs our understanding of how this comorbidity negatively influences treatment outcome. More effective programs might be designed with (i) insight into the patient's experience of comorbid chronic pain and obesity and (ii) improved understanding of the behavioral linkages between the experience of pain, engagement in health behaviors, and obesity treatment outcomes. Thirty adult primary care patients with mean BMI = 36.8 (SD 8.9) and average 0-10 pain intensity = 5.6 (SD 1.9) participated in semistructured, in-depth interviews. Transcriptions were analyzed using the constant comparative method. Five themes emerged indicating that patients with comorbid chronic pain and obesity experience: depression as magnifying the comorbid physical symptoms and complicating treatment; hedonic hunger triggered by physical pain and associated with depression and shame; emotional or "binge" eating in response to pain; altered dietary choices in response to pain; and low self-efficacy for physical activity due to pain. Individuals with chronic pain and obesity may be less responsive to traditional interventions that fail to address the symbiotic relationship between the two conditions. These individuals are at-risk for depressive symptoms and eating and activity patterns that sustain the comorbidity and make treatment problematic, and they may respond to pain with behaviors that promote weight gain, poor health and low mood. Further research is needed to examine behavioral mechanisms that promote comorbid pain and obesity, and to develop targeted treatment modules.

Progress in vibrotactile threshold evaluation techniques: a review

Vibrotactile threshold (VT) testing has been used for nearly a century to investigate activation of human somatosensory pathways. This use of vibrotactile stimuli provides a versatile tool for detecting peripheral neuropathies, and has been broadly used for investigation of carpal tunnel syndrome. New applications include investigation of drug-induced neuropathies and diabetes-related neuropathies. As a feedback device, the vibrotactile stimuli could be used as an information delivery system for rehabilitative feedback devices for upper limb musculoskeletal disorders or as information channels for the visually impaired. This review provides a comprehensive review of the advancement in VT measurement techniques over time and a comparison of these techniques in terms of various hardware features used and the testing protocols implemented. The advantages and limitations of these methods have been discussed along with specific recommendations for their implementation and suggestions for incorporation into clinical practice.

Restless legs syndrome and conditions associated with metabolic dysregulation, sympathoadrenal dysfunction, and cardiovascular disease risk: a systematic review

Restless legs syndrome (RLS) is a distressing sleep and sensorimotor disorder that affects a large percentage of adults in the western industrialized world and is associated with profound reductions in quality of life. However, the etiology of RLS remains incompletely understood. Enhanced understanding regarding both the antecedents and sequelae of RLS could shed new light on the pathogenesis of RLS. Evidence from an emerging body of literature suggests associations between RLS and diabetes, hypertension, obesity, and related conditions linked to sympathetic activation and metabolic dysregulation, raising the possibility that these factors may likewise play a significant role in the development and progression of RLS, and could help explain the recently documented associations between RLS and subsequent cardiovascular disease. However, the relation between RLS and these chronic conditions has received relatively little attention to date, although potential implications for the pathogenesis and treatment of RLS could be considerable. In this paper, we systematically review the recently published literature regarding the association of RLS to cardiovascular disease and related risk factors characterized by sympathoadrenal and metabolic dysregulation, discuss potential underlying mechanisms, and outline some possible directions for future research.

Mechanisms underlying center of pressure displacements in obese subjects during quiet stance

Objective

the aim of this study was to assess whether reduced balance capacity in obese subjects is secondary to altered sensory information.

Design

cross sectional study.

Subjects

44 obese (BMI = 40.6 ± 4.6 kg/m² , age = 34.2 ± 10.8 years, body weight: 114,0 ± 16,0 Kg, body height 167,5 ± 9,8 cm) and 20 healthy controls (10 females, 10 males, BMI: 21.6 ± 2.2 kg/m², age: 30.5 ± 5.5 years, body weight: 62,9 ± 9,3 Kg, body height 170,1 ± 5,8 cm) were enrolled.

Measurements

center of pressure (CoP) displacements were evaluated during quiet stance on a force platform with eyes open (EO) and closed (EC). The Romberg quotient (EC/EO) was computed and compared between groups.

Results

we found statistically significant differences between obese and controls in CoP displacements (p < 0.01) and no statistically significant differences in Romberg quotients (p > 0.08).

Conclusion

the increased CoP displacements in obese subjects do not need an hypothesis about altered sensory information. The integration of different sensory inputs appears similar in controls and obese. In the latter, the increased mass, ankle torque and muscle activity may probably account for the higher CoP displacements.

Mechanisms of association between obesity and chronic pain in the elderly

Chronic pain is more common in the elderly and impairs functioning and quality of life. Though obesity, defined by body mass index (BMI), has been associated with pain prevalence among older adults, the mechanism of this association remains unclear. We examined components of the metabolic syndrome, insulin resistance, a marker of inflammation, and the presence of painful comorbidities as possible mediators of this association. Participants were 407 individuals aged >70 in the Einstein Aging Study. Chronic pain and pain over the last 3 months were defined using the Total Pain Index (TPI). Insulin resistance was modeled as fasting insulin, HOMA and QUICKI. High sensitivity C-reactive protein was used as a marker of inflammation. Cross-sectional logistic regression models were constructed to assess the associations of these factors with prevalent pain, adjusted for other known pain correlates. Prevalence of chronic pain was 52%. Of the clinical components of metabolic syndrome, central obesity was significantly associated with pain (OR 2.03, 95% CI 1.36-3.01). After adjustment for insulin resistance, inflammation, and pain-related comorbidities, central obesity predicted higher TPI scores (OR 1.55, 95% CI 1.04-2.33) and nearly doubled the risk of chronic pain (OR 1.70, 95% CI 1.05-2.75). Central obesity is the metabolic syndrome component showing the strongest independent association with pain, and the relationship is not explained by markers of insulin resistance or inflammation, nor by the presence of osteoarthritis or neuropathy.

Palmitate induces apoptosis in Schwann cells via both ceramide-dependent and independent pathways

Peripheral neuropathy has been reported to prevail in obese or pre-diabetic individuals, yet its etiology remains unknown. Palmitate, a saturated fatty acid increased in obesity and diabetes, is known to induce apoptosis in multiple types of cells and this effect may be mediated by ceramide, a member of the sphingolipid family. To clarify whether de novo ceramide synthesis from palmitate contributes to apoptosis of Schwann cells, we cultured immortalized mouse Schwann cells (IMS) and rat primary Schwann cells with palmitate, a ceramide analogue C2-ceramide as well as inhibitors of the de novo ceramide synthesis (myriocin and fumonisin B1). Apoptosis of IMS detected by nuclear staining and cell membrane inversion was significantly increased by incubation with palmitate for 48 h in a dose-dependent fashion. This enhanced apoptosis was partially but significantly suppressed by myriocin and fumonisin B1. Western blot analysis and immunostaining revealed that palmitate clearly activated caspase-3 in IMS. Unexpectedly, the ceramide synthesis inhibitors failed to suppress the palmitate-induced caspase-3 activation in spite of complete restoration in ceramide accumulation. The results seemed relevant to the observations that C2-ceramide did not activate caspase-3 while provoking apoptosis with a clear dose-dependency. In agreement, the pro-apoptotic action of C2-ceramide was not attenuated by caspase inhibitors that partially suppressed palmitate-induced apoptosis. These results in IMS were well reproducible in rat primary Schwann cells, indicating that the observed phenomena are not specific to the cell line. Collectively, we have reached a conclusion that palmitate induces apoptosis in Schwann cells via both a ceramide-mediated, caspase-3-independent pathway and ceramide-independent, caspase-3-dependent pathways. Given the fact that palmitate and ceramide are increased in obese or pre-diabetic subjects, these lipids may be implicated in the pathogenesis of peripheral neuropathy observed in these disorders.

Exercise and fitness are related to peripheral nervous system function in overweight adults

PURPOSE

This study examined the association between physical activity and fitness and peripheral nervous system (PNS) function in overweight and obese individuals.

METHODS

Forty nondiabetic overweight adults (mean +/- SD; age = 44 +/- 11 yr) were recruited for the study. Peroneal motor nerve and radial, sural, and medial plantar sensory nerve conductions were studied. Maximal oxygen uptake was measured in an incremental bicycle ergometer test. Physical activity was assessed by accelerometer and self-reporting. We analyzed the data using multiple stepwise linear regression models adjusted for age, height, and skin temperature.

RESULTS

VO2max predicted 17% of peroneal distal compound muscle action potential (CMAP) amplitude variation and 16% of peroneal proximal CMAP amplitude variation. Physical activity index at the age of 30 yr predicted 9% of peroneal motor nerve conduction velocity (NCV), 8% of peroneal F-wave maximum latency, 14% of medial plantar sensory latency, and 10% of medial plantar sensory NCV variation.

CONCLUSIONS

Physical activity and fitness are positively associated with PNS function and should be encouraged in overweight people.

Factors influencing time course of pain after depot oil intramuscular injection of testosterone undecanoate

Pain following depot intramuscular (IM) injection of oil vehicle-based drugs has been little studied. This study aimed to determine prospectively the prevalence, determinants, severity and functional consequences of pain during the week after IM injection of 1 000 mg testosterone undecanoate (TU) in a 4-mL castor oil vehicle. Androgen-deficient men receiving regular T replacement therapy at an academic andrology clinic were recruited to report pain scores using a coloured visual linear analogue scale at seven times over the first day and daily for a week after a deep IM gluteal injection. The time course and covariables influencing pain scores were analysed by mixed model analysis of variance (ANOVA). Following 168 injections in 125 men, pain was reported by 80% of men, peaking immediately after injection, reaching only moderate severity, lasting 1-2 days and returning to baseline by day 4. The pain required little analgesic use and produced minimal interference in daily activities. The time course of pain scores was reproducible in the 43 men who underwent two consecutive injections. Pain was more severe in men who had an earlier painful injection, but less severe in older and more obese men. There were negligible differences in post-injection pain experience between experienced nurses administering injections. Deep IM gluteal injection of depot TU in 4-mL castor oil is well tolerated and post-injection pain is influenced by earlier painful injection experience, as well as age and obesity.

Tibial nerve decompression in patients with tarsal tunnel syndrome: pressures in the tarsal, medial plantar, and lateral plantar tunnels

BACKGROUND

The anatomical basis for the surgical techniques used to treat tarsal tunnel syndrome is not well studied. The authors sought to evaluate their hypotheses that (1) pronation and pronation with plantar flexion of the intact foot would have higher pressures than the intact foot in other positions; (2) decompression surgery would significantly lower the pressure in all three tunnels in all foot positions, and roof incision plus septum excision would lower the pressure further in some positions; and (3) the pressures in symptomatic patients would be significantly higher than those in an analogous cadaver study.

METHODS

In 10 patients with tarsal tunnel syndrome, the authors intraoperatively measured pressures in the tarsal, medial plantar, and lateral plantar tunnels in multiple foot positions before and after excision of the tunnel roofs and intertunnel septum.

RESULTS

The authors found that (1) pronation and plantar flexion significantly increased pressures in the medial and lateral plantar tunnels, to levels sufficient to cause chronic nerve compression; (2) tunnel release and septum excision significantly decreased those pressures; and (3) compared with cadaver pressures, patients had similar tarsal tunnel pressures but higher lateral plantar tunnel pressures in some positions.

CONCLUSIONS

Many surgeons operating on patients with tarsal tunnel syndrome do not decompress the respective medial plantar and lateral plantar nerves and excise the septum. The authors' study validates the hypotheses that patients who are clinically suspected of having chronic compression of the tibial nerve and its branches at the ankle have higher tunnel pressures and that releasing these structures decreases the pressures.

Sural nerve biopsy may predict future nerve dysfunction

OBJECTIVE

Sural nerve pathology in peripheral neuropathy shows correlation with clinical findings and neurophysiological tests. The aim was to investigate progression of nerve dysfunction over time in relation to a baseline nerve biopsy.

METHODS

Baseline myelinated nerve fiber density (MNFD) was assessed in sural nerve biopsies from 10 men with type 2 diabetes, 10 with impaired and 10 with normal glucose tolerance. Nerve conduction and quantitative perception thresholds were estimated at baseline and follow-up (7-10 years later).

RESULTS

Subjects with low MNFD (< or = 4700 fibers/mm(2)) showed decline of peroneal amplitude (P < 0.02) and conduction velocity (P < 0.04), as well as median nerve sensory amplitude (P < 0.05) and motor conduction velocity (P < 0.04) from baseline to follow-up. In linear regression analyses, diabetes influenced decline of nerve conduction. MNFD correlated negatively with body mass index (r = -0.469; P < 0.02).

CONCLUSION

Low MNFD may predict progression of neurophysiological dysfunction and links obesity to myelinated nerve fiber loss.

High insulin levels are positively associated with peripheral nervous system function

OBJECTIVE

The aim of this study was to analyze peripheral nervous system (PNS) function in overweight and obese individuals.

MATERIALS AND METHODS

Forty-four adult non-diabetic overweight individuals were recruited. Peroneal motor nerve conduction and radial, sural, and medial plantar sensory nerve conduction were studied. Insulin and glucose levels were determined twice (over a 2- to 3-year period) with an oral glucose tolerance test (OGTT). Multiple stepwise linear regression models adjusted for age, height, weight, and skin temperature were used to analyze the data.

RESULTS

Analysis revealed that baseline insulin levels measured 120 min after an OGTT explained 18% of the variation in peroneal F-wave minimum latency, 8% of peroneal F-wave maximum latency variation, 15% of sural sensory latency variation, 13% of sural sensory nerve conduction velocity (NCV) variation, and 10% of the variation in medial plantar sensory NCV.

DISCUSSION AND CONCLUSION

Our study shows that serum insulin levels measured 120 min after an OGGT are positively associated with PNS function. High insulin levels without notably high glucose levels appear to be beneficial for the function of the PNS.

Idiopathic polyneuropathy and impaired glucose metabolism in a Norwegian patient series

BACKGROUND AND PURPOSE

North American studies have indicated a high prevalence of impaired glucose tolerance (IGT) in patients with sensory polyneuropathy. We searched for the occurrence of IGT in a Norwegian patient material with polyneuropathy.

METHODS

Seventy patients with symptoms and signs of sensory polyneuropathy were included. Cases with known causes of neuropathy were excluded. All patients underwent a 2 h oral glucose tolerance test (OGTT). Nerve conduction studies (NCS), quantitative sensory testing (QST) and skin biopsy with assessment of intra-epidermal nerve fibre (IENF) density were performed.

RESULTS

Sixteen patients (23%) had impaired glucose metabolism (IGM): 2 (3%) were found to have diabetes, 9 (13%) had IGT, 3 (4%) had impaired fasting glucose (IFG) and 2 (3%) both IFG and IGT. About 62% of the patients with IGM and polyneuropathy and 50% of those with chronic idiopathic axonal polyneuropathy (CIAP) had abnormalities on NCS. Reduction of IENF occurred in 37% of the patients with IGM and 43% of those with CIAP.

CONCLUSIONS

Patients with polyneuropathy and IGM had essentially the same degree of involvement of small and large nerve fibres as patients with CIAP. IGT seems less frequent in Norwegian patients with polyneuropathy than reported in North American populations.