Validation of the Toronto Clinical Scoring System for diabetic polyneuropathy

Association between a MIR499A polymorphism and diabetic neuropathy in type 2 diabetes

AIMS

Diabetic polyneuropathy (DPN) and cardiovascular autonomic neuropathy (CAN) affect a large percentage of diabetic people and impact severely on quality of life. As it seems that miRNAs and their variations might play a role in these complications, we investigated whether the rs3746444 SNP in the MIR499A gene could be associated with susceptibility to DPN and/or CAN.

METHODS

We analyzed 150 participants with type 2 diabetes. DNA was extracted from peripheral blood samples and genotyping was performed by TaqMan genotyping assay. Cardiovascular tests, MNSI-Q and MDNS for neuropathic symptoms and signs, VPT, and thermal thresholds were used for CAN and DPN assessment. We performed a genotype-phenotype correlation analysis.

RESULTS

We observed that the GG genotype was associated with a higher risk of developing CAN (P=0.002 and OR=16.08, P=0.0005 and OR=35.02, for early and confirmed CAN, respectively) and DPN (P=0.037 and OR=6.56), after correction for BMI, sex, age, HbA1c and disease duration. Moreover, the GG genotype was associated with worse values of MDNS (P=0.017), VPT (P=0.01), thermal thresholds (P=0.01), and CAN score (P<0.001). A logistic multivariate analysis confirmed that MIR499A GG genotype, disease duration and HbA1c contributed to early CAN (R²=0.26), while the same variables and age contributed to DPN (R²=0.21). With a multiple linear regression, we observed that GG genotype (P=0.001) and disease duration (P=0.035) were the main variables contributing to the CAN score (R²=0.35).

CONCLUSIONS

We described for the first time that the MIR499A genetic variation could be involved in diabetic neuropathies susceptibility. In particular, patients carrying the rs3746444 GG genotype had a higher risk of CAN development, together with a more severe form of CAN.

Decompression nerve surgery for diabetic neuropathy: a structured review of published clinical trials

AIM

To assess lower extremity decompression nerve surgery (DNS) to treat the consequences of diabetic distal symmetric peripheral neuropathy (DPN).

RESEARCH DESIGN AND METHODS

MEDLINE, PubMed, and related registries were searched through December 2017 to identify randomized, quasi-randomized or observational trials that evaluated the efficacy of lower extremity DNS on pain relief (primary outcome) or other secondary outcomes. Observational studies were included, given investigators' reluctance to use sham surgery controls. Outcome effect size was estimated, and a weighted average was calculated.

RESULTS

Eight of 23 studies evaluated pain relief, including a double-blind randomized controlled trial (with a sham surgery leg), an unblinded trial with a nonsurgical control leg, and 6 observational studies. All reported substantial pain relief post-DNS with average effect sizes between two and five. Unexpectedly, the double-blind trial showed improvement in the sham leg comparable to the DNS leg and exceeding the improvement observed in the nonsurgical leg in the unblinded study. Sensory testing showed generally favorable results supporting DNS, and nerve conduction velocities increased post-DNS relative to deterioration in controls. Ultrasound revealed fusiform nerve swelling near compression sites. Morphological results of DNS were generally favorable but inconsistent, whereas hemodynamic measures showed a positive effect on arterial parameters, as did transcutaneous oximetry (improved microcirculation). The incidence of initial and recurrent neuropathic diabetic foot ulcers appeared reduced post-DNS relative to the contralateral foot (borderline significant).

CONCLUSION

The data remain insufficient to recommend DNS for painful DPN, given conflicting and unexpectedly positive results involving sham surgery relative to unblinded controls. The generally supportive sensory and nerve conduction results are compromised by methodological issues, whereas more favorable results support DNS to prevent new or recurrent neuropathic foot ulcers. Future studies need to clarify subject selection vis-à-vis DPN vs superimposed compressed nerves, utilize appropriate validated instruments, and readdress use of sham surgical controls in light of recent results.

High resolution ultrasonography of the tibial nerve in diabetic peripheral neuropathy

Aim of the study

High-resolution ultrasonography of the tibial nerve is a fast and non invasive tool for diagnosis of diabetic peripheral neuropathy. Our study was aimed at finding out the correlation of the cross sectional area and maximum thickness of nerve fascicles of the tibial nerve with the presence and severity of diabetic peripheral neuropathy.

Material and methods

75 patients with type 2 diabetes mellitus clinically diagnosed with diabetic peripheral neuropathy were analysed, and the severity of neuropathy was determined using the Toronto Clinical Neuropathy Score. 58 diabetic patients with no clinical suspicion of diabetic peripheral neuropathy and 75 healthy non-diabetic subjects were taken as controls. The cross sectional area and maximum thickness of nerve fascicles of the tibial nerves were calculated 3 cm cranial to the medial malleolus in both lower limbs.

Results

The mean cross sectional area (22.63 +/- 2.66 mm²) and maximum thickness of nerve fascicles (0.70 mm) of the tibial nerves in patients with diabetic peripheral neuropathy compared with both control groups was significantly larger, and statistically significant correlation was found with the Toronto Clinical Neuropathy Score (p < 0.001). The diabetic patients with no signs of peripheral neuropathy had a larger mean cross sectional area (14.40 +/- 1.72 mm²) and maximum thickness of nerve fascicles of the tibial nerve (0.40 mm) than healthy non-diabetic subjects (12.42 +/- 1.01 mm² and 0.30 mm respectively).

Conclusion

The cross sectional area and maximum thickness of nerve fascicles of the tibial nerve is larger in diabetic patients with or without peripheral neuropathy than in healthy control subjects, and ultrasonography can be used as a good screening tool in these patients.

Toronto Clinical Neuropathy Score is valid for a wide spectrum of polyneuropathies

BACKGROUND AND PURPOSE

The Toronto Clinical Neuropathy Score (TCNS) is a valid and reliable scale for the diagnosis and staging of diabetic sensorimotor polyneuropathy. In this study, we aimed to explore the performance of the TCNS in non-diabetic polyneuropathies.

METHODS

We performed a prospective study from November 2016 to May 2017 of patients with non-diabetic polyneuropathy. Patients had clinical, electrophysiological and functional assessments of their polyneuropathy, and the findings were correlated with the TCNS.

RESULTS

The TCNS correlated with all clinical, electrophysiological and disability measures of polyneuropathy, mostly at a moderate level (e.g. r = -0.58 for sural nerve action potential amplitude). Higher TCNS severity grades were associated with worse polyneuropathy on all measures in the lower limbs, and with worse electrophysiological parameters and vibration perception thresholds in the upper limbs. The scale also showed excellent reliability and accuracy (kappa, 0.92-0.93 for inter- and intra-observer reliability; area under the receiver operating characteristics curve, 0.93).

CONCLUSION

The TCNS is a valid and reliable scale for a wide spectrum of polyneuropathies, and might be useful in clinical practise and research for the diagnosis and staging of polyneuropathy.

Overcoming barriers to diabetic polyneuropathy management in primary care

Diabetic polyneuropathy is a highly prevalent and costly complication of diabetes that is frequently underdiagnosed and undertreated in primary care settings. In this article, we discuss challenges in the management of diabetic polyneuropathy symptoms, including diagnostic complexity, the limited efficacy and high side effect rates associated with available treatments and the time constrained primary care visit. We call for the development of novel patient-centric, system-level strategies that engage patients between physician visits in order to facilitate timely communication of symptoms and treatment response and to promote patient-centered care.

Cross-cultural adaptation and measurement properties of the Brazilian Version of the Michigan Neuropathy Screening Instrument

BACKGROUND

The Michigan Neuropathy Screening Instrument is an easy-to-use questionnaire aimed at screening and detecting diabetic polyneuropathy.

OBJECTIVE

To translate and cross-culturally adapt the MNSI to Brazilian Portuguese and evaluate its measurement properties.

METHODS

Two bilingual translators translated from English into Brazilian Portuguese and made a synthetic version. The synthetic version was back translated into English. A committee of specialists and the translator checked the cultural adaptations and developed a pre-final questionnaire in Brazilian Portuguese (prefinal version). In pretesting, the prefinal version was applied to a sample of 34 subjects in which each subject was interviewed to determine whether they understood each item. For the later assessment of measurement properties, 84 subjects were assessed.

RESULTS

A final Brazilian Portuguese version of the instrument was produced after obtaining 80% agreement (SEM<0.01%) among diabetic patients and specialists. We obtained excellent intra-rater reliability (ICC_3,1=0.90), inter-rater reliability (ICC_2,1=0.90) and within-subject reliability ICC_3,1=0.80, excellent internal consistency (Cronbach's alpha>0.92), reasonable construct validity for the association between the MNSI and Neuropathy Symptom Score (r=0.46, p<0.05) and excellent association between the MNSI and Neuropathy Disability Score (r=0.79, p<0.05). We did not detect floor and ceiling effects (<9.5% of patients with maximum scores).

CONCLUSIONS

The Brazilian Portuguese version of the MNSI is suitable for application in the Brazilian diabetic population and is a reliable tool for the screening and detection of DPN. The MNSI can be used both in clinical practice and also for research purposes.

A standardized clinical evaluation of phenotypic diversity in diabetic polyneuropathy

Diabetic polyneuropathy (DPN) is a major cause of neuropathic pain and a frequent target condition in analgesic treatment trials. Differences in the clinical symptoms and signs associated with DPN suggest distinct pathophysiological mechanisms underlying nerve damage and dysfunction that are likely to have therapeutic relevance. The aim of this study was to develop a tool for the bedside assessment of painful neuropathies such as DPN that captures the diversity of phenotypes. Sixty-one patients with type 2 diabetes and painful neuropathy, 19 patients with painless DPN, 25 patients with type 2 diabetes but no clinical evidence of neuropathy, and 20 healthy control subjects completed a structured interview (47 items) and a standardized physical examination (39 items). After analyzing critical features of pain and painless symptoms and examining the outcome of physical tests of sensory function, we determined principal components of the phenotypic variance among patients. Increased sensitivity to mechanical or thermal stimuli and, to a lesser extent, the sensory quality of pain or paresthesia were the most discriminating elements of DPN phenotypes. Correlation patterns of symptoms and signs indicated the involvement of functionally distinct nerve fiber populations. We combined interview questions and physical tests identifying these differences in a shortened assessment protocol that we named Standardized Evaluation of Pain and Somatosensory Function (StEPS). The protocol StEPS generates a phenotypic profile of patients with neuropathy. Separate intensity ratings for spontaneous painful symptoms and pain evoked by standard stimuli support a detailed documentation of neuropathic pain and its response to analgesic treatment.

The relationship between neutrophil-to-lymphocyte ratio and diabetic peripheral neuropathy in Type 2 diabetes mellitus

To explore the relationship between neutrophil-to-lymphocyte ratio (NLR) and diabetic peripheral neuropathy (DPN) in type 2 diabetes mellitus.A total of 557 newly diagnosed Type 2 Diabetes Mellitus (T2DM) patients were recruited, including 397 T2DM patients without complication (DM group) as well as 160 T2DM patients complicated with DPN (DPN group). Student t test, Mann-Whitney U test, or χ test was applied to the data of the 2 groups, including the levels of neutrophils and lymphocytes as well as the NLR values of peripheral blood and other biochemistry indexes; Pearson correlation analysis was used to calculate the correlation of NLR and detected factors; risk factors of DPN were estimated via logistic regression analysis and multivariate analysis.The values of triglyceride (TG), neutrophils, fasting insulin, urinary albumin, and 2 hour postglucose in DPN group were significantly higher than those of the DM group, whereas the number of lymphocytes of DPN group was considerably lower than that of the DM group (P < .05 respectively); NLR values were remarkably higher in DPN group compared with those of DM group (2.58 ± 0.50 vs 2.18 ± 0.61, P < .001); logistic regression analysis showed that NLR (P = .002, OR = 4.960, 95% CI = 1.843-13.349) was a risk factor of DPN. Multivariate logistic regression analysis showed that DPN was independently related to NLR (P = .002, OR = 4.960, 95% CI = 1.843-13.349). The ROC curve analysis confirmed that the optimal cut-off point, specificity, and sensitivity in diagnosing DPN by NLR were 2.13%, 48.1%, and 81.3% respectively.Our results showed that NLR is significantly correlated with DPN, which suggested that NLR may be an independent risk factor of DPN.

Patient perspectives on peripheral neuropathic pain experience within the community

Purpose of this cross-sectional study was to explore the relationship between neuropathic physical complaints (NPC) and quality-of-life (QoL) in community-dwelling patients with diabetes in Broward County, Florida. Adult patients were invited to complete a 10-minute paper questionnaire at a community hospital between October 2014-April 2016. Analysis of data from 124 participants (60 with distal symmetric polyneuropathy (DSPN) diagnosis versus 64 without DSPN diagnosis) with NPC, showed those with DSPN had a longer duration of diabetes, suffered a higher number of NPC, and had a lower QoL (all p≤0.001) with more impediments to performing daily activities. While differences in pain severity and QoL were present in patients with DSPN versus those without DSPN diagnosis, NPC were still reported by those without DSPN diagnosis. Healthcare providers are encouraged to identify possible NPC during earlier stages of glycemic dysregulation and address foot care issues promptly to mitigate the disease's effect on QoL.

Effectiveness and feasibility of nailfold microcirculation test to screen for diabetic peripheral neuropathy

AIMS

The nailfold microcirculation index (MI) is a non-invasive, objective, and highly sensitive blood capillary detection method. This study evaluated the diagnostic efficiency of the nailfold MI relative to the more subjective vibration perception threshold (VPT) examination for early diagnostic screening of diabetic peripheral neuropathy (DPN).

METHODS

From February 2015 to February 2016, 227 diabetes mellitus patients and 39 healthy individuals were enrolled. Each subject underwent the MI test and the VPT examination.

RESULTS

MI was more closely associated with DPN than age, diabetic duration, smoking, drinking, systolic pressure, serum creatinine, 24-h urinary protein, hypoxia-inducible factor-1α (HIF1A), vascular endothelial growth factor (VEGF), the VEGF receptors Flt-1 and Flt-4, ankle branchial index (ABI), DPN, or DPN stage (OR=11.819). Both the MI and VPT closely correlated with age, diabetic duration, serum creatinine, 24-h urinary protein, HIF1A, VEGF, Flt-1, Flt-4, ABI, DPN, and DPN stage. By the receiver operating characteristic (ROC) curve, the MI diagnostic cutoff point was 2.56, where the corresponding Youden's index was maximum and the area under ROC curve was 0.943. The diagnostic efficiency of MI and VPT were similar. MI and VPT indicated similar percentages of diabetic patients with DPN at the most severe stage, while MI achieved a higher diagnostic rate for the earliest stages.

CONCLUSIONS

The nailfold MI is a feasible method for clinical early diagnostic screening of DPN in diabetic patients, and is more objective and reliable than VPT.

Serum methylmalonic acid correlates with neuropathic pain in idiopathic Parkinson's disease

Recent studies have shown a relatively higher prevalence of peripheral neuropathy in idiopathic Parkinson's disease (IPD). The hypothesis is that prolonged levodopa exposure causes vitamin B12 deficiency, which leads to peripheral neuropathy. The aim of our study was to find the relationship between vitamin B12 and its precursor methylmalonic acid (MMA) in IPD patients with neuropathic pain. We performed a cross-sectional study by enrolling consecutive 43 patients who were clinically tested positive for F-18 FP-CIT PET and 15 patients were diagnosed with peripheral neuropathy according to the Toronto clinical scoring system (TCSS). The severity of neuropathic pain was evaluated using total neuropathy scale, revised (TNSr), and Korean Neuropathic Pain Questionnaire (KNPQ). The correlations between age, IPD duration, levodopa equivalent dose (LED), UPDRS III, vitamin B12, MMA, and homocysteine levels were assessed. The prevalence rate of peripheral neuropathy in IPD patients was 35%. Among the serums assessed, MMA levels showed a positive correlation to TNSr and KNPQ in the IPD patients with peripheral neuropathy (TNSr r = 0.882, p < 0.001, KNPQ r = 0.710, p = 0.004), while Vitamin B12 and homocysteine showed no statistically significant correlation. Our study showed a prevalence of peripheral neuropathy in 35% of Korean IPD patients. The serum MMA positively correlated with the severity of neuropathic pain and this can be used as a useful marker in assessment of peripheral neuropathy in Parkinson's disease.

Declining Skeletal Muscle Function in Diabetic Peripheral Neuropathy

PURPOSE

The present review highlights current concepts regarding the effects of diabetic peripheral neuropathy (DPN) in skeletal muscle. It discusses the lack of effective pharmacologic treatments and the role of physical exercise intervention in limb protection and symptom reversal. It also highlights the importance of magnetic resonance imaging (MRI) techniques in providing a mechanistic understanding of the disease and helping develop targeted treatments.

METHODS

This review provides a comprehensive reporting on the effects of DPN in the skeletal muscle of patients with diabetes. It also provides an update on the most recent trials of exercise intervention targeting DPN pathology. Lastly, we report on emerging MRI techniques that have shown promise in providing a mechanistic understanding of DPN and can help improve the design and implementation of clinical trials in the future.

FINDINGS

Impairments in lower limb muscles reduce functional capacity and contribute to altered gait, increased fall risk, and impaired balance in patients with DPN. This finding is an important concern for patients with DPN because their falls are likely to be injurious and lead to bone fractures, poorly healing wounds, and chronic infections that may require amputation. Preliminary studies have shown that moderate-intensity exercise programs are well tolerated by patients with DPN. They can improve their cardiorespiratory function and partially reverse some of the symptoms of DPN. MRI has the potential to bring new mechanistic insights into the effects of DPN as well as to objectively measure small changes in DPN pathology as a result of intervention.

IMPLICATIONS

Noninvasive exercise intervention is particularly valuable in DPN because of its safety, low cost, and potential to augment pharmacologic interventions. As we gain a better mechanistic understanding of the disease, more targeted and effective interventions can be designed.

Agreement between automated and manual quantification of corneal nerve fiber length: Implications for diabetic neuropathy research

AIMS

Quantification of corneal nerve fiber length (CNFL) by in vivo corneal confocal microscopy represents a promising diabetic neuropathy biomarker, but applicability is limited by resource-intensive image analysis. We aimed to evaluate, in cross-sectional analysis of non-diabetic controls and patients with type 1 and type 2 diabetes with and without neuropathy, the agreement between manual and automated analysis protocols.

METHODS

Sixty-eight controls, 139 type 1 diabetes, and 249 type 2 diabetes participants underwent CNFL measurement (N=456). Neuropathy status was determined by clinical and electrophysiological criteria. CNFL was determined by manual (CNFL_Manual, reference standard) and automated (CNFL_Auto) protocols, and results were compared for correlation and agreement using Spearman coefficients and the method of Bland and Altman (CNFL_Manual subtracted from CNFL_Auto).

RESULTS

Participants demonstrated broad variability in clinical characteristics associated with neuropathy. The mean age, diabetes duration, and HbA1c were 53±18years, 15.9±12.6years, and 7.4±1.7%, respectively, and 218 (56%) individuals with diabetes had neuropathy. Mean CNFL_Manual was 15.1±4.9mm/mm², and mean CNFL_Auto was 10.5±3.7mm/mm² (CNFL_Auto underestimation bias, -4.6±2.6mm/mm² corresponding to -29±17%). Percent bias was similar across non-diabetic controls (-33±12%), type 1 (-30±20%), and type 2 diabetes (-28±16%) subgroups (ANOVA, p=0.068), and similarly in diabetes participants with and without neuropathy. Levels of CNFL_Auto and CNFL_Manual were both inversely associated with neuropathy status.

CONCLUSIONS

Although CNFL_Auto substantially underestimated CNFL_Manual, its bias was non-differential between diverse patient groups and its relationship with neuropathy status was preserved. Determination of diagnostic thresholds specific to CNFL_Auto should be pursued in diagnostic studies of diabetic neuropathy.

Effect of omega-3 supplementation on neuropathy in type 1 diabetes: A 12-month pilot trial

OBJECTIVE

To test the hypothesis that 12 months of seal oil omega-3 polyunsaturated fatty acids (ω-3 PUFA) supplementation will stop the known progression of diabetic sensorimotor polyneuropathy (DSP) in type 1 diabetes mellitus (T1DM).

METHODS

Individuals with T1DM and evidence of DSP as determined by a Toronto Clinical Neuropathy Score ≥1 were recruited to participate in a single-arm, open-label trial of seal oil ω-3 PUFA supplementation (10 mL·d^-1; 750 mg eicosapentaenoic acid, 560 mg docosapentaenoic acid, and 1,020 mg docosahexaenoic acid) for 1 year. The primary outcome was the 1-year change in corneal nerve fiber length (CNFL) measured by in vivo corneal confocal microscopy, with sensory and nerve conduction measures as secondary outcomes.

RESULTS

Forty participants (53% female), aged 48 ± 14 years, body mass index 28.1 ± 5.8 with diabetes duration of 27 ± 18 years, were enrolled. At baseline, 23 participants had clinical DSP and 17 did not. Baseline CNFL was 8.3 ± 2.9 mm/mm² and increased 29% to 10.1 ± 3.7 mm/mm² (p = 0.002) after 12 months of supplementation. There was no change in nerve conduction or sensory function.

CONCLUSIONS

Twelve months of ω-3 supplementation was associated with increase in CNFL in T1DM.

CLINICALTRIALSGOVIDENTIFIER

NCT02034266.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that for patients with T1DM and evidence of DSP, 12 months of seal oil omega-3 supplementation increases CNFL.

The sensitivity and specificity of the neurological examination in polyneuropathy patients with clinical and electrophysiological correlations

Introduction

Polyneuropathy is one of the most prevalent neurologic disorders. Although several studies explored the role of the neurological examination in polyneuropathy, they were mostly restricted to specific subgroups of patients and have not correlated examination findings with symptoms and electrophysiological results.

Objectives

To explore the sensitivity and specificity of different neurological examination components in patients with diverse etiologies for polyneuropathy, find the most sensitive combination of examination components for polyneuropathy detection, and correlate examination findings with symptoms and electrophysiological results.

Methods

Patients with polyneuropathy attending the neuromuscular clinic from 01/2013 to 09/2015 were evaluated. Inclusion criteria included symptomatic polyneuropathy, which was confirmed by electrophysiological studies. 47 subjects with no symptoms or electrophysiological findings suggestive for polyneuropathy, served as controls.

Results

The total cohort included 312 polyneuropathy patients, with a mean age of 60±14 years. Abnormal examination was found in 95%, most commonly sensory findings (86%). The most common abnormal examination components were impaired ankle reflexes (74%), vibration (73%), and pinprick (72%) sensation. Combining ankle reflex examination with vibration or pinprick perception had the highest sensitivity, of 88%. The specificities of individual examination component were generally high, excluding ankle reflexes (62%), and vibration perception (77%). Abnormal examination findings were correlated with symptomatic weakness and worse electrophysiological parameters.

Conclusion

The neurological examination is a valid, sensitive and specific tool for diagnosing polyneuropathy, and findings correlate with polyneuropathy severity. Ankle reflex examination combined with either vibration or pinprick sensory testing is the most sensitive combination for diagnosing polyneuropathy, and should be considered minimal essential components of the physical examination in patients with suspected polyneuropathy.

Vitamin D deficiency increases the risk of peripheral neuropathy in Chinese patients with type 2 diabetes

BACKGROUND

Vitamin D deficiency was reported to be associated with diabetic peripheral neuropathy. But the association in Chinese population and the screening value of vitamin D deficiency for diabetic peripheral neuropathy were unknown.

METHODS

A total of 861 patients with type 2 diabetes were recruited in this cross-sectional study. Vitamin D deficiency was defined as serum circulating 25-hydroxyvitamin D(25(OH)D) level < 20 ng/mL. Peripheral neuropathy was evaluated by neurological symptoms, neurological signs, neurothesiometer and electromyogram.

RESULTS

The patients with diabetic peripheral neuropathy had significantly lower serum 25(OH)D concentration (15.59 ± 7.68 ng/mL) and higher prevalence of vitamin D deficiency (80%) than patients with signs of diabetic peripheral neuropathy (17.66 ± 7.50 ng/mL; 64.5%) and non-DPN patients (18.35 ± 6.60; 61.7%) (all p < 0.01). Spearman's correlation analysis showed that serum circulating 25(OH)D level was closely associated with DPN (r = 0.121) and signs of DPN (r = 0.111) (both p < 0.01). After adjusting for all potential confounders, VDD was still linked with increased risk of DPN [odds ratio 2.59 (1.48-4.53)] (p < 0.01). Logistical regression analysis further revealed that VDD was an independent risk factor for DPN (β = 0.88) (p < 0.01). Receiver operating characteristic analysis indicated that serum 25(OH)D < 17.22 ng/mL hinted the signs of DPN and serum 25(OH)D < 16.01 ng/mL predicted the occurrence of DPN (both p < 0.01).

CONCLUSIONS

Vitamin D deficiency is an independent risk factor for diabetic peripheral neuropathy and may be a potential biomarker for peripheral neuropathy in Chinese patients with type 2 diabetes. Copyright © 2016 John Wiley & Sons, Ltd.

The Pain in Neuropathy Study (PiNS): a cross-sectional observational study determining the somatosensory phenotype of painful and painless diabetic neuropathy

Supplemental Digital Content is Available in the Text.

The Pain in Neuropathy Study (PiNS), an observational cross-sectional multicentre study, demonstrated a positive correlation between greater diabetic neuropathy severity and the presence and severity of neuropathic pain.

Disabling neuropathic pain (NeuP) is a common sequel of diabetic peripheral neuropathy (DPN). We aimed to characterise the sensory phenotype of patients with and without NeuP, assess screening tools for NeuP, and relate DPN severity to NeuP. The Pain in Neuropathy Study (PiNS) is an observational cross-sectional multicentre study. A total of 191 patients with DPN underwent neurological examination, quantitative sensory testing, nerve conduction studies, and skin biopsy for intraepidermal nerve fibre density assessment. A set of questionnaires assessed the presence of pain, pain intensity, pain distribution, and the psychological and functional impact of pain. Patients were divided according to the presence of DPN, and thereafter according to the presence and severity of NeuP. The DN4 questionnaire demonstrated excellent sensitivity (88%) and specificity (93%) in screening for NeuP. There was a positive correlation between greater neuropathy severity (r = 0.39, P < 0.01), higher HbA1c (r = 0.21, P < 0.01), and the presence (and severity) of NeuP. Diabetic peripheral neuropathy sensory phenotype is characterised by hyposensitivity to applied stimuli that was more marked in the moderate/severe NeuP group than in the mild NeuP or no NeuP groups. Brush-evoked allodynia was present in only those with NeuP (15%); the paradoxical heat sensation did not discriminate between those with (40%) and without (41.3%) NeuP. The “irritable nociceptor” subgroup could only be applied to a minority of patients (6.3%) with NeuP. This study provides a firm basis to rationalise further phenotyping of painful DPN, for instance, stratification of patients with DPN for analgesic drug trials.

Using in vivo corneal confocal microscopy to identify diabetic sensorimotor polyneuropathy risk profiles in patients with type 1 diabetes

OBJECTIVE

Diabetic sensorimotor peripheral neuropathy (DSP) is the most prevalent complication in diabetes mellitus. Identifying DSP risk is essential for intervening early in the natural history of the disease. Small nerve fibers are affected earliest in the disease progression and evidence of this damage can be identified using in vivo corneal confocal microscopy (IVCCM).

RESEARCH DESIGN AND METHODS

We applied IVCCM to a cohort of 40 patients with type 1 diabetes to identify their DSP risk profile. We measured standard IVCCM parameters including corneal nerve fiber length (CNFL), and performed nerve conduction studies and quantitative sensory testing.

RESULTS

40 patients (53% female), with a mean age of 48±14, BMI 28.1±5.8, and diabetes duration of 27±18 years were enrolled between March 2014 and June 2015. Mean IVCCM CNFL was 12.0±5.2 mm/mm² (normal ≥15 mm/mm²). Ten patients (26%) without DSP were identified as being at risk of future DSP with mean CNFL 11.0±2.1 mm/mm². Six patients (15%) were at low risk of future DSP with mean CNFL 19.0±4.6 mm/mm², while 23 (59%) had established DSP with mean CNFL 10.5±4.5 mm/mm².

CONCLUSIONS

IVCCM can be used successfully to identify the risk profile for DSP in patients with type 1 diabetes. This methodology may prove useful to classify patients for DSP intervention clinical trials.

Four-year sequential nerve conduction changes since first visit in Japanese patients with early type 2 diabetes

Aims/Introduction

Despite being the most common complication of diabetes, the pattern of clinical development of diabetic neuropathy is not well‐known. In the present study, we retrospectively examined sequential changes in nerve conduction studies (NCS) for 4 years to characterize the way neuropathic changes develop in patients with type 2 diabetes.

Materials and Methods

We randomly selected 158 patients with type 2 diabetes who newly visited Naka Memorial Clinic, Ibaraki, Japan, and underwent serial 4‐year NCS. Records of clinical profile, signs and symptoms of neuropathy, and NCS data from median and tibial nerves were extracted to determine the progression of neuropathy. NCS data were represented by motor nerve conduction velocities, amplitudes of compound muscle action potentials (CMAPs) and minimal latencies of F‐wave.

Results

The prevalence of clinical neuropathy in 158 cases was 30% at baseline and 29% at the end of the study, with improvement of glycated hemoglobin (8.6–6.9%). Over 4 years, there were no changes of the signs and symptoms of neuropathy. Motor nerve conduction velocities were slightly improved or consistent at the fourth year compared with those at the beginning (+1.5% in median nerve, P < 0.05; +0.8%, not significant in the tibial nerve). The extent of the glycated hemoglobin correction correlated with the improvement of motor nerve conduction velocity. In contrast, CMAPs of both median and tibial nerves were decreased (−11.6%, P < 0.01; −3.7%, P < 0.05, respectively). For the decrease in CMAPs, no specific risk factors were identified by logistic regression analysis.

Conclusions

The present study showed progressive decline of CMAPs despite improved glycemic controls or the lack of NCV slowing in patients with early type 2 diabetes.

Peripheral nerve high-resolution ultrasound in diabetes

INTRODUCTION

High-resolution ultrasound (HRU) is used in the diagnosis of peripheral neuropathies. There are conflicting data regarding HRU findings in patients with diabetic sensorimotor polyneuropathy (DSP). Our purpose in this study was to measure nerve cross-sectional areas (CSAs) in patients with diabetes, with and without DSP.

METHODS

We performed a prospective peripheral nerve HRU study of 100 diabetic subjects, assessed the CSA at predefined sites, and compared the results with those of 100 normal subjects. We evaluated the use of individual CSA values and various summary scores for diagnosis of DSP.

RESULTS

Diabetic subjects had higher CSA values than healthy volunteers, and those with DSP had higher CSA values. Three or more enlarged CSA sites predicted DSP with 64% sensitivity and 77% specificity.

CONCLUSIONS

Peripheral nerves are enlarged diffusely in diabetic patients, including sites not susceptible to bony compression. The number of enlarged CSA values can help predict the presence of DSP. Muscle Nerve, 2016 Muscle Nerve 55: 171-178, 2017.

Polyneuropathy in levodopa-treated Parkinson's patients

Recently published studies show that the prevalence of polyneuropathy (PNP) is higher in patients with Parkinson's disease (PD) than in age-matched controls. Its pathogenesis, however is a matter of controversy. The major hypothesis is the toxicity of high concentrations of homocysteine (Hcy) possibly related to levodopa (LD) therapy. The aim of the present study was to determine the prevalence of PNP, independent of other etiologies, and to determine the relationship to demographic and clinical factors in LD-treated Parkinson's patients. A total of 102 patients (51 patients with PD and 51 sex- and age-matched healthy controls) were enrolled in the study. The presence of any risk factors for PNP, ascertained from the history and laboratory tests, was an exclusion criterion. The Toronto Clinical Scoring System (TCSS) was used for clinical assessment of PNP. The objective assessment was based on electroneurography (ENG) studies in which motor nerves (peroneal and tibial nerves) as well as sensory nerves (sural and superficial peroneal nerves) were bilaterally examined. The severity of the disease was determined using the UPDRS scale (Unified Parkinson's Disease Rating Scale) and the Hoehn-Yahr (H-Y) scale. In the PD group, the clinical and neurophysiological indicators of PNP, manifested as a symmetrical and predominantly sensory axonal neuropathy, were more frequent then in the control group and observed in 43.1% vs. 13.7% and 15.7% vs. 2% of subjects respectively. The presence of PNP correlated with age and the severity of PD. Patients with PD and PNP had a higher level of Hcy as compared to PD patients without PNP, however the difference was not statistically significant. The frequency of PNP in PD patients is higher than in controls. The characteristics and discrepancy between the number of patients with clinical and ENG detected PNP may suggest the small fiber neuropathy (SFN) as the dominant form of neuropathy in PD patients.

Electrophysiologic testing in diabetic neuropathy

Electrophysiologic studies provide objective data concerning nerve and muscle function. This information enables the diagnosis of disease states and monitoring of disease progression. This chapter describes the changes in electrophysiologic function in both prediabetes and diabetes and discusses the utility of this testing in patients with diabetes. Both the strengths and limitations of electrophysiology are discussed.

A high thyroid stimulating hormone level is associated with diabetic peripheral neuropathy in type 2 diabetes patients

AIM

The association between thyroid stimulating hormone (TSH) and type 2 diabetes mellitus (T2DM) is well known. However, whether TSH is related to diabetic peripheral neuropathy (DPN) has not been studied. The aim of this study was to explore the relationship between TSH and DPN in Chinese patients with T2DM.

METHODS

In this cross-sectional study, 605 patients with T2DM were enrolled. Subclinical hypothyroidism (SCH) was defined as an elevated TSH level (>4.0mIU/L) and a normal free thyroxine level. DPN was evaluated by neurological symptoms, neurological signs, and electromyogram.

RESULTS

Serum TSH levels were significantly higher in DPN and signs of DPN compared with non-DPN T2DM patients (both P<0.01).The prevalence of DPN and signs of DPN in SCH subjects was higher than that in euthyroid subjects (both P<0.01). Spearman's correlation analysis showed that the serum TSH level was positively associated with DPN (r=0.172, P<0.01). A significant independent association between TSH and DPN was found by multiple logistic regression analysis after adjusting for potential confounding variables [odds ratio (OR)=1.365, P<0.01]. The patients were sequentially assigned to quartiles according to TSH level. Compared with quartile 1, patients in quartile 2 (P<0.01), quartile 3 (P=0.01), and quartile 4 (P<0.01) had a higher risk of DPN. Receiver-operating characteristic curve analysis revealed that the optimal cutoff point of TSH to indicate DPN was 3.045mIU/L in men and 2.94mIU/L in women.

CONCLUSION

TSH level is independently associated with DPN in Chinese population with T2DM. A high serum TSH level may be a potential risk factor for DPN.

Validation of cooling detection threshold as a marker of sensorimotor polyneuropathy in type 2 diabetes

AIM

We aimed to validate the performance cooling detection thresholds (CDT) to detect diabetic sensorimotor polyneuropathy (DSP) in type 2 diabetes.

METHODS

Two hundred and twenty participants with type 2 diabetes underwent clinical and electrophysiological examinations including 3 small fiber function tests: CDT, heart rate variability (HRV) and LDIFLARE. Clinical DSP was defined by consensus criteria whereas preclinical DSP was defined by presence of at least one electrophysiological abnormality. Area under the curve (AUC) and optimal thresholds were determined by receiver operating characteristic curves.

RESULTS

Participants were aged 63 ± 11 years with mean HbA1c of 7.5 ± 1.6%. The 139 (63%) clinical DSP cases had mean CDT values of 18.3 ± 8.9°C; the 52 (24%) preclinical DSP cases had 25.3 ± 3.5°C; and the 29 (13%) controls had 27.1 ± 3.8°C; (p-value<0.02 for all comparisons). For identification of clinical DSP cases, AUCCDT was 0.79 which exceeded AUCHRV (0.60, p=<0.0001) and AUCLDI FLARE (0.69, p=0.0003), optimal threshold <22.8°C (64% sensitivity, 83% specificity). Preclinical DSP AUCCDT was 0.80, also exceeding the other 2 measures (p<0.02 for both comparisons), optimal threshold ≤27.5°C (83% sensitivity, 72% specificity).

CONCLUSIONS

CDT had good diagnostic performance for identification of both clinical and preclinical neuropathy in type 2 diabetes. Its use as a non-invasive screening tool should be considered for research and clinical practice.

The Perfect Clinical Trial

Multiple phase III clinical trials have failed to show disease-modifying benefits for diabetic sensorimotor polyneuropathy (DSP) and this may be due to the design of the clinical trials. The perfect clinical trial in DSP would enroll sufficiently large numbers of patients having early or minimal disease, as demonstrated by nerve conduction studies (NCS). These patients would be treated with an intervention given at an effective and well-tolerated dose for a sufficient duration of time to show change in the end points selected. For objective or surrogate measures such as NCS and for some small fiber measures, the duration needed to show positive change may be as brief as 6-12 months, but subsequently, trials lasting 5-8 years will be required to demonstrate clinical benefits.

Assessment scales for the diagnosis of polyneuropathy

Epidemiological studies that investigate the occurrence and determinants of chronic length-dependent polyneuropathy are scarce. Population-based studies on polyneuropathy require a valid and reliable screening protocol with both good sensitivity and specificity. Several questionnaires and scoring scales have been developed for the detection of polyneuropathy, grading the severity of the disease, or evaluating the clinical course during follow-up. This review summarizes the aims and content of existing diagnostic polyneuropathy screening tools in order to help future studies decide which scale to use for screening in specific situations. We searched the PubMed database and identified 27 scales, 13 are based on symptoms alone, 8 on neurological signs alone, and 6 on a combination of symptoms and signs. Scales that combine questions concerning symptoms and a neurological examination with a focus on sensory alterations seem to have the best discriminatory power. However, all scoring scales were developed for and investigated in prespecified patient populations. Therefore, the generalizability of specific findings to the general population may be limited. We also discuss other limitations of existing scales. Future studies are required to determine which clinimetrically well-developed scales are preferred for use in population-based studies.

Effect of Ranirestat on Sensory and Motor Nerve Function in Japanese Patients with Diabetic Polyneuropathy: A Randomized Double-Blind Placebo-Controlled Study

We conducted a 26-week oral-administration study of ranirestat (an aldose reductase inhibitor) at a once-daily dose of 20 mg to evaluate its efficacy and safety in Japanese patients with diabetic polyneuropathy (DPN). The primary endpoint was summed change in sensory nerve conduction velocity (NCV) for the bilateral sural and proximal median sensory nerves. The sensory NCV was significantly (P = 0.006) improved by ranirestat. On clinical symptoms evaluated with the use of modified Toronto Clinical Neuropathy Score (mTCNS), obvious efficacy was not found in total score. However, improvement in the sensory test domain of the mTCNS was significant (P = 0.037) in a subgroup of patients diagnosed with neuropathy according to the TCNS severity classification. No clinically significant effects on safety parameters including hepatic and renal functions were observed. Our results indicate that ranirestat is effective on DPN (Japic CTI-121994).

Diabetic Polyneuropathy in Type 2 Diabetes Mellitus: Inflammation, Oxidative Stress, and Mitochondrial Function

Diabetic polyneuropathy (DPN) is defined as peripheral nerve dysfunction. There are three main alterations involved in the pathologic changes of DPN: inflammation, oxidative stress, and mitochondrial dysfunction. Inflammation induces activation of nuclear factor kappa B, activator protein 1, and mitogen-activated protein kinases. Oxidative stress induced by hyperglycemia is mediated by several identified pathways: polyol, hexosamine, protein kinase C, advanced glycosylation end-products, and glycolysis. In addition, mitochondrial dysfunction accounts for most of the production of reactive oxygen and nitrosative species. These free radicals cause lipid peroxidation, protein modification, and nucleic acid damage, to finally induce axonal degeneration and segmental demyelination. The prevalence of DPN ranges from 2.4% to 78.8% worldwide, depending on the diagnostic method and the population assessed (hospital-based or outpatients). Risk factors include age, male gender, duration of diabetes, uncontrolled glycaemia, height, overweight and obesity, and insulin treatment. Several diagnostic methods have been developed, and composite scores combined with nerve conduction studies are the most reliable to identify early DPN. Treatment should be directed to improve etiologic factors besides reducing symptoms; several approaches have been evaluated to reduce neuropathic impairments and improve nerve conduction, such as oral antidiabetics, statins, and antioxidants (alpha-lipoic acid, ubiquinone, and flavonoids).

Treatment Responsiveness in CIDP Patients with Diabetes Is Associated with Higher Degrees of Demyelination

Introduction

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is one of several chronic treatable acquired demyelinating neuropathies.

Objectives

To explore the association between the degree of demyelination in CIDP, and treatment responsiveness.

Methods

A retrospective chart review of CIDP subjects assessed between 1997 and 2013 was performed to compare treatment responsiveness using different sets of criteria.

Results

99 CIDP patients were included, 34 with diabetes mellitus (DM). Treatment responsiveness was higher in CIDP-DM fulfilling 1 or more EFNS/PNS criteria, (63% vs. 31%, p = 0.03), and in CIDP+DM fulfilling 2 or more criteria (89% vs. 36%, p = 0.01). Nonetheless, treatment responsiveness in CIDP+DM had the highest odds ratio (3.73, p = 0.01). Similar results were also shown in simplified uniform study criteria, with 10% cut off values for CIDP-DM, compared to 30% for CIDP+DM.

Conclusion

In CIDP+DM, higher degrees of demyelination are associated with treatment responsiveness, implying the need to adjust current criteria in these patients.

Distal Sensorimotor Neuropathy: Improvements in Diagnosis

Neurological complications of diabetes are common, affecting up to 50% of people with diabetes. In these patients, diabetic sensorimotor neuropathy (DSPN) is by far the most frequent complication. Detecting DSPN has traditionally been a clinical exercise that is based on signs and symptoms. However, the appearance of morphometric and neurophysiological techniques along with composite scoring systems and new screening tools has induced a paradigm change in the detection and stratification of DSPN and our understanding of its natural history and etiopathogenesis. These newer techniques have provided further evidence that changes in small nerve fiber structure and function precede large fiber changes in diabetes. Although useful, the challenge for the use of these new techniques will be their sensitivity and specificity when widely adopted and ultimately, their ability to demonstrate improvement when pathogenic mechanisms are corrected. Concurrently, we have also witnessed an emergence of simpler screening tools or methods that are mainly aimed at quicker detection of large fiber neuropathy in the outpatient setting. In this review, we have focused on techniques and tools that receive particular attention in the current literature, their use in research and potential use in the clinical environment.

Single-fiber electromyography of facial and limb muscles in diabetic patients with or without neuropathy

PURPOSE

In diabetic patients, single-fiber electromyography (SFEMG) is often abnormal in the limb muscles and is considered unreliable in diagnosis of synaptic disorders. We aimed to compare SFEMG abnormalities of frontalis muscle (FM) and extensor digitorum communis muscle in diabetic patients with neuropathy and without neuropathy.

METHODS

Stimulation SFEMG of FM and extensor digitorum communis muscle was performed in matched groups of 30 diabetic patients with neuropathy and 20 diabetic patients without neuropathy.

RESULTS

Single-fiber electromyography in the FM was abnormal in four diabetic patients with neuropathy and in one diabetic patient without neuropathy. Changes were rather mild. Extensor digitorum communis abnormalities were significantly more frequent-in 20 diabetic patients with neuropathy and in 7 diabetic patients without neuropathy (P < 0.001). We never observed a patient with abnormal FM but normal extensor digitorum communis muscle.

CONCLUSIONS

In diabetes, FM exhibits rare and quite mild SFEMG changes. This muscle may be suitable for SFEMG in diabetic patients with clinical suspicion for synaptic disorder.

In vivo corneal confocal microscopy and prediction of future-incident neuropathy in type 1 diabetes: a preliminary longitudinal analysis

OBJECTIVE

In vivo corneal confocal microscopy (IVCCM) has been established in cross-sectional studies as a valid measure for the identification of diabetic sensorimotor polyneuropathy (DSP). We aimed to determine the predictive validity of a baseline IVCCM measure in identifying future DSP onset in patients with type 1 diabetes.

METHODS

We followed 65 patients with type 1 diabetes without DSP at baseline. They were followed longitudinally for a mean of 3.5±0.9 years and underwent IVCCM, clinical and electrophysiologic examinations at baseline and follow up. At the end of follow up, participants were assigned as new-onset cases of DSP or as controls. Predictive validity was assessed using receiver operating characteristic curves.

RESULTS

At baseline, participants were 34±15 years of age with mean diabetes duration of 18±12 years. The 11 (17%) new-onset cases of DSP were similar to the 54 (83%) controls in baseline age, diabetes duration, gender, glycated hemoglobin levels and electrophysiologic parameters (p≥0.20). However, cases of new onset had significantly lower baseline corneal nerve fibre length (CNFL) and branch density (p<0.05). For identification of new-onset cases, area under the receiver operating characteristic curve for CNFL was 0.78 with an optimal threshold of 14.9 mm/mm(2) (sensitivity=0.82, specificity=0.69).

CONCLUSIONS

Despite similar clinical and electrophysiologic parameters, participants with type 1 diabetes at risk for future DSP had significantly lower baseline IVCCM measures. CNFL may have applicability in identifying high-risk patients for therapeutic intervention in clinical research and practice.

Clinical neuropathy scales in neuropathy associated with impaired glucose tolerance

AIMS

Disagreement exists on effective and sensitive outcome measures in neuropathy associated with impaired glucose tolerance (IGT). Nerve conduction studies and skin biopsies are costly, invasive and may have their problems with reproducibility and clinical applicability. A clinical measure of neuropathy that has sufficient sensitivity and correlates to invasive measures would enable significant future research.

METHODS

Data was collected prospectively on patients with IGT and symptomatic early neuropathy (neuropathy symptoms <2years) and normal controls. The seven scales that were examined were the Neuropathy Impairment Score of the Lower Limb (NIS-LL), Michigan Diabetic Neuropathy Score (MNDS), modified Toronto Clinical Neuropathy Scale (mTCNS), Total Neuropathy Score (Clinical) (TNSc), The Utah Early Neuropathy Scale (UENS), the Early Neuropathy Score (ENS), and the Neuropathy Disability Score (NDS).

RESULTS

All seven clinical scales were determined to be excellent in discriminating between patients with neuropathy from controls without neuropathy. The strongest discrimination was seen with the mTCNS. The best sensitivity and specificity for the range of scores obtained, as determined by using receiver operating characteristic curves, was seen for the mTCNS followed by the TNSc. Most scales show a stronger correlation with measures of large rather than small fiber neuropathy.

CONCLUSIONS

All seven scales identify patients with neuropathy. For the purpose of screening potential patients for a clinical study, the mTCNS followed by the TNSc would be most helpful to select patients with neuropathy.

Treatment responsiveness in CIDP patients with diabetes is associated with unique electrophysiological characteristics, and not with common criteria for CIDP

OBJECTIVES

Characterize treatment responsiveness in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) patients with diabetes mellitus (DM).

METHODS

We performed a retrospective chart review of CIDP subjects assessed between 1997 and 2013 and compared treatment response rates in those with and without DM, using different sets of criteria.

RESULTS

99 CIDP patients were included, 34 CIDP+DM and 65 CIDP-DM patients, both having similar treatment response rates. CIDP patients fulfilling European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) criteria had higher treatment response rates. Responders fulfilled a higher number of American Academy of Neurology (AAN) and EFNS/PNS criteria and had a higher number of demyelinating features in the total cohort and in CIDP-DM but not in CIDP+DM patients. CIDP+DM responders, however, had unique electrophysiologic characteristics.

CONCLUSION

Fulfilling EFNS/PNS and AAN criteria, and higher number of demyelinating features, are associated with higher treatment response rates in CIDP-DM but not in CIDP+DM patients, implying the need for adjusting current criteria to predict treatment response rates in CIDP-DM patients.

Association between serum cystatin C and diabetic peripheral neuropathy: a cross-sectional study of a Chinese type 2 diabetic population

OBJECTIVE

Serum cystatin C (CysC) is a sensitive marker of kidney function and recent studies have shown that CysC plays a critical role in degenerative diseases in both the central and the peripheral nervous systems. The aim of this study was to explore the relationship between serum CysC and diabetic peripheral neuropathy (DPN) in patients with type 2 diabetes.

METHODS

In total, 937 type 2 diabetic patients were enrolled in this cross-sectional study. Serum CysC concentration was measured by immunoturbidimetry. DPN was evaluated by neurological symptoms, neurological signs, neurothesiometer, and electromyogram.

RESULTS

Serum CysC levels were significantly higher in DPN patients (1.3 (1.1-1.5) mg/l) compared with patients with signs of DPN (1.1 (0.9-1.3) mg/l, P<0.001) and non-DPN patients (1.0 (0.9-1.3) mg/l, P<0.001). Multiple regression analysis revealed that DPN was associated with age, diabetes duration, HbA1c, and serum CysC. Spearman's correlation analysis showed that serum CysC was closely related with age, sex, diabetes duration, hypertension, glomerular infiltration rate, and serum creatinine (Cr) level. The patients were divided into quartiles according to the serum CysC levels. Compared with quartile 1 (referent), the risk of DPN was significantly higher in quartile 2 (odds ratio (OR), 1.753; 95% CI, 1.055-2.912; P<0.05), quartile 3 (OR, 2.463; 95% CI, 1.445-4.917; P<0.01), and quartile 4 (OR, 5.867; 95% CI, 2.075-16.589; P<0.01). Receiver-operating characteristic analysis revealed that the optimal cutoff point of serum CysC to indicate DPN was 1.25 mg/l in male patients and 1.05 mg/l in female patients. High serum CysC level indicated a onefold higher risk of DPN.

CONCLUSIONS

High serum CysC level is closely associated with DPN and may be a potential biomarker for DPN in type 2 diabetic patients.

Surgical decompression of painful diabetic peripheral neuropathy: the role of pain distribution

Objective

To investigate the effect of surgical decompression on painful diabetic peripheral neuropathy (DPN) patients and discuss the role which pain distribution and characterization play in the management of painful DPN as well as the underlying mechanism involved.

Methods

A total of 306 patients with painful diabetic lower-extremity neuropathy were treated with Dellon surgical nerve decompression in our department. Clinical evaluation including Visual analogue scale (VAS), Brief Pain Inventory Short Form for diabetic peripheral neuropathy (BPI-DPN) questionnaire, two-point discrimination (2-PD), nerve conduction velocity (NCV) and high-resolution ultrasonography (cross-sectional area, CSA) were performed in all cases preoperatively, and at 6 month intervals for 2 years post-decompression. The patients who underwent surgery were retrospectively assigned into two subgroups (focal and diffuse pain) according to the distribution of the diabetic neuropathic pain. The control group included 92 painful DPN patients without surgery.

Results

The levels of VAS, scores in BPI-DPN, 2-PD, NCV results and CSA were all improved in surgical group when compared to the control group (P<0.05). More improvement of VAS, scores in BPI-DPN and CSA was observed in focal pain group than that in diffuse group (P<0.05).

Conclusions

Efficacy of decompression of multiple lower-extremity peripheral nerves in patients with painful diabetic neuropathy was confirmed in this study. While both focal and diffuse group could benefit from surgical decompression, pain relief and morphological restoration could be better achieved in focal group.

Cerebral microvascular lesions on high-resolution 7-Tesla MRI in patients with type 2 diabetes

Cerebral small vessel disease, including microvascular lesions, is considered to play an important role in the development of type 2 diabetes mellitus (T2DM)-associated cognitive deficits. With ultra-high field MRI, microvascular lesions (e.g., microinfarcts and microbleeds) can now be visualized in vivo. For the current study, 48 nondemented older individuals with T2DM (mean age 70.3 ± 4.1 years) and 49 age-, sex-, and education-matched control subjects underwent a 7-Tesla brain MRI scan and a detailed cognitive assessment. The occurrence of cortical microinfarcts and cerebral microbleeds was assessed on fluid-attenuated inversion recovery and T1-weighted and T2*-weighted images, respectively, compared between the groups, and related to cognitive performance. Microinfarcts were found in 38% of control subjects and 48% of patients with T2DM. Microbleeds were present in 41% of control subjects and 33% of patients (all P > 0.05). The presence and number of microinfarcts or microbleeds were unrelated to cognitive performance. This study showed that microvascular brain lesions on ultra-high field MRI are not significantly more common in well-controlled patients with T2DM than in control subjects.

Measurement of cooling detection thresholds for identification of diabetic sensorimotor polyneuropathy in type 1 diabetes

Objective

Compared to recently-studied novel morphological measures, conventional small nerve fiber functional tests have not been systematically studied for identification of diabetic sensorimotor polyneuropathy (DSP). We aimed to determine and compare the diagnostic performance of cooling detection thresholds (CDT) in a cross-sectional type 1 diabetes cohort.

Research Design and Methods

136 subjects with type 1 diabetes and 52 healthy volunteers underwent clinical and electrophysiological examination for DSP classification concomitantly with the Toronto Clinical Neuropathy Score (TCNS) and three small fiber function tests: CDT, heart rate variability (HRV), and laser doppler imaging of axon-mediated neurogenic flare responses to cutaneous heating (LDI_FLARE). Area under the curve (AUC) and optimal thresholds were determined by receiver operating characteristic (ROC) curves in the type 1 diabetes cohort.

Results

Type 1 diabetes subjects were 42±17 years of age with mean HbA1c 7.9±1.7%. Fifty-nine (45%) met the case definition for DSP. CDT values were lowest in cases with DSP (18.3±8.4°C) compared to controls without DSP (28.4±3.5°C) and to healthy volunteers (29.6±1.8°C; p-value for both comparisons<0.0001). AUC_CDT was 0.863 which was similar to AUC_TCNS (0.858, p = 0.24) and AUC_HRV (0.788, p = 0.05), but exceeded AUC_LDIFLARE (0.750, p = 0.001). The threshold of <25.1°C was equivalent to the lower bound of the healthy volunteer 95% distribution [25.1, 30.8°C] and performed with 83% sensitivity and 82% specificity.

Conclusions

Akin to novel small fiber morphological measures, CDT is a functional test that identifies DSP with very good diagnostic performance. These findings support further research that revisits the role of CDT in early DSP detection.

Common polymorphisms in MIR146a, MIR128a and MIR27a genes contribute to neuropathy susceptibility in type 2 diabetes

Diabetic polyneuropathy (DPN) and cardiovascular autonomic neuropathy (CAN) are common type 2 diabetes complications with a large inter-individual variability in terms of clinical manifestations and severity. Our aim was to evaluate a possible involvement of genetic polymorphisms in miRNA regions in the susceptibility to DPN and CAN. Nine polymorphisms in miRNA genes were studied in a sample of 132 type 2 diabetes patients (T2D) analysed for DPN and 128 T2D patients analysed for CAN. A genotype-phenotype correlation analysis was performed. The T allele of rs11888095 single nucleotide polymorphism (SNP) in MIR128a was significantly associated with a higher risk (ORadj = 4.89, P adj = 0.02), whereas the C allele of rs2910164 SNP in MIR146a was associated with a lower risk to develop DPN (ORadj = 0.49, P adj = 0.09), respectively. A multivariate logistic regression analysis confirmed that both SNPs contribute to DPN (p < 0.001 and p = 0.01 for MIR128a and MIR146a, respectively). MIR128a SNP significantly contributed also to DPN score (p = 0.026). Rs895819 SNP in MIR27a was significantly associated with a higher risk to develop early CAN (P adj = 0.023 and ORadj = 3.43). The rs2910164 SNP in MIR146a showed a protective effect respect to early CAN (P adj = 0.052, ORadj = 0.32) and to confirmed CAN (P adj = 0.041, ORadj = 0.13). The same SNP resulted significantly associated with a lower CAN score and a higher E/I (p = 0.002 and p = 0.003, respectively). In conclusion, we described associations of MIR128a and MIR146a SNPs with DPN susceptibility and of MIR146a and MIR27a SNPs with CAN susceptibility. This is the first study showing that genetic variability in miRNA genes could be involved in diabetic neuropathies susceptibility.

Impact of diabetes mellitus duration on effect of lower extremity nerve decompression in 1,526 diabetic peripheral neuropathy patients

BACKGROUND

Diabetic peripheral neuropathy (DPN) is one of the most common complications of diabetes mellitus (DM). The aim of this study was to analyze DM duration in the prognosis of diabetic peripheral neuropathy of the lower extremity.

METHODS

A total of 1,526 DPN patients who were treated with DELLON surgical nerve decompression were divided into a short DM duration group and long DM duration group using a length of 5 years as the standard duration. Before and 1.5 years after surgery, high-resolution ultrasound, quantitative sensory testing (QST), and nerve conduction velocity (NCV) were performed and compared to the normal control.

RESULTS

Postoperative NCV of all the patients in either treatment group significantly increased (p < 0.05) and postoperative CSA significantly decreased (p < 0.05) compared with that before surgery. The CPT significantly increased compared with the preoperative value (p < 0.05). The postoperative WPT was significantly lower than the preoperative value (p < 0.01), and the postoperative VPT was significantly lower than the preoperative value (p < 0.05). Overall, the postoperative NCV, CSA, CPT, WPT, and VPT values from the short DM duration group were significantly different from that of the long DM duration group (p < 0.05).

CONCLUSIONS

The duration of DM is critical to the prognosis of DPN of the lower extremity, and the data from this study suggest that an early diagnosis and subsequent surgery for DPN have important clinical value.

Sensory, psychological, and metabolic dysfunction in HIV-associated peripheral neuropathy: A cross-sectional deep profiling study

HIV-associated sensory neuropathy (HIV-SN) is a frequent complication of HIV infection and a major source of morbidity. A cross-sectional deep profiling study examining HIV-SN was conducted in people living with HIV in a high resource setting using a battery of measures which included the following: parameters of pain and sensory symptoms (7day pain diary, Neuropathic Pain Symptom Inventory [NPSI] and Brief Pain Inventory [BPI]), sensory innervation (structured neurological examination, quantitative sensory testing [QST] and intraepidermal nerve fibre density [IENFD]), psychological state (Pain Anxiety Symptoms Scale-20 [PASS-20], Depression Anxiety and Positive Outlook Scale [DAPOS], and Pain Catastrophizing Scale [PCS], insomnia (Insomnia Severity Index [ISI]), and quality of life (Short Form (36) Health Survey [SF-36]). The diagnostic utility of the Brief Peripheral Neuropathy Screen (BPNS), Utah Early Neuropathy Scale (UENS), and Toronto Clinical Scoring System (TCSS) were evaluated. Thirty-six healthy volunteers and 66 HIV infected participants were recruited. A novel triumvirate case definition for HIV-SN was used that required 2 out of 3 of the following: 2 or more abnormal QST findings, reduced IENFD, and signs of a peripheral neuropathy on a structured neurological examination. Of those with HIV, 42% fulfilled the case definition for HIV-SN (n=28), of whom 75% (n=21) reported pain. The most frequent QST abnormalities in HIV-SN were loss of function in mechanical and vibration detection. Structured clinical examination was superior to QST or IENFD in HIV-SN diagnosis. HIV-SN participants had higher plasma triglyceride, concentrations depression, anxiety and catastrophizing scores, and prevalence of insomnia than HIV participants without HIV-SN.

Recent advances in the management of diabetic distal symmetrical polyneuropathy

There is now little doubt that poor blood glucose control is an important risk factor for the development of diabetic peripheral neuropathy (DPN). Furthermore, traditional cardiovascular risk factors for macrovascular disease appear to be associated with an increased risk of DPN. The recently established International Expert Group on Diabetic Neuropathy has recommended new criteria for the diagnosis of DPN in the context of clinical and research settings. Studies in experimental diabetes examining the pathogenesis of DPN have identified a number of metabolic abnormalities including polyol pathway hyperactivity, increased advanced glycation end‐point formation, alterations in the protein kinase C beta pathway through diacylglycerol and oxidative stress. There is now strong evidence implicating nerve ischemia as the cause of DPN. Studies in human and animal models have shown reduced nerve perfusion and endoneurial hypoxia. These endoneurial microvascular changes strongly correlate with clinical severity and the degree of nerve‐fiber pathology. Unfortunately, many compounds that have been effective in animal models of neuropathy have not been successful in human diabetic neuropathy. The only compounds found to be efficacious in human diabetic neuropathy, and are in clinical use, are the anti‐oxidant, α‐lipoic acid and the aldose reductase inhibitor, epalrestat. Overall, the evidence emphasizes the importance of vascular dysfunction, driven by metabolic change, in the etiology of DPN, and highlights potential therapeutic approaches. Epidemiological data on diabetic painful neuropathic pain (DPNP) are limited. In one population‐based study, the prevalence of DPNP, as assessed by a structured questionnaire and examination, was estimated at 16%. It was notable that, of these patients, 12.5% had never reported symptoms to their doctor and 39% had never received treatment for their pain. Thus, despite being common, DPNP continues to be underdiagnosed and undertreated. Pharmacological treatment of DPNP include tricyclic compounds, serotonin noradrenalin reuptake inhibitors, the anti‐oxidant α‐lipoic acid, anticonvulsants, opiates, membrane stabilizers, topical capsaicin and so on. Management of the patient with DPNP must be tailored to individual requirements and will depend on the presence of other comorbidities. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00083.x)

Neuromuscular complications of diabetes mellitus

PURPOSE OF REVIEW

Diabetes mellitus has become a modern global epidemic, with steadily increasing prevalence rates related to lifestyle such that 27% of individuals aged 65 years or older have diabetes mellitus, 95% of whom have type 2. This article reviews the effects of diabetes mellitus on the neuromuscular system.

RECENT FINDINGS

Diabetes mellitus leads to diverse forms of peripheral neuropathy as the major neuromuscular complication. Both focal and diffuse types of neuropathy can develop, with the most common form being diabetic sensorimotor polyneuropathy. Small fibers are damaged early in the development of diabetic sensorimotor polyneuropathy and are not assessed by nerve conduction studies. Small fiber damage occurs even in the prediabetes stage. No disease-modifying therapy for diabetic sensorimotor polyneuropathy is available at this time, but this complication can be limited in patients who have type 1 diabetes mellitus with strict glycemic control; the same outcome is not clearly observed in patients who have type 2 diabetes mellitus. Recently, the evidence base for symptomatic treatments of painful diabetic sensorimotor polyneuropathy underwent systematic review. Effective evidence-based treatments include some anticonvulsants (eg, pregabalin, gabapentin), antidepressants (eg, amitriptyline, duloxetine), opioids (eg, morphine sulfate, oxycodone), capsaicin cream, and transcutaneous electrical nerve stimulation.

SUMMARY

This article reviews the increasing prevalence of diabetes mellitus and diabetic sensorimotor polyneuropathy and discusses recent consensus opinion on the objective confirmation needed for the diagnosis in the clinical research setting. The evidence from clinical trials shows that intensive glycemic control reduces prevalence of diabetic sensorimotor polyneuropathy in patients with type 1 diabetes mellitus, but variable outcomes are observed in patients with type 2 diabetes mellitus. Finally, despite the lack of disease-modifying treatment, effective evidence-based therapy can control painful symptoms of diabetic sensorimotor polyneuropathy.

Characteristics of muscle cramps in patients with polyneuropathy

Muscle cramps are common in the general population and can be disabling for patients, but there is little evidence comprehensively evaluating cramp characteristics in patients with polyneuropathy. This study describes the prevalence and characteristics of muscle cramps in this patient group. Patients over 18 diagnosed with polyneuropathy were invited to join the study. Patients completed nerve conduction studies, the Toronto Clinical Neuropathy score, neuropathy-specific Vickrey's Quality of Life Assessment and a self-administered questionnaire examining demographics, neuropathy symptoms and cramp characteristics. Two hundred and twenty-five participants were enrolled (28.0% female). Sixty-three percent of patients experienced cramps, occurring on average 6 times per week, lasting 10.5 min and scoring 6 out of 10 on a pain scale and described as disabling by 43.6% of patients. No significant difference was found in cramp prevalence according to underlying pathophysiology (p = 0.52) or fiber type (p = 0.41). Patients with disabling cramps rated their physical (p < 0.0001) and mental (p = 0.04) quality of life lower than patients without disabling cramps. This study confirms that muscle cramps are common, disabling and associated with reduced quality of life in patients with polyneuropathy. Similar prevalence of cramps across predominant nerve fiber type suggests a role of sensory afferents in cramp generation, although this needs to be confirmed in larger cohorts.

Comparison of monoclonal gammopathy of undetermined significance-associated neuropathy and chronic inflammatory demyelinating polyneuropathy patients

OBJECTIVES

There are varying reports on whether monoclonal gammopathy of undetermined significance-associated neuropathy (MGUSN) patients are distinguishable from those with chronic inflammatory demyelinating polyneuropathy (CIDP) and whether specific MGUSN subclasses are associated with specific clinical phenotypes.

METHODS

We performed a retrospective chart review of MGUSN (n = 56) and CIDP (n = 67) patients. Data extracted included: demographics, neurological examination, and nerve conduction studies (NCS) at baseline and last visit. Clinical status was rated as 0 = worse, 1 = unchanged, 2 = stabilized after a declining course, or 3 = improved. The electrophysiology data were rated as 0 = worse, 1 = stable, or 2 = improved. Statistical analyses were performed using JMP (version 9.0.2 for Macintosh, from SAS).

RESULTS

Seventy percent were males, aged 68.1 ± 12.6 years with neuropathy for 9.8 ± 6.8 years and follow-up of 4.0 ± 3.2 years. CIDP patients had more severe neuropathy, and were more likely to receive treatment and to respond. The clinical neuropathy status remained unchanged in 52.8 % of the MGUSN and 24.2 % of the CIDP patients, and stabilized in 7.6 % of MGUSN and 30.3 % of CIDP patients. IgM-MGUSN patients did not differ from other immunoglobulin subclasses in response to treatment. The clinical severity and the number of abnormal NCS parameters were greater in the demyelinating MGUSN in comparison to the axonal group.

CONCLUSION

MGUSN patients have less severe neuropathy than CIDP patients, but among the MGUSN patients the severity is greater in the demyelinating and the IgM groups. MGUSN patients may do well without treatment and exposure to potential adverse effects.

Sensory-motor assessment in clinical research trials

The assessment of changes in sensory-motor function in clinical research presents a unique set of difficulties. Clinimetrics is the science of measurement as related to the identification of a clinical disorder, the tracing of the progression of the condition under study, and calculation of its impact. The selection of appropriate measures for clinical studies of sensory-motor function must consider validity, sensitivity, specificity, responsiveness, reliability, and feasibility. Reasonable measures of motor function in clinical research include manual examination of muscle strength, electrophysiology, functional scales, patient-reported outcomes (e.g., quality of life), and for severe conditions such as ALS, survival. The assessment of sensory function includes targeted electrophysiology and QOL, as well as more focused measures such as quantitative sensory testing and the scoring of positive symptoms. Each individual measure and each combination of endpoints has its strengths and limitations.