Median and ulnar nerve conduction measurements in patients with symptoms of diabetic peripheral neuropathy using the NC-stat system

Effect of apple peel extract on diabetes-induced peripheral neuropathy and wound injury

PURPOSE

Diabetic peripheral neuropathy (DPN) affects up to 50 % diabetic patients. Moreover, uncontrolled diabetes associated with impaired wound healing. The present study was aimed at exploring the effect of apple peel extract (APE) on type 2 diabetes (T2D)-induced DPN and delayed wound healing.

METHODS

In adult male Sprague-Dawley rats on high-fat diet, a single low dose streptozotocin (STZ, 35 mg/kg) was administered via intraperitoneal route to induce T2D. Plantar test using Hargreaves apparatus was used to evaluate the DPN. Six different groups of rats were treated orally with saline (naïve control and DPN control), APE (100, 200 and 400 mg/kg) and gabapentin (30 mg/kg) daily for 7 consecutive days and thermal paw withdrawal latency (PWL) was measured. To elucidate the underlying antioxidant effect of APE, the catalase (CAT), glutathione (GSH) and malonaldehyde (MDA) levels were measured. To evaluate the wound healing potential of APE, excision ischemic open wound model was used. Six different groups of rats were applied with 2 % gum acacia (naïve control and diabetic control), 1 % silver sulfadiazine (SSD) cream and APE cream (5, 10 and 20 %) twice daily for 28 days. Dry connective tissue parameters like hydroxyproline and hexosamine were also measured to further confirm the wound healing activity.

RESULTS

Diabetes produced thermal hyperalgesia in rats with a significant decrease in PWL as compared to naive controls indicating induction of DPN. APE and gabapentin significantly improved PWL in diabetic animals. Biochemical analysis revealed a significant improvement in oxidative stress parameters such as catalase, GSH and MDA. Wound closure was significantly more after day 15 of topical application of APE and SSD as compared to control group. APE significantly increased hydroxyproline and hexosamine levels as compared to standard cream. Moreover, histopathology revealed that, topical application of APE cream showed an enhanced healing process.

CONCLUSIONS

On the basis of the findings, we conclude that APE has a potential to be used as a therapeutic intervention for the management of DPN and delayed wound healing in the diabetic condition.

Comparison of automated versus traditional nerve conduction study methods for median nerve testing in a general worker population

OBJECTIVE

To investigate the validity of automated nerve conduction studies compared to traditional electrodiagnostic studies (EDS) for testing median nerve abnormalities in a working population.

DESIGN

Agreement study and sensitivity investigation from 2 devices.

SETTING

Field research testing laboratory.

PARTICIPANTS

Active workers from several industries participating in a longitudinal study of carpal tunnel syndrome.

METHODS

Sixty-two subjects received bilateral median and ulnar nerve conduction testing across the wrist with a traditional device and the NC-stat automated device. We compared the intermethod agreement of analogous measurements.

MAIN OUTCOME MEASUREMENT

Nerve conduction study parameters.

RESULTS

Median motor and sensory latency comparisons showed excellent agreement (intraclass correlation coefficients 0.85 and 0.80, respectively). Areas under the receiver operating characteristic curves were 0.97 and 0.96, respectively, using the optimal thresholds of 4.4-millisecond median motor latency (sensitivity 100%, specificity 86%) and 3.9-millisecond median sensory latency (sensitivity 100%, specificity 87%). Ulnar nerve testing results were less favorable.

CONCLUSION

The automated NC-stat device showed excellent agreement with traditional EDS for detecting median nerve conduction abnormalities in a general population of workers, suggesting that this automated nerve conduction device can be used to ascertain research case definitions of carpal tunnel syndrome in population health studies. Further study is needed to determine optimal thresholds for defining median conduction abnormalities in populations that are not seeking clinical care.

New vistas in the diagnosis of diabetic polyneuropathy

New modalities are now available to improve the diagnosis of diabetic polyneuropathy (DPN). The present review discusses the progress achieved in this area. First, the minimal diagnostic criteria have been better clarified. Moreover, there are now new bedside tests available, such as the indicator test Neuropad, NeuroQuick, Ipswich Touch Test (IpTT), Vibratip, NC-stat(®)/DPNCheck™ for automated nerve conduction study (NCS), tactile circumferential discriminator, steel ball-bearing, and SUDOSCAN(®), while more sophisticated modalities include skin biopsy and corneal confocal microscopy (CCM). Some tests can be used as screening tools, including primary care setting (Neuropad, IpTT, Vibratip, automated NCS), while others are more suitable for research, including evaluation of DPN in prospective studies (CCM, skin biopsy). Importantly, there is some evidence of earlier DPN diagnosis with the aid of some tests (Neuropad, skin biopsy, CCM). Further advantages provided by different tests are educational value and self-examination. Thus far, the potential of these tests has not been fully utilised. In particular, they have not been validated against standardised clinical examination scores in terms of predicting foot ulcers and amputations. Hence, it now remains to investigate the potential benefits from the widespread use of these tests for earlier and easier diagnosis of DPN in the everyday clinic.

Effects of varying case definition on carpal tunnel syndrome prevalence estimates in a pooled cohort

OBJECTIVE

To analyze differences in carpal tunnel syndrome (CTS) prevalence using a combination of electrodiagnostic studies (EDSs) and symptoms using EDS criteria varied across a range of cutpoints and compared with symptoms in both ≥1 and ≥2 median nerve-served digits.

DESIGN

Pooled data from 5 prospective cohorts.

SETTING

Hand-intensive industrial settings, including manufacturing, assembly, production, service, construction, and health care.

PARTICIPANTS

Employed, working-age participants who are able to provide consent and undergo EDS testing (N=3130).

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

CTS prevalence was estimated while varying the thresholds for median sensory latency, median motor latency, and transcarpal delta latency difference. EDS criteria examined included the following: median sensory latency of 3.3 to 4.1 milliseconds, median motor latency of 4.1 to 4.9 milliseconds, and median-ulnar sensory difference of 0.4 to 1.2 milliseconds. EDS criteria were combined with symptoms in ≥1 or ≥2 median nerve-served digits. EDS criteria from other published studies were applied to allow for comparison.

RESULTS

CTS prevalence ranged from 6.3% to 11.7%. CTS prevalence estimates changed most per millisecond of sensory latency compared with motor latency or transcarpal delta. CTS prevalence decreased by 0.9% to 2.0% if the criteria required symptoms in 2 digits instead of 1.

CONCLUSIONS

There are meaningful differences in CTS prevalence when different EDS criteria are applied. The digital sensory latency criteria result in the largest variance in prevalence.

Accuracy of in-office nerve conduction studies for median neuropathy: a meta-analysis

PURPOSE

Carpal tunnel syndrome is the most common focal neuropathy. It is typically diagnosed clinically and confirmed by abnormal median nerve conduction across the wrist (median neuropathy [MN]). In-office nerve conduction testing devices facilitate performance of nerve conduction studies (NCS) and are used by hand surgeons in the evaluation of patients with upper extremity symptoms. The purpose of this meta-analysis was to determine the diagnostic accuracy of this testing method for MN in symptomatic patients.

METHODS

We searched the MEDLINE database for prospective cohort studies that evaluated the diagnostic accuracy of in-office NCS for MN in symptomatic patients with traditional electrodiagnostic laboratories as reference standards. We assessed included studies for quality and heterogeneity in diagnostic performance and determined pooled statistical outcome measures when appropriate.

RESULTS

We identified 5 studies with a total of 448 symptomatic hands. The pooled sensitivity and specificity were 0.88 (95% confidence interval [CI], 0.83-0.91) and 0.93 (95% CI, 0.88-0.96), respectively. Specificities exhibited heterogeneity. The diagnostic odds ratios were homogeneous, with a pooled value of 62.0 (95% CI, 30.1-127).

CONCLUSIONS

This meta-analysis showed that in-office NCS detects MN with clinically relevant accuracy. Performance was similar to interexaminer agreement for MN within a traditional electrodiagnostic laboratory. There was some variation in diagnostic operating characteristics. Therefore, physicians using this technology should interpret test results within a clinical context and with attention to the pretest probability of MN, rather than in absolute terms.

New diagnostic tests for diabetic distal symmetric polyneuropathy

Neuropathy needs to be diagnosed early to prevent complications, such as neuropathic pain or the diabetic foot. It is obvious that diagnosis of neuropathy needs to be improved. New peripheral nerve function tests that appear to facilitate diagnosis are now emerging. This review outlines the new tests that have been proposed for the diagnosis of diabetic distal symmetric polyneuropathy, the commonest form of neuropathy in diabetes. New tests are classified into those mainly assessing large-fiber function (tactile circumferential discriminator, steel ball-bearing, and automated nerve conduction study) and those mainly assessing small-fiber function (NeuroQuick and Neuropad). Emerging tests are promising but must be evaluated in prospective studies. Moreover, their cost-effectiveness needs more careful appraisal. The clinician should, therefore, still rely on established modalities to diagnose neuropathy, but wider use of the new tests is expected in the near future.

Risk factors for carpal tunnel syndrome and median neuropathy in a working population

OBJECTIVE

To assess whether work-related physical activities are associated with Carpal tunnel syndrome (CTS), even when controlling for personal risk factors.

METHODS

A cross-sectional assessment of 1108 workers from eight employers and three unions completed nerve conduction testing, physical examination, and questionnaires. CTS was defined by median neuropathy and associated symptoms.

RESULTS

Eighteen workers had CTS and 131 had evidence of median neuropathy. CTS was highest among construction workers (3.0%) compared to other subjects (<1%). Logistic regression models for median neuropathy both personal and work-related risk factors. Work-related exposures were estimated by two methods: self-report and job title based ratings.

CONCLUSIONS

Both work and personal factors mediated median nerve impairment. Construction workers are at an increased risk of CTS so awareness should be raised and interventions should specifically target this risk group.

Median and ulnar nerve conduction studies at the wrist: criterion validity of the NC-stat automated device

OBJECTIVE

To compare results obtained with the NC-stat--an automated nerve testing device--to traditional nerve conduction studies relevant to carpal tunnel syndrome screening.

METHODS

Thirty-three subjects recruited from patients referred for electrodiagnostic testing were studied. Measurements including the distal motor latency (DML), distal sensory latency (DSL), and median-ulnar latency difference (MUD) were obtained by the NC-stat and by standard nerve conduction studies.

RESULTS

With modifications to the NC-stat's suggested reference ranges, sensitivity with respect to the traditional results ranged from 93.8% (sensory MUD) to 100% (median DML and DSL) and specificity ranged from 84.6% (motor MUD) to 94.1% (sensory MUD). Sensitivity was as high or higher and specificity was lower when using the manufacturer's suggested cutoffs.

CONCLUSION

The NC-stat appears to be a convenient and sensitive method for detecting median nerve pathology at the wrist.

Multi-site testing with a point-of-care nerve conduction device can be used in an algorithm to diagnose diabetic sensorimotor polyneuropathy

OBJECTIVE

We aimed to establish whether multi-nerve testing with a point-of-care nerve conduction device could be used to diagnose diabetic sensorimotor polyneuropathy.

RESEARCH DESIGN AND METHODS

A total of 72 consecutive patients with diabetes underwent a full neurological examination and a concurrent evaluation for nine standard electrophysiological parameters using conventional nerve conduction studies (the reference standard) and a point-of-care device.

RESULTS

Spearman coefficients for correlation of point-of-care and conventional parameters ranged between 0.76 and 0.91 (P < 0.001 in all comparisons). Agreement by the method of Bland and Altman was acceptable despite small systematic biases. Fifty subjects (69%) had neuropathy according to conventional criteria. The sensitivity and specificity for the point-of-care device to identify such neuropathy was 88 and 82%, respectively.

CONCLUSIONS

A novel point-of-care device has reasonable diagnostic accuracy and thus may represent a sufficiently accurate alternative for detecting the diffuse electrophysiological criteria necessary to make the diagnosis of diabetic sensorimotor polyneuropathy.

Diabetic nerve conduction abnormalities in the primary care setting

BACKGROUND

Nerve conduction studies (NCS) are the most objective measure of nerve function, and their use is recommended in the clinical and epidemiological evaluation of diabetic polyneuropathy (DPN). The purpose of this study was to utilize automated NCS technology to characterize nerve conduction of patients with diabetes in primary care settings.

METHODS

The Diabetes cohort was drawn from 28 community clinics. The Control cohort consisted of subjects without diabetes and without evidence of neuropathy. Bilateral peroneal NCS were performed with an automated NCS instrument (NC-stat, NeuroMetrix, Inc., Waltham, MA). Neuropathic symptoms were quantified using an abbreviated form of the NTSS-6 questionnaire. Risk factors for abnormal NCS were determined using multivariate regression modeling.

RESULTS

Data were collected for 172 control subjects and 1,358 subjects with diabetes. Statistically significant differences in peroneal NCS were found. Of the Diabetes cohort, 75.1% had at least one NCS abnormality, and 53.2% had bilateral abnormalities. Of the asymptomatic patients, 45% had bilateral NCS abnormalities. By contrast, 40% of those with clinically significant symptoms lacked bilateral NCS abnormalities. Independent predictors for bilateral NCS abnormalities were age, height, weight, hemoglobin A1c (HbA1c), and duration of diabetes. Up to 16% of the variance in NCS measurements was explained by HbA1c, duration of diabetes, and several demographic variables.

CONCLUSIONS

This study suggests that automated NCS can provide nerve conduction confirmation of DPN in primary care settings and has clinical utility. These findings have important implications for the clinical and epidemiological evaluation of DPN.

Criterion validity of the NC-stat automated nerve conduction measurement instrument

The purpose of this study is to assess the criterion validity of peroneal and posterior tibial nerve conduction measurements obtained with the NC-stat system. Sixty patients referred to the Boston VA EMG laboratory were enrolled. Each subject had a full study of the lower extremity performed using traditional EMG equipment prior to obtaining the NC-stat measurements. These included peroneal and posterior tibial distal motor latency (DML), amplitude (AMP) and F-wave latency (FLAT) measurements. Excellent criterion validity was demonstrated for the peroneal and posterior tibial FLATs and the peroneal AMP. Acceptable criterion validity was identified in the peroneal DML and the posterior tibial AMP. The validity of the posterior tibial DML could not be demonstrated. With the exception of the peroneal DML, criterion validity was maintained in a sub-group analysis of the 50% most abnormal parameter values. The comparability of NCS performed with the NC-stat and in traditional settings has been demonstrated for motor studies of the median and ulnar nerves in previous studies. This study shows that the technology used by the NC-stat for studying the peroneal and posterior tibial nerves compares favorably as well with that obtained with traditional EMG equipment used under neurologist supervision.

NC-stat sensory nerve conduction studies in the median and ulnar nerves of symptomatic patients

OBJECTIVE

This study evaluated validity and reliability of automated median and ulnar sensory nerve conduction study (NCS) measurements by the NC-stat.

METHODS

Median and ulnar distal sensory latencies (DSL) and amplitudes (SNAP) were measured in sixty subjects with the NC-stat and by a neurologist (reference) using traditional instrumentation. The median-ulnar DSL differences (MUD) was calculated. Validity was quantified by the Pearson correlation. Reliability was evaluated by the intraclass correlation coefficient (ICC), Bland-Altman analysis, and inter-rater agreement of MUD abnormalities.

RESULTS

As a result of differences in electrode placement, NC-stat and reference mean values had systematic differences. The correlation ranged from 0.70 (ulnar DSL) to 0.91 (median DSL). The ICC ranged from 0.69 (ulnar DSL) to 0.91 (median DSL). In Bland-Altman analysis of DSLs, NC-stat measurements had a bias of 0.56 ms (median) and 0.31 ms (ulnar) and precision of 0.31 and 0.30 ms. Inter-rater agreement for MUD abnormalities was 93.8% (raw) and 0.80 (Kappa).

CONCLUSIONS

NC-stat validity and reliability metrics were similar to traditional NCS. Use of the NC-stat would require applicable reference ranges.

SIGNIFICANCE

NC-stat median and ulnar NCS are valid and reliable. This device may be useful for increasing availability of NCS when clinically appropriate.