Useful application of the Neuropad test for assessment of diabetic polyneuropathy

Assessment of autonomic nervous system dysfunction associated with peripheral neuropathies in the context of clinical neurophysiology practice

Peripheral neuropathies may involve the small diameter nerve fibers of the autonomic nervous system. In the presence of clinical signs compatible with dysautonomia, it is very difficult to affirm that these signs are really linked to an alteration in postganglionic autonomic innervation, and not to a lesion of the central nervous system or to a direct damage to the tissues and innervated organs. Also, in the context of the investigation of peripheral neuropathies, there is an interest in performing objective and quantitative assessment of distal autonomic innervation. The corresponding autonomic tests are mainly based on the exploration of sudomotor or vasomotor disorders of the limb extremities. In this article, we provide an overview of the various tests available for the study of the autonomic nervous system in clinical practice, including vasomotor reactivity tests, in particular based on laser Doppler techniques, and sudomotor tests, based on axon-reflexes produced by iontophoresis of cholinergic drugs or on the simpler measurement of electrochemical skin conductance by the Sudoscan® device.

Renal hemodynamic dysfunction and neuropathy in longstanding type 1 diabetes: Results from the Canadian study of longevity in type 1 diabetes

AIMS

To determine the relationship between renal hemodynamic function and neuropathy in adults with ≥50-years of type 1 diabetes (T1D) compared to nondiabetic controls.

METHODS

Glomerular filtration rate (GFR, inulin), effective renal plasma flow (ERPF, p-aminohippurate), modified Toronto Clinical Neuropathy Score (mTCNS), corneal confocal microscopy, nerve conduction, and heart rate variability (autonomic function) were measured; afferent (RA) and efferent (RE) arteriolar resistances were estimated using the Gomez equations in 74 participants with T1D and in 75 controls. Diabetic kidney disease (DKD) non-resistors were defined by eGFRMDRD < 60 ml/min/1.73 m2 or 24-h urine albumin excretion >30 mg/day. Linear regression was applied to examine the relationships between renal function (dependent variable) and neuropathy measures (independent variable), adjusted for age, sex, HbA1c, systolic blood pressure, low density lipoprotein cholesterol, and 24-h urine albumin to creatinine ratio.

RESULTS

Higher mTCNS associated with lower renal blood flow (β ± SE:-9.29 ± 4.20, p = 0.03) and greater RE (β ± SE:32.97 ± 15.43, p = 0.04) in participants with T1D, but not in controls. DKD non-resistors had a higher mTCNS and worse measures of corneal nerve morphology compared to those without DKD. Renal hemodynamic parameters did not associate with autonomic nerve function.

CONCLUSIONS

Although neurological dysfunction in the presence of diabetes may contribute to impaired renal blood flow resulting in ischemic injury in patients with T1D, early autonomic dysfunction does not appear to be associated with kidney function changes.

Concordance between sudomotor disorder and the clinical diagnosis of diabetic peripheral neuropathy, according to various clinical guidelines

AIM

To assess the concordance between variations in Neuropad® results and the those in different diagnostic criteria of Diabetic Peripheral Neuropathy, according to various clinical guidelines.

METHODS

A descriptive observational study was conducted of 111 patients with a confirmed diagnosis of diabetes mellitus. The criteria for inclusion in the study were that patients should be aged 18 years or more and have at least 10 years' history of diabetes mellitus.

RESULTS

73 (65.8%) were male and 38 (34.2%) were female. Their mean age was 57.92 ± 13.24 years (95% CI 55.45-60.38). Healthy Neuropad® findings were obtained for 35 right feet (31.5%) and 31 left feet (27.9%).

CONCLUSION

Neuropad® is an effective instrument for detecting macro and microvascular complications such as early-stage neuropathy, although its use should always be accompanied by a clinical examination of the foot.

Validation of Neuropad in the Assessment of Peripheral Diabetic Neuropathy in Patients with Diabetes Mellitus Versus the Michigan Neuropathy Screening Instrument, 10g Monofilament Application and Biothesiometer Measurement

Objective:

Sudomotor dysfunction is a feature of Diabetic Peripheral Neuropathy (DPN). The indicator plaster Neuropad can provide an easy and accurate way to diagnose DPN. The aim of the present study was to evaluate Neuropad’s specificity, sensitivity and accuracy in detecting DPN in patients with Diabetes Mellitus (DM).

Methods:

A total of 174 patients with DM (79 with type 1 DM, 88 women), mean age 49.8 ± 16.1 years and mean DM duration 17.3 ± 7.7 years were included in the present study. The following methods were used to diagnose DPN: the Michigan Neuropathy Screening Instrument Questionnaire and Examination (MNSIQ and MNSIE, respectively), application of 10 g monofilament (MONO) and measurement of vibration perception threshold with biothesiometer (BIO). Neuropad was applied to both feet in all patients and according to the presence or absence of color change of the sticker, patients were divided in two groups: group A (n = 82, complete change in color from blue to pink, depicting normal perspiration) and group B (n = 92, incomplete or no change, depicting abnormal perspiration).

Results:

MNSIQ and MNSIE were positive for DPN in 111 and 119 patients, respectively. BIO was abnormal in 109 and MONO in 59 patients. Sensitivity of Neuropad testing was 95% vs. MONO, 73% vs. BIO, 73% vs. MNSIE and 75% vs. ΜNSIQ. Specificity was 69, 81, 90 and 92%, respectively and accuracy of the test was 78, 76, 78 and 83%, respectively.

Conclusion:

Neuropad has a high sensitivity and specificity in detecting DPN vs. MNSIQ, MNSIE and BIO. Neuropad has a high sensitivity but moderate specificity vs. MONO. The accuracy of the test was high in all measurements.

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.

A simple plaster for screening for diabetic neuropathy: a diagnostic test accuracy systematic review and meta-analysis

OBJECTIVE

Neuropad is an adhesive indicator test applied at the plantar surface of the foot that detects sweating through color change. We examined the diagnostic accuracy of this simple plaster as triage test for screening for clinically relevant diabetic sensorimotor polyneuropathy in adult outpatients with type 1 or type 2 diabetes.

MATERIALS/METHODS

Systematic review and meta-analysis of diagnostic accuracy studies. We searched Medline, Embase, Cochrane Library, Biosis Previews, Web of Science, Scopus and gray literature without date or language restrictions. We pooled estimates of sensitivity and specificity, and fitted hierarchical models to produce summary receiver operating characteristic curves. We assessed methodological quality of included studies utilizing the Quality Assessment of Diagnostic Accuracy Studies 2 tool.

RESULTS

Eighteen studies with 3470 participants met the inclusion criteria. Average sensitivity and specificity were 86% (95% CI 79 to 91) and 65% (95% CI 51 to 76) respectively. Likelihood ratios (LRs) were LR+=2.44 and LR-=0.22. Subgroup analyses per reference standard utilized provided similar estimates. Most studies were at risk of bias for patient selection and use of index or reference test, and had concerns regarding applicability due to patient selection.

CONCLUSION

The adhesive indicator test has reasonable sensitivity and could be used for triage of diabetic neuropathy to rule out foot at risk. Patients who tested positive should be referred to specialized care to establish a definite diagnosis. There is insufficient evidence for effectiveness on patient-important outcomes and cost-effectiveness of implementation in the diagnostic pathway compared with the standard clinical examination.