How to better systematize the diagnosis of neuropathy?

Impaired auditory neural performance, another dimension of hearing loss in type-2 diabetes mellitus

AIM

to evaluate auditory performance in subjects with poorly controlled type-2 diabetes mellitus, using a simple test battery assessing sensitivity to pure tones and neuronal function.

METHODS

Enrolled subjects, aged between 23-79 years, reported several auditory dysfunctions. They were tested using pure-tone audiometry, otoacoustic emissions for cochlear-function evaluation, and measurement of middle-ear muscle-reflex thresholds in search of an auditory neuropathy.

RESULTS

Compared to the standard established for an age-matched normative population, the distribution of averaged pure-tone thresholds in enrolled subjects shifted by about one standard deviation with respect to the normal distribution, in line with past reports of mild sensorineural hearing impairment in diabetes, even though many diabetic subjects fell well within the normative interval of audiometric thresholds. Otoacoustic emissions showed that pure-tone thresholds correctly predicted the status of cochlear sensory cells that, by amplifying sound, ensure normal hearing sensitivity. Whereas the observed hearing losses should not have affected the acoustic levels above which the protective middle-ear muscle reflex is triggered by intense sounds, this reflex was undetectable in around 40% enrolled subjects, a marker of auditory neuropathy.

CONCLUSION

auditory-neural function should be evaluated to identify diabetic subjects whose hearing is impaired. Simple automatic tests are available for this purpose, for example middle-ear muscle reflex detection, which turns out to be more sensitive than the standard audiogram.

Skin autofluorescence and peripheral neuropathy four years later in type 1 diabetes

OBJECTIVE

Advanced glycation end products (AGEs) are involved in diabetes complications. We aimed to investigate whether the accumulation of AGEs measured by skin autofluorescence (sAF) was associated with signs of diabetic peripheral neuropathy and to sensitivity, pain, motor and autonomic function 4 years later in patients with type 1 diabetes.

METHODS

At baseline, 188 patients (age 51 years, diabetes duration 22 years) underwent skin autofluorescence measurement using the AGE Reader. Four years later, signs of diabetic peripheral neuropathy were defined as the presence of neuropathic pain and/or feet sensory loss or foot ulceration. Neurological tests were systematically performed: vibration perception threshold by neuroesthesiometry, neuropathic pain by the Douleur Neuropathique en 4 Questions score, muscle strength by dynamometry and electrochemical skin conductance. Multivariate analyses were adjusted by age, sex, height, body mass index, tobacco, HbA_1c , diabetes duration, estimated glomerular filtration rate and albumin excretion rate.

RESULTS

At the 4-year follow-up, 13.8% of patients had signs of diabetic peripheral neuropathy. The baseline sAF was higher in those with signs of diabetic peripheral neuropathy (2.5 ± 0.7 vs 2.1 ± 0.5 arbitrary units (AU), p < 0.0005). In the multivariate analysis, a 1 SD higher skin autofluorescence at baseline was associated with an increased risk of signs of neuropathy (OR = 2.68, p = 0.01). All of the neurological tests were significantly altered in the highest quartile of the baseline sAF (>2.4 AU) compared with the lowest quartiles after multivariate adjustment.

CONCLUSION

This non-invasive measurement of skin autofluorescence may have a value for diabetic peripheral neuropathy in type 1 diabetes and a potential clinical utility for detection of diabetic peripheral neuropathy. Copyright © 2016 John Wiley & Sons, Ltd.

An 'Importance' Map of Signs and Symptoms to Classify Diabetic Polyneuropathy: An Exploratory Data Analysis

Aims/Hypothesis

Early diagnosis of diabetic polyneuropathy (DPN) is critical for a good prognosis. We aimed to identify different groups of patients, based on the various common clinical signs and symptoms of DPN, that represent a progressive worsening of the disease before the onset of plantar ulceration or amputation. We also sought to identify the most important DPN-related variables that can discriminate between groups, thus representing the most informative variables for early detection.

Methods

In 193 diabetic patients, we assessed 16 DPN-related signs, symptoms, and foot characteristics, based on the literature and the International Consensus on the Diabetic Foot. We used multiple correspondence analysis and the Kohonen algorithm to group the variables into micro and macro-classes and to identify clusters of patients that represent different DPN conditions.

Results

Four distinct groups were observed. One group showed no indication of DPN. The remaining groups were characterized by a progressive loss of the vibration perception, without a worsening of symptoms or tactile perception. The 2 intermediate groups presented different aspects of DPN: one showed mostly DPN symptoms and the other showed the incipient vibration impairment, callus and crack formation, and foot arch alteration. The fourth group showed more severe foot and DPN conditions, including ulceration and amputation, absence of vibration and tactile perception (irrespective of how many compromised foot areas), and worse foot deformities and callus and crack formation.

Conclusion

Vibration perception was more informative than tactile sensitivity in discriminating early DPN onset because its impairment was evident in more groups. Symptoms and callus and cracks did not discriminate the severity status and should be interpreted in association with other clinical variables. Reconsideration of the current screening techniques is needed to clinically determine the early onset of neuropathy using tactile perception.

A new simple method for assessing sudomotor function: relevance in type 2 diabetes

AIM

The current sudomotor function tests are too time-consuming to be used for diabetic patients in daily practice. EZSCAN is a new, patented technology that measures electrochemical skin conductance (ESC) through reverse iontophoresis and chronoamperometry. The aim of the present study was to assess the sensitivity, specificity and reproducibility of the method in type 2 diabetic patients in comparison to control subjects with no risk of diabetes.

METHODS

A total of 133 type 2 diabetic patients and 41 control subjects were tested. Participants placed their hands and feet on nickel electrodes, and an incremental low direct current was applied to the anode for 2 min. ESC was calculated from the resulting voltage and generated current. ESC diagnostic accuracy was analyzed by ROC curve modeling, and reproducibility was assessed using Bland-Altman analysis.

RESULTS

The ESC of hands and feet was significantly reduced in diabetic patients (53±16μSi and 67±14μSi, respectively) compared with control subjects (68±16μSi and 80±7μSi, respectively; P<0.0001). ESC values had a sensitivity of 75% and specificity of 100%, with an area under the ROC curve of 0.88 at a threshold of 50% on the EZSCAN scale. Coefficients of variation in hand and foot measurements were 15 and 7%, respectively.

CONCLUSION

The good sensitivity, specificity and reproducibility of EZSCAN make it a feasible alternative for assessing sudomotor dysfunction, a clinical manifestation of autonomic neuropathy in diabetic patients. The test takes<3 min to perform, and requires neither special patient preparation nor medical personnel training.