A simple new non-invasive sweat indicator test for the diagnosis of diabetic neuropathy

A simple non-invasive indicator test (Neuropad(®)) has been developed for the assessment of sweating and, hence, cholinergic innervation in the diabetic foot. The present review summarizes current knowledge on this diagnostic test. The diagnostic ability of this test is based on a colour change from blue to pink at 10 min, with excellent reproducibility, which lends itself to patient self-examination. It has a high sensitivity (65.1-100%) and negative predictive value (63-100%), with moderate specificity (32-78.5%) and positive predictive value (23.3-93.2%) for the diagnosis of diabetic peripheral neuropathy. It also has moderate to high sensitivity (59.1-89%) and negative predictive value (64.7-91%), but low to moderate specificity (27-78%) and positive predictive value (24-48.6%) for the diagnosis of diabetic cardiac autonomic neuropathy. There are some data to suggest that Neuropad can detect early diabetic neuropathy, but this needs further evaluation. It remains to be established whether this test can predict foot ulceration and amputation, thereby contributing to the identification of high-risk patients.

Frequency-modulated electromagnetic neural stimulation (FREMS) as a treatment for symptomatic diabetic neuropathy: results from a double-blind, randomised, multicentre, long-term, placebo-controlled clinical trial

AIMS/HYPOTHESIS

The aim was to evaluate the efficacy and safety of transcutaneous frequency-modulated electromagnetic neural stimulation (frequency rhythmic electrical modulation system, FREMS) as a treatment for symptomatic peripheral neuropathy in patients with diabetes mellitus.

METHODS

This was a double-blind, randomised, multicentre, parallel-group study of three series, each of ten treatment sessions of FREMS or placebo administered within 3 weeks, 3 months apart, with an overall follow-up of about 51 weeks. The primary endpoint was the change in nerve conduction velocity (NCV) of deep peroneal, tibial and sural nerves. Secondary endpoints included the effects of treatment on pain, tactile, thermal and vibration sensations. Patients eligible to participate were aged 18-75 years with diabetes for ≥ 1 year, HbA(1c) <11.0% (97 mmol/mol), with symptomatic diabetic polyneuropathy at the lower extremities (i.e. abnormal amplitude, latency or NCV of either tibial, deep peroneal or sural nerve, but with an evocable potential and measurable NCV of the sural nerve), a Michigan Diabetes Neuropathy Score ≥ 7 and on a stable dose of medications for diabetic neuropathy in the month prior to enrolment. Data were collected in an outpatient setting. Participants were allocated to the FREMS or placebo arm (1:1 ratio) according to a sequence generated by a computer random number generator, without block or stratification factors. Investigators digitised patients' date of birth and site number into an interactive voice recording system to obtain the assigned treatment. Participants, investigators conducting the trial, or people assessing the outcomes were blinded to group assignment.

RESULTS

Patients (n = 110) with symptomatic neuropathy were randomised to FREMS (n = 54) or placebo (n = 56). In the intention-to-treat population (50 FREMS, 51 placebo), changes in NCV of the three examined nerves were not different between FREMS and placebo (deep peroneal [means ± SE]: 0.74 ± 0.71 vs 0.06 ± 1.38 m/s; tibial: 2.08 ± 0.84 vs 0.61 ± 0.43 m/s; and sural: 0.80 ± 1.08 vs -0.91 ± 1.13 m/s; FREMS vs placebo, respectively). FREMS induced a significant reduction in day and night pain as measured by a visual analogue scale immediately after each treatment session, although this beneficial effect was no longer measurable 3 months after treatment. Compared with the placebo group, in the FREMS group the cold sensation threshold was significantly improved, while non-significant differences were observed in the vibration and warm sensation thresholds. No relevant side effects were recorded during the study.

CONCLUSIONS/INTERPRETATION

FREMS proved to be a safe treatment for symptomatic diabetic neuropathy, with immediate, although transient, reduction in pain, and no effect on NCV.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01628627.

FUNDING

The clinical trial was sponsored by Lorenz Biotech (Medolla, Italy), lately Lorenz Lifetech (Ozzano dell'Emilia, Italy).

Evaluation of the Neuropad sudomotor function test as a screening tool for polyneuropathy in the elderly population with diabetes and pre-diabetes: the KORA F4 survey

BACKGROUND

Neuropad is a novel indicator test for sudomotor dysfunction, which has not been validated as a screening tool in a population-based study. This study aimed to evaluate the utility of Neuropad as a screening tool for distal symmetric polyneuropathy among elderly subjects with diabetes and pre-diabetes in the general population.

METHODS

Eligible subjects aged 61-82 years (n = 940) from the KORA F4 survey were examined, 201 of whom had diabetes and 231 had pre-diabetes (WHO 1999 criteria). Polyneuropathy was defined by the Michigan Neuropathy Screening Instrument (MNSI) score >3.

RESULTS

Polyneuropathy was diagnosed in 60 (29.9%) subjects with diabetes and in 45 (19.5%) subjects with pre-diabetes, respectively (p = 0.013). The sensitivity and negative predictive value of Neuropad (reading time: 10 min) for the diagnosis of polyneuropathy were moderately high, reaching 76.7% and 78.1% in subjects with diabetes and 57.8% and 76.5% in those with pre-diabetes, respectively. Conversely, the specificity and positive predictive value for the diagnosis of polyneuropathy were rather low: 35.5% and 33.6% in diabetic individuals and 33.3% and 17.3% in subjects with pre-diabetes, respectively. Use of the >2 cut-off and MNSI combined with monofilament examination did not improve the diagnostic performance of Neuropad.

CONCLUSIONS

In the elderly general population with diabetes and pre-diabetes, Neuropad has reasonable sensitivity but rather low specificity for the diagnosis of polyneuropathy. It is a useful simple and inexpensive tool to screen for and to exclude polyneuropathy as desired, while its low specificity implies that a longer reading time merits consideration.

[Artificial synostosis for traumatic metacarpal defect: a case report]

Reconstruction of traumatic metacarpal defects is still challenging because of the key function of the architecture of the metacarpus for the function of the entire hand. Especially the exact restoration of the rotation for a parallel finger movement plays an important role. There are less information on this topic in the literature. We present a 28-year old patient with a traumatic almost complete defect of the fourth metacarpal. Reconstruction of the metacarpal arch was achieved with an artificial synostosis between the intact head of the 4th metacarpal and the 3rd metacarpal.

[Image reconstruction of the corneal subbasal nerve plexus with extended field of view from focus image stacks of a confocal laser scanning microscope]

BACKGROUND

Confocal laser scanning microscopy (CLSM) allows the in vivo analysis of nerve structures of the human cornea. In this way, pathological alterations of the peripheral nervous system that also affect the corneal subbasal nerve plexus (SNP) can be diagnosed non-invasively and possibly earlier than with other methods. The field of view of in vivo CLSM images of the cornea (ca. 0.4 × 0.4 mm²) is not sufficient for a reliable assessment. Two phenomena make the image assessment difficult: the presence of ridge-like tissue deformations in the neighbourhood of the SNP and image distortions that are induced by involuntary and unavoidable eye movements during image acquisition. This paper presents an image processing method for generating undistorted images of the SNP with an extended field of view.

METHODS

The presented method has been tested on five volunteers. Eight focus image stacks have been taken and processed from each subject using a Heidelberg Retina Tomograph with Rostock Cornea Module (HRT). An image registration scheme specifically adapted to the image acquisition system corrects the non-linear motion-induced image distortions and reconstructs a volume from each focus image stack. The epithelial basal boundary surface including the SNP appears as a distinctive hyper-reflective layer inside the reconstructed volume. Extracting this continuous layer generates a depth map and finally a two-dimensional image of the SNP. A final fusion step of the single reconstructed SNP images leads to laterally extended images.

RESULTS

Out of 40 focus image stacks, 34 have been fully processed into two-dimensional SNP reconstruction images. Six focus image stacks could not be transformed into volumes because of extremely fast eye movements during the image acquisition that prevented the complete image registration of the stacks. The 34 SNP reconstruction images depict an average area of 94.7 % ( ± 6.2 %) with respect to the field of view of a single HRT image. The final fusion of the reconstructed images resulted in an average increase of the image area by a factor of 2.6 (ranging from 2.2 to 3.1).

CONCLUSION

The presented image processing algorithms are capable of correcting the motion-induced image distortions and of generating larger two-dimensional images of the SNP even in presence of severe tissue deformations. These images provide the basis for a more reliable assessment of the corneal nerve fibres.

Neuropad: evaluation of three cut-off points of sudomotor dysfunction for early detection of polyneuropathy in recently diagnosed diabetes

AIMS

To examine the sensitivity and specificity of three cut-off points of Neuropad for the diagnosis of distal symmetric polyneuropathy and small-fibre dysfunction in patients within the first year after diagnosis of diabetes.

METHODS

Neuropad results were read at 10, 15 and 20 min and evaluated for diagnostic utility in distal symmetric polyneuropathy confirmed by electrophysiology and small-fibre dysfunction in 52 patients with Type 1 diabetes and 99 patients with Type 2 diabetes.

RESULTS

The prevalence of distal symmetric polyneuropathy was 15.4% in Type 1 diabetes and 43.4% in Type 2 diabetes, while that of small-fibre dysfunction was 9.6 and 31.3%, respectively. Sensitivity of Neuropad for the diagnosis of distal symmetric polyneuropathy and small-fibre dysfunction was highest in Type 1 diabetes for the 10-min threshold reaching 87.5 and 80.0%, respectively, while it was modestly high in Type 2 diabetes at 65.1 and 67.7%, respectively. Specificity in both diabetes types was modest for the 10-min threshold (44.7-48.2%). It was highest for the 20-min threshold (83.8-89.3%) at the cost of poor sensitivity at 12.5-34.9%. Negative predictive values were relatively high for all three cut-off points in both types of diabetes (64.1-97.1%) at the cost of poor positive predictive values at 12.5-71.4%.

CONCLUSIONS

In patients within the first year after diagnosis of diabetes, the 10-min cut-off for Neuropad provides a relatively high sensitivity and modest specificity for distal symmetric polyneuropathy and small-fibre dysfunction, rendering the test more suitable as a screening tool than the 15- and 20-min cut-offs.

Treatment with Actovegin® improves sensory nerve function and pathology in streptozotocin-diabetic rats via mechanisms involving inhibition of PARP activation

BACKGROUND

Diabetic neuropathy is one of the most severe complications of diabetes, affecting approximately one-third of diabetic patients. We investigated the potential neuroprotective effect of Actovegin®, a deproteinized hemoderivative of calf blood, in an animal model of diabetic neuropathy.

METHODS

A single intravenous injection of streptozotocin (STZ, 55 mg/kg) was used to induce experimental diabetes in male Sprague-Dawley rats. Actovegin® (200 or 600 mg/kg) was administered intraperitoneally from day 11 to day 40 post-STZ exposure. N-acetylcysteine (NAC) was used as a positive control and was added to drinking water (0.2 g/l) from day 2 until day 40. Measurements to assess efficacy included sensory nerve conduction velocity (SNCV), intraepidermal nerve fiber density (IENFD), and poly(ADP-ribose) content.

RESULTS

A decrease (35%) in sensory nerve conduction velocity (SNCV) was seen in STZ-induced diabetic rats from day 10 post-STZ administration and persisted at days 25 and 39. At study completion (day 41), a decrease (32%) in intraepidermal nerve fiber density (IENFD) was found in hind-paw skin biopsies from STZ-rats. Reduced SNCV and IENFD were significantly ameliorated by both doses of Actovegin®. More-over, 600 mg/kg Actovegin® markedly decreased poly(ADP-ribose) polymerase (PARP) activity in sciatic nerves from STZ-diabetic rats as assessed by poly(ADP-ribose) content.

CONCLUSION

Actovegin® improved several para-meters of experimental diabetic neuropathy via mechanisms involving suppression of PARP activation, providing a rationale for treatment of this disease in humans.

Management strategies for gastrointestinal, erectile, bladder, and sudomotor dysfunction in patients with diabetes

There are substantial advances in understanding disordered gastrointestinal autonomic dysfunction in diabetes. It occurs frequently. The underlying pathogenesis is complex involving defects in multiple interacting cell types of the myenteric plexus as well. These defects may be irreversible or reversible. Gastrointestinal symptoms represent a major and generally underestimated source of morbidity for escalating health care costs in diabetes. Acute changes in glycaemia are both determinants and consequences of altered gastrointestinal motility. 35-90% of diabetic men have moderate-to-severe erectile dysfunction (ED). ED shares common risk factors with CVD. Diagnosis is based on medical/sexual history, including validated questionnaires. Physical examination and laboratory testing must be tailored to patient's complaints and risk factors. Treatment is based on PDE5-inhibitors (PDE5-I). Other explorations may be useful in patients who do not respond to PDE5-I. Patients at high cardiovascular risk should be stabilized by their cardiologists before sexual activity is considered or ED treatment is recommended. Estimates on bladder dysfunction prevalence are 43-87% of type 1 and 25% of type 2 diabetic patients, respectively. Common symptoms include dysuria, frequency, urgency, nocturia and incomplete bladder emptying. Diagnosis should use validated questionnaire for lower urinary tract symptoms. The type of bladder dysfunction is readily characterized with complete urodynamic testing. Sudomotor dysfunction is a cause of dry skin and is associated with foot ulcerations. Sudomotor function can be assessed by thermoregulatory sweat testing, quantitative sudomotor axon reflex test, sympathetic skin response, quantitative direct/indirect axon reflex testing and the indicator plaster.

Autonomic imbalance: prophet of doom or scope for hope?

It has long been recognized that cardiac autonomic neuropathy increases morbidity and mortality in diabetes and may have greater predictive power than traditional risk factors for cardiovascular events. Significant morbidity and mortality can now be attributable to autonomic imbalance between the sympathetic and parasympathetic nervous system regulation of cardiovascular function. New and emerging syndromes include orthostatic tachycardia, orthostatic bradycardia and an inability to use heart rate as a guide to exercise intensity because of the resting tachycardia. Recent studies have shown that autonomic imbalance may be a predictor of risk of sudden death with intensification of glycaemic control. This review examines an association of autonomic dysregulation and the role of inflammatory cytokines and adipocytokines that promote cardiovascular risk. In addition, conditions of autonomic imbalance associated with cardiovascular risk are discussed. Potential treatment for restoration of autonomic balance is outlined.

Angiotensin-converting enzyme inhibition and blood pressure response during total intravenous anaesthesia for minor surgery

BACKGROUND

This study investigates whether long-term treatment with an angiotensin-converting enzyme inhibitor (ACEI) impairs the haemodynamic regulation during total intravenous anaesthesia (TIVA) for minor surgery.

METHODS

In a prospective, two-armed observational study, 36 patients undergoing TIVA for minor surgery were studied. Seventeen were taking ACEIs regularly but no other antihypertensive medication (ACEI group); 19 patients without any cardiovascular medication served as controls (non-ACEI group). Haemodynamic variables were measured every minute during induction and every 5 min during surgery. The plasma levels of renin, angiotensin II, vasopressin and catecholamines were measured before and 18 min after the induction of anaesthesia.

RESULTS

The mean arterial pressure decreased to the same extent in both the groups during the induction of TIVA. There were also no differences between the groups regarding the heart rate, systolic and diastolic arterial pressure, as well as the use of vasoconstrictors, and fluids during induction and throughout surgery. In the ACEI group, the plasma renin concentration was higher at baseline and after the induction of anaesthesia presumably due to the interruption of the negative renin-angiotensin feedback loop (P<0.05). Angiotensin II increased only in the non-ACEI group (6.2 ± 2.2 before vs. 9.6 ± 3.5 pg/ml after induction; P<0.05). In both groups, the plasma norepinephrine concentration decreased after the induction of TIVA (P<0.05). Plasma vasopressin and plasma epinephrine concentrations did not change in either group.

CONCLUSION

Long-term ACEI treatment does not further aggravate the blood pressure decrease under TIVA during minor surgery, provided the induction procedure is slow, the patient is kept well hydrated and vasoconstrictors are promptly applied.

Cardiovascular autonomic neuropathy contributes to left ventricular diastolic dysfunction in subjects with Type 2 diabetes and impaired glucose tolerance undergoing coronary angiography

AIMS

Left ventricular diastolic dysfunction is considered a precursor of diabetic cardiomyopathy, while diabetic cardiovascular autonomic neuropathy is associated with an increased risk of mortality. This study aimed to evaluate the association between left ventricular diastolic dysfunction and cardiovascular autonomic neuropathy, both diagnosed according to the current guidelines.

METHODS

We evaluated 145 patients referred for an elective coronary angiography, 52 of whom had Type 2 diabetes and 48 had impaired glucose tolerance, while 45 subjects had normal glucose tolerance. Cardiovascular autonomic neuropathy was diagnosed using autonomic function tests, while left ventricular diastolic dysfunction was verified by tissue Doppler imaging echocardiography.

RESULTS

Cardiovascular autonomic neuropathy was diagnosed in 15 (28.8%) patients with Type 2 diabetes and in six (12.5%) individuals with impaired glucose tolerance. The rates of left ventricular diastolic dysfunction were 81 and 33% in patients with and without cardiovascular autonomic neuropathy, respectively (P < 0.001). In the cardiovascular autonomic neuropathy group (n = 21), early diastolic relaxation velocity (Em) was significantly reduced (5.4 ± 0.9 vs. 7.3 ± 2.1 cm/s; P < 0.001) and the E/Em ratio was significantly higher (13.6 ± 4.6 vs. 10.3 ± 3.4 cm/s, P < 0.001) as compared with the group without cardiovascular autonomic neuropathy (n = 79). These findings remained significant after adjustment for age, sex, coronary artery disease, hypertension and HbA(1c) . A severe form of left ventricular diastolic dysfunction was observed in 33 and 15% of patients with and without cardiovascular autonomic neuropathy, respectively (P = 0.001).

CONCLUSION

  Cardiovascular autonomic neuropathy is associated with a higher prevalence and a more severe form of left ventricular diastolic dysfunction in patients with diabetes or impaired glucose tolerance undergoing coronary angiography. Because both cardiovascular autonomic neuropathy and left ventricular diastolic dysfunction are associated with increased cardiovascular morbidity and mortality, screening for patients with left ventricular diastolic dysfunction and cardiovascular autonomic neuropathy with diabetes or impaired glucose tolerance may identify those at high risk.

Evaluation of matrix-assisted laser desorption/ionization time of flight mass spectrometry for characterization of Culicoides nubeculosus biting midges

Matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) has shown promise in species identification of insect species. We evaluated its potential to consistently characterize laboratory-reared biting midges of the species Culicoides nubeculosus (Meigen) (Diptera: Ceratopogonidae). Twenty-one reproducible potential biomarker masses for C. nubeculosus were identified under different experimental treatments. These treatments included the homogenization of insects in either water or known concentrations of formic acid. The biomarker masses were present independent of age, gender and different periods of storage of individuals in 70% ethanol (a standard preservation method). It was found that the presence of blood in females reduced the intensity of the MALDI-TOF pattern, necessitating the removal of the abdomen before analysis. The protein profiles of a related non-biting midge, Forcipomyia sp. (Diptera: Ceratopogonidae), and of Aedes japonicus japonicus (Theobald) (Diptera: Culicidae) mosquitoes were also examined and were distinctly different. These findings provide preliminary data to optimize future studies in differentiation of species within the Culicoides genus using MALDI-TOF MS which is a rapid, simple, reliable and cost-effective technique.