Normative values of the vibration perception thresholds at finger pulps and metatarsal heads in healthy adults

Cortical processes of multisensory plausibility modulation of vibrotactile perception in virtual environments in middled-aged and older adults

Digital technologies, such as virtual or augmented reality, can potentially support neurocognitive functions of the aging populations worldwide and complement existing intervention methods. However, aging-related declines in the frontal-parietal network and dopaminergic modulation which progress gradually across the later periods of the adult lifespan may affect the processing of multisensory congruence and expectancy based contextual plausibility. We assessed hemodynamic brain responses while middle-aged and old adults experienced car-riding virtual-reality scenarios where the plausibility of vibrotactile stimulations was manipulated by delivering stimulus intensities that were either congruent or incongruent with the digitalized audio-visual contexts of the respective scenarios. Relative to previous findings observed in young adults, although highly plausible vibrotactile stimulations confirming with contextual expectations also elicited higher brain hemodynamic responses in middle-aged and old adults, this effect was limited to virtual scenarios with extreme expectancy violations. Moreover, individual differences in plausibility-related frontal activity did not correlate with plausibility violation costs in the sensorimotor cortex, indicating less systematic frontal context-based sensory filtering in older ages. These findings have practical implications for advancing digital technologies to support aging societies.

Diagnostic contribution of multi-frequency vibrometry to detection of peripheral neuropathy in type 1 diabetes mellitus compared with nerve conduction studies

AIM

The aim was to assess the use of multi-frequency vibrometry (MFV) in detecting diabetic peripheral neuropathy (DPN) in type 1 diabetes in comparison to nerve conduction studies (NCS) and neurothesiometer (NT). Our objectives were to examine how VPTs correlated with NCS parameters, evaluate the efficacy of MFV in distinguishing DPN as well as to investigate whether MFV procedure could be based on fewer frequencies.

METHODS

Adults with type 1 diabetes with previous MFV examinations were recruited at Skåne University Hospital in Malmö, Sweden, between 2018 and 2020. Participants were examined regarding nerve function in the lower limbs through MFV, NT and NCS.

RESULTS

A total of 66 participants (28 women and 38 men) with a median age of 50 (39 to 64) years were included in the study. Through NCS assessment, 33 participants (50%) were diagnosed with DPN. We found negative correlations between VPTs and all NCS parameters, where the strongest correlation was found between sural nerve amplitude and the 125 Hz frequency of MFV. A combination of four frequencies, two low (4 and 8 Hz) and two high (125 and 250 Hz), showed the highest classification efficacy (AUC 0.83, 95% CI 0.73-0.93).

CONCLUSION

We conclude that a strong correlation exists between the sural nerve amplitude and the VPTs at 125 Hz and that VPT testing with MFV can be focused on only four frequencies instead of seven, thus shortening test time, to distinguish DPN in the lower limb.

Near-wall hemodynamic parameters of finger arteries altered by hand-transmitted vibration

BACKGROUND

Sustained exposure to high-level hand-transmitted vibrations may result in angioneurotic disorders, which partly originate from vibration-altered hemodynamics in the finger arteries when repeating these disturbances throughout working life. Hence, the aim of this study is to assess the most relevant hemodynamic descriptors in the digital arteries, determine the relationship between the latter and vibration features, and gain better understanding of the physiological mechanisms involved.

METHODS

An experimental setup, mainly comprised of an ultra-high frequency ultrasound scanner and a vibration shaker, was used to image the digital proper volar arteries of the forefinger. Raw ultrasound data were post-processed by custom-made numerical routines to supply a pulsatile fluid mechanics model for computing the hemodynamic descriptors. Twenty-four healthy volunteers participated in the measurement campaign. Classical statistical methods were then applied to the dataset and also the wavelet transform for calculating the signal power in the frequency bands matching cardiac, respiratory, myogenic and neurogenic activities.

RESULTS

The artery diameter, the wall shear stress - WSS - and the WSS temporal gradient - WSSTG - were found to be the most relevant descriptors. Vibration-induced WSS was divided by three compared to its basal value whatever the vibration frequency and it was proportional to log2 of the acceleration level. Marked increases in WSSTG when stopping vibration might also lead to adverse health effects. Vibration caused a drop in WSS power for the frequency band associated with the neurogenic activity of the sympathetic nervous system.

CONCLUSION

This study may pave the way for a new framework to prevent vibration-induced vascular risk.

Neurosensory and vascular symptoms and clinical findings in the hands of Arctic open-pit miners in Sweden and Norway - a descriptive study

This cross-sectional study aimed to describe exposure to cold climate and hand-arm vibration (HAV) as well as neurosensory and vascular symptoms and clinical findings among open-pit Arctic miners. It was based on data from questionnaires and physical examinations, including 177 men and 75 women from two open-pit mines in Sweden and Norway (response rate 54%). Working outdoors or in an unheated building or machine for at least two hours per day was reported by 44% and HAV exposure of the same duration by 10%. Neurosensory symptoms (e.g. reduced perception of touch) in the hands were reported by 47% and Raynaud's phenomenon by 14%. In brief conclusion, the study showed that Arctic miners were commonly exposed to both cold temperatures and HAV. They also reported a broad range of neurosensory and vascular symptoms in their hands and had abnormal clinical findings related to the symptoms. The results emphasise the need for additional preventive measures in this occupational setting.

Skin Sensitivity Assessment Using Smartphone Haptic Feedback

Goal: This work presents a smartphone application to assess cutaneous sensory perception by establishing Vibrational Perception Thresholds (VPTs). Cutaneous sensory perception diagnostics allow for the early detection and symptom tracking of tactile dysfunction. However, lack of access to healthcare and the limited frequency of current screening tools can leave skin sensation impairments undiscovered or unmonitored. Methods: A 23-participant cross-sectional study in subjects with a range of finger sensation tests Smartphone Established VPTs (SE-VPTs) by varying device vibrational intensity. These are compared against monofilament test scores, a clinical measure of skin sensitivity. Results: We find a strong positive correlation between SE-VPTs and monofilament scores ([Formula: see text] = 0.86, p = 1.65e-07). Conclusions: These results demonstrate the feasibility of using a smartphone as a skin sensation screening tool.

Diabetic Neuropathy Assessed with Multifrequency Vibrometry Develops Earlier than Nephropathy but Later than Retinopathy

BACKGROUND

Diabetes is associated with systemic complications. Prevalence of diabetic nephropathy, and retinopathy, in type 1 diabetes mellitus (T1DM) is declining, but it is not known if this is true also for diabetic neuropathy.

AIM

To investigate the relationship between large fibre diabetic neuropathy and other diabetic complications.

MATERIALS AND METHODS

Neuropathy, defined here as large fibre neuropathy, was assessed by measuring vibration perception thresholds at four different frequencies on the sole of the foot, using a standard VibroSense Meter and/or neuropathic symptoms, in 599 individuals with T1DM. Retinopathy status was graded using the International Clinical Disease Severity Scale. Grade of albuminuria and previous history of any macrovascular complications were registered.

RESULTS

Diabetic individuals without retinopathy had similar vibration thresholds as age- and gender-matched control participants without diabetes, whereas those without microalbuminuria had higher thresholds than controls. Two individuals out of 599 (0.3%) had microalbuminuria, but not retinopathy or neuropathy, and 12/134 (9%) without retinopathy had signs of neuropathy. Totally 119/536 (22%) of the patients without microalbuminuria had neuropathy. Vibration thresholds increased with the rising severity of retinopathy and grade of albuminuria. In a multinomial logistic regression analysis, neuropathy was associated with retinopathy (OR 2.96 [1.35-6.49], p=0.007), nephropathy (OR 6.25 [3.21-12.15]; p=6.7×10-8) and macrovascular disease (OR 2.72 [1.50-4.93], p=0.001).

CONCLUSIONS

Despite recent changes in the incidence of diabetic complications, the onset of large fibre neuropathy follows that of retinopathy but precedes the onset of nephropathy in T1DM.

Perception Accuracy of a Multi-Channel Tactile Feedback System for Assistive Technology

Assistive technology uses multi-modal feedback devices, focusing on the visual, auditory, and haptic modalities. Tactile devices provide additional information via touch sense. Perception accuracy of vibrations depends on the spectral and temporal attributes of the signal, as well as on the body parts they are attached to. The widespread use of AR/VR devices, wearables, and gaming interfaces requires information about the usability of feedback devices. This paper presents results of an experiment using an 8-channel tactile feedback system with vibrators placed on the wrists, arms, ankles, and forehead. Different vibration patterns were designed and presented using sinusoidal frequency bursts on 2, 4, and 8 channels. In total, 27 subjects reported their sensation formally and informally on questionnaires. Results indicate that 2 and 4 channels could be used simultaneously with high accuracy, and the transducers' optimal placement (best sensitivity) is on the wrists, followed by the ankles. Arm and head positions were inferior and generally inadequate for signal presentation. For optimal performance, signal length should exceed 500 ms. Furthermore, the amplitude level and temporal pattern of the presented signals have to be used for carrying information rather than the frequency of the vibration.

Oral cannabidiol for prevention of acute and transient chemotherapy-induced peripheral neuropathy

PURPOSE

To assess the safety, dosing, and preventive effects of cannabidiol (CBD) on chemotherapy-induced peripheral neuropathy (CIPN) in patients receiving oxaliplatin- or paclitaxel-based chemotherapy.

METHODS

Patients with cancer scheduled to undergo treatment with carboplatin and paclitaxel (Carbo-Tax) or capecitabine and oxaliplatin (CAPOX) received 150 mg CBD oil twice daily (300 mg/daily) for 8 days beginning 1 day before initiation of chemotherapy. Ten CIPN-specific patient-reported outcome (PRO) measures were captured at baseline and each day after the first cycle of chemotherapy for 8 days. Multi-frequency vibrometry (MF-V) was captured at baseline and day 4 ± 1 after initiation of chemotherapy. Controls were obtained from a similar patient cohort that did not receive CBD. Adverse events were captured using the CTCAE ver. 4.03.

RESULTS

From March to December 2021, 54 patients were recruited. CBD-treated patients were significantly older (p = 0.013/0.037, CAPOX/Carbo-Tax) compared to controls. Patients receiving CBD and CAPOX or Carbo-Tax showed significantly lower (better) change in Z-scores in high-frequency MF-V (125 and 250 Hz) compared to controls. This difference was most pronounced for patients receiving Carbo-Tax (- 1.76, CI-95 = [- 2.52; - 1.02] at 250 Hz). CAPOX patients treated with CBD had significantly lower peak baseline-adjusted difference in three PRO items on cold sensitivity to touch, discomfort swallowing cold liquids, and throat discomfort (- 2.08, - 2.06, and - 1.81, CI-95 = [- 3.89; - 0.12], NRS 0-10). No significant differences in PRO items were found for patients receiving Carbo-Tax. Possible side effects included stomach pain (grades 1-2) for patients receiving CAPOX.

CONCLUSION

CBD attenuated early symptoms of CIPN with no major safety concerns. Long-term follow-up is ongoing. Results should be confirmed in a larger, randomized study.

TRIAL REGISTRATION NUMBER

NCT 04,167,319 (U.S National Library of Medicine; ClinicalTrials.gov). Date of registration: November 18, 2019.

Acute physiological and functional effects of repetitive shocks on the hand-arm system - a pilot study on healthy subjects

PURPOSE

Exposure to hand-transmitted shocks is a widespread phenomenon at the workplace. Separate risk assessments for shocks do not exist in current international hand-arm vibration regulations, leading to a potential underestimation of associated health risks.

METHODS

In a pilot study approach, N = 8 healthy males were exposed to sets of 3×5 minutes of repetitive shocks and 1×5 minutes of random vibration, controlled at a weighted vibration total value of 10 m/s² respectively. Baseline and post-exposure measurements of vibration perception thresholds, finger skin temperature, maximal grip / pinch force and the Purdue Pegboard test were conducted. Muscle activity was monitored continuously by surface electromyography.

RESULTS

Shock exposures evoked a temporary increase of vibration perception thresholds with high examination frequencies. A decrease of skin temperature was hinted for 1 s^-1 and 20 s^-1 shocks. Electromyographical findings indicated an additional load on two forearm muscles during shock transmission. Maximum grip force and manual dexterity were not affected, pinch force only partially reduced after the exposures.

CONCLUSION

Physiological effects from shock exposure conform to those described for hand-arm vibration exposure in principle, although some divergence can be hypothesized. Randomized designs are required to conclusively assess the need of occupational health concepts specifically for hand-transmitted shocks.

The evaluation of tactile dysfunction in the hand in type 1 diabetes: a novel method based on haptics

AIMS

We present an innovative method based on haptics for the evaluation of the sense of touch in the hand, in people affected by type 1 diabetes.

METHODS

Forty individuals affected by diabetes and 20 healthy controls took part in the study; the diabetes group was further divided into two subgroups based on vibration sensitivity in the lower limb. By means of a novel haptic device, tactile sensitivity in the fingertip was measured as the ability of the participants to discriminate slip motion speed.

RESULTS

Tactile sensitivity was significantly lower in individuals affected by diabetes as compared to controls. Depending on the subgroup, the difference from the controls was equal to 0.11 (95% CI from 0.029 to 0.186) and to 0.267 (95% CI from 0.198 to 0.336). Within the diabetes group, tactile sensitivity correlated with vibration sensitivity in the upper (p = 0.001) and lower limb (p = 0.003). A significant relationship between nerve conduction parameters and tactile sensitivity was found (p = 0.03). Finally, we combined the different predictors (clinical, vibratory and electroneurography data) by using cluster analysis; tactile sensitivity was found to be significantly different between different clusters (p = 0.004).

CONCLUSIONS

Early signs of tactile dysfunction in the hand were found in individuals affected by diabetes, even in absence of diabetic neuropathy. The protocol presented in this study is a promising tool for the assessment of tactile dysfunction in the hand in people affected by type 1 diabetes.

Exposure-response relationship between hand-arm vibration exposure and vibrotactile thresholds among rock drill operators: a 4-year cohort study

OBJECTIVES

The risk of developing hand-arm vibration syndrome (HAVS) from occupational hand-arm vibration (HAV) exposure is traditionally determined by the onset of vascular symptoms (white fingers). However, changes in tactile sensibility at the fingertips is a clinical sign of HAVS which in most cases precedes vascular signs. We aimed to assess relationships between occupational HAV exposure and HAVS-related signs including vibration perception thresholds (VPT) and pegboard score on an individual level, using a longitudinal study design with follow-up tests.

METHODS

We followed-up 148 workers exposed to different HAV levels for 4 years, with health examinations including VPT tests and pegboard tests carried out at baseline, 2 years and 4 years. VPT testing included seven frequencies, from 8 to 500 Hz. Second and fifth finger on both hands were tested, thus a total of 28 tests on each subject. We investigated associations using linear mixed models and significance level at p≤0.05.

RESULTS

There was a significant exposure-response relationship on an individual level between HAV exposure from rock drills and VPT for 16 of 28 test frequencies. The highest rise (worsening) in VPT was found at the 500 Hz test frequency with 1.54 dB increased VPT per 10-fold increase in cumulative exposure. We found no deterioration in pegboard performance associated with HAV exposure among the participants.

CONCLUSIONS

Risk predictions of HAVS may be based on exposure-response relationships between HAV exposure and VPT. The 500 Hz test frequency should be included in the VPT test protocols for early detection of signs related to reduced tactile sensibility.

Addressing Chemotherapy-Induced Peripheral Neuropathy Using Multi-Frequency Vibrometry and Patient-Reported Outcomes

(1) The study evaluated correlations between multi-frequency vibrometry (MF-V) and the measure of chemotherapy-induced peripheral neuropathy developed by the European Organization for the Research and Treatment of Cancer (CIPN18). (2) Patients with cancer scheduled to undergo treatment with capecitabine and oxaliplatin (CAPOX) or carboplatin and paclitaxel (Carbo-Tax) were recruited in a prospective, observational study with MF-V and the CIPN18 from baseline to one year after end of treatment. (3) The study recruited 31 evaluable patients. All MF-V measurements correlated significantly with the CIPN18 scores (r = 0.25−0.48, p > 0.003), with a low frequency (32 Hz) from metatarsals showing the best correlation coefficients (0.059 Z-score per CIPN18 point change, r = 0.48, CI-95 = [0.32; 0.60], p > 0.0001). The largest change in MF-V scores from baseline was seen in low-frequency VPTs taken from metatarsals at 8 Hz three months after end of treatment (from −0.26, CI-95 [−0.85, 0.38] to 1.15, CI-95 [0.53, 1.84]) for patients treated with oxaliplatin and at 32 Hz one year after end of treatment (from 0.09, CI-95 [−0.56, 0.77] to 0.88, CI-95 [0.34, 1.47]) for patients treated with paclitaxel. (4) Low-frequency vibration perception thresholds (8 and 32 Hz) correlated better with CIPN18 scores than high-frequency ones (128 and 250 Hz). If validated, this finding will advance CIPN pathophysiological understanding and inform the development of assessment methods.

Quantitative proteomic analysis of human peripheral nerves from subjects with type 2 diabetes

AIMS

Diabetic peripheral neuropathy (DPN) is a common and severe complication to type 2 diabetes. The pathogenesis of DPN is not fully known, but several pathways and gene polymorphisms contributing to DPN are described. DPN can be studied using nerve biopsies, but studies on the proteome of the nerve itself, and its surrounding tissue as a whole, are lacking. Studies on the posterior interosseous nerve (PIN) have proposed PIN a useful indicator of DPN.

METHODS

A quantitative mass spectrometry-based proteomics analysis was made of peripheral nerves from age- and gender-matched living human male tissue donors; nine type 2 diabetes subjects, with decreased sural nerve action potentials indicating DPN, and six controls without type 2 diabetes, with normal electrophysiology results.

RESULTS

A total of 2617 proteins were identified. Linear regression was used to discover which proteins were differentially expressed between type 2 diabetes and controls. Only soft signals were found. Therefore, clustering of the 500 most variable proteins was made to find clusters of similar proteins in type 2 diabetes subjects and healthy controls.

CONCLUSIONS

This feasibility study shows, for the first time, that the use of quantitative mass spectrometry enables quantification of proteins from nerve biopsies from subjects with and without type 2 diabetes, which may aid in finding biomarkers of importance to DPN development.

Peripheral and Autonomic Neuropathy Status of Young Patients With Type 1 Diabetes Mellitus at the Time of Transition From Pediatric Care to Adult-Oriented Diabetes Care

INTRODUCTION

The prevalence of neuropathic lesions in young patients with type 1 diabetes mellitus (T1DM) at the time of transition from pediatric care to adult-oriented diabetes care is poorly studied. A comparative study with healthy volunteers to assess the possible neuropathic condition of this special population and to identify the potential early screening needs has not been performed yet. The results may provide important feedback to pediatric diabetes care and a remarkable baseline reference point for further follow up in adult diabetes care.

PATIENTS AND METHODS

Twenty-nine young patients with T1DM [age: 22.4 ± 2.9 years; HbA1c: 8.5 ± 2.1%, diabetes duration: 12.2 ± 5.8 years; (mean ± SD)] and 30 healthy volunteers (age: 21.5 ± 1.6 years; HbA1c: 5.3 ± 0.3%) were involved in the study. Autonomic function was assessed by standard cardiovascular reflex tests. Complex peripheral neuropathic testing was performed by Neurometer^®, Neuropad^®-test, Tiptherm^®, Monofilament^®, and Rydel-Seiffer tuning fork tests.

RESULTS

T1DM patients had significantly higher diastolic blood pressure than controls (80 ± 9 vs. 74 ± 8 mmHg, p < 0.01), but there was no significant difference in systolic blood pressure (127 ± 26 vs. 121 ± 13 mmHg). Cardiovascular reflex tests had not revealed any significant differences between the T1DM patients and controls. No significant differences with Neurometer^®, Neuropad^®-test, and Monofilament^® were detected between the two groups. The vibrational sensing on the radius on both sides was significantly impaired in the T1DM group compared to the controls with Rydel-Seiffer tuning fork test (right: 7.5 ± 1.0 vs. 7.9 ± 0.3; left: 7.5 ± 0.9 vs. 7.9 ± 0.3, p < 0.05). The Tiptherm^®-test also identified a significant impairment in T1DM patients (11 sensing failures vs. 1, p < 0.001). In addition, the neuropathic complaints were significantly more frequently present in the T1DM patient group than in the controls (9 vs. 0, p < 0.01).

CONCLUSION

In this young T1DM population, cardiovascular autonomic neuropathy and cardiac morphological alterations could not be found. However, Rydel-Seiffer tuning fork and Tiptherm^®-tests revealed peripheral sensory neurological impairments in young T1DM patients at the time of their transition to adult diabetes care.