Hand-arm vibration syndrome: a common occupational hazard in industrialized countries

Evaluation of hand-arm vibration (HAV) exposure among groundskeepers in the southeastern United States

OBJECTIVE

The objectives of this study were to evaluate daily hand-arm vibration (HAV) exposure among groundskeepers, characterize power tools used, and estimate lifetime cumulative HAV exposure dose.

METHODS

Seventeen groundskeepers and ten office workers employed at two US southeasterrn institutions were recruited as a target exposure group and a reference group, respectively. A 6-d exposure assessment of HAV was scheduled, and vibration dosimeters were used to obtain daily vibration exposure value, A(8). Information on power tools used and corresponding operation duration was recorded to assign the real-time vibration data collected from the dosimeters for tool characterization in terms of vibration total value (ahv) and frequency. Lifetime cumulative exposure dose, ahv-lifetime, was determined using ahv for all tools used and lifetime exposure duration obtained through a questionnaire.

RESULTS

The individual groundskeepers' average A(8) ranged from 0.8 to 2.6 and from 1.0 to 2.6 m/s2 for the right hand and left hands, respectively. Among 11 power tools used by the groundskeepers, grass trimmers contributed the most to the vibration exposure. The average ahv of the individual tools ranged from 8.0 (chainsaws) to 1.9 m/s2 (seating mowers and handheld blowers) for the right hand and from 6.4 (push mowers) to 1.4 m/s2 (backpack blowers) for the left hand. The highest acceleration peak of grass trimmers, edgers, backpack blowers, pole saws, riding blowers, and hedgers was observed between 100 and 200 Hz while riding mowers, seating mowers, push mowers, and chainsaws showed the highest acceleration peak at lower frequencies (≤63.5 Hz). The groundskeepers' average ahv-lifetime was 76,520.6 and 61,955.5 h m/s2 for the right and left hands, respectively. The average ahv-lifetime of office workers was 2,306.2 and 2,205.8 h m/s2 for the right and left hands, respectively, which was attributed to personal hobby activities.

CONCLUSION

Three groundskeepers' average A(8) reached 2.5 m/s2, the Action Limit recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). The highest contribution to the vibration exposure was observed during grass trimmer operations with a major acceleration peak at 100 Hz. The groundskeepers' ahv-lifetime was 33 and 28 times higher for the right and left hands, respectively, than the office workers.

Serum levels of biomarkers related to severity staging of Raynaud's phenomenon, neurosensory manifestations, and vibration exposure in patients with hand-arm vibration injury

Our aim was to explore possible relationships between serum levels of biomarkers in patients with hand-arm vibration injury in relation to the severity of the vascular, i.e., Raynaud's phenomenon (RP), and neurosensory manifestations, the current exposure level, and the duration of exposure. This study was of case series design and involved 92 patients diagnosed with hand-arm vibration injury. Jonckheere's trend test was used to assess any association between serum levels of biomarkers and RP as well as neurosensory manifestations, graded by the International Consensus Criteria. Generalized linear models with adjustment for possible confounders were also used for associations between serum levels of biomarkers and; (1) severity of RP recorded as the extent of finger blanching calculated with Griffin score, (2) vibration perception thresholds, (3) magnitude of current exposure as [A(8); (m/s2)] value, and (4) the duration of exposure in years. Serum levels of thrombomodulin, von Willebrand factor, calcitonin gene related peptide (CGRP), heat shock protein 27, and caspase-3 were positively associated with severity of RP. Serum levels of CGRP were positively associated with the neurosensory component. No associations with exposure were shown for these biomarkers. For Intercellular adhesion molecule 1 and monocyte chemoattractant protein 1, no associations were found with neither severity nor exposure. Levels of serum biomarkers associated with endothelial injury or dysfunction, inflammation, vasodilation, neuroprotection, and apoptosis were positively associated with the severity of hand-arm vibration injury.

Evaluation of Hand-Arm Vibration Syndrome Owing to Nerve Conduction Study and Cumulative Exposure Index-A 2.5-Year Cohort Study

OBJECTIVE

This study aims to clarify the relationship between peripheral neuropathy in hand-arm vibration syndrome and cumulative exposure index.

METHODS

68 participants without symptoms were surveyed. The participants were divided into three groups based on past and current vibration exposure (VE).

RESULTS

Comparison among groups according to past VE showed that the median and ulnar sensory nerve conduction velocities and median sensory nerve action potential (SNAP) amplitude were significantly lower in past high and low exposure groups than in the past nonexposure group. Comparison among groups according to current VE showed that the median and ulnar SNAP amplitudes were significantly lower in the current high exposure group than in the current low or nonexposure group.

CONCLUSIONS

Vibration tool handlers have potential peripheral nerve lesions at a certain stage without subjective symptoms of the finger.

A follow-up study of vibration-induced injuries in workers exposed to transient and high frequency vibrations

BACKGROUND

In a previous study from 2018, 38 wheel loader assembly workers were examined, showing high exposures to transient and high-frequency vibrations. After the investigation, preventive measures were immediately implemented to reduce the vibration exposure. In 2022, a follow-up study was carried out to examine the effect of these measures.

METHODS

The follow-up study included 35 (27 men and 8 women) of the original 38 workers. They were divided into two groups, 24 workers with ongoing vibration exposure and 11 workers, not vibration exposed since 2018. All participants completed a questionnaire and underwent a thorough examination, including several neurophysiological tests and a comprehensive assessment of musculoskeletal symptoms. The questionnaire responses and on-site vibration level measurements formed the basis for the individual vibration exposure assessment.

RESULTS

In 2018, clear differences were noted between the two groups regarding vibration perception thresholds (VPT), needle test, 2-PD (2-point discrimination), and monofilament test with deviating results in the unexposed group. The difference between the two groups was significantly smaller at the follow-up examination in 2022, where differences remained for VPT and monofilament tests, with deviating test results in the unexposed group. When comparing variable values between 2018 and 2022 within the exposed and unexposed groups, respectively, the unexposed group showed mostly unchanged values, while a deterioration was observed for VPT, needle test and temperature sensitivity test among the exposed workers during follow-up. The prevalence of VWF (Vibration white fingers) was around 30-40% and neuropathy around 75% among exposed workers during follow-up compared to about 60% and 85% respectively, in the unexposed group.

CONCLUSION

The overall categorization of white fingers and neuropathy, according to the Stockholm Workshop Scale, remained largely unchanged in both study groups from 2018 to 2022. The introduction of cost-effective and relatively simple preventive measures may have contributed to this result. Throughout the follow-up period, the number of exposed workers who developed musculoskeletal disorders and newly reported cases of vibration injuries at the factory decreased. Without this preventive program, increased vascular and nerve symptoms would most likely have occurred during follow-up due to continued vibration exposure.

Mottled Raynaud's phenomenon and hand-arm vibration syndrome: followed up for 10 years

Vibration white finger is a form of secondary Raynaud's phenomenon (RP) caused by the use of handheld vibrating tools. RP usually appears on the extremities of the fingers, and its borders are well recognised. No reports have been published on 'mottled' RP in continuous observation from the onset to the disappearance of RP. A man in his 60s who had been using vibrating tools such as jackhammers and tampers for 30 years presented with sensations of coldness, burning and numbness. Whole-body cold exposure was performed outdoors in winter, and RP was photographed continuously. 'Mottled' RP can be defined as triphasic colour changes: white, blue and red. The patient was taken off work, kept warm and medicated. His symptoms improved slightly after 10 years of follow-up, but the RP did not disappear. 'Mottled' RP is rare and refractory and should be recognised as a form of RP.

Prevalence of carpal tunnel syndrome symptoms among neurosurgical spine surgeons

Background

Neurosurgeons, particularly spine surgeons, have high exposure to vibrations via electric or pneumatic drills and repetitive motion. Although no data exist for the prevalence of carpal tunnel syndrome (CTS) among these surgeons, anecdotal evidence suggests the rate of symptoms is higher than in the general population.

Methods

An anonymous questionnaire was developed to assess demographics, practice patterns, presence of CTS symptoms, and treatment (time off, bracing, medication, injections, surgery). The survey was sent via anonymous email link to members of the AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerve.

Results

101 members responded: 44 reported at least one symptom related to CTS (43.6%). There was no statistically significant relationship between overall or spine case volume, the number of cases performed annually/daily, and CTS symptoms. Respondents working in non-teaching settings were significantly more likely to have CTS symptoms than academic teaching institutions (50.0% v. 45.0%; p = 0.0112).

Conclusions

Our survey demonstrated CTS to be more prevalent in spine neurosurgeons (43.6%) than in the general population (1-5%). The lack of significant association between most practice-based metrics and CTS symptoms may indicate that respondents have a minimum case volume that exceeds the amount of vibration exposure/repetitive motion to develop symptoms. The significantly increased prevalence of CTS among neurosurgeons at non-teaching institutions suggests that residents provide operative assistance offsetting the vibration exposure/repetitive motion by attendings. Further research may determine the root cause for the high prevalence of CTS in spine neurosurgeons and devise methods for reducing vibration exposure.

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.

Turbine effect on dental students' lateral pinch modulation and performances

BACKGROUND

Dental turbines can generate significant vibrations that may be transmitted to dentists' hands. The vibrations contribute to neural impairment and decrease dexterity over the long duration. It is unclear whether such vibration effects would be detected in the short time during the pre-clinical year of dentistry study.

AIMS

To investigate the effect of vibrations on lateral pinch modulation and manual performance of dentistry students.

METHODS

Four lateral pinch modulation tests by a square-shaped force sensing resistor (FSR) were administered to 30 dental students during their phantom course. Tests were performed with dominant and non-dominant hands at two time points: T0 (2 months after commencing phantom training) and T1 (end of phantom training). At each time point, students accomplished two manual performance tests on plastic teeth. Comparisons were made between lateral pinch modulation test scores at different times, considering the differences between hands and gender. The relationships between the FSR tests and manual performance were also determined.

RESULTS

The participating 19 female and 11 male students had a combined 50% response rate. At T1, the lateral pinch modulation for all tests significantly decreased for the dominant hand (P < 0.05) and non-dominant hand (P < 0.05). For the non-dominant hand at T1, the lateral pinch modulation of females significantly decreased as compared to males (P < 0.05). No significant correlations were found between lateral pinch modulation and manual tasks at T0 and T1.

CONCLUSIONS

The lateral pinch modulation of the fingers of dental students deteriorated after only 8 months of training at phantom (short-time exposure), with females at higher risk and possibly earlier symptoms manifestation.

Influence of ergonomic factors on peripheral neuropathy under HAV exposure

BACKGROUND

Hand-arm vibration (HAV) is a risk factor for carpal tunnel syndrome (CTS) and ulnar neuropathy at the elbow (UNE). It is unclear how ergonomic factors influence the relationship between HAV exposure and CTS and UNE.

AIMS

We aimed to assess the relationship between cumulative HAV exposure and CTS and UNE in workers exposed to HAV from two tools with different ergonomic profiles.

METHODS

We performed nerve conduction studies (NCSs) of the sensory and motor median and ulnar nerves and recorded symptoms indicating CTS and UNE in workers exposed to HAV from impact wrenches or from rock drills. Exposure was measured as cumulative lifetime exposure. We used linear regression adjusted for age and body mass index to assess linear relationships.

RESULTS

Sixty-five workers participated (33 rock drill and 32 impact wrench operators). We found inverse linear associations between cumulative HAV exposure and median nerve sensory conduction velocity in impact wrench operators and ulnar nerve motor conduction velocity in rock drill operators (beta of 0.63 and 0.75). Based on NCS findings and symptoms, seven impact wrench operators had CTS and one UNE, and four rock drill operators had CTS and six UNE.

CONCLUSIONS

Our findings indicate that ergonomic factors influence the development of CTS and UNE under HAV exposure. The ergonomic profile seems to influence which type of neuropathy workers exposed to HAV will develop. Design of occupational exposure guidelines and future studies should be based on ergonomic profile and exposure characteristics for different tools and not merely HAV.

Cryoglobulins and cold agglutinins for hand arm vibration syndrome

BACKGROUND

Hand arm vibration syndrome (HAVS) is a condition caused by hand transmitted vibration from the use of hand-held vibrating tools or workpieces. The disease affects the vascular, neurological and musculoskeletal systems. The vascular component of HAVS is a form of secondary Raynaud's phenomenon. Other causes of disease must be excluded before attributing the cause to hand transmitted vibration.

AIMS

To evaluate the prevalence, and utility of testing for, cryoglobulins and cold agglutinins in patients with HAVS symptoms.

METHODS

A retrospective cohort study of 1183 patients referred for HAVS clinical assessment at St. Michael's Hospital, Toronto, Canada, between 2014 and 2020. The standard operating procedure at the clinic includes a detailed clinical and exposure history, physical examination, objective investigations and blood tests. Data were retrieved from patient chart review and laboratory investigation results for all cases with cryoglobulin and cold agglutinin testing.

RESULTS

A total of 1183 patients had a serum cryoglobulin measurement. Eleven patients (1%) were positive. Seven positive results were 'low titre' (1% positive) and the other four results were 2%, 6%, 9% and 18%. The patient with a 9% positive cryoglobulin titre had previously diagnosed Sjögren's syndrome. There were no positive cold agglutinin tests in the 795 patients tested.

CONCLUSIONS

Routine testing for cryoglobulins and cold agglutinins in patients with HAVS symptoms is not recommended because test positivity rates are negligible. Testing may be considered if the clinical history or routine blood investigations suggest evidence of underlying cryoglobulinaemia or cold agglutinin disease.

Hand-arm vibration syndrome among harvesting farmers: A cross-sectional study from Pakistan

BACKGROUND

Constant use of hand-held vibratory tools may cause health issues, including hand dysfunction, among farmers. Thus, exposure to these vibratory instruments may cause hand-arm vibration syndrome (HAVS).

OBJECTIVE

The study aimed to measure the prevalence of HAVS and evaluate neurological and vascular symptoms among farmers.

METHODS

This cross-sectional study included 20 villages in Pakistan and used a three-part questionnaire to collect data from farmers exposed to vibration while farming. The study included demographics, the Health Surveillance Questionnaire, and the Stockholm Workshop Classification Scale. SPSS version 22 was used for the data entry and statistical analysis.

RESULTS

433 (43%) participants had musculoskeletal discomfort and 568 (57%) had hand vibration. Raynaud phenomenon was evident in 430 (43%) participants, whereas carpal tunnel syndrome was found in 218 (22%). Tingling was reported by 255 participants (26%), and numbness was reported by 543 (54%). According to the grading of neurological symptoms, 461 (46%) participants were exposed to vibration but did not experience any symptoms, placing them in stage 0. 185 (18.5%) participants with HAVS with infrequent episodes affecting just the tips of one or more fingers were categorized in stage 01 based on grading of vascular symptoms.

CONCLUSION

HAVS are common among harvesting farmers, with the most noticeable vibrations occurring in the shoulder region. Similarly, most farmers had no vascular symptoms, and most were exposed to vibration but had no neurological symptoms.

Proposal of Combined Noise and Hand-Arm Vibration Index for Occupational Exposure: Application to a Study Case in the Olive Sector

In many production and industrial sectors, workers are exposed to noise and hand-arm vibrations (HAV). European directives have established the maximum limit values or exposure action values for noise and vibration independently. However, in many cases, workers who endure hand-arm vibration also receive high noise levels. This research suggests a procedure to aid the establishment of precautionary measures for workers with simultaneous exposure to both physical agents. This procedure defines a combined index based on the energy doses for both noise and HAV. From this combined index, the suggested methodology allows a recommended exposure time for workers with simultaneous noise and HAV exposure to be calculated. This methodology can be adapted to tackle the relative importance assigned to both agents according to the safety manager and new knowledge on combined health effects. To test this method, a measurement campaign under real working conditions was conducted with workers from the olive fruit-harvesting sector, where a variety of hand-held machinery is used. The results of the study case show that the suggested procedure can obtain reliable exposure time recommendations for simultaneous noise and HAV exposures and is therefore a useful tool for establishing prevention measures.

Human Exposure to Hand-Arm Vibration from a Surgical Drill During Simulated Spine Surgery

OBJECTIVE

During spine surgery, surgeons are exposed to vibrations from surgical drills. Increased exposure to vibration can result in neurologic, vascular, and musculoskeletal impairments. To reduce these risks, occupational health standards have been implemented to limit exposure levels. The purpose of this study was to quantify human exposure to hand-arm vibration from a surgical drill during a simulation of a common spine procedure.

METHODS

Vibration measurements were collected during three 30-second surgical trials on a fresh frozen cadaver torso specimen using a standard surgical drill. The daily vibration exposure A(8) was evaluated on the basis of International Organization for Standardization 5349-1, and the occupational health standards, exposure action value, and exposure limit value were calculated.

RESULTS

On the basis of vibration exposure, surgeons in this study reached their exposure limits in 8 minutes to monitor tool usage and 32 minutes to terminate equipment usage.

CONCLUSIONS

The results demonstrate that a common surgical drill transmits hand-arm vibration levels approaching the exposure action value and exposure limit value over short periods of use. Further investigation is needed to determine the total vibration exposure over an entire workday, specifically in surgeons who perform multiple surgeries within a single day.

An Experimental Study on the Vibration Transmission Characteristics of Wrist Exposure to Hand Transmitted Vibration

This research intends to further improve the understanding of vibration damage mechanisms in the wrist area and to establish a more effective biodynamic model of the hand-arm system. Scholars have conducted some research work around the influencing factors of vibration response and commonly used vibration transmissibility to characterize the local vibration transmission characteristics of the hand-arm system. In this paper, a hand-transmitted vibration test platform was built according to ISO 10819, and a random combination of four ergonomic factors, namely wrist posture, arm posture, grip force, and thrust force, was used to test the vibration response of six subjects’ wrists; the total vibration transmissibility of the wrist was calculated according to the transmissibility formula. The effect of the four factors on the total vibration transmissibility of the wrist part was comprehensively analyzed, in which the wrist posture was proposed for the first time. The results show that (1) vibration transmissibility of the wrist is not only related to the arm posture, thrust force, and grip force but also related to the wrist posture; (2) the total vibration transmissibility and resonance frequency on the wrist has small correlation with large grip force and thrust force, and the vibration transmissibility of grip force 30 N and 60 N are basically equal in the low-frequency band (from 5–10 Hz to 5–20 Hz); (3) the wrist postures have a significant effect on the total vibration transmissibility at the wrist.

The clinical consequence of using less than four sensory perception examination methods in the Swedish surveillance system for Hand-Arm vibration syndrome

OBJECTIVES

The Swedish surveillance system aiming to reveal undetected Hand-Arm Vibration Syndrome (HAVS) in workers exposed for vibrations is regulated by the provision AFS 2019:3. The goal for the surveillance system is to diagnose HAVS, as well as to find workers at risk for developing HAVS due to other conditions. The national guidelines stipulate examination using at least two out of four hand sensory examination methods (SEM); monofilament (touch), two-point discrimination (discriminative), tuning fork (vibrotactile), and Rolltemp (thermotactile). The aim of this study was to examine the clinical consequence of using less than four of these SEMs.

METHODS

We collected data on SEMs from the medical records of all individuals that went through the specific surveillance medical check-up in a large occupational health service for 1 year. We then calculated the number of workers found with HAVS when using one, two, or three SEMs, and compared with the result from using all available SEMs.

RESULTS

Out of 677 examined individuals, 199 had positive findings in at least one SEM. The detection rate for these findings was on average 47% when using one SEM, 71% using two SEMs, and 88% using three SEMs (out of 100% detection when all four SEMs were used).

CONCLUSIONS

If fewer than four sensory examination methods are used for surveillance of HAVS, many workers with incipient injuries may stay undetected. This may lead to further exposure resulting in aggravation of injury.

Raynaud Phenomenon and Other Vasospastic Disorders

Vasospastic disorders are prevalent in the general population and can affect individuals of any age. Primary (or idiopathic) vasospastic disorders often have a benign course; treatment focuses on the control of symptoms. Secondary vasospastic disorders occur owing to an underlying condition and have an increased risk of complications, including tissue loss and digital ulcerations; treatment should focus on the underlying condition. In this review, we discuss the pathophysiology, clinical presentation, diagnosis, and management of vasospastic disorders, including Raynaud syndrome, acrocyanosis, livedo reticularis, and pernio.

Transparent and Flexible Vibration Sensor Based on a Wheel-Shaped Hybrid Thin Membrane

With the advent of human–machine interaction and the Internet of Things, wearable and flexible vibration sensors have been developed to detect human voices and surrounding vibrations transmitted to humans. However, previous wearable vibration sensors have limitations in the sensing performance, such as frequency response, linearity of sensitivity, and esthetics. In this study, a transparent and flexible vibration sensor was developed by incorporating organic/inorganic hybrid materials into ultrathin membranes. The sensor exhibited a linear and high sensitivity (20 mV/g) and a flat frequency response (80–3000 Hz), which are attributed to the wheel-shaped capacitive diaphragm structure fabricated by exploiting the high processability and low stiffness of the organic material SU-8 and the high conductivity of the inorganic material ITO. The sensor also has sufficient esthetics as a wearable device because of the high transparency of SU-8 and ITO. In addition, the temperature of the post-annealing process after ITO sputtering was optimized for the high transparency and conductivity. The fabricated sensor showed significant potential for use in transparent healthcare devices to monitor the vibrations transmitted from hand-held vibration tools and in a skin-attachable vocal sensor.

Exposure to Hand-Arm Vibration in the Australian Workforce

OBJECTIVE

To estimate the prevalence of hand-arm vibration (HAV) in Australian workplaces.

METHODS

The Australian Workplace Exposure Survey (AWES)-Hearing was a cross-sectional telephone survey of Australian workers conducted in 2016-2017. Respondents were asked about the time spent using tools or performing tasks known to be associated with HAV during their most recent working day. We created a library of HAV magnitude levels for each tool/task and estimated each worker's daily HAV exposure level using standard formulae. We categorized each worker as to whether they exceeded the daily occupational limits of 2.5 and 5.0 m/s2. Results were extrapolated to the Australian working population using a raked weighting method.

RESULTS

In our sample of 4991 workers, 5.4% of men and 0.7% of women exceeded the HAV action limit of 2.5 m/s2 on their most recent working day. We estimate that 3.8% of the Australian workforce exceeds the HAV limit of 2.5 m/s2 and 0.8% exceeds the 5 m/s2 limit. Men were more likely to exceed the HAV limits than women, as were those with trade qualifications, and those who worked in remote locations. Workers in the construction, farming, and automobile industries had the highest prevalence of HAV exposure. Tool groups that contributed to higher exposure levels included: compactors, rollers, and tampers; power hammers and jackhammers; and underground mining equipment.

CONCLUSIONS

HAV is common in the Australian working population. Given the health risks associated with this exposure, reduction strategies and interventions should be developed, with engineering controls as the starting point for exposure reduction strategies.

Persistent neuropathy among early-stage breast cancer survivors in a population-based cohort

BACKGROUND

The prevalence of persistent peripheral neuropathy (PN) in early-stage breast cancer (ESBC) survivors is largely unknown. We explored the occurrence and risk factors of PN among long-term ESBC survivors treated with taxane chemotherapy.

METHODS

A population-based cohort of 884 recurrence-free ESBC survivors diagnosed 2010-2015 in the South East Health Care region, Sweden and 1768 control women without prior cancer received a postal questionnaire that included the European Organisation for Research and Treatment of Cancer chemotherapy-induced peripheral neuropathy (CIPN20) items. Prevalence, relative risks (RRs) (Poisson regression) and risk factors (binomial regression) were calculated. Adjustments were made for confounding factors (e.g. age, body mass index, comorbidities).

RESULTS

The response rate was 79% for survivors and 59% for controls. The median time post taxane was 3.6 years (1.5-7.3 years). The adjusted RR was highest (RR 1.8) for "tingling/numbness of toes/feet". Individual sensory symptoms occurred in 8.9-48.4% and motor symptoms in 7.2-61.3% of survivors; the most prevalent symptoms were "difficulty opening jar" and "cramps in feet". Paclitaxel, older age, overweight, diabetes mellitus, vibrating hand tools, autoimmune disease and smoking were independent risk factors.

CONCLUSIONS

PN was more common among ESBC survivors than control women and many symptoms persisted over time. Risk factors should be considered when treatment decisions are made.

A Review of Hand-Arm Vibration Studies Conducted by US NIOSH since 2000

Studies on hand-transmitted vibration exposure, biodynamic responses, and biological effects were conducted by researchers at the Health Effects Laboratory Division (HELD) of the National Institute for Occupational Safety and Health (NIOSH) during the last 20 years. These studies are systematically reviewed in this report, along with the identification of areas where additional research is needed. The majority of the studies cover the following aspects: (i) the methods and techniques for measuring hand-transmitted vibration exposure; (ii) vibration biodynamics of the hand-arm system and the quantification of vibration exposure; (iii) biological effects of hand-transmitted vibration exposure; (iv) measurements of vibration-induced health effects; (iv) quantification of influencing biomechanical effects; and (v) intervention methods and technologies for controlling hand-transmitted vibration exposure. The major findings of the studies are summarized and discussed.

Tremor measurements in a 22-year cohort study of workers exposed to hand-held vibrating tools

OBJECTIVES

The objectives of this cohort study were to evaluate possible long-term effects of occupational exposure to hand-arm vibration (HAV) in terms of increased tremor. The aims were to evaluate whether exposure during follow-up, baseline hand-arm vibration syndrome (HAVS), baseline manual dexterity or current medical conditions or life-style habits might be associated with increased tremor. A further aim was to compare two different activation conditions: postural vs rest tremor.

METHODS

Forty men (current age: 60.4 years) who had previously worked as manual workers in a specialized engineering and construction company enrolled in the study. Their hand functions had been examined in 1994. At the baseline examination, 27 had been diagnosed with HAVS, while 13 were not exposed. The follow-up examination in 2016-2017 comprised the CATSYS Tremor Pen^® for measuring postural and rest tremor and the Grooved Pegboard Test for assessing manual dexterity. Blood samples were taken for assessing biomarkers that might have impact on tremor.

RESULTS

Neither cumulative exposure to HAV during follow-up nor HAVS at baseline were associated with increased tremor. A test for manual dexterity at baseline was significantly associated with increased tremor (Tremor Intensity) at follow-up. Blood markers of current medical conditions and tobacco consumption were associated with increased tremor. Rest tremor frequency was higher than postural tremor frequency (p < 0.001).

CONCLUSIONS

The main findings of this 22-year cohort study were no indications of long-term effects on tremor related to HAV exposure and previous HAVS status. However, baseline manual dexterity was significantly associated with increased tremor at follow-up. Activation conditions (e.g., hand position) are important when testing tremor.

Vibration related symptoms and signs in quarry and foundry workers

Purpose

The development of vascular and neurosensory findings were studied in two groups of long-term exposed quarry and foundry workers with different vibration exposures, working conditions and work tasks.

Methods

The study included 10 quarry workers (mean age 43 yrs., mean exposure time 16 yrs.) and 15 foundry workers (35 yrs.; 11 yrs.) at two plants in Sweden. All participants completed a basic questionnaire and passed a medical examination including a number of neurosensory tests, e.g. the determination of vibration (VPT) and temperature (TPT) perception thresholds as well as a musculoskeletal examination of the neck, shoulders, arms and hands.

Results

A high prevalence of neurosensory findings (40%) was found among the quarry workers. Both groups, however, showed a low prevalence of vibration white fingers (VWF). Foundry workers showed significantly better sensitivity than quarry workers for all monofilament tests (p ≤ 0.016), TPT warmth in dig 2 (p = 0.048) and 5 dexter (p = 0.008), and in dig 5 sinister (p = 0.005). They also showed a better VPT performance in dig 5 dexter (p = 0.031).

Conclusions

Despite high vibration exposure, the prevalence of VWF was low. The high prevalence of neurosensory findings among the quarry workers may depend on higher A(8) vibration exposure and higher exposure to high-frequency vibrations. An age-effect and exposure to cold could also be contributing factors. The nervous system seems to be more susceptible to high-frequency vibrations than the vascular system. For neurosensory injuries, the current ISO 5349-1 standard is not applicable.

The Influence of Self-Reported Hand-Arm Vibration Exposure on Functional Outcomes Following Carpal Tunnel Release

PURPOSE

This study describes the impact of self-reported hand-arm vibration (HAV) exposure on patient-reported outcomes, health-related quality of life, and satisfaction after carpal tunnel release.

METHODS

We prospectively collected data from Quick-Disabilities of the Arm, Shoulder, and Hand (QuickDASH), patient satisfaction, and 5-level EuroQol-5D questionnaires before and after surgery. Patient-reported outcomes were available for 475 patients (78% follow-up at a mean of 14 months). Fifteen patients were excluded, giving a final cohort of 460 patients.

RESULTS

A total of 119 patients reported HAV exposure (26%). Median postoperative QuickDASH and QuickDASH improvement were significantly worse in the HAV-exposed group, although both groups improved after surgery. Multivariable linear regression revealed a significantly worse postoperative score and change in QuickDASH in HAV-exposed patients. There was no difference in satisfaction, but after surgery, the 5-level EuroQol-5D score was significantly worse in HAV-exposed patients.

CONCLUSIONS

Carpal tunnel release in HAV-exposed patients results in a significantly lower improvement in self-reported disability compared with patients without HAV exposure. This study provides important prognostic information for patients with previous HAV exposure undergoing carpal tunnel release.

TYPE OF STUDY/LEVEL OF EVIDENCE

Prognostic III.

Organische und funktionelle Durchblutungsstörungen der Hand – differenzialdiagnostische Aspekte

Die Abklärung von venösen und arteriellen Durchblutungsstörungen sowie Lymphödemen gehört zur täglichen Praxisroutine des Gefäßmediziners. Nicht selten werden von chirurgischen Kollegen Patienten mit Beschwerden im Schulter-, Arm- und Handbereich zum Ausschluss einer vaskulären Ursache vorgestellt. Der wohl häufigste Abklärungsgrund im Handbereich ist das Raynaud-Phänomen. Neben arteriosklerotischen Durchblutungsstörungen und der Thrombangiitis obliterans sind das Hypothenar-/Thenar-Hammer-Syndrom und das Vibrationssyndrom in den Fingern eher wenig bekannte Entitäten, deren Kenntnis jedoch neben dem medizinischen Vorgehen auch versicherungsrelevante Konsequenzen haben kann. Während beim Hypothenar-/Thenar-Hammer-Syndrom eine organische Durchblutungsstörung vorliegt, beinhaltet das Vibrationssyndrom der Finger eine funktionell vaskuläre sowie eine nervale Komponente, die eine Trennung vom Karpaltunnelsyndrom erschwert. Bei beiden Entitäten ist eine Berufsanamnese häufig hilfreich. Schon der Verdacht auf eine Berufskrankheit muss nach Gesetzeslage zur Anzeige gebracht werden. Der Artikel beschreibt die wesentlichen pathophysiologischen Mechanismen beider Entitäten und stellt diagnostische und therapeutische Optionen dar. Die Kenntnis beider Erkrankungen erweitert die differenzialdiagnostische Vorgehensweise in der täglichen Praxisroutine bei Patienten mit Schulter-Arm-Hand-Beschwerden und bei Patienten mit Raynaud-Phänomen.

Vibration-induced injuries in workers exposed to transient and high frequency vibrations

Background

The risk of developing vibration white fingers and neurosensory symptoms increases with the duration and intensity of the exposure. The aim of this study was to investigate the risk of developing vibration white fingers (VWF), neurosensory symptoms and musculoskeletal disorders among workers exposed to transient and high frequency vibrations.

Methods

The study included 38 vibration exposed workers from a loader assembly plant in Sweden (30 males and 8 females). All participants answered questionnaires and had a structured interview about work and medical history. A following medical examination included the determination of vibration and temperature perception thresholds and musculoskeletal symptoms in the neck, shoulder, elbow and hands. The individual vibration exposure expressed as A (8)-values and vibration exposure in minutes per day, were obtained from questionnaires answered by the participants.

Results

The prevalence of VWF was 30% among the male workers and 50% among the females. The corresponding prevalence of neurosensory symptoms was 70% among the males and 88% among the females. Musculoskeletal findings were common among the male workers. Dominant symptoms/syndromes were tension neck syndrome, biceps tendinitis, carpal tunnel syndrome and ulnar entrapment in hand/wrist. A total of 32 diagnoses were observed among the male workers and four diagnoses among the female workers. Numbness in fingers and age had the strongest impact on perceived work ability.

Conclusions

ISO 5349-1 considerably underestimates the risks of VWF for this group of workers exposed to transient and high frequency vibrations. It is therefore important to develop a risk assessment standard also covering this frequency range.

Riveting hammer vibration damages mechanosensory nerve endings

Hand-arm vibration syndrome (HAVS) is an irreversible neurodegenerative, vasospastic, and musculoskeletal occupational disease of workers who use powered hand tools. The etiology is poorly understood. Neurological symptoms include numbness, tingling, and pain. This study examines impact hammer vibration-induced injury and recoverability of hair mechanosensory innervation. Rat tails were vibrated 12 min/d for 5 weeks followed by 5 week recovery with synchronous non-vibrated controls. Nerve fibers were PGP9.5 immunostained. Lanceolate complex innervation was compared quantitatively in vibrated vs sham. Vibration peak acceleration magnitudes were characterized by frequency power spectral analysis. Average magnitude (2515 m/s² , root mean squared) in kHz frequencies was 109 times that (23 m/s² ) in low Hz. Percentage of hairs innervated by lanceolate complexes was 69.1% in 5-week sham and 53.4% in 5-week vibration generating a denervation difference of 15.7% higher in vibration. Hair innervation was 76.9% in 5-weeks recovery sham and 62.0% in 5-week recovery vibration producing a denervation difference 14.9% higher in recovery vibration. Lanceolate number per complex (18.4 ± 0.2) after vibration remained near sham (19.3 ± 0.3), but 44.9% of lanceolate complexes were abnormal in 5 weeks vibrated compared to 18.8% in sham. The largest vibration energies are peak kHz accelerations (approximately 100 000 m/s² ) from shock waves. The existing ISO 5349-1 standard excludes kHz vibrations, seriously underestimating vibration injury risk. The present study validates the rat tail, impact hammer vibration as a model for investigating irreversible nerve damage. Persistence of higher denervation difference after 5-week recovery suggests repeated vibration injury destroys the capability of lanceolate nerve endings to regenerate.

Hand-arm Vibration Syndrome in Farmers and its Correlation with Degenerative Triangular Fibrocartilage Complex Injury

Context

Hand-arm vibration syndrome (HAVS) is an occupational disease that affects workers who are exposed to vibrations. Farmers are prone to various musculoskeletal and cumulative trauma disorders. These occur owing to overuse, degeneration, and excess physical efforts along with whole-body vibrations- owing to the use of farming equipment such as tractors and harvesters.

Aims

Aims of the study were to find out the prevalence of various symptoms of HAVS among farmers using tractors, harvesters, etc., and to find out the correlation of triangular fibrocartilage complex (TFCC) injury with HAVS.

Subjects and Methods

A prevalence study was conducted among farmers. Farmers were selected by random sampling method and were asked to fill-up a HAVS surveillance questionnaire. The handgrip strength was recorded with a hand dynamometer. Assessment of carpal tunnel syndrome was done, and correlation of HAVS with TFCC injury was assessed.

Results

Data from 100 farmers was obtained and analyzed. The musculoskeletal symptoms of HAVS, more specifically pain was prevalent (n = 65), followed by sensorineural symptoms (n = 70), and the vascular symptoms were less common (n = 43). HAVS accounts for a prevalence of 64% with 39% of farmers having TFCC injury along with HAVS (P value = <0.0001).

Conclusions

These findings reported in the study provide a better understanding of the impact and extent of HAVS in farmers. There is a significant prevalence of HAVS with mild symptoms of vascular component, mild to moderate symptoms of sensorineural component, and significant involvement of the musculoskeletal component. In addition, TFCC injury is correlated with HAVS.

Application of cold intolerance symptom severity questionnaire among vibration-exposed workers as a screening tool for the early detection of hand-arm vibration syndrome: a cross-sectional study

Background

The detection rate of hand-arm vibration syndrome (HAVS) is very low in South Korea compared with other countries. The absence of uniform consensus and guidelines for diagnosing HAVS has been presumed to be one of the reasons. The HAVS has various manifestations including cold intolerance and its severity can be measured using the cold intolerance symptom severity (CISS) questionnaire. This study aimed to determine whether the CISS questionnaire, being used as a screening tool, can aid in the early detection of HAVS.

Methods

A total of 76 male workers with vibration-induced symptoms were enrolled as the final study participants. To compare the CISS score of healthy individuals, 41 men who had never been exposed to local vibration were included in the study. In addition to the former medical questionnaire, the participants answered the CISS questionnaire. A statistical analysis was conducted to identify the association of CISS scores with vibration induced symptom and to determine its cut off value.

Results

The reliability of the CISS questionnaire was proven to be good, with a total Cronbach’s alpha of 0.922. The mean CISS score of the exposed group increased in every vascular stage [stage 0 = 42.6 (18.5); stage 1 = 59.4 (14.1); and over stage 2 = 60.2 (21.6)]. They were significantly higher than that of the non-exposed group. The result was fairly consistent with those in the sensorineural stage. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and area under curve (AUC) of 30 were 88.5, 65.3, 76.1, 82.1 and 0.769, respectively. From the result of logistic regression, the adjusted odds ratio of both components increased by the CISS score grouped by 30s.

Conclusions

The self-reported CISS questionnaire, used to measure the degree of cold intolerance, showed high agreement with the Stockholm classification of HAVS. Hence, we recommend the use of this questionnaire to assess the level of cold intolerance among vibration-exposed workers and detect individuals who are at risk of vibration-induced impairment with a cutoff value of 30.

Trial registration

IRB No. 2018–07–040-001. Registered on 4 September 2018.

Hand-arm vibration syndrome: Workers' experience with functional impairment and disability

STUDY DESIGN

Qualitative and descriptive study.

INTRODUCTION

Hand-arm vibration syndrome (HAVS) is a prevalent disease in Canada. There is little work on the perspectives of HAVS patients.

PURPOSE OF THE STUDY

Explore perceptions of disability and functional compromise in patients with HAVS.

METHODS

Semi-structured telephone interviews were conducted with HAVS patients and analysed using content analysis.

RESULTS

The 11 participants reported numbness, pain, and reduced dexterity, strength, and sensation. Participants noted that HAVS was an inevitable aspect of their work. They indicated frustration with their condition and viewed it as a disability. To overcome impairments risky strategies are often used. Participants reported lack of support to manage symptoms and overcome work disability.

DISCUSSION

HAVS related impairment is disabling. Workers require improved resources and support to address symptom management and safe strategies to minimize work disability.

CONCLUSION

HAVS patients experience functional, social, emotional, and psychological disability.

LEVEL OF EVIDENCE

Not applicable.

Prevalence and occupational impact of arthritis in Saskatchewan farmers

Agricultural workers have physically demanding occupations. In this study of Saskatchewan farmers, the authors examined (1) self-reported prevalence of physician-diagnosed rheumatoid arthritis and osteoarthritis; and (2) the impact of these chronic arthridities on engagement in physical tasks related to farming. This study was conducted through a cross-sectional analysis of baseline data from the Saskatchewan Farm Injury Cohort Study in which 2,473 adult residents upon 1,216 farms participated. Collected survey data included demographic and health information; regional musculoskeletal symptoms for each participant assessed via the Standard Nordic Questionnaire; and engagement in various specific physical tasks or activities associated with mixed farming practices. Of the 2,473 respondents, 13% reported chronic arthritic diagnoses (10% osteoarthritis, 4% rheumatoid arthritis, with 1% from each category overlapping with both forms of arthritis). Participants reporting arthritis were more likely to also report disabling musculoskeletal symptoms involving their shoulders, elbows, hands, lower back, hips, knees, and ankles. Farmers with arthritis reported less participation in all physical farming activities studied, including various machinery operations, herd maintenance and veterinary activities, overhead work, shoveling/pitchfork work, and lifting/carrying. When adjusted for age, gender, and comorbidities, operation of combines and shoveling/pitchfork work continued to be significantly less engaged in by farmers with arthritis. The overall prevalence of arthritis was consistent with general population prevalence, although the category of rheumatoid arthritis was overrepresented. Farmers with arthritis were significantly less likely to participate in combine operation and shoveling/pitchfork chores compared with their counterparts without arthritis.

Nailfold capillary morphological characteristics of hand-arm vibration syndrome: a cross-sectional study

OBJECTIVE

The purpose of this study was to investigate the characteristics of nailfold capillaroscopy associated with hand-arm vibration syndrome (HAVS).

METHODS

In total, 113 male gold miners were recruited: 35 workers who were chronically exposed to vibration and developed vibration-induced white finger were defined as the HAVS group, 39 workers who were exposed to vibration but did not have HAVS were classified as the vibration-exposed controls (VEC) group, and 39 workers without vibration exposure were categorised as the non-VEC (NVEC) group. Video capillaroscopy was used to capture images of the 2nd, 3rd and 4th fingers of both hands. The following nailfold capillary characteristics were included: number of capillaries/mm, avascular areas, haemorrhages and enlarged capillaries. The experiments were carried out in the same winter. All characteristics were evaluated under blinded conditions.

RESULTS

Significant differences in all morphological characteristics existed between the groups (p<0.05). Avascular areas in the HAVS, VEC and NVEC groups appeared in 74.3%, 43.6% and 25.0% of participants, respectively. A higher percentage of participants had haemorrhages in the HAVS group (65.7%) compared with the other groups (VEC: 7.7% and NVEC: 7.5%). The number of capillaries/mm, input limb width, output limb width, apical width, and ratio of output limb and input limb all had more than 70% sensitivity or specificity of their cut-off value.

CONCLUSIONS

Nailfold capillary characteristics, especially the number of capillaries/mm, avascular areas, haemorrhages, output limb width, input limb width and apical width alterations, revealed significant associations with HAVS.

Tremor and hand-arm vibration syndrome (HAVS) in road maintenance workers

Objectives

The aim of this study was to evaluate postural and rest tremor among workers using vibrating hand tools, taking into account the possible effects of toxicants such as alcohol and tobacco. A further aim was to study workers diagnosed with hand-arm vibration syndrome (HAVS) at the time of examination.

Methods

This study comprises 103 road maintenance workers, 55 exposed to vibrating hand tools (age 41.0 years; range 21–62) and 48 referents (age 38.5 years; range 19–64). They were examined with the CATSYS Tremor Pen^®. Exposure to vibrating tools and serum biomarkers of alcohol and tobacco consumption were measured.

Results

Cumulative exposure to vibrating tools was associated with increased postural (p < 0.01) and rest tremor (p < 0.05) and with a higher Center Frequency of postural tremor (p < 0.01) among smokers and users of smokeless tobacco. Rest tremor Center Frequency was higher than postural tremor frequency (p < 0.001).

Conclusions

The main findings indicate an association between cumulative exposure to hand-held vibrating tools, tremor parameters and consumption of tobacco products. The hand position is important when testing for tremor. Rest tremor had a higher Center Frequency. Postural tremor was more strongly associated with exposure than rest tremor. The finding of increased tremor among the HAVS subjects indicated that tremor might be a part of the clinical picture of a HAVS diagnosis. As with all cross-sectional studies, inferences should be made with caution when drawing conclusions about associations between exposure and possible effects. Future research using longitudinal design is required to validate the findings of the present study.

Neuromagnetic correlates of adaptive plasticity across the hand-face border in human primary somatosensory cortex

It is well established that permanent or transient reduction of somatosensory inputs, following hand deafferentation or anesthesia, induces plastic changes across the hand-face border, supposedly responsible for some altered perceptual phenomena such as tactile sensations being referred from the face to the phantom hand. It is also known that transient increase of hand somatosensory inputs, via repetitive somatosensory stimulation (RSS) at a fingertip, induces local somatosensory discriminative improvement accompanied by cortical representational changes in the primary somatosensory cortex (SI). We recently demonstrated that RSS at the tip of the right index finger induces similar training-independent perceptual learning across the hand-face border, improving somatosensory perception at the lips (Muret D, Dinse HR, Macchione S, Urquizar C, Farnè A, Reilly KT.Curr Biol24: R736-R737, 2014). Whether neural plastic changes across the hand-face border accompany such remote and adaptive perceptual plasticity remains unknown. Here we used magnetoencephalography to investigate the electrophysiological correlates underlying RSS-induced behavioral changes across the hand-face border. The results highlight significant changes in dipole location after RSS both for the stimulated finger and for the lips. These findings reveal plastic changes that cross the hand-face border after an increase, instead of a decrease, in somatosensory inputs.

Upper Extremity Injuries in NASCAR Drivers and Pit Crew

Background:

Understanding the position-specific musculoskeletal forces placed on the body of athletes facilitates treatment, prevention, and return-to-play decisions. While position-specific injuries are well documented in most major sports, little is known about the epidemiology of position-specific injuries in National Association for Stock Car Automobile Racing (NASCAR) drivers and pit crew.

Purpose:

To investigate position-specific upper extremity injuries in NASCAR drivers and pit crew members.

Study Design:

Descriptive epidemiological study.

Methods:

A retrospective chart review was performed to assess position-specific injuries in NASCAR drivers and pit crew members. Included in the study were patients seen by a single institution between July 2003 and October 2014 with upper extremity injuries from race-related NASCAR events or practices. Charts were reviewed to identify the diagnosis, mechanism of injury, and position of each patient.

Results:

A total of 226 NASCAR team members were treated between July 2003 and October 2014. Of these, 118 injuries (52%) occurred during NASCAR racing events or practices. The majority of these injuries occurred in NASCAR changers (42%), followed by injuries in drivers (16%), carriers (14%), jack men (11%), fuel men (9%), and utility men (8%). The majority of the pit crew positions are at risk for epicondylitis, while drivers are most likely to experience neuropathies, such as hand-arm vibration syndrome. The changer sustains the most hand-related injuries (42%) on the pit crew team, while carriers commonly sustain injuries to their digits (29%).

Conclusion:

Orthopaedic injuries in NASCAR vary between positions. Injuries in NASCAR drivers and pit crew members are a consequence of the distinctive forces associated with each position throughout the course of the racing season. Understanding these forces and position-associated injuries is important for preventive measures and facilitates diagnosis and return-to-play decisions so that each team can function at its maximal efficiency.

Effect of higher frequency components and duration of vibration on bone tissue alterations in the rat-tail model

To formulate more accurate guidelines for musculoskeletal disorders (MSD) linked to Hand-Arm Vibration Syndrome (HAVS), delineation of the response of bone tissue under different frequencies and duration of vibration needs elucidation. Rat-tails were vibrated at 125 Hz (9 rats) and 250 Hz (9 rats), at 49 m/s(2), for 1D (6 rats), 5D (6 rats) and 20D (6 rats); D=days (4 h/d). Rats in the control group (6 rats for the vibration groups; 2 each for 1D, 5D, and 20D) were left in their cages, without being subjected to any vibration. Structural and biochemical damages were quantified using empty lacunae count and nitrotyrosine signal-intensity, respectively. One-way repeated-measure mixed-model ANOVA at p<0.05 level of significance was used for analysis. In the cortical bone, structural damage quantified through empty lacunae count was significant (p<0.05) at 250 Hz (10.82 ± 0.66) in comparison to the control group (7.41 ± 0.76). The biochemical damage was significant (p<0.05) at both the 125 Hz and 250 Hz vibration frequencies. The structural damage was significant (p<0.05) at 5D for cortical bone while the trabecular bone showed significant (p<0.05) damage at 20D time point. Further, the biochemical damage increased with increase in the duration of vibration with a significant (p<0.05) damage observed at 20D time point and a near significant change (p=0.08) observed at 5D time point. Structural and biochemical changes in bone tissue are dependent upon higher vibration frequencies of 125 Hz, 250 Hz and the duration of vibration (5D, 20D).

Health-care barriers for workers with HAVS in Ontario, Canada

BACKGROUND

Hand-arm vibration syndrome (HAVS) becomes irreversible unless it is identified early and progression prevented.

AIMS

To describe the health-care-seeking behaviours of workers with HAVS and barriers to health care.

METHODS

We invited all patients assessed for HAVS between 15 January and 27 March 2013 at a hospital-based occupational health clinic (OHC) in Ontario, Canada, to complete a questionnaire asking why and from whom they sought health care, reasons they waited to seek care and barriers they encountered in accessing care. We analysed the data using descriptive statistics.

RESULTS

Forty-one (82%) patients agreed to participate. Thirty-seven had confirmed HAVS; 30 (84%) were Stockholm workshop vascular stage 2 or greater and 35 (97%) were sensorineural stage 1 or greater. The commonest employment sectors were construction [21 (57%)] and mining [6 (17%)]. The main reasons for seeking treatment were pain [11 (30%)], finger numbness [8 (22%)] and functional limitations [5 (14%)]. The commonest initial point of health care was the family physician [23 (66%)]. The mean wait between symptom onset and seeking treatment was 3.4 years, while the mean time between onset and OHC assessment was 9 years. Reasons for delay in seeking care were ignorance of the seriousness and irreversibility of HAVS and ability to continue to work. Family physicians suspected HAVS in 17% of cases and recommended job modification in 34%.

CONCLUSIONS

Workers with HAVS in Ontario delay seeking health care. Primary care physicians often fail to recognize HAVS. Barriers to health care include ignorance of HAVS and of the importance of prevention.

Test-retest reliability of neurophysiological tests of hand-arm vibration syndrome in vibration exposed workers and unexposed referents

Background

Exposure to hand-held vibrating tools may cause the hand-arm vibration syndrome (HAVS). The aim was to study the test-retest reliability of hand and muscle strength tests, and tests for the determination of thermal and vibration perception thresholds, which are used when investigating signs of neuropathy in vibration exposed workers.

Methods

In this study, 47 vibration exposed workers who had been investigated at the department of Occupational and Environmental Medicine in Gothenburg were compared with a randomized sample of 18 unexposed subjects from the general population of the city of Gothenburg. All participants passed a structured interview, answered several questionnaires and had a physical examination including hand and finger muscle strength tests, determination of vibrotactile (VPT) and thermal perception thresholds (TPT). Two weeks later, 23 workers and referents, selected in a randomized manner, were called back for the same test-procedures for the evaluation of test-retest reliability.

Results

The test-retest reliability after a two week interval expressed as limits of agreement (LOA; Bland-Altman), intra-class correlation coefficients (ICC) and Pearson correlation coefficients was excellent for tests with the Baseline hand grip, Pinch-grip and 3-Chuck grip among the exposed workers and referents (N = 23: percentage of differences within LOA 91 – 100%; ICC-values ≥0.93; Pearson r ≥0.93). The test-retest reliability was also excellent (percentage of differences within LOA 96–100 %) for the determination of vibration perception thresholds in digits 2 and 5 bilaterally as well as for temperature perception thresholds in digits 2 and 5, bilaterally (percentage of differences within LOA 91 – 96%). For ICC and Pearson r the results for vibration perception thresholds were good for digit 2, left hand and for digit 5, bilaterally (ICC ≥ 0.84; r ≥0.85), and lower (ICC = 0.59; r = 0.59) for digit 2, right hand. For the latter two indices the test-retest reliability for the determination of temperature thresholds was lower and showed more varying results.

Conclusion

The strong test-retest reliability for hand and muscle strength tests as well as for the determination of VPTs makes these procedures useful for diagnostic purposes and follow-up studies in vibration exposed workers.

Quantitatively measured tremor in hand-arm vibration-exposed workers

Objectives

The aim of the present study was to investigate the possible increase in hand tremor in relation to hand-arm vibration (HAV) exposure in a cohort of exposed and unexposed workers.

Methods

Participants were 178 male workers with or without exposure to HAV. The study is cross-sectional regarding the outcome of tremor and has a longitudinal design with respect to exposure. The dose of HAV exposure was collected via questionnaires and measurements at several follow-ups. The CATSYS Tremor Pen^® was used for measuring postural tremor. Multiple linear regression methods were used to analyze associations between different tremor variables and HAV exposure, along with predictor variables with biological relevance.

Results

There were no statistically significant associations between the different tremor variables and cumulative HAV or current exposure. Age was a statistically significant predictor of variation in tremor outcomes for three of the four tremor variables, whereas nicotine use was a statistically significant predictor of either left or right hand or both hands for all four tremor variables.

Conclusions

In the present study, there was no evidence of an exposure–response association between HAV exposure and measured postural tremor. Increase in age and nicotine use appeared to be the strongest predictors of tremor.

Potential regenerative rehabilitation technology: implications of mechanical stimuli to tissue health

BACKGROUND

Mechanical loads induced through muscle contraction, vibration, or compressive forces are thought to modulate tissue plasticity. With the emergence of regenerative medicine, there is a need to understand the optimal mechanical environment (vibration, load, or muscle force) that promotes cellular health. To our knowledge no mechanical system has been proposed to deliver these isolated mechanical stimuli in human tissue. We present the design, performance, and utilization of a new technology that may be used to study localized mechanical stimuli on human tissues. A servo-controlled vibration and limb loading system were developed and integrated into a single instrument to deliver vibration, compression, or muscle contractile loads to a single limb (tibia) in humans. The accuracy, repeatability, transmissibility, and safety of the mechanical delivery system were evaluated on eight individuals with spinal cord injury (SCI).

FINDINGS

The limb loading system was linear, repeatable, and accurate to less than 5, 1, and 1 percent of full scale, respectively, and transmissibility was excellent. The between session tests on individuals with spinal cord injury (SCI) showed high intra-class correlations (>0.9).

CONCLUSIONS

All tests supported that therapeutic loads can be delivered to a lower limb (tibia) in a safe, accurate, and measureable manner. Future collaborations between engineers and cellular physiologists will be important as research programs strive to determine the optimal mechanical environment for developing cells and tissues in humans.

Low myelinated nerve-fibre density may lead to symptoms associated with nerve entrapment in vibration-induced neuropathy

Prolonged exposure to hand-held vibrating tools may cause a hand-arm vibration syndrome (HAVS), sometimes with individual susceptibility. The neurological symptoms seen in HAVS are similar to symptoms seen in patients with carpal tunnel syndrome (CTS) and there is a strong relationship between CTS and the use of vibrating tools. Vibration exposure to the hand is known to induce demyelination of nerve fibres and to reduce the density of myelinated nerve fibres in the nerve trunks. In view of current knowledge regarding the clinical effects of low nerve-fibre density in patients with neuropathies of varying aetiologies, such as diabetes, and that such a low density may lead to nerve entrapment symptoms, a reduction in myelinated nerve fibres may be a key factor behind the symptoms also seen in patients with HAVS and CTS. Furthermore, a reduced nerve-fibre density may result in a changed afferent signal pattern, resulting in turn in alterations in the brain, further prompting the symptoms seen in patients with HAVS and CTS. We conclude that a low nerve-fibre density lead to symptoms associated with nerve entrapment, such as CTS, in some patients with HAVS.

Upper limb disability in Norwegian workers with hand-arm vibration syndrome

Background

Hand-arm vibration syndrome (HAVS) is a well-known disease among workers using hand-held vibrating tools. These patients experience major symptoms from their upper limbs. However, there are few studies on disability in this patient group. In this study we wanted to describe the disability of HAVS patients.

Methods

All HAVS patients diagnosed at Haukeland University Hospital in Bergen, Norway in a five-year period were invited. The disabilities of the arm, shoulder and hand (DASH) questionnaire was sent by mail. Clinical data were extracted from their hospital journals. Descriptive statistics and regression analyses were performed.

Results

Thirty-eight patients were recruited. Mean DASH score was 41.2, while the mean of a normal population is 10. Ability to perform tasks related to work and everyday life was affected in these patients. We found a significant association between the DASH score, hand grip strength and tendinitis, also after adjustment for age and smoking in pack-years.

Conclusion

HAVS patients demonstrate a high level of upper limb disability as assessed by the DASH score. Ability to perform tasks related to work and everyday life was affected. We found a significant association between the DASH score, hand grip strength and tendinitis. This should be focused upon in future research.

Dependence of vascular damage on higher frequency components in the rat-tail model

Hand-Arm Vibration Syndrome (HAVS) is caused by hand-transmitted vibration in industrial workers. Current ISO guidelines (ISO 5349) might underestimate vascular injury associated with range of vibration frequencies near resonance. A rat-tail model was used to investigate the effects of higher frequencies >100 Hz on early vascular damage. 13 Male Sprague-Dawley rats (250 ± 15 gm) were used. Rat-tails were vibrated at 125 Hz and 250 Hz (49 m/s(2)) for 1D, 5D and 10D; D=days (4 h/day). Structural damage of the ventral artery was quantified by vacuole count using Toluidine blue staining whereas biochemical changes were assessed by nitrotyrosine (NT) staining. The results were analyzed using one-way repeated measures mixed-model ANOVA at p<0.05 level of significance. The structural damage increased at 125 Hz causing significant number of vacuoles (40.62 ± 9.8) compared to control group (8.36 ± 2.49) and reduced at 250 Hz (12.33 ± 2.98) compared to control group (8.36 ± 2.49). However, the biochemical alterations (NT-signal) increased significantly for 125 Hz (143.35 ± 5.8 gray scale value, GSV) and for 250 Hz (155.8 ± 7.35 GSV) compared to the control group (101.7 ± 4.18 GSV). Our results demonstrate that vascular damage in the form of structural and bio chemical disruption is significant at 125 Hz and 250 Hz. Hence the current ISO guidelines might underestimate vascular damage at frequencies>100 Hz.