Forestry workers exposed to vibration: a neurological study

Neurological findings were examined in 186 forestry workers with a mean exposure to chain saw vibration of 16.6 hours. The prevalence of active vibration induced white fingers was 5%, parethaesias of the hands 53%, and muscle weakness 13%. Clinical polyneuropathy was observed in 16 forestry workers in the hands (7.5%) which did not correlate with alcohol consumption. Seventy nine forestry workers of the total population were selected for electromyographic examination. Generalised EMG based polyneuropathy in the hands was observed in only two of the 79 forestry workers (2.5%). The carpal tunnel syndrome was found in 20 of the 79 forestry workers (26%). Headache and vertigo were not linked with exposure to vibration in forestry and a significant part of the numbness reported may be due to the carpal tunnel syndrome. Sensorimotor polyneuropathy is rare among forestry workers. The rise in the vibration detection thresholds was linked to the carpal tunnel syndrome.     

Forestry workers exposed to vibration: a neurological study.

Neurological findings were examined in 186 forestry workers with a mean exposure to chain saw vibration of 16.6 hours. The prevalence of active vibration induced white fingers was 5%, parethaesias of the hands 53%, and muscle weakness 13%. Clinical polyneuropathy was observed in 16 forestry workers in the hands (7.5%) which did not correlate with alcohol consumption. Seventy nine forestry workers of the total population were selected for electromyographic examination. Generalised EMG based polyneuropathy in the hands was observed in only two of the 79 forestry workers (2.5%). The carpal tunnel syndrome was found in 20 of the 79 forestry workers (26%). Headache and vertigo were not linked with exposure to vibration in forestry and a significant part of the numbness reported may be due to the carpal tunnel syndrome. Sensorimotor polyneuropathy is rare among forestry workers. The rise in the vibration detection thresholds was linked to the carpal tunnel syndrome.     

Work-related musculoskeletal symptoms among sheet metal workers

We report results of two pilot studies of the relationship between musculoskeletal disorders and work tasks in sheet metal workers. These two studies were undertaken as pilot investigations to determine if symptoms of carpal tunnel syndrome or other work-related musculoskeletal symptoms are present in sheet metal workers, and to determine if we could begin to identify the factors in sheet metal work that cause them. In the first study, telephone interviews were conducted with 18 disabled sheet metal workers; the second survey entailed self-administered questionnaires completed by 47 active and retired sheet metal workers. Among the disabled workers, rotator cuff cases reported the greatest percent of time spent hanging duct, an overhead task commonly carried out during field work. Carpal tunnel cases reported more hand tool use than the rotator cuff cases. The questionnaire survey of active and retired workers found the proportion of time spent in a sheet metal shop (contrasted with field work) to be positively associated with hand symptoms; sheet metal workers who spent at least 65% of their time in the shop had an odds ratio of 3.4 for symptomatic hand cumulative trauma disorder (CTD) (p = 0.12). The proportion of time spent hanging duct was positively associated with both neck and shoulder symptoms, with odds ratios of 7.9 (p = 0.08) and 2.7 (p = 0.16), respectively. The results show that symptoms of neck, arm, and hand pain are common in sheet metal workers who are actively working, that carpal tunnel syndrome or hand pain is positively associated with more time spent working in the shop, and that shoulder pain or shoulder injuries is associated with work overhead (hanging duct). Ergonomic risks and cumulative trauma disorders have not been well characterized in the construction industry; these data strongly suggest that a subset of work tasks in construction increase the risk of cumulative trauma disorders.     

Risk assessment of vibration exposure and white fingers among platers

Summary The dose-response relationship between vibration exposure and vascular disorders in the hands was examined in platers. The study was based on a cross section of 89 platers and 61 office workers divided according to exposure to vibration into four groups. Vibration exposure was assessed by measuring the acceleration intensity on a sample of tools, together with both subjective rating and objective measurements of the exposure time. The frequency-weighted energy equivalent acceleration for 4 h was 4.6–4.7 m/s². The point prevalence of white fingers was 42% for the plater category currently exposed with an odds ratio of 85. The time laps before contraction of white fingers (latency time) was four years for the 10th percentile, and was shorter than predicted according to the ISO-5349 standard. The prevalence of white finger symptoms staged according to the Taylor-Pelmear scale was comparable to the prevalences according to the Stockholm Workshop Scale. Vibration exposure was the dominant source of white fingers and each year of vibration exposure increased the odds ratio for white fingers by 11%. Distal circulation in the hands was assessed by a timed Allen test. The odds ratio for a positive Allen test was higher for the workers exposed to vibration compared to the non-exposed workers. The use of the timed Allen test is suggested in the clinical examination for vibration white fingers. The observed high risk for contracting white fingers could be prevented by exposure level reduction and/or restriction of exposure duration.     

Hand-arm vibration syndrome and upper limb disorders associated with forestry work

BACKGROUND: Occupational exposure to hand-transmitted vibration in forestry workers is associated with an increased risk for vascular, neurological and musculo-skeletal disorders of the upper limbs. OBJECTIVES: To carry out a cross-sectional study of the hand-arm vibration syndrome and soft-tissue disorders of the upper limb in a group of forestry workers employed in the Forestry Service of the Province of Trento (Italy). In the forestry worker group, usage of anti-vibration chain-saws was intermittent over a typical work year (16 weeks/yr, on average). METHODS: To investigate vascular, neurological and musculo-skeletal disorders of the upper limbs, the forestry workers (n=159) and a control group of manual workers, unexposed to hand-transmitted vibration, employed in the same Forestry Service (n=146) underwent a structured medical interview and a complete physical examination. The clinical diagnoses of vibration-induced white finger (VWF) and carpal tunnel syndrome were made according to internationally recognised consensus criteria. Occupational exposure to hand-transmitted vibration was assessed according to the recommendations of the International Standard ISO 5349-1 (2001). RESULTS: The forestry workers showed an increased prevalence of peripheral sensory-neural disturbances (33.3%), musculo-skeletal disorders of the upper limbs (37.7%), and carpal tunnel syndrome (21.4%) compared to those observed in the control group. There was no significant difference in the prevalence ofRaynaud' sphenomenon between the forestry workers (6.3%) and the controls (4.1%). After adjustment for confounding factors (age, body mass index, tobacco and alcohol consumption), a significant association was observed between peripheral neuropathies (peripheral sensory-neural disorders, carpal tunnel syndrome) and several indices of vibration exposure such as 8-hr energy-equivalent frequency-weighted acceleration [A(8) in m/s2 r.m.s.], duration of exposure (years), and lifetime vibration dose (m2/s4 hr). An excess, although not significant, risk for VWF was observed only in the forestry workers with A(8) > or = 4 m/s2 r.m.s.. In the forestry workers, there was no significant association between VWF and sensory-neural disorders, and between VWF and carpal tunnel syndrome. This finding seems to support the hypothesis that the vascular and neurological components of the hand-arm vibration syndrome develop independently of each other. Within the forestry worker group, the variable "years of tool usage" showed the strongest association with peripheral sensory-neural symptoms, carpal tunnel syndrome, and soft-tissue disorders of the upper limbs. It is likely that in the forestry workers the variable "years of tool usage" represents an overall index of duration of exposure to several adverse ergonomic and mechanical risk factors. CONCLUSIONS: The results of this study suggest a tendency for a decrease in the occurrence of VWF among forestry workers, and this finding seems to be associated with the use of anti-vibration chain saws, the reduction of exposure duration, and the improvement of work organization. On the other hand, the forestry workers showed an increase in the occurrence of peripheral sensory neuropathies, carpal tunnel syndrome, and upper-extremity musculo-skeletal disorders. This finding seems to support the view that there is epidemiological evidence for a positive association between exposure to a combination of risk factors (segmental vibration, forcefulness, awkward posture) and the occurrence of soft-tissue disorders of the upper limb in working populations.     

Hand-arm symptoms related to impact and nonimpact hand-held power tools

 Hand and arm symptoms among workers using impact and non-impact hand-held power tools were investigated in a cross-sectional study and a 5-year follow-up study. The study population consisted of concrete workers (n=103), truck assemblers (n=234), electricians (n=101), platers (n=140) and lumberjacks (n=102). Of the original 680 subjects, we followed up 312 after 5 years. A questionnaire concerning ongoing hand and arm symptoms, daily exposure to hand-held power tools, type of tool used, and individual factors was administered. More workers using low-frequency impact tools than workers using non-impact tools reported symptoms in the elbows and shoulders. Elbow symptoms were accentuated in the cross-sectional study, while shoulder symptoms were accentuated in the follow-up study. Wrist symptoms were reported by more of those working with high-frequency impact tools than of those using only non-impact tools when the analyses were controlled for age, years in the occupation and smoking habits. A possible explanation of the results found in this study is that low-frequency impact vibration is transmitted to the upper arm, and thus the elbow and shoulder are at risk, while high-frequency impact vibration is attenuated in the hand and wrist and may predominantly cause symptoms there. Received: 7 June 1995 / Accepted: 2 May 1996     

Carpal tunnel syndrome among ski manufacturing workers

Carpal tunnel syndrome is a common disorder marked by pain and dysesthesias of the upper extremities. As a test of the hypothesis that carpal tunnel syndrome is associated with occupational risk factors, jobs at a ski assembly plant were classified as repetitive and nonrepetitive. The prevalence of carpal tunnel syndrome among 106 employees with repetitive jobs was compared with that among 67 employees with nonrepetitive jobs. The data collection included a questionnaire, a physical examination, and the measurement of distal sensory latencies of the median and ulnar nerves. Carpal tunnel syndrome was present in either or both hands in 15.4% of those workers with repetitive jobs, but only in 3.1% of those workers with nonrepetitive jobs (crude prevalence ratio 4.92, 95% confidence interval 1.17-20.7). The conclusion was drawn that carpal tunnel syndrome is associated with jobs requiring frequent and sustained hand work.     

Carpal tunnel syndrome among apprentice construction workers

BACKGROUND: In terms of lost-work time and restricted workdays, surgery, and rehabilitation, one of the most costly occupational musculoskeletal disorders is carpal tunnel syndrome (CTS). The purpose of this study was to determine the prevalence of CTS among apprentice construction workers. METHODS: This cross-sectional study included apprentices from four construction trades. Apprentices completed a self-administered questionnaire and received electrophysiologic studies assessing median nerve function across the carpal tunnel. A surveillance case definition for CTS was based on characteristic hand symptoms and the presence of median mononeuropathy across the carpal tunnel. RESULTS: Of the 1,325 eligible apprentices, 1,142 (86.2%) participated in the study. The prevalence of CTS among apprentices was 8.2%; sheet metal workers had the highest rate (9.2%). In operating engineers, the prevalence of CTS was significantly higher (OR = 6.9; 95% CI = 2.6-18.2) among the heavy equipment mechanics than the drivers of those vehicles. Body mass index, age, and self-reports of working overhead were associated with prevalent CTS. Less than 15% of the apprentices with CTS sought medical attention for their disorder. CONCLUSIONS: Many construction workers begin developing CTS before or during their apprenticeship. Few apprentices seek medical attention for hand symptoms characteristic of CTS. The results of this study indicate a public health need for the implementation of prevention strategies for CTS in the construction industry.     

Impact of occupations and job tasks on the prevalence of carpal tunnel syndrome.

In this investigation reported epidemiologic studies on carpal tunnel syndrome (CTS) (15 cross-sectional studies involving 32 occupational or exposure groups and six case-referent studies) were reviewed. The prevalence of CTS in the different occupational groups varied between 0.6 and 61%. The highest prevalence was noted for grinders, butchers, grocery store workers, frozen food factory workers, platers, and workers with high-force, high-repetitive manual movements. Odds ratios greater than 10 were reported for exposed groups in three studies. On the basis of epidemiologic and other evidence, it was concluded that exposure to physical work load factors, such as repetitive and forceful gripping, is probably a major risk factor for CTS in several types of worker populations. At least 50%, and as much as 90%, of all of the CTS cases in these exposed populations appeared to be attributable to physical work load.     

正中神经双卡综合征的围手术期康复治疗

目的介绍三级序贯式康复治疗在正中神经双卡综合征围手术期的应用。方法自2005年2月到2009年2月,应用以理疗、手法治疗,注射及小针刀微创治疗,开放手术为阶梯的三级序贯式康复治疗方案,对42例正中神经双卡综合征患者进行围手术期康复治疗。结果42例正中神经双卡综合征的患者中,10例经颈部理疗、手法椎孔外颈神经松解完全治愈。有18例经颈部理疗、手法治疗未完全好转,再行腕管糖皮质激素注射,10例治愈,其余8例行腕管小针刀微创切开治愈。8例先行腕管糖皮质激素注射未完全治愈,再经颈部非手术松解3周治愈。6例腕管综合征,手术切开减压,术后12周手麻未完全缓解,改颈部康复治疗后4周痊愈。结论正中神经双卡综合征首选非手术治疗,当非手术治疗失败或症状比较严重时应及时手术治疗。过于积极的手术减压不一定能达到预期的疗效,应用围手术期三级序贯式康复治疗方案,可以使早期患者免于手术,晚期患者免于两次手术,减少医疗风险。     

Vibration-induced white finger syndrome and carpal tunnel syndrome among Finnish metal workers

Objective  Officially 10–26 cases of vibration-induced white fingers (VWF) have been reported annually in Finland. It has been suggested that the numbers are underestimated. The purpose of the present study was to estimate the cumulative exposure to hand–arm vibration (HAV) and the prevalence of clinically diagnosed cases of VWF and carpal tunnel syndrome (CTS) in a population of Finnish metal workers and to determine the symptoms and clinical tests that would best predict the diagnosis. Methods  A questionnaire on vibration exposure at the workplace and symptoms of the upper extremities was sent to a sample (n = 530) of members of the local Metalworkers Union. Those who reported finger blanching, numbness or tingling of the fingers or symptoms of CTS were invited to take part in clinical examinations. Their cumulative lifelong exposure to HAV was evaluated. Those whose symptoms referred to VWF or CTS were given a cold provocation test with the measurement of finger systolic blood pressure and electroneuromyography of the upper arms. Results  Altogether 285 metal workers (54%) responded to the questionnaire, and 24 new cases of VWF (8.4%) and 12 cases of CTS (4.2%) were diagnosed. In the group of VWF patients, seven workers had both VWF and CTS. All of the workers diagnosed as having VWF also had numbness or tingling in their fingers. Consequently, questions concerning numbness and tingling, a two-point discrimination test, Phalen’s test, and Tinell’s test had a high predicting value for VWF. The exposure time of the VWF cases did not differ significantly from that of the study group as whole, but the cumulative exposure index was significantly higher. Conclusion  The results suggest that VWF is underdiagnosed in Finland. In screening for the health effects of HAV, sensorineural symptoms of hands should be carefully inquired about and examined in patients complaining of white fingers. More education on the recognition and evaluation of HAV exposure and its health effects is needed.     

Workplace ergonomic factors and the development of musculoskeletal disorders of the neck and upper limbs: a meta-analysis.

In the past 10 years there has been growing awareness among occupational health professionals worldwide of the large burden of illness associated with musculoskeletal disorders of the neck and upper limbs. It has been suggested that these disorders are associated with highly repetitive work and are due, at least in part, to ergonomic factors. This review examines the epidemiologic evidence of the relationship between workplace ergonomic factors such as repetition, force, static muscle loading, and extreme joint position and the development of muscle, tendon, and nerve entrapment disorders of the neck and upper limbs of exposed workers. An extensive search for relevant studies was undertaken. Of 54 potentially relevant studies identified, three met the a priori inclusion criteria. The validity of these studies was assessed, and one study was found to have major flaws. Criteria to demonstrate causality were also applied and were met in the most rigorously conducted study. When the results of these studies are compared and aggregated where appropriate, they provide strong evidence of a causal relationship between repetitive, forceful work and the development of musculoskeletal disorders of the tendons and tendon sheaths in the hands and wrists and nerve entrapment of the median nerve at the carpal tunnel. The comparison of exposed to controls for hand/wrist tendinitis gives an unadjusted common odds ratio of 9.1 (95% CI 4.9-16.2). The adjusted odds ratio for carpal tunnel syndrome is 15.5 (95% CI 1.7-141.5) based on the most rigorous study.     

Prevalence and Work-Relatedness of Self-Reported Carpal Tunnel Syndrome Among U.S. Workers: Analysis of the Occupational Health Supplement Data of 1988 National Health Interview Survey

To estimate the prevalence and work-relatedness of self-reported carpal tunnel syndrome (CTS) among U.S. workers, data from the Occupational Health Supplement of 1988 National Health Interview Survey (NHIS) were analyzed. Among 127 million “recent workers” who worked during the 12 months prior to the survey, 1.47% (95% CI: 1.30; 1.65), or 1.87 million self-reported CTS, and 0.53% (95% CI: 0.42; 0.65), or 675,000, stated that their prolonged hand discomfort was called CTS by a medical person. Occupations with the highest prevalence of self-reported CTS were mail service, health care, construction, and assembly and fabrication. Industries with the highest prevalence were food products, repair services, transportation, and construction. The risk factor most strongly associated with medically called CTS was exposure to repetitive bending/ twisting of the hands/wrists at work (OR = 5.2), followed by race (OR = 4.2; whites higher than nonwhites), gender (OR = 2.2; females higher than males), use of vibrating hand tools (OR = 1.8), and age (OR = 1.03; risk increasing per year). This result is consistent with previous reports in that repeated bending/twisting of the hands and wrists during manual work is etiologically related to occupational carpal tunnel syndrome.     

内镜下和双小切口手术方法治疗腕管综合征的疗效分析

目的：探讨内镜下腕管松解术和双小切口腕管松解术治疗腕管综合征的临床疗效和安全性差异。方法：将70例腕管综合征患者随机分为内镜下腕管松解术组（A组,35例）和双小切口腕管松解术组（B组,35例）,随访24个月,采用Kelly分级评定法评价比较两种手术的术后临床疗效和安全性差异。结果：A组优良率为91.4%,B组优良率为88.6%,两组的优良率比较差异无统计学意义（x2=0.328,P＞0.05）;A组的住院时间及术后恢复工作时间显著优于B组,差异有统计学意义（t=3.859,t=2.293;P＜0.05）。结论：双小切口腕管松解术及内镜下腕管松解术治疗腕管综合征均为有效的手术治疗方法,但内镜下腕管松解术的住院时间短、术后恢复更快。     

Agreement between symptom surveys, physical examination procedures and electrodiagnostic findings for the carpal tunnel syndrome.

OBJECTIVES: The goal of this study was to evaluate the concordance between various clinical screening procedures for carpal tunnel syndrome. METHODS: The subject population consisted of 824 workers from 6 facilities. The evaluated procedures included bilateral sensory nerve conduction testing, physical examinations, and symptom surveys, including hand diagrams. The agreement between the outcomes of various combinations of these procedures was assessed by determining the kappa coefficient. RESULTS: There was relatively poor overlap between the reported symptoms, the physical examination findings, and the electrodiagnostic results consistent with carpal tunnel syndrome. Overall, only 23 out of 449 subjects (5%) with at least 1 positive finding met all 3 criteria (symptoms, physical examination findings, and electrophysiological results consistent with carpal tunnel syndrome) for the dominant hand. The screening procedures showed poor or no agreement with kappa values ranging between 0.00 and 0.18 for all the case definitions evaluated for carpal tunnel syndrome. CONCLUSIONS: The poor overlap between the various screening procedures warns against the use of electrodiagnostic findings alone without the symptom presentation being considered. The results of this study also point to a need for the further development and evaluation of methods for detecting carpal tunnel syndrome.     

Hand-arm vibration syndrome with use of anti-vibration chain saws: 19-year follow-up study of forestry workers

Objectives: Hand-arm vibration syndrome (HAVS) consists of vascular and neurological component. Musculoskeletal component has not been delineated yet. In the present follow-up study, we evaluated the prevalence of HAVS and the cumulative exposure to vibration among a cohort of forestry workers. Special interest was given to numbness and musculoskeletal disorders of upper extremity and neck in forestry workers. Methods: A follow-up study starting from 1976 was conducted among forestry workers in Suomussalmi in Finland. Total exposure of hand-arm vibration was recorded during 11 cross-sectional surveys. The last study was carried out in 1995. The lifetime dose of vibration energy was calculated. A cohort of 52 forest workers participated to all 11 cross-sectional surveys 1976–1995. HAVS and musculoskeletal disorders were evaluated. Results: The prevalence of active vibration white finger (VWF) decreased from 13 to 4% in the cross-sectional study. In the cohort VWF decreased from 17 to 8% and numbness increased from 23 to 40%. Rotator cuff syndrome (P=0.034) and epicondylitis (P=0.004) associated with numbness. Regional neck pain was diagnosed in 38% of workers and associated with low back pain. In modeling VWF, the lifelong vibration energy (OR 1.03, CI 1.01–1.05), and smoking (OR 7.36, CI 1.07–50.76) were significant. Numbness was modeled by pain in upper extremities (OR 12.43, CI 2.42–63.80) and neck pain (5.97, CI 1.25–28.39), not by lifelong vibration energy. Right rotator cuff syndrome was modeled by age (OR 2.58, CI 1.04–6.41) and lifelong vibration energy (OR 1.04, CI 1.00–1.07). Conclusions: The prevalence of VWF constantly decreased. Numbness did not follow the vibration exposure profile. Numbness also associated with upper extremity musculoskeletal disorders. Hand-arm vibration associated with the right rotator cuff syndrome in forestry workers.     

Clinical features of the hand-arm vibration syndrome in miners

INTRODUCTION: It is well known that the vibrating tools used by the miners can cause hand-arm vibration syndrome. However no detailed reports on this field could be found in the Hungarian literature. AIM: The aim of this study was to clarify the clinical features of the hand-arm vibration syndrome of the miners. METHOD: The circulation, the peripheral nerves and the osteoarticular system of the upper extremities of 152 miners were examined by means of cold provocation test, Allen-test, measurement of systolic blood pressure performed by Doppler flowmeter, clinical neurological and neurographic examination and X-ray investigation of the bones and joints. RESULTS: Hand-arm vibration syndrome was diagnosed in 87 patients (57.2%). The most common symptom was the lesion of the circulation which occurred in 78 patients (89.6%). The peripheral nerves were affected in 44 cases (50.5%). Radiological alteration of the bones and joints of the upper extremities was observed in 32 patients (36.8%). Out of 78 damaged cases the frequency of the vascular diseases was as follows: angiopathy (diminished systolic blood pressure in the fingers): 66 patient (84.6%), occlusion of the hand arteries (positive Allen-test) and arterial form of the thoracic outlet syndrome (positive elevation-test) respectively: 28 and 28 cases (35.9%), Raynaud phenomenon (positive cold-provocation test): 26 cases (33.3%). The peripheral nerves were examined in detail in 141 cases. Pathological alterations were observed in 78 patients (55.3%) in the following forms: carpal tunnel syndrome: 66 cases (84.6%), peripheral neuropathy of the upper limbs: 20 patients (25.6%), lesion of the ulnar nerve: 3 cases (3.8%), brachial plexus lesion: one patient (1.3%). Radiological alteration was most common in the carpal region (87 cases, 57.2%). The frequency of the lesion of cubital (40.4%) and shoulder region (40.7%) was practically the same. In the carpal region the most common alterations were the degenerative processes (23 cases, 15.1%) followed by the aseptic osteonecroses (22 patients, 14.5%). In the cubital region the periarticular changes (31 patients, 23.9%) were most common followed by degenerative changes (21 cases, 16.2%) and the osteochondrosis dissecans (13 cases, 10.1%). In the shoulder region the degenerative processes were the most common changes (41 patients, 34.7%), first of all in the acromioclavicular joint (21 cases, 17.8%). Aseptic necrosis was observed in two patients. CONCLUSIONS: The miners are professionally exposed not only to hand-arm vibration, but also to increased physical stress. The symptoms on the upper limbs can develop as the result of both exposures.     

Carpal tunnel syndrome in vibration disease.

The presence of carpal tunnel syndrome (CTS) in 125 forestry workers with exposure to vibration was examined clinically by electromyography and by determining vibration detection thresholds. Numbness of the hands was present in 43%, history of diminished hand muscle force in 15%, and Raynaud's phenomenon in 27%. The muscle weakness correlated significantly with motor nerve conduction velocity in the median nerve in both hands. In 25 forestry workers CTS was diagnosed. The condition was bilateral in 48%; otherwise it was more common on the right side. Fifteen patients were referred for surgery but because of spontaneous recovery or refusal by the patients only five underwent surgery; of these four improved. The motor conduction velocity of the ulnar nerve was decreased among patients with CTS supporting the idea that entrapment neuropathies in the hands may be due to tissue swelling caused by vibration at work. Total exposure time to vibration correlated with the decrease in motor conduction velocity in the ulnar nerve.     

Carpal tunnel syndrome in vibration disease

The presence of carpal tunnel syndrome (CTS) in 125 forestry workers with exposure to vibration was examined clinically by electromyography and by determining vibration detection thresholds. Numbness of the hands was present in 43%, history of diminished hand muscle force in 15%, and Raynaud's phenomenon in 27%. The muscle weakness correlated significantly with motor nerve conduction velocity in the median nerve in both hands. In 25 forestry workers CTS was diagnosed. The condition was bilateral in 48%; otherwise it was more common on the right side. Fifteen patients were referred for surgery but because of spontaneous recovery or refusal by the patients only five underwent surgery; of these four improved. The motor conduction velocity of the ulnar nerve was decreased among patients with CTS supporting the idea that entrapment neuropathies in the hands may be due to tissue swelling caused by vibration at work. Total exposure time to vibration correlated with the decrease in motor conduction velocity in the ulnar nerve.     

Effective intervention with ergonomics, antivibration gloves, and medical surveillance to minimize hand-arm vibration hazards in the workplace

Medical surveillance was used in the workplace to determine and monitor the level of hand-arm vibration syndrome (HAVS) and carpal tunnel syndrome (CTS) present in workers exposed to upper extremity vibration. Ergonomic intervention in the form of new tools with lower vibration levels and the use of International Standards Organizaiton (ISO) 10819 antivibration gloves were associated with a decrease in the pathologic findings and symptoms in these workers. Workers without such intervention were more likely to show progression of symptoms and findings. These findings suggest that ergonomic intervention can be effective in controlling the workplace hazard of tool vibration.