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Background: Thermotactile thresholds and vibrotactile thresholds are measured to assist the diagnosis of the sensorineural component of the hand-arm vibration syndrome (HAVS)., Objectives: This study investigates whether thermotactile and vibrotactile thresholds distinguish between fingers with and without numbness and tingling., Methods: In 60 males reporting symptoms of the hand-arm vibration syndrome, thermotactile thresholds for detecting hot and cold temperatures and vibrotactile thresholds at 31.5 and 125 Hz were measured on the index and little fingers of both hands., Results: In fingers reported to suffer numbness or tingling, hot thresholds increased, cold thresholds decreased, and vibrotactile thresholds at both 31.5 and 125 Hz increased. With sensorineural symptoms on all three phalanges (i.e. numbness or tingling scores of 6), both thermotactile thresholds and both vibrotactile thresholds had sensitivities greater than 80% and specificities around 90%, with areas under the receiver operating characteristic curves around 0.9. There were correlations between all four thresholds, but cold thresholds had greater sensitivity and greater specificity on fingers with numbness or tingling on only the distal phalanx (i.e. numbness or tingling scores of 1) suggesting cold thresholds provide better indications of early sensorineural disorder., Conclusions: Thermotactile thresholds and vibrotactile thresholds can provide useful indications of sensorineural function in patients reporting symptoms of the sensorineural component of HAVS.

Purpose: This study investigates the effects of room temperature on two standard tests used to assist the diagnosis of vibration-induced white finger (VWF): finger rewarming times and finger systolic blood pressures., Methods: Twelve healthy males and twelve healthy females participated in four sessions to obtain either finger skin temperatures (FSTs) during cooling and rewarming of the hand or finger systolic blood pressures (FSBPs) after local cooling of the fingers to 15 and 10 °C. The measures were obtained with the room temperature at either 20 or 28 °C., Results: There were lower baseline finger skin temperatures, longer finger rewarming times, and lower finger systolic blood pressures with the room temperature at 20 than 28 °C. However, percentage reductions in FSBP at 15 and 10 °C relative to 30 °C (i.e. %FSBP) did not differ between the two room temperatures. Females had lower baseline FSTs, longer rewarming times, and lower FSBPs than males, but %FSBPs were similar in males and females., Conclusions: Finger rewarming times after cold provocation are heavily influenced by room temperature and gender. For evaluating peripheral circulatory function using finger rewarming times, the room temperature must be strictly controlled, and a different diagnostic criterion is required for females. The calculation of percentage changes in finger systolic blood pressure at 15 and 10 °C relative to 30 °C reduces effects of both room temperature and gender, and the test may be used in conditions where the ±1 °C tolerance on room temperature required by the current standard cannot be achieved.

Background: Vibration-induced white finger (VWF) is the vascular component of the hand-arm vibration syndrome (HAVS). Two tests have been standardised so as to assist the diagnosis of VWF: the measurement of finger rewarming times and the measurement of finger systolic blood pressures (FSBPs)., Objectives: This study investigates whether the two tests distinguish between fingers with and without symptoms of whiteness and compares individual results between the two test methods., Methods: In 60 men reporting symptoms of the HAVS, the times for their fingers to rewarm by 4°C (after immersion in 15°C water for 5 min) and FSBPs at 30°C, 15°C and 10°C were measured on the same day., Results: There were significant increases in finger rewarming times and significant reductions in FSBPs at both 15°C and 10°C in fingers reported to suffer blanching. The FSBPs had sensitivities and specificities >90%, whereas the finger rewarming test had a sensitivity of 77% and a specificity of 79%. Fingers having longer rewarming times had lower FSBPs at both temperatures., Conclusions: The findings suggest that, when the test conditions are controlled according to the relevant standard, finger rewarming times and FSBPs can provide useful information for the diagnosis of VWF, although FSBPs are more sensitive and more specific., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Aims: The relation between Dupuytren's contracture and occupational exposure to hand-transmitted vibration (HTV) has frequently been debated. We explored associations in a representative national sample of workers with well-characterised exposure to HTV., Methods: We mailed a questionnaire to 21 201 subjects aged 16-64 years, selected at random from the age-sex registers of 34 general practices in Great Britain and to 993 subjects chosen randomly from military pay records, asking about occupational exposure to 39 sources of HTV and about fixed flexion contracture of the little or ring finger. Analysis was restricted to men at work in the previous week. Estimates were made of average daily vibration dose (A(8) root mean squared velocity (rms)) over that week. Associations with Dupuytren's contracture were estimated by Poisson regression, for lifetime exposure to HTV and for exposures in the past week >A(8) of 2.8 ms(-2) rms. Estimates of relative risk (prevalence ratio (PR)) were adjusted for age, smoking status, social class and certain manual activities at work., Results: In all 4969 eligible male respondents supplied full information on the study variables. These included 72 men with Dupuytren's contracture, 2287 with occupational exposure to HTV and 409 with A(8)>2.8 ms(-2) in the past week. PRs for occupational exposure to HTV were elevated 1.5-fold. For men with an A(8)>2.8 ms(-2) in the past week, the adjusted PR was 2.85 (95% CI 1.37 to 5.97)., Conclusions: Our findings suggest that risk of Dupuytren's contracture is more than doubled in men with high levels of weekly exposure to HTV.

This invited paper reviews experimental studies of the frequency-dependence of absolute thresholds for the perception of vibration, equivalent comfort contours, temporary changes in sensation caused by vibration, and reductions in finger blood flow caused by hand-transmitted vibration. Absolute thresholds depend on the contact conditions but for a typical hand grip the thresholds show greatest sensitivity to acceleration around 125 Hz. The frequency-dependence of discomfort caused by hand-transmitted vibration depends on vibration magnitude: similar to absolute thresholds at low magnitudes, but the discomfort at higher magnitudes is similar when the vibration velocity is similar (at frequencies between about 16 and 400 Hz). Hand-transmitted vibration induces temporary elevations in vibrotactile thresholds that reflect the sensory mechanisms excited by the vibration and are therefore highly dependent on the frequency of vibration. Hand-transmitted vibration reduces finger blood flow during and after exposure; when the vibration velocity is similar at all frequencies there is more vasoconstriction at frequencies greater than 63 Hz than at lower frequencies. A single frequency weighting cannot provide a good indication of how all effects of hand-transmitted vibration depend on vibration frequency. Furthermore, a single frequency weighting provides only an approximate indication of any single response, because many factors influence the frequency-dependence of responses to hand-transmitted vibration, including the magnitude of vibration, contact conditions, and individual differences. Although the frequency weighting in current standards extends from 8 to 1,000 Hz, frequencies greater than 400 Hz rarely increase the weighted value on tools and there is currently little psychophysical or physiological evidence of their effects.

Objectives: If the negligence of an employer results in the disability in an employee, the employer is responsible, in whole or in part, for the disability. The employer is wholly responsible when the worker would not have developed the disability if the employer had taken all reasonable preventative measures. The employer is only partly responsible if the worker would probably have developed some disability even if the employer had taken all reasonable precautions. The employer's responsibility may be estimated from the difference between the actual disability of the worker and the disability that the worker would have suffered if the employer had taken all reasonable preventative measures. This paper considers alternative ways of apportioning negligent and non-negligent exposures to hand-transmitted vibration., Results: The equivalent daily vibration exposure, A(8), used in current EU Directives is shown to be unsuitable for distinguishing between the consequences of negligent and non-negligent exposures because the risks of developing a disorder from hand-transmitted vibration also depend on the years of exposure. Furthermore, daily exposures take no account of individual susceptibility or the practicality of reducing exposure. The consequences of employer negligence may be estimated from the delay in the onset and progression of disorder that would have been achieved if the employer had acted reasonably, such as by reducing vibration magnitude and exposure duration to the minimum that was reasonably achievable in the circumstances. This seems to be fair and reasonable for both employers and employees and indicates the consequences of negligence-the period of the worker's life with disease as a result of negligence and the period for which their employment opportunities may be restricted as a result of the onset of the disorder due to negligence., Conclusions: The effects of negligence may be estimated from the delay in the onset of disease or disability that would have occurred if the employer had behaved reasonably. This definition of negligence encourages employers to reduce risks to the lowest reasonably practical level, consistent with EU Directives.

Regular exposure to hand-transmitted vibration can result in symptoms and signs of peripheral vascular, neurological and other disorders collectively known as the hand-arm vibration syndrome. The measurement of the effects of hand-transmitted vibration involves converting the evidence of disorder (symptoms and signs) into information that can be stored. Evaluation requires the use of scales on which to indicate the severity of the various symptoms and signs. Assessment involves a judgement of severity relative to a criterion, usually for a specific purpose (e.g. to decide on removal from work or compensation). The measurement and evaluation of symptoms and signs is necessary when monitoring patient health and when performing epidemiological studies for research. The assessment of the severity of the hand-arm vibration syndrome is currently performed with staging systems, but the criteria are not clear and not related to defined methods for measuring or evaluating the symptoms and signs. Recognizing that similar symptoms can occur without injury from occupational exposures to hand-transmitted vibration, this paper attempts to define significant peripheral neurological symptoms caused by hand-transmitted vibration (i.e. 'unusual symptoms') and how these symptoms and related signs may be measured. Scales for evaluating the symptoms (e.g. their extent) and the related signs (e.g. their probability relative to the probability of the sign being present in persons not exposed to vibration) are defined. A method of relating unusual symptoms to both the signs of disorder and the pattern of vibration exposure is illustrated. Assessments of severity will vary according to the reasons for assessing the health effects of vibration, and will depend on local practice and convenience, but a way of combining evaluations of symptoms and signs is demonstrated in a staging system. Although inherently complex, the methods may assist the collection of data required to improve understanding of the effects of hand-transmitted vibration and also support a more complete reporting of the condition in those adversely affected by hand-transmitted vibration.

Objectives: This study was undertaken to compare normal values of thermotactile and vibrotactile thresholds in males and females and in younger and older age groups. In addition, for thermal thresholds, the effects of the contact area (small and large) and stimulus location (glabrous and non-glabrous skin) were investigated., Method: Eighty healthy subjects participated in the study: 20 males and 20 females aged 20-30 years, and 20 males and 20 females aged 55-65 years. Subjects attended one 45 min experimental session consisting of acclimatisation for 10 min followed by 35 min of testing. Using the method of limits, hot thresholds and cold thresholds were measured on the non-dominant upper limb at three locations (the distal phalanx of the middle finger, the thenar eminence, and the dorsal surface of the forearm) using two circular contactors 1.0 and 2.8 cm in diameter. Using the von Békésy method, vibrotactile thresholds at 31.5 and 125 Hz were measured on the distal phalanx of the middle finger of the non-dominant hand., Results: Among the younger subjects there were significant gender differences in thermotactile thresholds but not vibrotactile thresholds. Age did not have any significant effect on thermotactile or vibrotactile thresholds. Hot thresholds were significantly higher and cold thresholds significantly lower when the larger stimulus area was used. The thresholds exceeded by 18% of the population (the mean plus one standard deviation) and by 2.5% (the mean plus two standard deviations) are provided and may be used to consider whether measured thresholds are within a "normal" range., Conclusions: For males and females the same ranges of normal values may be used for vibrotactile thresholds but different ranges of normal values may be required for thermotactile thresholds. An age correction may not be needed for thermotactile or vibrotactile thresholds in persons aged 20-65 years. Contact area has an influence on thermotactile thresholds and should be controlled.

Vibration of one hand reduces blood flow in the exposed hand and in the contralateral hand not exposed to vibration, but the mechanisms involved are not understood. This study investigated whether vibration-induced reductions in finger blood flow are associated with vibrotactile perception thresholds mediated by the Pacinian channel and considered sex differences in both vibration thresholds and vibration-induced changes in digital circulation. With force and vibration applied to the thenar eminence of the right hand, finger blood flow and finger skin temperature were measured in the middle fingers of both hands at 30-s intervals during seven successive 4-min periods: 1) pre-exposure with no force or vibration, 2) pre-exposure with force, 3) vibration 1, 4) rest with force, 5) vibration 2, 6) postexposure with force, and 7) recovery with no force or vibration. A 2-N force was applied during periods 2-6 and 125-Hz vibration at 0.5 and 1.5 ms-2 root mean square (r.m.s.; unweighted) was applied during periods 3 and 5, respectively. Vibrotactile thresholds were measured at the thenar eminence of right hand using the same force, contact conditions, and vibration frequency. When the vibration magnitude was greater than individual vibration thresholds, changes in finger blood flow were correlated with thresholds (with both 0.5 and 1.5 ms-2 r.m.s, vibration): subjects with lower thresholds showed greater reductions in finger blood flow. Women had lower vibrotactile thresholds and showed greater vibration-induced reductions in finger blood flow. It is concluded that mechanoreceptors responsible for mediating vibration perception are involved in the vascular response to vibration. [ABSTRACT FROM AUTHOR]

Purpose: To investigate how temperature influences changes in finger circulation induced by hand-transmitted vibration in healthy subjects, and the variability in individual response to both vibration and temperature. Methods: With two room temperatures (20 and 28°C), finger blood flow (FBF) and finger skin temperature (FST) were measured on the left middle fingers of 12 subjects at 1-min intervals during three successive 10-min periods. A 5-N static force was applied throughout the 30-min period, and sinusoidal 125-Hz vibration at 44 ms rms. (unweighted) was applied to the right hand during the second of the three 10-min periods. Results: Before exposure to vibration, both FBF and FST were greater with the higher room temperature. Finger blood flow in the left hand reduced during vibration of the right hand. The reduction in absolute FBF differed between the two room temperatures, but the percentage reduction in FBF relative to FBF before exposure to vibration was similar. After cessation of vibration, there was continued reduction in FBF with both room temperatures. Before and after vibration exposure, the FST was correlated with FBF and the FBF and FST at 20°C were correlated with the FBF and FST at 28°C. Conclusions: Vibration of one hand can reduce finger blood flow and skin temperature on the unexposed hand, with the reduction dependent on temperature. The absolute reduction in FBF was greater with the higher room temperature, but the percentage reduction in FBF relative to FBF before vibration exposure was similar. Those with greater finger blood flow before vibration tend to have greater blood flow during vibration, and those with greater finger blood flow with one temperature tend to have greater blood flow with another temperature. [ABSTRACT FROM AUTHOR]

Objectives: To identify the current state of knowledge, current uncertainties and future needs related to the diagnosis of disorders associated with the use of vibratory hand-held tools. Method: An international workshop was convened with invited experts, medical doctors, scientists and engineers familiar with hand-transmitted vibration and the diagnosis of vascular, neurological and musculoskeletal disorders. This paper records the general conclusions from four panel discussions. Results: For the most common vascular disorder (vibration-induced white finger), the principal symptom and sign involves attacks of well-demarcated finger blanching (Raynaud's phenomenon); low finger systolic blood pressure following cooling is indicative of vibration-induced white finger and zero finger systolic blood pressure can confirm an attack of Raynaud's phenomenon. For neurological disorders, some symptoms can exist without detectable signs and some signs can exist without symptoms; numbness and tingling are commonly reported but neurological changes may be present without these symptoms. The pathogenesis of musculoskeletal disorders in users of vibratory tools is not clear; symptoms may include pain that may not be associated with abnormal results in objective tests. For both neurological and musculoskeletal disorders, a thorough neuromuscular and skeletal examination is required; diagnosis must consider the work history and medical history, the results of physical examination and any objective tests in addition to other factors (e.g. age, smoking, alcohol, systemic disorders, medication and neurotoxic agents) that might have contributed to symptoms, signs and test results. Conclusions: While vibration-induced white finger is caused by vibration, some neurological and musculoskeletal disorders are the result of work with vibratory tools where the separate roles of vibration, repetitive movements, grip and push forces, non-neutral postures and any other ergonomic stressors are often unclear. Such disorders may be more easily identified as being caused by the work rather than by exposure to hand-transmitted vibration per se. A person found to have developed disorders induced by either vibration or the work situation should not be returned to the same vibration exposure or work without any changes expected to lessen the risks. [ABSTRACT FROM AUTHOR]

Objectives: Vibrotactile thresholds on the fingers were compared using two alternative methods of controlling contact with a vibrating probe: control of the force of contact with the probe (force control) and control of skin indentation produced by the probe (indentation control). Both systems had the same control of push force on a static surround around the vibrating probe. Method: A group of 14 male subjects (aged 20–27 years) were tested at four frequencies (31.5, 63, 125, 250 Hz) in three separate sessions so as to quantify the repeatability of thresholds. Skin stiffness was also measured. Results: Control of skin indentation gave more repeatable thresholds than control of probe force. There was a practice effect whereby thresholds became more consistent over sessions. There were no systematic correlations between thresholds and skin stiffness. Conclusions: Repeatable and similar vibrotactile thresholds can be obtained with two alternative methods having different contact conditions. Either method may assist the diagnosis of disorders associated with hand-transmitted vibration, but control of skin indentation has the advantage of greater simplicity and, in this study, greater repeatability. [ABSTRACT FROM AUTHOR]

Objectives: To assist occupational health professionals to interpret the results of standardised tests for components of the hand-arm vibration syndrome by presenting data for healthy subjects and identifying the effects of some of the confounding variables. Method: Thermal thresholds, vibrotactile thresholds, the finger skin temperature (FST) response to cold provocation and percentage finger systolic blood pressures (%FSBP) were measured by standardised procedures. Normative data were obtained for healthy men of working age (17–62 years) during 237 experimental sessions encompassing ten different studies. Hot thermal thresholds and cold thermal thresholds were assessed independently with 38 subjects; 152 measurements of both hot and cold thresholds were made. Vibrotactile thresholds were measured at several locations on 81 subjects, giving a total of 216 measurements at 125 Hz and at 31.5 Hz. The FST response to cold provocation at 15 °C was monitored by thermocouples throughout a 2-min settling period, a 5-min immersion period and a 10-min recovery period. A total of 302 measurements was made on 70 subjects. The %FSBPs were measured in four test fingers and one reference finger by strain-gauge plethysmography. Measurements were made on 97 subjects. A total of 351 measurements was made at 15 °C, with 341 measurements at 10 °C. Results: Normative data and some example normal limits are presented from the current data set and from data presented in other studies. Age was found to influence thermal thresholds, vibrotactile thresholds and the FST response to cold provocation; older subjects exhibited deteriorated vascular and neurological function. Room temperature was found to influence %FSBPs and the FST response to cold provocation; warmer environments resulted in improved vascular response to cold. Outdoor temperature had a small effect on the FST response to cold provocation and on the vibrotactile thresholds. Thermal thresholds showed some influence of smoking habits and of the FST measured prior to testing. For all four tests, any differences between measurement locations were small and there were no differences between left-handed and right-handed subjects. Conclusions: The current data can assist occupational health professionals to interpret the results of the standardised tests. Comparison with the current data is considered valid for men of working age. Age and room temperature should be recognised as being capable of causing changes in neurological and vascular function. [ABSTRACT FROM AUTHOR]

Objectives: Users of hand-held vibratory tools report reductions in grip strength and manual dexterity. This study quantified the test-retest repeatability of grip strength and manual dexterity tests, investigated effects of gender and age, and determined normative measures in different subject groups. Methods: A total of 72 subjects in four groups (both genders and two age ranges) participated: men and women aged 18 to 25 years and 45 to 55 years. Grip strength was measured with a hand-held dynamometer, and dexterity measured with the Purdue pegboard. We assessed repeatability using one subject group (18 to 25-year-old men) who attended over three successive weeks. Results: Repeated measures of grip strength were correlated for both hands and for each combination of weekly tests (P=0.01), and there were no significant changes in strength over weeks. Repeated measures of dexterity were correlated in both hands (P=0.01) for all test combinations, except between weeks 1 and 3 in the non-dominant hand (P=0.15). Further analysis suggested an improvement in dexterity, consistent with a practice effect. In both age groups, grip strength of the men was significantly greater than that of the women (P<0.01), but there were no gender differences in dexterity scores (P>0.1). There were no significant effects of age for either grip strength or dexterity (P>0.1). Conclusions: Both tests showed sufficient repeatability, with no age effect on either grip or manual dexterity (between approximately 20 to 55 years), although a decline in grip and dexterity is expected at greater ages. Dexterity scores were similar in both genders for the groups studied. Grip strength was greater in men. Occupational effects might exist for both tests, irrespective of any occupational disorder, and might be reflected in increases or decreases in grip strength and dexterity. [ABSTRACT FROM AUTHOR]