Ron House

Upper extremity disability in workers with hand–arm vibration syndrome

BACKGROUND Hand-arm vibration syndrome (HAVS) is a common occupational problem and it is important to understand the disability associated with this condition. AIMS To measure upper extremity disability using the disabilities of the arm, shoulder and hand (DASH) questionnaire in workers with HAVS and to determine how this disability is affected by the vascular and neurological components of HAVS and other factors, in particular musculoskeletal variables. METHODS Subjects were recruited from HAVS patients assessed at St Michaels Hospital, Toronto, Canada, over a 2-year period. All participants were assessed by an occupational medicine specialist to determine the specific components of HAVS and musculoskeletal variables including upper extremity pain score measured by the Borg scale. The DASH questionnaire was completed on the same day as the clinical assessment and before any feedback had been given about the clinical findings. RESULTS A total of 141 workers with HAVS were recruited and 139 agreed to participate in the study. This study group had a statistically significantly higher mean DASH score than the US population (P < 0.001). The multiple linear regression analysis indicated that upper extremity pain score (P < 0.001), the Stockholm sensorineural scale (P < 0.01) and the number of fingers blanching (P < 0.05) had a statistically significant association with an increase in the DASH score. The highest partial R(2) value was for the upper extremity pain score. CONCLUSIONS Workers with HAVS have significant upper extremity disability and musculoskeletal factors appear to make an important contribution to this disability.

DASH work module in workers with hand–arm vibration syndrome

BACKGROUND The Disabilities of the Arm, Shoulder and Hand work module (DASH-W) questionnaire has not previously been described in relation to hand-arm vibration syndrome (HAVS). AIMS To measure work-related disability in workers with HAVS using the DASH-W questionnaire and to determine how the various components of HAVS affect the DASH-W score. METHODS Workers with HAVS from a variety of industries were assessed over a 2-year period at the occupational health clinic, St Michaels Hospital, Toronto. Subjects completed the DASH-W questionnaire and were assessed by an occupational physician to determine their Stockholm sensorineural and vascular stages and upper extremity pain score measured by the Borg scale, as an indication of musculoskeletal problems associated with HAVS. The average DASH-W score was compared with the average value for the US population. Multiple linear regression was used to determine the contribution of the various components of HAVS to the DASH-W score. RESULTS There were 139 (134 men and 5 women) participants. The subjects with HAVS had a mean DASH-W score of 54.7 (95% CI: 50.3-59.1), which was considerably higher than the average for the US population (P < 0.001). Statistically significant HAVS variables in the multiple linear regression included the Stockholm sensorineural stage (P < 0.05) and the upper extremity pain score (P < 0.001) with the pain score having the highest partial R (2) value. CONCLUSIONS Workers with HAVS reported significant upper extremity work-related disability as measured by the DASH-W questionnaire, and the upper extremity pain score made the largest contribution to the DASH-W scores in these subjects.

Peripheral sensory neuropathy associated with 1,1,1-trichloroethane

A case is described of peripheral sensory neuropathy in a woman who had daily exposure to 1,1,1-trichloroethane, used as a degreasing agent. Although previous reviews of the health effects of 1,1,1-trichloroethane have not indicated long-term neurotoxicity, there are recent animal studies that suggest chronic central neurotoxic effects and previous case reports of peripheral neuropathy in three exposed workers in one plant. Our case provides additional evidence that 1,1,1-trichloroethane exposure may be associated with peripheral sensory neuropathy. Reporting of similar cases is encouraged and investigation of the neurotoxic effects of 1,1,1-trichloroethane is recommended.

Current perception threshold and the HAVS Stockholm sensorineural scale

BACKGROUND It is important to determine which tests of sensorineural dysfunction identify the neurological damage from hand-arm vibration exposure. AIMS To examine the association between the hand-arm vibration syndrome (HAVS) Stockholm sensorineural scale stages and tests of peripheral neurological function including measurement of current perception threshold (CPT) and nerve conduction. METHODS All the subjects were men who were assessed for HAVS with a medical and occupational history and physical examination to determine the Stockholm stage, CPT testing at frequencies of 5, 250 and 2000 Hz for the median and ulnar nerves and measurement of nerve conduction carried out in a blinded fashion. RESULTS A total of 155 of the 157 recruited subjects agreed to take part in the study, a 99% participation rate. CPT was statistically significantly increased (P < 0.001) in both Stockholm sensorineural Stages 1 and > or =2 in comparison to Stage 0 for every frequency and nerve combination. However, CPT could not discriminate well between Stages 1 and > or =2. There was no association between median or ulnar neuropathy measured by nerve conduction and the Stockholm stages. Polychotomous multinomial logistic regression indicated that the CPT measurements at 2000 Hz, corresponding to damage to large myelinated nerve fibres, were most predictive of both Stockholm Stages 1 and > or =2 in comparison to Stage 0. CONCLUSIONS Neuropathy measured by nerve conduction was unrelated to the Stockholm scale stages. CPT was increased above Stage 0 but did not distinguish well between the higher stages of the Stockholm scale.

The sensitivity and specificity of thermometry and plethysmography in the assessment of hand-arm vibration syndrome

BACKGROUND Finger plethysmography and thermometry are objective measures used to assess the vascular aspect of hand-arm vibration syndrome (HAVS). Research to date shows poor correlation between these tests and Stockholm Workshop Scale (SWS) vascular stage. Clinicians, researchers and compensation boards require objective means to diagnose and quantify HAVS. AIMS To define the specificity and sensitivity of thermometry and plethysmography using the SWS as the reference criterion. A secondary goal was to consider cut points for the tests optimizing sensitivity and specificity. METHODS A cross-sectional analysis was conducted on HAVS patients seen at an occupational medicine specialty clinic. Plethysmography and thermometry were analyzed using SWS vascular stage as the outcome variable. Logistic regression controlled for age, smoking and time since last vibration exposure and use of vasoactive medications. The sensitivity and specificity of the combined tests were calculated using varying cut points. RESULTS A total of 139 patients consented to participate in the study. Plethysmography stage 1 or greater showed the highest sensitivity (sensitivity 94% and specificity 15%). Specificity was optimized combining plethysmography stage 3 and thermometry stage 3 (specificity 98% and sensitivity 23%). Maximal diagnostic accuracy was achieved by plethysmography alone setting the criteria for a positive test as being stage 1 or greater (70%). CONCLUSIONS Neither plethysmography nor thermometry either alone or in combination demonstrated sufficient sensitivity and specificity to serve as an objective correlate for SWS vascular stage. All combinations of plethysmography and thermometry showed a lower specificity than sensitivity indicating that the SWS may be less sensitive in detecting vascular pathology than the objective tests.

Vasospasm in the feet in workers assessed for HAVS

BACKGROUND Previous studies have suggested that the presence of the vascular component of hand-arm vibration syndrome (HAVS) in the hands increases the risk of cold-induced vasospasm in the feet. AIMS To determine if objectively measured cold-induced vasospasm in the hands is a risk factor for objectively measured cold-induced vasospasm in the feet in workers being assessed for HAVS. METHODS The subjects were 191 male construction workers who had a standardized assessment for HAVS including cold provocation digital photocell plethysmography of the hands and feet to measure cold-induced vasospasm. Bivariate analysis and multinomial logistic regression were used to examine the association between plethysmographic findings in the feet and predictor variables including years worked in construction, occupation, current smoking, cold intolerance in the feet, the Stockholm vascular stage and plethysmographic findings in the hands. RESULTS Sixty-one (32%) subjects had non-severe vasospasm and 59 (31%) had severe vasospasm in the right foot with the corresponding values being 57(30%) and 62 (32%) in the left foot. Multinomial logistic regression indicated that the only statistically significant predictor of severe vasospasm in the feet was the presence of severe vasospasm in the hands (OR: 4.11, 95% CI: 1.60-10.6, P < 0.01 on the right side and OR: 4.97, 95% CI: 1.82-13.53, P < 0.01 on the left side). Multinomial logistic regression analysis did not indicate any statistically significant predictors of non-severe vasospasm in the feet. CONCLUSIONS Workers assessed for HAVS frequently have cold-induced vasospasm of their feet. The main predictor of severe vasospastic foot abnormalities is severe cold-induced vasospasm in the hands.

Investigation of factors affecting mass psychogenic illness in employees in a fish-packing plant

This study of the factors affecting the development of mass psychogenic illness (MPI) was carried out in a large fish-packing plant in New Brunswick, Canada. A total of 269 out of 270 plant employees (99.6%) participated in the study and of these, 208 cases were affected with symptoms of MPI and 61 controls were unaffected over a period of 2 1/2 months. A questionnaire was administered to participating employees to collect information about symptoms, demographic factors, work history, pre-existing medical problems, potential workplace triggering exposure factors, and various psychosocial factors. Multiple logistic regression indicated that the main factors associated with MPI, in decreasing order of importance, were skill creation in the job, odor perception, and female sex. Management of this incident required reassurance of employees that there was no hazardous exposure in the plant as well as recognition of the need to reduce underlying sources of stress in the work environment.

Vibration induced white-feet: Overview and field study of vibration exposure and reported symptoms in workers

BACKGROUND Workers who stand on platforms or equipment that vibrate are exposed to foot-transmitted vibration (FTV). Exposure to FTV can lead to vibration white feet/toes resulting in blanching of the toes, and tingling and numbness in the feet and toes. OBJECTIVES The objectives are 1) to review the current state of knowledge of the health risks associated with foot-transmitted vibration (FTV), and 2) to identify the characteristics of FTV and discuss the associated risk of vibration-induced injury. PARTICIPANTS Workers who operated locomotives (n=3), bolting platforms (n=10), jumbo drills (n=7), raise drilling platforms (n=4), and crushers (n=3), participated. METHODS A tri-axial accelerometer was used to measure FTV in accordance with ISO 2631-1 guidelines. Frequency-weighted root-mean-square acceleration and the dominant frequency are reported. Participants were also asked to report pain/ache/discomfort in the hands and/or feet. RESULTS Reports of pain/discomfort/ache were highest in raise platform workers and jumbo drill operators who were exposed to FTV in the 40 Hz and 28 Hz range respectively. Reports of discomfort/ache/pain were lowest in the locomotive and crusher operators who were exposed to FTV below 10 Hz. These findings are consistent with animal studies that have shown vascular and neural damage in exposed appendages occurs at frequencies above 40 Hz. CONCLUSIONS Operators exposed to FTV at 40 Hz appear to be at greater risk of experiencing vibration induced injury. Future research is required to document the characteristics of FTV and epidemiological evidence is required to link exposure with injury.

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.

Dermatitis in a particleboard manufacturing facility

Exposure to wood dust and other chemicals used in particleboard manufacture may cause contact dermatitis. To assess the prevalence and nature of skin complaints in the refining and drying department of a particleboard manufacturing facility following introduction of a new process, workers were assessed by a physician, using a standardized questionnaire concerning symptoms, past and family history, workplace exposures, and use of protective equipment. Cutaneous examination and patch testing were then performed. Questionnaire results showed that workers complained of rash, nasal and eye irritation, as well as cough and bothersome odours. Cutaneous examination identified a heterogeneity of skin problems, with dermatitis being mainly irritant rather than allergic. Quaternium‐15 (Dowicil 200) was the only allergen to which more than 1 individual reacted. Aside from the odours, exposure to wood dust could account for the other reported symptoms. Allergic reactions on patch testing were few and did not explain the dermatitis; most skin reactions were irritant. Recommendations to the company included improved dust control, through ventilation and personal hygiene measures, as well as protective clothing. The investigation highlights how the introduction of a new process may focus attention on health complaints that have been present for some time before.