Vitamin B6, vitamin C, and carpal tunnel syndrome.
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Ascorbic Acid Deficiency↗
Biomedical subjects
A Franzblau
Publications and source records attributed to A Franzblau.
Consensus criteria for the classification of carpal tunnel syndrome in epidemiologic studies.
Criteria for the classification of carpal tunnel syndrome for use in epidemiologic studies were developed by means of a consensus process. Twelve medical researchers with experience in conducting epidemiologic studies of carpal tunnel syndrome participated in the process. The group reached agreement on several conceptual issues. First, there is no perfect gold standard for carpal tunnel syndrome. The combination of electrodiagnostic study findings and symptom characteristics will provide the most accurate information for classification of carpal tunnel syndrome. Second, use of only electrodiagnostic study findings is not recommended. Finally, in the absence of electrodiagnostic studies, specific combinations of symptom characteristics and physical examination findings may be useful in some settings but are likely to result in greater misclassification of disease status.
Carpal Tunnel Syndrome↗
Chemical pneumonitis following household exposure to hydrofluoric acid.
A previously healthy 26-year-old woman developed hemorrhagic alveolitis and adult respiratory distress syndrome (ARDS) following use of a hydrofluoric acid-containing household cleaning agent. Exposure was inhalational in nature. The circumstances and possible mechanism of chemical pneumonitis from low-dose inhalational exposure to hydrofluoric acid are discussed.
Adult↗
Acute respiratory effects on workers exposed to metalworking fluid aerosols in an automotive transmission plant.
Exposure to metalworking fluids has been linked to modest cross-shift reductions in FEV1 and occupational asthma. To identify responsible agents, we measured personal exposures to thoracic particulate (TP), viable plus nonviable thoracic bacteria (BAC), and vapor phase nicotine (VPN) (as a surrogate for tobacco particulate) among 83 machinists exposed to soluble oils and 46 dry assemblers working in an automotive transmission machining plant using biocides infrequently. The participants completed interviews and performed pre- and postshift spirometry on Monday and Thursday of the same week in each of three rounds of data collection (June 1992, January 1993, June 1993). Generalized estimating equations were used to combine information across rounds in multiple regression models of cross-shift and cross-week changes in forced expiratory volume, I second (FEV1) and forced vital capacity (FVC). Mean seniority was 19 years among machinists. Mean personal TP levels were 0.41 mg/m3 in machinists and 0.13 mg/m3 in assemblers. Six of the 83 machinists and none of the 46 assemblers experienced a greater than 19% cross-shift decrement in FEV1 or FVC at least once (p = .07). In regression models using either TP or BAC, among subjects with lower baseline (Monday preshift) FEV1/FVC ratios, increasing exposure was significantly associated with increasing cross-shift decrements in FEV1 and FVC in linear models, and with increased likelihood of a 10% or greater cross-shift decrement in FEV1 or FVC in logistic models. Adjustment of TP for VPN did not affect models significantly. We conclude that clinically important cross-shift decrements in pulmonary function are associated with exposure to metalworking fluid aerosols within a high-seniority population.
Adult↗
Re: Comparison of single photon emission computed tomography findings in cases of healthy adults and solvent-exposed adults.
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Adult↗
Time-resolved cutaneous absorption and permeation rates of methanol in human volunteers.
This paper reports on an experimental study of dermal exposure to neat methanol in human volunteers for the purposes of estimating percutaneous absorption rates, permeation kinetics, baseline (pre-exposure) levels of methanol in blood, and inter- and intrasubject variability. A total of 12 volunteers (seven men and five women) were exposed to methanol via one hand for durations of 0 to 16 min in a total of 65 sessions, making this the largest controlled study of percutaneous absorption for this common solvent. In each session, 14 blood samples were collected sequentially and analyzed for methanol. These data were used to derive absorption rates and delivery kinetics using a two compartment model that accounts for elimination and pre-exposure levels. The pre-exposure methanol concentration in blood was 1.7 +/- 0.9 mg 1(-1), and subjects had statistically different mean concentrations. The maximum methanol concentration in blood was reached 1.9 +/- 1.0 h after exposure. Delivery rates from skin into blood lagged exposure by 0.5 h, and methanol continued to enter the systemic circulation for 4 h following exposure. While in vitro studies have reported comparable lag times, the prolonged permeation or epidermal reservoir effect for such miscible solvents has not been previously measured. The mean derived absorption rate, 8.1 +/- 3.7 mg cm-2 h-1, is compatible with that found in the other in vivo study of methanol absorption. Both in vivo absorption rate estimates considerably exceed in vitro estimates. The maximum concentration of methanol in blood following an exposure to one hand lasting approximately 20 min is comparable to that reached following inhalational exposures at a methanol concentration of 200 ppm, the threshold limit value-time weighted average (TLV-TWA). While variability in blood concentrations and absorption rates approached a factor of two, differences between individuals were not statistically significant. The derived absorption and permeation rates provide information regarding kinetics and absorbed dose that can help to interpret biological monitoring data and confirm mathematical models of chemical permeation.
Adult↗
Use of screening nerve conduction studies for predicting future carpal tunnel syndrome.
OBJECTIVE: To determine if an abnormal sensory nerve conduction study consistent with median mononeuropathy in asymptomatic workers was predictive of future complaints of the hand or finger suggestive of carpal tunnel syndrome. METHODS: This was a case-control study of over 700 active workers at five different work sites: four sites involved manufacturing workers and one site represented clerical workers. Patients' reports of symptoms of pain, numbness, tingling, or burning in the hand or finger that lasted more than one week or occurred three or more times after the initial screening were investigated. 77 cases were defined as asymptomatic workers with electrodiagnostic findings of median mononeuropathy in either hand based on a comparison of median and ulnar sensory evoked peak latencies. A difference > or = 0.5 ms was defined as abnormal; a normal difference was < or = 0.2 ms. Controls were asymptomatic age, and sex matched workers with normal nerve conduction studies in both hands. Follow up questionnaires were completed 17 (SD 6) months later. RESULTS: The follow up participation rate was 72%. Cases had a 12% risk of developing symptoms during the follow up period compared with 10% in the control group, chi 2 = 0.12, P = 0.73. CONCLUSIONS: Abnormal median sensory nerve conduction studies in asymptomatic workers were not predictive of future hand or fingers complaints and if used for preplacement screening among active workers this should be done with caution.
Adolescent↗
Influence of body mass index and work activity on the prevalence of median mononeuropathy at the wrist.
OBJECTIVE: To determine which proposed risk factor, work activity (industrial v clerical), body mass index (BMI), or other demographic factors had the most influence on the prevalence of median mononeuropathy at the wrist, and if there was an interaction between the risk factors. METHODS: This was a cross sectional study of active workers at five different worksites; four were industrial sites and one was clerical. 527 workers were recruited--164 clerical and 363 industrial. The presence of a median mononeuropathy in either hand was measured by electrodiagnostic techniques comparing median and ulnar sensory latencies. RESULTS: 30% of workers had an abnormality of the median sensory nerve at the wrist (34% of the industrial v 21% of the clerical workers). The adjusted risk for industrial workers was twice that of clerical workers. Obese workers (BMI > 29) were four times more likely to present with a median mononeuropathy than workers who were normal or slender (BMI < 25). There was no significant interaction between BMI and worksite in relation to median mononeuropathy. Increasing age was also related to an increased risk of median mononeuropathy. CONCLUSIONS: Obesity, industrial work, and age are independent risk factors that influence the prevalence of median mononeuropathies among active workers.
Adolescent↗
Test-retest reliability of an upper-extremity discomfort questionnaire in an industrial population.
OBJECTIVES: Efforts to understand or to monitor upper-extremity musculoskeletal disorders among workers have usually involved the use of questionnaires. The goal of this study was to assess the test-retest reliability of an upper-extremity discomfort questionnaire among industrial workers. METHODS: Test-retest agreement among 148 workers was analyzed using the kappa coefficient for categorical outcomes. Values of kappa greater than 0.75 are considered excellent, values between 0.40 and 0.75 are fair to good, and values of less than 0.40 represent poor agreement beyond chance alone. Test-retest results of continuous measures (eg, visual analogue scale responses) were compared with paired t-tests. RESULTS: The test-retest reliability of the questionnaire used to elicit demographic information, medical history, exercise participation, and information on musculoskeletal symptoms among industrial workers appears to be good to excellent in most instances. CONCLUSIONS: These results suggest that most results of this discomfort questionnaire are reliable and suitable for use in epidemiologic studies. For reassurance of the robustness of these findings, similar studies should be carried out in other worker populations with this, and other, questionnaire instruments.
Adult↗
Hypersensitivity pneumonitis-like reaction and occupational asthma associated with 1,3-bis(isocyanatomethyl) cyclohexane pre-polymer.
Twenty-three of 34 workers who had worked in the injection molding operation making polyurethane foam parts at an automobile parts manufacturing plant developed respiratory symptoms and/or systemic symptoms over a 2-month period following the full production use of a new diisocyanate paint that contained 1,3-bis(isocyanatomethyl)cyclohexane pre-polymer (BIC)(CAS #75138-76-0, 38661-72-2). At 3 months, all subjects underwent an interview, physical examination, pre- and post-shift pulmonary function tests, and either methacholine challenge test or bronchodilator challenge at an occupational health clinic. The most frequently cited symptoms were dyspnea (65%), cough (61%), chest tightness (57%), chills (57%), wheezing (30%), and myalgias, arthralgias, and nausea (26%). Thirteen subjects had either a positive methacholine challenge test or a positive response to bronchodilator challenge, making the overall prevalence of airway hyperresponsiveness 38%. The overall prevalence of hypersensitivity pneumonitis-like reactions among line operators in the injection molding process was 27%. This disease outbreak suggests that 1,3-bis(isocyanatomethyl)cyclohexane pre-polymer may cause asthma and hypersensitivity pneumonitis-like reactions. The use of BIC was discontinued 6 months after the first workers developed symptoms.
Adult↗
Airborne emissions at skin surfaces: a potential biological exposure index.
Dermal exposures of methanol were administered in a clinical study designed to compare several biological indicators. Four subjects were exposed in five exposure sessions of varying length. In each session, a sequence of measurements of methanol concentrations in blood, breath, and headspace samples of air at exposed and unexposed skin were collected before and after dermal exposures. Skin headspace samples, collected in gas sampling bags, were designed to reflect equilibrium skin: air partitioning. At exposed skin, headspace samples were highly elevated for at least 8 h following exposure, indicating the presence of a methanol reservoir in skin. After exposure, methanol concentrations at exposed skin showed a rapid initial decline, then a slower first-order decrease. Methanol concentrations were clearly detectable in headspace samples at unexposed skin. Substantial transfer from exposed skin occurred due to mechanical contact and washing. When transfer was restricted, surface concentrations at unexposed skin were similar to levels in breath and were strongly correlated to methanol concentrations in blood. While results are preliminary due to the small sample sizes and several unresolved experimental issues, the simple, rapid, and noninvasive skin headspace measurements appear useful as a biological exposure indicator that clearly shows the presence and site of a dermal exposure, and measurements at unexposed skin reflect concentrations in blood.
Adult↗
Hand dominance effect on median and ulnar sensory evoked amplitude and latency in asymptomatic workers.
OBJECTIVE: To examine the relative effect of hand dominance on the median and ulnar sensory evoked responses and grip strength in active workers. DESIGN: A cross-sectional or survey design. SETTING: Workers from 4 different sites underwent on-site testing of the median and ulnar sensory nerves in both hands (antidromic stimulation, 14 cm), and testing of bilateral grip strength. PATIENTS: 224 workers, asymptomatic of hand, wrist, or finger pain, numbness, or tingling: 87% were right handed. MAIN OUTCOME MEASURES: Amplitude and latency of the median and ulnar sensory response and the grip strength of each hand. RESULTS: The amplitude of the median sensory response in the dominant hand was significantly lower in right handed individuals (34.6 microm V versus 38.8 microm V) but not in left handed workers (34.2 microm V versus 34.3 microm V). A similar relationship held for the ulnar evoked responses and the grip strength. Median and ulnar sensory latencies in right handed individuals did not differ side to side, whereas left handed workers had a slightly shorter latency on the left. CONCLUSIONS: The left hand of a right handed worker may not be exposed to as much trauma, resulting in relative protection of the nerves in the hand and a higher amplitude of the left median and ulnar evoked response. Left handed individuals may be more likely to use both hands equally and thus expose the nerves in each hand to an equal amount of trauma, resulting in their sensory amplitudes being equivalent (and also equal to the dominant hand of a right handed individual).
Adult↗
The relationship of vitamin B6 status to median nerve function and carpal tunnel syndrome among active industrial workers.
Case reports and small case series suggest that vitamin B6 deficiency is an important etiologic factor in carpal tunnel syndrome (CTS). This hypothesis has never examined in a randomly selected study population, particularly among active workers. We examined 125 randomly selected active workers from two industrial plants. Each worker completed a self-administered symptom questionnaire and underwent electrodiagnostic testing of the median and ulnar sensory nerves. Laboratory biochemical analyses of vitamin B6 status were also performed using the erythrocyte glutamic pyruvic transaminase assay, and quantification of plasma pyridoxal-5'-phosphate. Measurements of vitamin B6 status were unrelated to self-reported symptoms potentially consistent with CTS, electrophysiologically determined median or ulnar nerve function, and CTS defined on the basis of self-reported symptoms and electrophysiologic measurements. These results suggest that CTS among active industrial workers is unrelated to vitamin B6 status. Furthermore, in our opinion, empiric prescription of vitamin B6 to patients with CTS is unwarranted and potentially hazardous.
Adult↗
RADS after exposure to a riot-control agent: a case report.
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Chronic Disease↗
The relationship between body mass index and the diagnosis of carpal tunnel syndrome.
Increased weight and, more recently, body mass index (BMI), have been suggested as risk factors for carpal tunnel syndrome (CTS). In an effort to determine the relative risk (RR) of obesity in the development of CTS, 949 patients who had an evaluation of the right upper extremity that included motor and sensory conduction studies of the median and ulnar nerves were reviewed. Of these patients, 261 were diagnosed with a median mononeuropathy at the wrist. Those individuals who were classified as obese (BMI > 29) were 2.5 times more likely than slender individuals (BMI < 20) to be diagnosed with CTS. Forty-three percent of obese women and 32% of obese men had the diagnosis of CTS compared to 21% of slender women and 0% of slender men.
Adult↗
Quantitative vibrometry and electrophysiological assessment in screening for carpal tunnel syndrome among industrial workers: a comparison.
Vibrometry has been demonstrated to be an effective adjunct to electrophysiological evaluation of nerve integrity in diffuse peripheral neuropathies but there is controversy over its value in the diagnosis of isolated compression neuropathy such as carpal tunnel syndrome (CTS). One hundred thirty factory workers were screened for peripheral nerve impairment using both vibrometry and electrophysiologic testing of digits 2 and 5 in both hands. Vibrometry had a low sensitivity in identifying individuals with symptoms of CTS or a median mononeuropathy defined by nerve conduction studies (NCS). The correlation of vibratory and the sensory evoked latencies were modest in the median nerve distribution (r = 0.297 to 0.370, p = 0.001). Using a comparison between vibration thresholds from digit 2 to 5 was not helpful in identifying cases of CTS and the difference in thresholds did not correlate with the difference in sensory evoked latencies. CTS is primarily a demyelinating process and can be easily detected with NCS. Because vibration threshold sensation is related to axonal loss it is not as sensitive in early CTS. Our results do not support the use of quantitative vibrometry as a screening tool median nerve impairment among industrial workers.
Adult↗
A computerized method for assessment of musculoskeletal discomfort in the workforce: a tool for surveillance.
A musculoskeletal discomfort survey was conducted to assess musculoskeletal discomforts among rural mail carriers in two post offices. Perceived musculoskeletal discomfort was collected directly from the workforce by means of a computerized discomfort assessment system (DAS). This investigation aimed at: (1) assessing the rural mail carrier's perception of DAS; and (2) assessing the rural mail carrier's musculoskeletal discomforts resulting from work. Most participants in the study found the computer tool easy to learn and easy to use. The information collected by DAS was used: (1) to determine the number of participating employees who were experiencing some kind of musculoskeletal problem; (2) to determine subtasks associated with discomfort; (3) to determine the body areas most affected by different subtasks; and (4) to investigate the patterns of discomfort that occurred with time.
Adult↗
Evaluation of current perception threshold testing as a screening procedure for carpal tunnel syndrome among industrial workers.
Eighty-four workers participated in a work-site screening program designed, in part, to estimate the prevalence of carpal tunnel syndrome (CTS). Each worker completed a discomfort survey, limited electrodiagnostic testing of the median and ulnar sensory nerves in each wrist, and current perception threshold (CPT) testing in the right 2nd digit using the NEUROMETER CPT device. A subset of study participants also completed CPT testing in digit 5 on the right (n = 33). Comparisons were made among the CPT results, symptoms consistent with CTS, and electrophysiologic findings. The CPT results correlated poorly with electrophysiologic parameters from the same nerve distribution, and CPT results were statistically unrelated to self-reported symptoms that may be suggestive of CTS. The test performance characteristics of CPT testing (sensitivity, specificity, positive predictive value, and negative predictive value) were low in comparison with electrodiagnostic measurements and self-reported symptoms consistent with CTS. The electrophysiologic results were significantly associated with the constellation of symptoms that are consistent with CTS. On the basis of these results, CPT testing cannot be recommended as a screening procedure for identification of possible cases of CTS among active industrial workers.
Adult↗