Evidence-based guideline: Neuromuscular ultrasound for the diagnosis of ulnar neuropathy at the elbow.

INTRODUCTION/AIMS: The purpose of this literature review is to develop an evidence-based guideline for the use of neuromuscular ultrasound in the diagnosis of ulnar neuropathy at the elbow (UNE). The proposed research question was: "In patients with suspected UNE, does ulnar nerve enlargement as measured with ultrasound accurately identify those patients with UNE?" METHODS: A systematic review and meta-analysis was performed, and studies were classified according to American Academy of Neurology criteria for rating articles for diagnostic accuracy. RESULTS: Based on Class I evidence in four studies, it is probable that neuromuscular ultrasound measurement of the ulnar nerve at the elbow, either of diameter or cross-sectional area (CSA), is accurate for the diagnosis of UNE. RECOMMENDATION: For patients with symptoms and signs suggestive of ulnar neuropathy, clinicians should offer ultrasonographic measurement of ulnar nerve cross-sectional area or diameter to confirm the diagnosis and localize the site of compression (Level B).

Ulnar Neuropathy Among Active Workers Based Upon Hand Diagram Ratings.

BACKGROUND: Limited studies have estimated the prevalence of ulnar neuropathy (UN) in the workplace. Hand diagrams have been demonstrated to have a good sensitivity and specificity when attempting to identify patients with UN. OBJECTIVE: To determine the prevalence and associated risk factors for UN among active workers based on results of a hand diagram, and to determine the reliability of hand diagram scoring. DESIGN: Cross-sectional study. SETTING: Seven different industrial and clerical work sites. METHODS: A total of 501 active workers were screened. Subjects completed a hand diagram and the Job Content Questionnaire, and had ergonomic assessment of their job. Each hand diagram was scored independently by 2 raters. MAIN OUTCOME MEASURES: Rating of the hand diagram for UN. RESULTS: Interrater reliability of scoring the hand diagram for UN was very high. The estimated prevalence of UN was 3.6%. Suspected UN was associated with positioning of the elbow but not by contact stress at the elbow or force at the hand. Smokers had a lower prevalence, but smokers with suspected UN had higher-pack year histories. Workers with suspected UN had a greater sense of job insecurity and lower job satisfaction rating. CONCLUSIONS: Hand diagram rating has a high interrater reliability. Suspected UN has a relatively high prevalence among active workers in comparison to prior estimates of the prevalence of UN among the general population and is not strongly associated with ergonomic factors.

Electrodiagnostic evaluation of carpal tunnel syndrome and ulnar neuropathies.

Carpal tunnel syndrome (CTS) and ulnar mononeuropathies at the elbow and wrist are the most common nerve entrapments in the upper extremities. Electrodiagnostic studies are a valid and reliable means of confirming the clinical diagnosis. This review addresses various electrodiagnostic techniques to evaluate the median and ulnar nerves at the wrist and elbow. It also discusses the limitations of electrodiagnostic studies with regard to the sensitivity and specificity of such testing.

Use of hand diagrams in screening for ulnar neuropathy: comparison with electrodiagnostic studies.

INTRODUCTION: The objective of this study was to determine whether a hand diagram could be used to predict ulnar mononeuropathy. METHODS: This was a prospective study of 117 consecutive patients referred for hand symptoms. Each subject filled out a hand diagram of symptoms and had median and ulnar sensory and motor nerve conduction studies, including ulnar conduction across the elbow. RESULTS: The best model for predicting an ulnar mononeuropathy included hand diagram scores of definite or possible. The model had a sensitivity of 50% and specificity of 93% with an ROC area of 0.90. CONCLUSIONS: The ulnar hand diagram scoring system can be useful as a screening tool in the electrodiagnostic laboratory or for epidemiologic studies.

Evidence-based guideline: neuromuscular ultrasound for the diagnosis of carpal tunnel syndrome.

INTRODUCTION: The purpose of this study was to develop an evidence-based guideline for the use of neuromuscular ultrasound in the diagnosis of carpal tunnel syndrome (CTS). METHODS: Two questions were asked: (1) What is the accuracy of median nerve cross-sectional area enlargement as measured with ultrasound for the diagnosis of CTS? (2) What added value, if any, does neuromuscular ultrasound provide over electrodiagnostic studies alone for the diagnosis of CTS? A systematic review was performed, and studies were classified according to American Academy of Neurology criteria for rating articles of diagnostic accuracy (question 1) and for screening articles (question 2). RESULTS: Neuromuscular ultrasound measurement of median nerve cross-sectional area at the wrist is accurate and may be offered as a diagnostic test for CTS (Level A). Neuromuscular ultrasound probably adds value to electrodiagnostic studies when diagnosing CTS and should be considered in screening for structural abnormalities at the wrist in those with CTS (Level B).

Does the presence of the palmaris longus tendon influence median nerve function?

INTRODUCTION: The objective of this study was to determine if the presence or absence of a palmaris longis tendon influenced the function of the median nerve across the wrist. The primary hypothesis was that the presence of a palmaris longus tendon would be associated with more median nerve entrapment at the wrist. METHODS: This was a cross-sectional study. Subjects were recruited at a screening of dental professionals. The median and ulnar sensory nerve latencies across the wrist (relative prolongation of the median compared with the ulnar) and the presence or absence of the palmaris longus tendon were the primary outcome measures. RESULTS: A total of 462 subjects were recruited into the study of which 16.2% lacked a palmaris longus tendon. There was no difference in the median nerve function or the percentage with a 0.5 ms prolongation of the median sensory latency when comparing subjects with and without a palmaris longus tendon. CONCLUSIONS: The presence of a palmaris longus tendon does not influence the median nerve function across the wrist.

The effect of prolonged standing on touch sensitivity threshold of the foot: a pilot study.

OBJECTIVE: To determine the effect of prolonged standing on touch sensitivity of the foot. DESIGN: An observational study with replications. SETTING: University laboratory. PARTICIPANTS: Ten healthy college students (5 men and 5 women), with a mean ± SD age of 23.5 ± 4.1 years and body mass of 67.4 ± 12.6 kg. METHODS: Semmes-Weinstein monofilament tests were administered to 12 locations on the dorsal and plantar surfaces of the foot before and after 4 hours of standing. These locations were formed into several groupings (toes, metatarsal heads, midfoot, heel, all plantar sites, all dorsal sites), and paired t-tests were used to test for significant changes in sensitivity threshold after standing. MAIN OUTCOME MEASUREMENT: The difference between sensitivity thresholds measured before and after standing for different locations on the foot. RESULTS: The average of all sensitivity thresholds on the plantar surface of the foot decreased (indicating increased sensitivity) from 0.56 to 0.36 g (P < .01) after 4 hours of prolonged standing. This change in threshold equated to a difference of 1 Semmes-Weinstein monofilament level. Changes in the sensitivity threshold of the dorsal aspect of the foot were not significant. CONCLUSIONS: Analysis of the results suggests that the plantar foot has greater sensitivity to touch after prolonged standing. These findings may be useful for identifying potential unintended bias in clinical touch sensitivity testing. Future research is necessary to understand the underlying mechanisms for this sensitivity change and to determine the onset and recovery times for sensitivity changes.

Low-level mercury exposure and peripheral nerve function.

BACKGROUND: Mercury is known to be neurotoxic at high levels. There have been few studies of potential peripheral neurotoxicity among persons with exposure to elemental mercury at or near background levels. OBJECTIVES: The present study sought to examine the association between urinary mercury concentration and peripheral nerve function as assessed by sensory nerve conduction studies in a large group of dental professionals. METHODS: From 1997 through 2006 urine mercury measurements and sensory nerve conduction of the median and ulnar nerves in the dominant hand were performed, and questionnaires were completed, on the same day in a convenience sample of dental professionals who attended annual conventions of the American Dental Association. Linear regression models, including repeated measures models, were used to assess the association of urine mercury with measured nerve function. RESULTS: 3594 observations from 2656 subjects were available for analyses. Urine mercury levels in our study population were higher than, but substantially overlap with, the general population. The only stable significant positive association involved median (not ulnar) sensory peak latency, and only for the model that was based on initial observations and exclusion of subjects with imputed BMI. The present study found no significant association between median or ulnar amplitudes and urine mercury concentration. CONCLUSIONS: At levels of urine mercury that overlap with the general population we found no consistent effect of urine mercury concentration on objectively measured sensory nerve function.

Differential aging of median and ulnar sensory nerve parameters.

INTRODUCTION: Nerve conduction velocity slows and amplitude declines with aging. METHODS: Median and ulnar sensory nerves were tested at the annual meetings of the American Dental Association. Seven hundred four subjects had at least two observations. The rate of change in the nerve parameters was estimated while controlling for gender, age, change in hand temperature, baseline body mass index (BMI), and change in BMI. RESULTS: Amplitudes of the median sensory nerve action potentials decreased by 0.58 µV per year, whereas conduction velocity decreased at a rate of 0.41 m/s per year. Corresponding values for the ulnar nerve were 0.89 µV and 0.29 m/s per year. The rates of change in amplitudes did not differ, but the median nerve demonstrated a more rapid loss of conduction velocity. CONCLUSIONS: The rate of change for the median conduction velocity was higher than previously reported. The rate of change of median conduction velocity was significantly greater than for the ulnar nerve.

Electrodiagnostic evaluation of carpal tunnel syndrome.

Carpal tunnel syndrome (CTS) is the most common nerve entrapment. Electrodiagnostic (EDX) studies are a valid and reliable means of confirming the diagnosis. This monograph addresses the various EDX techniques used to evaluate the median nerve at the wrist. It also demonstrates the limitations of EDX studies with a focus on the sensitivity and specificity of EDX testing for CTS. The need to use reference values for populations such as diabetics and active workers, where normative values differ from conventional cutoffs used to confirm suspected CTS, is presented. The value of needle electromyography (EMG) is examined.

Risk factors for lower extremity fatigue among assembly plant workers.

BACKGROUND: Work-related fatigue of the lower extremities is a known cause of lost productivity and significant employer costs. Common workplace solutions to reduce fatigue levels include anti-fatigue matting, shoe orthoses, or sit/stand work stations. However, assessment of these anti-fatigue measures within the workplace has been limited. METHODS: This was a cross sectional study in an automotive assembly plant on employees with at least 6 months tenure. Subject data were collected via questionnaires including Likert-scale questions to define fatigue severity. Jobs were evaluated for lower extremity ergonomic exposures via videotaping, pedometers, interviews, and industrial engineering records. RESULTS: Lower extremity fatigue at the end of the work day was associated with a higher prevalence of smoking, rheumatoid arthritis, job dissatisfaction, use of shoes with firmer outsoles, and increased time on the job spent standing or walking. Supervisor support and increased time spent on carpet were protective. Lower extremity fatigue that interfered with activities outside of work had additional risk factors including higher BMI, prior diagnosis of osteoarthritis, and increased hours per week spent working. CONCLUSIONS: While these results identify carpet as being protective against lower extremity fatigue, no similar relationship was identified for anti-fatigue mats. No adverse relationship was found between hard surfaces such as concrete and lower extremity fatigue. Given the high costs associated with work-related fatigue, future areas for potential intervention include smoking cessation, specific shoe recommendations, and enhancing psychosocial aspects of work such as supervisor support.

Risk factors for hip problems among assembly plant workers.

OBJECTIVE: The objective of this study was to determine the relative contributions of work activity (time spent standing, walking or sitting), floor surface characteristics, weight, BMI, age, foot biomechanics, and other demographic and medical history factors to the prevalence of hip disorders. METHODS: A cross-sectional observational study design was used to engine assembly plant workers. The main outcome measure was the finding of a hip disorder. The independent variables included baseline demographics, medical history, ergonomic exposures, psychosocial factors, shoe characteristics and foot biomechanics. RESULTS: Logistic regression revealed that increasing age, female gender, pes planus, smoking, history of a knee or hip injury, and a history of rheumatoid arthritis were significant risk factors while time on carpeted surfaces was protective. CONCLUSIONS: Hip disorders are associated with a history of biomechanical trauma to the hip but also from gait abnormalities such as pes planus.

Risk factors for foot and ankle disorders among assembly plant workers.

BACKGROUND: Jobs that necessitate prolonged standing and walking activities are commonly associated with worker's complaints of foot and ankle pain. The objective of this study was to determine the relative contributions of work activity (time spent standing, walking, or sitting), floor surface characteristics, weight, BMI, age, foot biomechanics, and other demographic and medical history factors to the prevalence of foot and ankle disorders. METHODS: A cross-sectional observational study design was used to evaluate employees of an engine manufacturing plant. The main outcome variable was foot or ankle disorders defined by pain and a positive physical examination. The independent variables included baseline demographics, medical history, ergonomic exposures, psychosocial factors, shoe characteristics and foot biomechanics. RESULTS: Twenty-four percent of the cohort met the case definition of foot/ankle disorder with 10% defined as new cases. Fifty-two percent had symptoms of foot/ankle. An increased risk of presenting with foot/ankle disorders was associated with high metatarsal pressure on gait assessment, increased time spent walking, female gender, reported high job dissatisfaction, a history of rheumatoid arthritis, osteoporosis or vascular disorder. For the truck/forklift drivers, an increased number of times getting in and out of the vehicle was associated with a higher prevalence of ankle/foot problems. CONCLUSIONS: An increased risk is associated with higher metatarsal pressure and increased time spent walking. These findings suggest several options for primary and secondary prevention strategies. The use of shoe orthoses with a medial longitudinal arch and metatarsal pad as well as including optional sit/stand workstations may be helpful.

Inter-worker variability in lower body postures during assembly line work: implications for exposure assessment.

This study evaluated inter-worker variability in lower body posture and work activity during highly-structured assembly line work. Data were collected from 79 unique assembly line workstations in an engine manufacturing plant. Because the plant utilized work teams, 4-8 workers rotated through each workstation. At least 30 min of videotape was collected from at least three workers at each workstation. A computer-assisted work sampling procedure randomly selected 200 video "freeze-frames" for each worker. Lower body posture/movement (e.g., sit, stand, walk, etc.) was determined for each frame and used to estimate the percentage of time the worker spent in various postures and activities. Chi-square analyses were performed for each workstation to assess the significance of inter-worker differences. Due to variations in individual work methods, significant differences (p <.05) were found at 57 out of 79 workstations (72%). The greatest differences occurred when workers had the option to choose between standing and sitting (significant in 8 of 8 cases; in extreme examples, sit time ranged between 0-100% on one job, and 6.5-98% on another). Studying a single worker (or "proxy") can contribute to substantial error when estimating exposures in workplace studies of ergonomic stressors, since the proxy may not be representative of all workers who perform the job. Individual measurements are preferable, particularly for jobs where workers have substantial latitude to develop individualized work methods.

Risk factors for plantar fasciitis among assembly plant workers.

OBJECTIVE: The objective of this study was to determine the relative contributions of work activity (time spent standing, walking, or sitting), floor surface characteristics, weight, body mass index, age, foot biomechanics, and other demographic and medical history factors to the prevalence of plantar fasciitis. DESIGN: A cross-sectional observational study design was used. SETTING: The study site was an automobile engine assembly plant. PARTICIPANTS: Full-time employees of the assembly plant who had been working at least 6 months. ASSESSMENT OF RISK FACTORS: The independent variables included baseline demographics, medical history, ergonomic exposures, psychosocial factors, discomfort ratings, shoe characteristics, and foot biomechanics. MAIN OUTCOME MEASUREMENTS: The dependent variable was the finding of plantar fasciitis on physical examination. RESULTS: The study demonstrated that forefoot pronation on physical examination, high metatarsal pressure on the gait assessment, increasing time spent standing on hard surfaces, increased time spent walking, medium tenure at the plant, and an increased number of times getting in and out of the vehicle (for the truck/forklift drivers) increased the risk of presenting with plantar fasciitis. Rotation of shoes during the work week was found to reduce the risk of presenting with plantar fasciitis. Increased supervisor support showed a trend toward reducing the prevalence of plantar fasciitis. CONCLUSIONS: Plantar fasciitis is relatively common in the manufacturing setting. These findings suggest several options for primary and secondary prevention strategies. Shoe rotation may be an effective strategy that may be used as either a primary or secondary strategy. The use of shoe orthoses with a medial longitudinal arch and metatarsal pad may be used as a preventive or treatment strategy. Work stations that decrease the percentage of time walking or standing on hard surfaces (eg, allowing workers to alternate between sitting and standing postures or providing cushioning mats for concrete surfaces) may lower the risk for plantar fasciitis.

Analysis of the Third National Health and Nutrition Examination Survey (NHANES III) using expert ratings of job categories.

BACKGROUND: Few epidemiologic studies have addressed the exposure-response relationships between work activities and symptomatic knee osteoarthritis (OA). This analysis used data from a national survey and ergonomists' ratings to address this issue. METHODS: Interview and knee X-ray data were obtained from the Third National Health and Nutrition Examination Survey. Occupational ratings were obtained using ergonomists. A weighted logistic regression was used. RESULTS: Among men, a significant exposure-response relationship was found between symptomatic knee OA and kneeling. In both genders, there was a significant trend in heavy lifting and severe symptomatic knee OA. Approximately 20.7% of knee OA can be attributed to kneeling >14% of the workday among men. CONCLUSIONS: The significant exposure-response relationships suggest that modest reductions in certain occupational activities can reduce the burden of knee OA. The study was limited by unvalidated expert ratings. Research is needed to identify hazardous characteristics of work activities and to clarify exposure-response relationships.

Expert consensus ratings of job categories from the Third National Health and Nutrition Examination Survey (NHANES III).

BACKGROUND: A method of occupational physical exposure assessment is needed to improve analyses using large data sets (e.g., national surveys) that provide only job title/category information as a proxy for exposure. METHODS: Five ergonomic experts rated and arrived at consensus ratings for job categories used in the Third National Health and Nutrition Examination Survey. Interrater agreement was examined for initial (pre-consensus) ratings. Correlation between consensus ratings and an independent source of ratings (US Department of Labor (DOL)) was used as a basis of comparison. RESULTS: Interrater agreements for the initial ratings were weak. Highest interrater agreement was for sitting (weighted kappa (kappa(w)) = 0.56). Lowest agreement was for standing (kappa(w) = 0.07). Consensus ratings were well correlated with DOL ratings (correlation coefficients >or=0.6). CONCLUSIONS: The correlation between consensus ratings and DOL ratings support the use of expert consensus to assess physical exposures in national data sets. However, validation of expert consensus ratings is required.