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).

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.

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.

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.

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).

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.

Incidence of carpal tunnel syndrome among automobile assembly workers and assessment of risk factors.

OBJECTIVES: This study defined the incidence rate of carpal tunnel syndrome (CTS) among active assembly workers and evaluated risk factors. METHODS: This study followed 189 automobile assembly workers over 1 year. Incident cases were defined as workers who had no current or prior history of CTS and were subsequently diagnosed with CTS by means of active surveillance during the study. RESULTS: The estimated annual incidence rate ranged from 1% to 10%, depending on the case definition. Significant predictors for CTS include a higher baseline median-ulnar peak latency difference, history of wrist/hand/finger tendonitis, history of diabetes, nonneutral wrist and elbow postures, and a lower self-reported social support. CONCLUSIONS: This is similar to other prospective studies that demonstrate both ergonomic and medical history are independent risk factors for development of CTS.

Risk factors for visiting a medical department because of upper-extremity musculoskeletal disorders.

OBJECTIVES: This study followed 279 auto assembly workers over 1 year to identify which factors influenced whether a worker would visit the plant medical department because of an upper-extremity musculoskeletal problem. METHODS: Incident cases were defined as involving workers who had not gone to the plant medical department in the preceding 6 months and then subsequently visited the medical department with a work-related musculoskeletal disorder that was potentially due to repetitive work activity (acute fractures or lacerations were excluded). RESULTS: There were 45 cases identified during the study period. Based on Cox regression analysis, significant predictors for visiting a medical department included exceeding the threshold limit value for hand activity and peak force, a history of diabetes, a current diagnosis of carpal tunnel syndrome, elbow tendonitis, and age under 40 years. CONCLUSIONS: The results of this study are consistent with those of other prospective studies that showed that both ergonomic and past medical history are risk factors for an upper-extremity musculoskeletal disorder and suggests that there is a healthy worker or survivor effect among older workers.

Prevalence of upper extremity symptoms and disorders among dental and dental hygiene students.

CONTEXT: Upper extremity musculoskeletal disorders are common among dental professionals. The natural history of these disorders is not well-understood. These disorders are more common in older workers, but the prevalence among younger workers has not been well-studied. OBJECTIVE: The objective of this study was to determine if dental/dental hygiene students had a similar prevalence of upper extremity musculoskeletal disorders compared to age-matched clerical workers. We hypothesize students will have a lower prevalence of upper extremity musculoskeletal disorders compared to clerical workers. DESIGN: This was a cross-sectional design. SETTING: Dental and dental hygiene students from three schools were compared to clerical workers from three locations (an insurance company and two data processing plants). SUBJECTS: There were 343 dental and dental hygiene students and 164 age-matched clerical workers. MAIN OUTCOME MEASURES: Regional discomfort was the primary outcome. The secondary health outcomes were diagnoses of carpal tunnel syndrome and upper extremity tendinitis. RESULTS: Clerical workers had a higher prevalence of hand symptoms (62 percent vs. 20 percent), elbow symptoms (34 percent vs. 6 percent) and shoulder/neck symptoms (48 percent vs. 16 percent) and a higher prevalence of carpal tunnel syndrome (2.5 percent vs. .6 percent) and upper extremity tendinitis (12 percent vs. 5 percent). The clerical workers were more obese, smoked more, exercised less frequently, and had lower educational levels and less control of their work environment. CONCLUSIONS: Dental and dental hygiene students have a very low prevalence of upper extremity musculoskeletal disorders. A longitudinal study is necessary to evaluate ergonomic and personal risk factors.

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.

Carpal tunnel syndrome: pathophysiology and clinical neurophysiology.

Carpal tunnel syndrome (CTS) is a constellation of symptoms associated with compression of the median nerve at the wrist. The pathophysiology of CTS is not fully understood but mechanical aspects of injury within the carpal tunnel are most likely. The issues of ischemia, mechanical trauma, ectopic impulse generation, demyelination, tendonitis, elevated carpal tunnel pressure, mechanical factors, small and large fiber involvement and the variability of symptoms are presented. Documentation of neurophysiologic abnormalities in the median nerve is helpful to establish the diagnosis for CTS. There are several types of clinical neurophysiologic evaluations of the median nerve across the wrist. Sensory and motor nerve conduction studies (NCS) of the median nerve segment across the wrist compared to another nerve segment that does not go through the carpal tunnel (i.e. median, radial, or ulnar) are the most sensitive and accurate techniques. Other neurophysiologic techniques used to document CTS include vibrometry threshold testing, current perception testing, Semmes-Weinstein monofilament testing and two-point discrimination. These techniques have considerable subjective components and have not been found to be as sensitive as traditional NCS.

Preplacement nerve testing for carpal tunnel syndrome: is it cost effective?

UNLABELLED: Is not hiring otherwise-qualified workers who have an abnormal post-offer preplacement (POPP) median nerve test a cost-effective strategy to reduce workers' compensation expenses related to carpal tunnel syndrome (CTS)? We performed a retrospective dynamic cohort study based on 2150 workers hired at a company between January 1996 and December 2001 and who underwent POPP median nerve testing. Workers were followed until they left the company or until follow-up ended in May 2003. RESULTS: Thirty-five cases of work-related CTS occurred during follow-up, and 9.13 cases could have been avoided. However, if the company had not hired workers with abnormal POPP nerve test results, it would have suffered a net loss of $357,353. CONCLUSION: Not hiring workers with abnormal POPP nerve tests to reduce costs of work-related CTS is not a cost-effective strategy for employers.

Prevalence of carpal tunnel syndrome and upper extremity tendinitis among dental hygienists.

PURPOSE: This study was undertaken to determine the prevalence of carpal tunnel syndrome (CTS) and upper extremity (UE) tendinitis among dental hygienists. METHODS: In a cross-sectional study dental hygienists (n = 305) were screened using sensory nerve conduction, a focused physical examination of the UE, and a symptom questionnaire. CTS was diagnosed if the subject had slowing of the median nerve at the wrist and symptoms of numbness, tingling of pain in the median distribution. Localized tendinitis of the UE was diagnosed if the subject had focal symptoms and associated findings on physical examination. RESULTS: Three percent of the participating dental hygienists were diagnosed with CTS. Thirteen were diagnosed with shoulder tendinitis, while 6% had a tendinitis of the elbow and 7% had tendinitis of the hand or wrist. Twenty-eight percent had a diagnosis of some UE tendinitis or CTS. CONCLUSIONS: The prevalence of hand and finger symptoms in the dominant hand among dental hygienists in this study was high, but the prevalence for CTS was nearly the same as the general population. There was a high rate of UE tendinitis noted within this population.