Carpal tunnel syndrome affects approximately 3 percent of adults in the United States. Pain and paresthesias in the distribution of the median nerve are the classic symptoms. While Tinel's sign and a positive Phalen's maneuver are classic clinical signs of the syndrome, hypalgesia and weak thumb abduction are more predictive of abnormal nerve conduction studies. Conservative treatment options include splinting the wrist in a neutral position and ultrasound therapy. Orally administered corticosteroids can be effective for short-term management (two to four weeks), but local corticosteroid injections may improve symptoms for a longer period. A recent systematic review demonstrated that nonsteroidal anti-inflammatory drugs, pyridoxine, and diuretics are no more effective than placebo in relieving the symptoms of carpal tunnel syndrome. If symptoms are refractory to conservative measures or if nerve conduction studies show severe entrapment, open or endoscopic carpal tunnel release may be necessary. Carpal tunnel syndrome should be treated conservatively in pregnant women because spontaneous postpartum resolution is common.

Management of carpal tunnel syndrome.

Objective: To assess whether work-related physical activities are associated with Carpal tunnel syndrome (CTS), even when controlling for personal risk factors. Methods: A cross-sectional assessment of 1108 workers from eight employers and three unions completed nerve conduction testing, physical examination, and questionnaires. CTS was defined by median neuropathy and associated symptoms. Results: Eighteen workers had CTS and 131 had evidence of median neuropathy. CTS was highest among construction workers (3.0%) compared to other subjects (<1%). Logistic regression models for median neuropathy both personal and work-related risk factors. Work-related exposures were estimated by two methods: self-report and job title based ratings. Conclusions: Both work and personal factors mediated median nerve impairment. Construction workers are at an increased risk of CTS so awareness should be raised and interventions should specifically target this risk group.

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Risk factors for carpal tunnel syndrome and median neuropathy in a working population.

Objectives: Carpal tunnel syndrome (CTS) is common in the industrial setting but there are still some advocates who argue that CTS is not a work related problem. There are also controversies about the proper way to establish the diagnosis and whether screening for CTS in the industrial setting is warranted. Methods: A comprehensive literature review. Results: The literature does demonstrate that the prevalence of CTS in the industrial setting is significantly higher than in the general population. Numerous epidemiologic studies have identified independent risk factors, which include repetitiveness of work, forceful exertions, mechanical stress, posture, and vibration as well as several personal co-factors. The strength of these associations are discussed. The diagnostic criteria for establishing work-related CTS are discussed as well as the effectiveness of various screening methods that are commonly used in the workplace. The sensitivity and specificity of nerve conduction studies to establish or confirm the diagnosis of CTS is presented along with normative data for the industrial worker. Conclusions: CTS has both work-related and personal risk factors. The diagnosis is best established using a combination of history, symptom distribution and confirmation using the relative latency of median sensory testing using normative data. Screening for CTS in the industrial setting has questionable benefit.

Evaluation of Work-Related Carpal Tunnel Syndrome

Objectives The incidence of upper-limb, neck-shoulder, and low-back disorders and their induction times were investigated among new workers in tasks with various physical workloads.

Methods New trailer assemblers (N=364) were followed prospectively for 45 months - the workers` health status via medical records and exposure to physical workload factors via job titles, walk-throughs, task descriptions, and some direct measurements. The incidence rate of first sick leave due to such disorders was calculated for different workload groups. The proportion of workers surviving without musculoskeletal disorders was estimated by the Kaplan-Maier product-limit estimator, and the effect of the exposure on the risk of incident disorders was estimated with the Cox proportional hazards model.

Results The highest annual incidences were observed for strenuous tasks, the incidence rate for men being 16.8 per 100 person-years [95% confidence interval (95% CI) 8.0-30.9] for upper-limb disorders in strenuous tasks and 6.1 (95% CI 2.0-14.1) in nonstrenuous tasks and that for women being 32.0 (95% CI 11.7-69.7) and 9.9 (95% CI 0.2-54.9), respectively. The men`s risk of contracting an upper-limb or neck-shoulder disorder in strenuous tasks was about threefold [hazard ratio (HR) 3.2 (95% CI 1.1-9.4) for upper-limb disorders and 2.7 (95% CI 0.9-8.1) for neck-shoulder disorders] that of nonstrenuous tasks, whereas workload seemed not to affect low-back disorders. The workers first sought medical advice for their disorders typically some months after employment began.

Conclusions Newly employed workers in hand-intensive tasks have a high risk of upper-limb and neck-shoulder disorders. An etiologic role for activities involving high force demands in upper-limb and neck-shoulder disorders is possible.

Incidence of musculoskeletal disorders among newly employed manufacturing workers.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/jor.20363

Towards development of a nonhuman primate model of carpal tunnel syndrome: performance of a voluntary, repetitive pinching task induces median mononeuropathy in Macaca fascicularis.

There is some controversy regarding the relationship between development of median nerve dysfunction and employment activities. We performed nerve conduction studies of median nerve function on individuals before and after starting employment in the pork processing industry. After working an average of 64 days, employees (n = 45) showed significant prolongation of median motor and sensory nerve latency when comparing initial and final testing results in both dominant and non-dominant hands (P = < 0.01 to 0.03). A similar trend was found when testing a smaller group of employees (n = 17) who were already working (mean of 3 days), though this did not generally reach statistical significance. This study supports the conclusion that prolongation of median motor and sensory nerve latency can occur within as little as 2 months after beginning employment in the pork processing industry.

Paul Eby

Papers

Pre- and post-employment median nerve latency in pork processing employees.