Current Trends Occupational Disease Surveillance: Carpal Tunnel Syndrome

Manifestations of carpal tunnel syndrome (CTS) (see box, page 486) include pain, numbness, and weakness in the median nerve distribution of the hand as a result of compression or irritation of the median nerve as it passes through the carpal tunnel in the wrist (3). Without intervention, CTS can lead to marked discomfort, impaired hand function, and disability. Workers who perform repetitive tasks are at risk for CTS and include garment workers, butchers, grocery checkers, electronics assembly workers, typists, musicians, packers, housekeepers/cooks, and carpenters (4,5). However, no reliable data exist on the frequency of work-related CTS in the general working population. Surveillance of work-related CTS is limited because of inadequate training of health professionals (6) and underreporting of recognized cases (7). In addition, standard definitions for work-related musculoskeletal injuries are necessary to improve surveillance (8).

In early 1988, the California Occupational Health Program (COHP) surveyed health-care practitioners to measure the occurrence of this condition in Santa Clara County (1987 population, 1.4 million), which has a variety of service and manufacturing industries, and to compare these studies with cases actually reported to the state. The survey was conducted as part of the Sentinel Event Notification System for Occupational Risks (SENSOR) program--a collaborative effort involving the National Institute for Occupational Safety and Health (NIOSH), of CDC, and 10 state health departments--which is intended to improve occupational disease surveillance at the state and local levels.

COHP staff identified 1698 Santa Clara County health-care providers who practiced in specialties and settings considered to be relevant to the care of CTS patients. Practitioners were administered questionnaires by either telephone or mail. Of 515 (30%) providers who responded, 489 (95%) reported caring for a total of 7214 CTS patients in 1987. Of these, responding providers believed 3413 (47%) cases may have been work-related. Work-related cases were seen by 377 providers in various settings, including internal medicine, industrial/occupational medicine, chiropractic, and physical therapy (Table 1).

In contrast to these figures, 71 cases of work-related CTS were reported in 1986 from Santa Clara County under the California Doctor's First Report program, which requires that physicians report all cases of suspected occupational injury or illness to the state. Even though the Santa Clara County provider survey may have counted some CTS cases more than once, the low overall response rate (30%) suggests that the number of reported work-related cases may be an underestimation of the annual occurrence of CTS in the county. The data also indicate that work-related CTS is greatly underreported to the Doctor's First Report program. Reported by: K Cummings, MPH, N Maizlish, PhD, L Rudolph, MD, K Dervin, MPH, A Ervin, Epidemiologic Studies Section, California Occupational Health Program, California Dept of Health Svcs. Div of Surveillance, Hazard Evaluations, and Field Studies, and Office of the Director, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: Work-related CTS is a cumulative trauma disorder (4) caused by job tasks that subject the hand and wrist to certain biomechanical stresses, including 1) repetitive movements of the hand, 2) forceful grasping or pinching of tools or other objects, 3) awkward positions of the hand and wrist, 4) direct pressure over the carpal tunnel, and 5) use of vibrating hand-held tools (5). Because repetitive hand movements are required in many service and industrial occupations, new high-risk groups for CTS and other cumulative trauma disorders continue to be identified. Nonoccupational factors associated with CTS include diabetes mellitus, rheumatoid arthritis, and pregnancy (5); patients with nonoccupational risk factors are also at risk for work-related CTS.

The diagnosis is confirmed by physical examination or electrodiagnostic studies (5). Other conditions that produce similar symptoms should be excluded by appropriate clinical evaluation. Even though CTS can often be managed with conservative measures (e.g., wrist immobilization and nonsteroidal anti-inflammatory medications (4)), recognition of work-related CTS is important, since without job redesign or reassignment, symptoms are likely to recur when the patient resumes the precipitating tasks (4). For all patients with symptoms suggestive of CTS, an occupational history should be obtained that includes a description of tasks involving use of the hands. Failure to eliminate contributory job factors can result in recurrence or progression of symptoms, impaired use of the hand, and the need for surgical treatment. Redesign of tools, workstations, and job tasks can prevent occurrence of CTS among co-workers (4). Surveillance of work-related CTS, including the use of health-care-provider reports, can aid in identifying high-risk workplaces, occupations, and industries and in directing appropriate preventive measures.

The COHP survey indicates that although work-related CTS was commonly recognized by health-care providers, it was substantially underreported. Even though more than half the states have reporting programs for occupational illnesses (9), underreporting is common (7).

The SENSOR program aims to help state health departments increase both health-care-provider reporting of work-related illness and prevention efforts. To facilitate these provider-based surveillance activities and to enhance uniformity of reporting in the states, NIOSH will periodically disseminate recommended surveillance case definitions for selected occupational diseases and injuries. Because these definitions are designed for surveillance-related functions, they may differ from those used for other purposes, such as determining workers' compensation or level of disability.

The surveillance case definition for work-related CTS* (criteria A, B, and C, see box) is recommended for surveillance of work-related CTS by state health departments receiving reports of cases from physicians and other health-care providers. In certain settings, such as workplace surveys, a case definition consisting of criteria A and C can be used. References

1. Sandzen SC Jr. Carpal tunnel syndrome. Am Fam Physician 1981;24:190-204.

2. Goodgold J, Eberstein A. Electrodiagnosis of neuromuscular diseases. 2nd ed. Baltimore: Williams & Wilkins, 1977.

3. Bleecker ML, Agnew J. New techniques for the diagnosis of carpal tunnel syndrome. Scand J Work Environ Health 1987;13:385-8.

4. Putz-Anderson V, ed. Cumulative trauma disorders: a manual for musculoskeletal diseases of the upper limbs. London: Taylor and Francis, 1988.

5. Feldman RG, Goldman R, Keyserling WM. Classical syndromes in occupational medicine: peripheral nerve entrapment syndromes and ergonomic factors. Am J Ind Med 1983;4: 661-81.

6. Wegman DH, Froines JR. Surveillance needs for occupational health (Editorial). Am J Public Health 1985;75:1259-61.

7. Seixas NS, Rosenman KD. Voluntary reporting system for occupational disease: pilot project, evaluation. Public Health Rep 1986;101:278-82.

8. Association of Schools of Public Health/National Institute for Occupational Safety and Health. Proposed national strategies for the prevention of leading work-related diseases and injuries: part 1. Washington, DC: Association of Schools of Public Health, 1986:17-34.

9. Muldoon JT, Wintermeyer LA, Eure JA, et al. Occupational disease surveillance data sources, 1985. Am J Public Health 1987;77:1006-8. *This definition was reviewed and approved by a panel of consultants convened by NIOSH that comprise the Surveillance Subcommittee of the NIOSH Board of Scientific Counselors: H Anderson, MD, Wisconsin Department of Health and Social Services; M Cullen, MD, Yale University School of Medicine; E Eisen, ScD, Harvard School of Public Health; R Feldman, MD, Boston University School of Medicine; J Hughes, MD, University of California, San Francisco; MJ Jacobs, MD, University of California, Berkeley; K Kriess, MD, National Jewish Center for Immunology and Respiratory Medicine; J Melius, MD, New York State Department of Health; J Peters, MD, University of Southern California School of Medicine; D Wegman, MD, University of Lowell.

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