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Occupational Medicine Advance Access originally published online on January 21, 2008
Occupational Medicine 2008 58(3):212-214; doi:10.1093/occmed/kqm157
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© The Author 2008. Published by Oxford University Press on behalf of the Society of Occupational Medicine. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org

Short Reports

Carpal tunnel syndrome in the Turkish steel industry

Muhtesem Gedizlioglu1, Esra Arpaci2, Demet Cevher1, Pinar Ce1, Can Ahmet Kulan1, Ilhan Colak2 and Baran Duzgun2

1 Izmir Teaching and Research Hospital, Bozyaka Izmir
2 Aliaga Local State Hospital, Aliaga Izmir

Correspondence to: Pinar Ce, 1420 sok N0=64/4 Kahramanlar/Izmir, Izmir 35230, Turkey. Tel: +902322505050/5241; fax: +902322614444; e-mail: kurceren{at}hotmail.com


   Abstract
Top
 Abstract
Introduction
 Methods
 Results
 Discussion
 Conflicts of interest
 References
 
Aim Certain occupations are reported to be associated with a high risk for carpal tunnel syndrome (CTS). In this study, we investigated the development of CTS in iron–steel industry workers.

Methods Subjects were recruited from a factory of 650 workers and assessed by means of history, physical examination and electrophysiological testing.

Results Seventy-nine subjects from the factory and 53 healthy controls with occupations unrelated to heavy physical work were assessed. None of the worker group had electrophysiological evidence of CTS. One subject in the control group has electrophysiological evidence of CTS. In the worker group, all sensory nerve conduction velocities and ulnar nerve action potential amplitudes in both hands and distal motor latencies were statistically different.

Conclusions In our study, among a group of heavy labourers, no cases of CTS were detected. However, all electrophysiologic parameters of workers were different from controls. Our results point to a diffuse, but subclinical injury of peripheral nerves under heavy physical work conditions, instead of a local effect such as CTS.

Keywords      Carpal tunnel syndrome; occupational; steel industry workers


   Introduction
Top
 Abstract
 Introduction
Methods
 Results
 Discussion
 Conflicts of interest
 References
 
Carpal tunnel syndrome (CTS) is traditionally thought to be the most common occupational injury of the peripheral nerves [1]. In this study, we performed electrophysiological tests on the peripheral nerves in the upper extremities of heavy labourers working in a steel industry to assess possible injury of these nerves.


   Methods
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 Abstract
 Introduction
 Methods
Results
 Discussion
 Conflicts of interest
 References
 
Seventy-nine workers of a steel factory (12% of the working population of the factory) were randomly recruited into the study between January 2005 and January 2006. The employees were selected randomly who covers the inclusion criteria. Inclusion criteria were 30–60 years of age, absence of drug or alcohol abuse, absence of systemic illnesses including diabetes mellitus or thyroid dysfunction (self-reported) and >10 years of exposure to the same job. The worker group was exposed to lifting, pushing and pulling heavy steel blocks and bars using both arms.

A control group was identified, consisting of 53 males who had relatively light jobs such as doctors, nurses and officers working for >10 years in our hospital.

All participants were asked questions regarding their number of working hours per week, paraesthesia, tingling, numbness or pain in the hands and fingers. Participants were examined by performing Phalen's and Tinel's tests. Nerve conduction studies were performed on every participant using the Nihon-Kohden Notebook apparatus. A diagnosis of CTS was made using the standardized electrophysiologic protocol for evaluation of CTS [2]. The nerve conduction studies were performed by three certified personnel after obtaining informed consent from all subjects. Participants underwent a standardized protocol measuring sensory nerve conduction velocities (SNCVs), sensory nerve action potential amplitudes, distal motor latencies, motor nerve conduction velocities (NCVs) and compound muscle action potential amplitudes. As only one ulnar nerve motor measurement is enough for CTS diagnosis according to CTS detection criteria, we measured right ulnar motor nerve. CTS was diagnosed if the median nerve velocity or amplitude was low or if the distal motor latency was prolonged compared to the normalized values of our laboratory for age. Results were compared with the normalized values of our laboratory using the chi-square test. A comparison was made between the mean values of electrophysiologic parameters of the worker and control groups using the Student's t-tests. Significance level was set as P < 0.05. The approval of local and ministerial ethical committees was obtained.


   Results
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 Abstract
 Introduction
 Methods
 Results
Discussion
 Conflicts of interest
 References
 
Neurological and systemic examination of all subjects were normal. None had any symptoms or signs suggestive of CTS. The mean age of workers was 41.7 ± 5.0 years and 41.1 ± 6.2 in the control group. Body mass indices (BMI) were 27.2 ± 3.6 in the worker group and 26.7 ± 3.7 in the control group. All subjects were right handed. The mean working hours per week were 47.7 ± 1.4 in the worker group and 41.8 ± 17.4 in the control group (P < 0.05). None of the subjects in the worker group had CTS, while one in the control group, an ex-masseur, had apparent bilateral CTS. Although within normal limits, peripheral nerve measurements revealed statistically significant differences between the electrophysiological parameters for workers and controls. A summary of abnormal findings is shown in Tables 1 and 2.


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  		Table 1. Electrophysiologic findings in motor nerves

 

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  		Table 2. Electrophysiological findings in sensory nerves

 

   Discussion
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 Abstract
 Introduction
 Methods
 Results
 Discussion
Conflicts of interest
 References
 
In our study, we did not find any cases of CTS in manual workers. However, we found significant peripheral nerve abnormalities, more marked in non-dominant hands and ulnar nerves.

One problem when performing studies on CTS is the fact that work-related CTS case definitions are not strictly established. Some authors accept a diagnosis based on self-reported symptoms and the existence of physical signs but this may lead to an overestimation of CTS frequency and electrophysiological studies are considered the gold standard investigation [3], and a major strength of our study was the fact that we used electrophysiological measurements as part of the investigation.

CTS is accepted as a work-related disorder by some authors [1]. However, this notion is controversial and many authors do not agree with it [4]. In the longest prospective longitudinal study by Nathan, occupation was not associated with CTS although being female and overweight was [5]. Some smaller cross-sectional studies have reported an association between CTS and repetitive work in various occupations [6,7]. The study by Szabo [8] pointed to the rarity of work-related CTS. Most of the studies reporting a positive association between CTS and occupation also refer to confounding factors, which could be responsible for any association [9]. Of these, some are well-known personal risk factors such as age, gender and obesity. In our study, we could not evaluate the effect of weight or gender, as BMI of both worker and control groups were similar and all subjects were males. This did, however, enable us to directly compare the effect of occupational factors. In our study, working conditions did not include vibration, repetition and twisting, but only heavy manual handling.

Our study did find subclinical involvement of peripheral nerves in manual workers. This finding is in keeping with the results of other studies [3,10]. It is uncertain whether or not this subclinical involvement leads to any reduction in functional ability or future development of CTS. Nathan et al. [5] showed the lack of any association between abnormality in SNCV and severity of hand activity. Werner et al. [3] did not find any relationship between current slowing of median sensory NCV and future CTS development. The evidence therefore for subclinical peripheral nerve involvement leading to functional impairment and CTS in the future is lacking.

Our study has found no cases of CTS in heavy manual workers, but subclinical involvement of peripheral nerves. The key point of our study is that in this group of manual workers, manual work was not a risk factor for development of clinical CTS. Further larger studies using electrophysiological measurements would be welcome.


Key point
  • In this group of manual workers, manual work was not a risk factor for development of clinical CTS, there were subclinical affection of all peripheral nerves and further larger studies using electrophysiological measurement would be welcome.

 


   Conflicts of interest
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Conflicts of interest
References
 
None declared.


   References
Top
 Abstract
 Introduction
 Methods
 Results
 Discussion
 Conflicts of interest
 References
 

  1. Wellman H, Davis L, Punnett L, et al. Work-related carpal tunnel syndrome (WR-CTS) in Massachusetts 1992-1997: source of WR-CTS, outcomes, and employer intervention practices. Am J Ind Med (2004) 45:139–152.[CrossRef][Web of Science][Medline]

  2. Oh SJ. Nerve conduction in focal neuropathies. In: Clinical Electromyography: Nerve Conduction Studies. (1993) Baltimore: Williams & Wilkins. 517–26.

  3. Werner RA, Franzblau A, Albers JW, et al. Use of screening nerve conduction studies for predicting future carpal tunnel syndrome. Occup Environ Med (1997) 54:96–100.[Abstract/Free Full Text]

  4. Stapleton MJ. Occupation and carpal tunnel syndrome. ANZ J Surg (2006) 76:494–496.[CrossRef][Web of Science][Medline]

  5. Nathan PA, Istvan JA, Meadows KD. A longitudinal study of predictors of research-defined carpal tunnel syndrome in industrial workers: findings at 17 years. J Hand Surg (2005) 30:593–598.[Medline]

  6. Barnhart S, Rosenstock L. Carpal tunnel syndrome in grocery checkers: a cluster of work-related illness. West J Med (1987) 147:37–40.[Web of Science][Medline]

  7. Barton NJ. Carpal tunnel syndrome and work. J Hand Surg (2004) 29:329–333.[Medline]

  8. Szabo RM. Carpal tunnel syndrome as a repetitive motion disorder. Clin Orthop Relat Res (1998) 351:78–89.[Medline]

  9. Bekkelund SI, Pierre-Jerome C, Torbergsen T, et al. Impact of occupational variables in carpal tunnel syndrome. Acta Neurol Scand (2001) 103:193–197.[CrossRef][Web of Science][Medline]

  10. Violante FS, Mattioli S, Occhipinti E. Biomechanical overload disease: epidemiologic data. G Ital Med Lav Ergon (2003) 2:301–302.


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This Article
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kqm157v1
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