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Int Arch Occup Environ Health (1991) 63:267-270 internationalArchivesofOe upationala dEnvironmentalHealth Springer-Verlag 1991

Carpal tunnel syndrome: role of occupationIvano Delgrosso and M arcel-Andr 6 BoillatInstitute of Occupational Health Sciences, University of Lausanne, CH-1005 Lausanne, SwitzerlandReceived February 18, Accepted June 17, 1991

Summary A total of 21 consecutive patients who under-went surgery for carpal tunnel syndrome in a regionalhospital were analysed for their trade and serum al-anti-trypsin phenotypes The majority of these cases werewomen and mostly manual trades and professions wereinvolved Furthermore, heterozygous antitrypsin pheno-types were more frequent among the surgical cases thanamong the general Swiss population In a second stage,the incidence of carpal tunnel syndrome in Switzerlandwas studied for 1 year from June 1988 through May 1989using the sentinel system developed by the FederalOffice of Public Health Administration In all, 188 caseswere found, most of whom were women, which wascompatible with the frequency in other countries Acomplementary questionnaire that was filled out by 65cases and their matched controls showed that house-wifes and shop clerks were overrepresented among thepatients Likewise, exposure to vibrating tools and fre-quent extensions and/or flexions of the wrist were men-tioned more often by the cases than by the controls Thepresent study confirms previous findings that women areat greater risk of developing carpal tunnel syndromeespecially in jobs requiring repetitive movements oroperation of vibrating tools A constitutional elementin pathogenesis was suggested by observations that themothers of the cases had often also been afflicted withcarpal tunnel syndrome and that the frequency of dis-tribution of antitrypsin phenotypes in patients differedfrom that in the general population.Key words: Carpal tunnel syndrome Sentinel system -Vibration Wrist movement Antitrypsin phenotypes

sions may be as high as 15%-30% (Dagostino 1989).Thus, it is the most common clinical entity among thecompression neuropathy states (Shuman et al 1987).Apart from the actual physical compression of the me-dian nerve by the palmar aponeurosis, the syndromemay be associated with Lyme disease (Halperin et al.1989), uremia (Fraser and Arieff 1988), hemodialysis(Chanard et al 1989) and may be attributable to repeti-tive wrist movements (Lockwood 1989 ; Werner et al.1983) Women are more frequently affected than men(Stevens et al 1988).

Amyloid deposits have been found around the me-dian nerve and in the carpal tunnel tenosynovium in 124cases who showed no evidence of systemic amyloidosis(Kyle et al 1989) Serum serine antiproteases (serpins;for review see Carrell 1986) are so-called acute-phasereactants in inflammation, and especially al-chymo-trypsin has been found in amyloid deposits in the brain(Abraham et al 1988) One of the serpins, al-antitryp-sin, shows extensive genetic polymorphism (Lapp 6 1988)with some phenotypes predisposing to pulmonary dis-ease, neonatal hepatitis (Dycaico et al 1988) or post-infectious polyradiculitis (McCombe et al 1985).In the present study, we evaluated the role of occupa-tion in the development of carpal tunnel syndrome in 21consecutive patients who underwent surgery for the dis-ease We also analysed their al-antitrypsin phenotypesand compared then with those in the general Swiss popu-lation (Baer and Kratzer 1988) In a second stage, acase-control study was undertaken for 1 year using theSwiss sentinel doctor network to verify the annual inci-dence of carpal tunnel syndrome in Switzerland and toconfirm the role of occupation or manual work that hadbeen found in the preceding clinical study.

IntroductionCarpal tunnel syndrome is common If affects 0 1 % ofthe general population in the United States (Katz et al.1990), and its prevalence in selected trades and profes-Offprint requests to: M -A Boillat

Patients and methodsA total of 21 consecutive patients exhibiting carpal tunnel syn-drome (4 men and 17 women) were interviewed by an occupa-tional health specialist after they had undergone fascioplasty in aregional clinic that surgically treated most of the affected patients

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268Table 1 Clinical presentation of patients wh o underwent surgeryfor carpal tunnel syndromeCase Sex Age Work Occupation Onset of Anti-(years) history symptoms trypsin(years) (months) pheno-typeBilateral disease:1 F 38 15 Housewife 12 M 1M22 F 56 10 Farmer 7 5 M 1M,3 F 59 30 Watchmaker 108 M 1M24 F 50 18 Watchmaker 48 M 1M25 M 31 6 Farmer 36 M 1M 16 F 72 15 Housewife 60 MIM 37 F 59 15 Watchmaker 144 M 1M 28 F 52 20 Watchmaker 36 S S9 F 53 24 Watchmaker 24 M 1M 1

Unilateral disease:10 F 37 6 Decorator 36 M 1M111 F 46 5 Secretary 24 MIM 212 M 79 40 Watchmaker 18 Mi Ml13 F 58 5 Shop clerk 24 M 1M 314 F 48 29 Hairdresser 60 M 1M 315 F 51 33 Watchmaker 36 M 1M 216 F 59 25 Housewife 48 M 1M117 F 27 10 Farmer 120 M 1M 318 F 28 6 5 Hospital nurse 24 M 1M319 F 42 12 Farmer 24 M 1M120 M 72 50 Farmer 24 M 1M 121 M 66 40 Stonemason 60 M 1Z

Table 2 Main aspects of the complementary medical question-naireIdentity, including country of birthEducational level reachedFormer occupationsCurrent occupationDescription of occupational aspects (employment years):Repetitive flexion-extension of the wristMotion of hands involving exertion of strengthUse of various hand tools (e g , hammer, knife, staple gun)Exposure to vibrationsknitting, painting, other handicraftsTime of onset of symptoms of carpal tunnel syndromeConfounding factors or diseases (diabetes, rheumatoid arthritis,gout, oral contraception, others)Family history of carpal tunnel syndrome

in the area In each case, the diagnosis was based on clinical andelectrophysiological data and was confirmed during the surgicalprocedure In all, 9 cases, including 1 man, showed bilateral in-volvement and 12 displayed unilateral disease The mean age ofthe former was 52 12 years, an d the mean duration of symptomswas 53+43 months The mean age of the latter was 52 16 yearsand the mean duration of symptoms wa s 42 + 29 months (Table 1).All patients worked in manual occupations involving prolongedwrist strain or repetitive movements (Table 1) None had diabetes,nephropathy, malignancy or other metabolic disease Blood sam-ples (5 ml) were taken and serum al-antitrypsin phenotypes were

determined by isoelectric focusing (Brooks and Iammarino 1985).Th e distribution of the phenotypes in the patients was comparedwith that in the general Swiss population (Baer and Kratzer 1988)using the chi-square test.About 2% of all Swiss medical practitioners distributedthroughout Switzerland form the so-called sentinel physician net-work They report to the Federal Office of Public Health (Frenchacronym, OFSP), and they were asked to register all cases of car-pa l tunnel syndrome who presented to them from June 1988through May 1989 Immediately after the receipt of the individualcase reports, the doctors were mailed a questionnaire on the occu-pational health aspects of each case, for patients aged up to 65years, which included items such as the subject's profession; theuse of hand tools; and the family history of the same disease, otherillnesses an d pregnancies (Table 2) The next patient of the sameage ( 2years) and sex who wa s seen by the doctor served as acontrol and was asked to fill out the same questionnaire with thephysician The results were statistically evaluated using the chi-square test.

ResultsOn clinical examination, all 21 surgically treated casesshowed some degree of thenar atrophy in the affectedhand All patients complained of experiencing nocturnalpain, which they typically relieved by shaking the hand;over-the-counter pain killers were ineffective, and thepain was strong enough to wake them These variousaspects, in agreement with electroneurophysiologicalstudies, confirmed that the patients were suffering fromboth sensory and motor disturbances The symptomshad lasted for years in most cases and in one patient for7.5 months (Table 1); this was not necessarily an indica-tion of their indolence of tenacity but may rather havereflected the partial success of the conservative therapy,at least in the work-related form of the disease (Harter1989).The patients mainly worked in manual jobs, with theexception of three housewives (Table 1); it seemed thatthe work of the latter included at least all of the usualdomestic chores, as none of them had hired help Sincethe watch industry is a particularity of the region, manywatchmakers were included in the present series ofcases; this occupation includes many tonic hand posi-tions coupled with fine, extremely restrained wristmovements Despite mechanisation, farming is also amanual job in Switzerland, and the farms are mainlysmall, with most farmers also tending cattle or sheep.A significant work component was also found in theetiology of the syndrome in the stone mason, the hair-dresser, the nurse and the shop clerk.

The distribution of al-antitrypsin phenotypes in ourpatients differed significantly from that in the generalSwiss population (Table 3) Specifically, one-third of thecases of bilateral carpal tunnel syndrome exhibited themost common phenotype, M 1M 1, which was detected in52 % of the controls The heterozygous M 1M2 and M1M 3phenotypes were overrepresented in the patients (Table3) One case displayed a pathological SS phenotype andanother patient exhibited the M 1Z phenotype associatedwith decreased serum antitrypsin activity.However, gender was the most decisive factor in thisstudy In all, 4 of the 21 cases were men, giving roughly

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269Table 3 Distribution of c-antitrypsin phenotypesPhenotype Number Frequency Frequency

(% ) in Swiss controls(%)MIM 1 8 38 52M 1M2 6 29 19M 1M3 5 23 13M1Z 1 5 1 4SS 1 5 0 2Others 0 0 14 4The distribution of phenotypes in patients exhibiting carpal tunnelsyndrome differed significantly (P < 0 0001, chi-square test) fromthat in controls (Baer and Kratzer 1988)

the same overall risk previously found in Minnesota(Stevens et al 1988) Nevertheless, as judged by theonset of symptoms, the duration of the disease in womendid not differ markedly from than in men (Table 1).

A total of 188 cases of carpal tunnel syndrome werereported by the sentinel doctors; 65 case-control pairscould be established using the completed questionnaires.Women suffered from the syndrome more frequentlythan men (66 2%) The patients were more often shopclerks or housewives than were the controls (13 8% and30 % vs 3 1% and 21 5%, respectively; X = 4 86 , P

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270data included in this study We also thank Prof Dr H Savolainen,Dr.M Droguett, Mrs M Berode, Mrs M Strebel and Mrs M.Badan for their help and advice.

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