True or False? The most common cause of carpal
tunnel syndrome is job-related overuse of the hands and wrists, such as
when typing on computer keyboards for hours at a time.
False. The issue of whether
occupation and job-related hand or wrist overuse are risk factors for developing
CTS is highly controversial. Several investigators have listed occupation
and heavy manual labor as causal factors for the disorder.[1-4] But the
opposite view has been argued for as long.[5-8] Nathan and colleagues[9]
reported that results of nerve conduction studies of large numbers of industrial
employees showed no consistent association between the prevalence of CTS
(detected by decreased sensory nerve conduction) and the type and level
of occupational hand activity, length of employment, or bilateral versus
unilateral activity. Anything that compromises the space available for
the median nerve in the carpal tunnel can cause CTS. Local structural changes
and masses at the wrist are known causes, including distal radius fractures,
blunt trauma with associated hemorrhage and swelling, and tumors such as
lipomas and ganglion cysts. A wide variety of systemic illnesses, metabolic
diseases, overuse syndromes, and aberrant anatomic structures also have
been described as causes of CTS.
Source: Slater RR.: Carpal
Tunnel Syndrome: Current Concepts.J South Orthop Assoc. 1999;8(3).
References
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Armstrong TJ, Chaffin DB: Carpal tunnel syndrome
and selected personal attributes. J Occup Environ Med. 1979;21:481-486.
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Birkbeck MQ, Beer TC: Occupation in relation
to the carpal tunnel syndrome. Rheumatol Rehab. 1975;14:218-221.
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Cannon LJ, Bernacki EJ, Walter SD. Personal
and occupational factors associated with carpal tunnel syndrome. J Occup
Med. 1981;23:255-258.
-
Posch JL, Marcotte DR. Carpal tunnel syndrome:
an analysis of 1,201 cases. Orthop Rev. 1976;5:25-35.
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Hadler NM: Illness in the workplace: the challenge
of musculoskeletal symptoms. J Hand Surg Am 10:451-456, 1985
-
Phalen GS. Neuropathy of the median nerve
due to compression beneath the transverse carpal ligament. J Bone Joint
Surg Am. 1950;32:109-112.
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Phalen GS. The carpal tunnel syndrome. Seventeen
years' experience in diagnosis and treatment of 654 hands. J Bone Joint
Surg Am. 1966;48:211-228.
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Phalen GS. The carpal-tunnel syndrome. Clinical
evaluation of 598 hands. Clin Orthop. 1972;83:29-40.
-
Hadler NM. Illness in the workplace: the challenge
of musculoskeletal symptoms. J Hand Surg Am. 1985;10:451-456.
Nathan PA, Meadows KD, Doyle LS. Occupation
as a risk factor for impaired sensory conduction of the median nerve at
the carpal tunnel. J Hand Surg Br. 1988;13:167-170.
Now, this flies in the face of the opinions
of many organizations including the US
Government Occupational Safety and Health Administration. Unfortunately,
even that body can not be expected to produce an unbiased opinion. The
government represents the interests of those influencing the government
- good or bad, right or wrong, and truth has no independent representation.
The OSHA guidelines do not take into account any factors other than occupation
(including age, sex, and activities outside the workplace), and do not
at all address the possibility that activities may exacerbate symptoms
of carpal tunnel syndrome without actually causing it. By the
same logic, one could conclude that a job which involved walking up stairs
caused lung disease, because people develop symptoms (shortness of breath)
while performing that activity.
Carpal tunnel syndrome is very common in
the general population, and does not always cause symptoms:
| 1: Am J Ind Med 1996 Sep;30(3):355-61 |
Prevalence of abnormal
median nerve conduction in applicants for industrial jobs.
Bingham RC, Rosecrance JC, Cook TM
Department of Preventive Medicine, University
of Iowa, Iowa City 52242-5000, USA.
There has been much debate regarding the
work relatedness of carpal tunnel syndrome (CTS) and whether workers diagnosed
with CTS had pre-existing disease at the time they were hired. To elucidate
the latter issue, we examined the prevalence of abnormal median nerve conduction
within the carpal tunnel in applicants for industrial jobs. Nerve conduction
studies (NCS) were performed on both hands of 1,021 applicants following
a conditional offer of employment. Each applicant completed a self-administered
symptom survey specific to the upper extremity. Applicants had worked previously
for an average of 4.4 (range 0-33) years and had a mean age of 30.1 (S.D.
8.9) years. Nerve conduction studies were performed in a private medical
clinic. Sensory palmar latencies were determined over an 8 cm segment for
the median and ulnar nerves. The difference between the median and ulnar
sensory latencies was the primary electrophysiologic measurement used to
determine median neuropathy. Using a very conservative criterion for abnormal
median nerve conduction, 17.5% of the applicants were classified with neuropathy
in at least one hand. Despite the relatively high prevalence of median
neuropathy, relatively few (10%) with positive NCS acknowledged symptoms
associated with CTS. Males had a higher percentage of median neuropathy
than did females. We conclude that a large percentage of industrial workers
have objective evidence of abnormal median nerve conduction within the
carpal tunnel when hired. The high prevalence of abnormal median nerve
conduction without corresponding symptoms may suggest a subclinical entity
associated with CTS.
PMID: 8876806, UI: 97030865
The incidence of carpal tunnel syndrome
relates to age and sex, not type of employment:
| J Hand Surg [Br] 1988 May;13(2):167-70 |
Occupation as a risk factor
for impaired sensory conduction of the median nerve at the carpal tunnel.
Nathan PA, Meadows KD, Doyle LS
Portland Hand Surgery and Rehabilitation
Center, Oregon 97210.
471 industrial employees from 27 occupations
in four industries were surveyed to evaluate the role of occupational hand
activity as a risk factor for slowing of sensory conduction of the median
nerve at the carpal tunnel. After age-adjusting the latency values, slowing
of the sensory fibres of the median nerve was found in 39% of the subjects
and in 26% of the hands. No consistent association was found between the
type and the level of occupational hand activity and the prevalence or
the severity of slowing. In addition, the prevalence of bilateral slowing
of conduction of the median nerve was not associated with bimanual occupational
hand activity, and the length of employment of the subjects in the current
industry did not influence the occurrence of impaired sensory conduction
of the median nerve at the carpal tunnel.
PMID: 3385295, UI: 88258259
|
