A previous report estimated that the prevalence of CTS in
the UK was 7% of the general population [20]. Another
study estimated that 3.72% of the general population in the
USA had clinical CTS [21]. Although Stevens et al reported
that the incidence of CTS among computer users was 3.5%
[22], similar to the incidence in the general US population,
the incidence of CTS among computer users at our facility
was 16.7% (15 of 90 hands). The different results with
respect to other reports may depend on case inclusion
criteria and the occupational activities of the population at
risk.
Of the 12 subjects with NCS findings consistent with
CTS, five presented with obvious wrist pain, while the other
seven’s symptoms were obscure. It is probable that hand
numbness always presents in CTS patients, but wrist pain
or a tingling sensation is not present at an early stage. It
is reported that repetitive activities in the workplace
not only affect the median nerve across the carpal tunnel
but also the ligaments, synovia, tendons, and muscles, producing
pain and local tenderness at the wrist [5]. Pain in this
location may suggest the possibility of a musculoskeletal
disorder contributing to the patient’s symptoms. Musculoskeletal
history, physical examination, and electrodiagnostic
studies will help distinguish between these
disorders and atypical presentations of CTS. Therefore, a
diagnosis that is based only on symptoms may be confusing.
This is why the diagnosis of CTS is based on electrodiagnostic
findings. Although their accuracy may vary among
laboratories and physicians, electrodiagnostic studies are
usually highly sensitive and specific for CTS.
There was no obvious correlation between the length of
employment of the subject in the medical facility and the
presence of CTS. This result is in agreement with the report
by Nathan et al that the length of employment has no
influence on impairment of sensory conduction [23].
We know that repetitive movement is a risk factor for CTS.
Repetitive manual tasks increase mechanical stress on the
median nerve and results in elevated carpal tunnel pressure,
ischemia, and, finally, histologic changes of the median nerve
and connective tissue within the carpal tunnel [24–26].
However, there is another risk factor that should be noted. In
this study, we found that there was a significant correlation
between wrist angle and the frequency of CTS. The computer
users who typed with a wider wrist angle had a higher risk of
CTS (especially when the angle was > 20°).