Dear Doc,

“I have been hearing conflicting information about what causes carpal tunnel syndrome.  Can you clarify the primary causes of this occupational disease?”
                                                                 – Curious in Great Falls

Dear Curious in Great Falls,

This is a great question and an extensive amount of research has been conducted about the causes of carpal tunnel syndrome, both from workplace stressors and predisposition.

Common symptoms exhibited by someone with this syndrome include:  numbness and tingling in the fingers (primarily on the palm side), numbness and tingling that awakens one from sleep, and a weakness in grasping objects.

According to studies* the work-related causes of carpal tunnel syndrome include: repeated use of vibrating hand tools and work that requires forceful and repetitive grasping of objects.  Notably this list does not include typing at a keyboard or data-entry, which is a common misconception about carpal tunnel syndrome.

It can also be caused by non-work related factors such as: obesity, hypothyroidism, rheumatoid arthritis, fluid retention from pregnancy and menopause, or simply having a smaller tunnel (this is why women are three times more likely to be affected).

Wondering what the heck a carpal tunnel is, and how it becomes a “syndrome?”  Check out this link

An example of a scenario in which I have seen a worker with job-related carpal tunnel syndrome was a woman who had worked as an industrial electrician for 30 years.  She used vibrating tools regularly and had to twist her wrist while applying pressure when working on control panels on a daily basis.  Although she did have a history of hypothyroidism, she had no other non-work related factors and I concluded that her injury was work related.

On the other side of the spectrum was a man employed in retail.  His work-related tasks included some lifting and cutting, customer service, answering phones, and computer work (i.e. keyboard and mouse).  He complained of numbness, burning, and weakness and pain in his hands, wrist and forearm.  His electrodiagnostic studies demonstrated a moderate bilateral carpal tunnel syndrome.  However, when reviewing his records and medical history it was clear he had a history of obesity and inactivity.  I determined that this particular case was not work-related but instead due to predispositions to the syndrome.

What treatments can help carpal tunnel syndrome?  I generally recommend non-surgical methods to start which include: a wrist splint (especially at night); additional intake of vitamin B6; an ergonomic workstation; frequent rests; avoiding or limiting positions that include the risk factors listed above; and occupational therapy to learn tendon gliding exercises.  If symptoms do not improve within a few months, a visit with a physician about whether a carpal tunnel release is necessary would be appropriate.

Carpal tunnel syndrome can be prevented proactively in the workplace by implementing breaks, ergonomic tools and positions, and stretching.
– The Doc

Further reading:

If you want to know more about how carpal tunnel is diagnosed, here are some links that explain a few of the tests we use during a physical exam to determine whether an injured employee is suffering from carpal tunnel syndrome:

·      Tinel’s and Phalen’s tests
·      Upper extremity nerve conduction studies

*References·      Mediouni Z, Bodin J, Dale AM, Herquelot E, Carton M, Leclerc A, Fouquet N, Dumontier C, Roquelaure Y, Evanoff BA and Descatha A. Carpal tunnel syndrome and computer exposure at work in two large complementary cohorts. BMJ Open2015;5:e008156.

·      Werner RA, Franzblau A, Albers JW, Armstrong TJ. Influence of body mass index and work activity on the prevalence of median mononeuropathy at the wrist.  Occup Environ Med. 1997 Apr;54(4):268-71.

·      El-Salem K, Ammari F. Neurophysiological changes in neurologically asymptomatic hypothyroid patients: a prospective cohort study. J Clin Neurophysiol. 2006 Dec;23(6):568-72.

·      Hou WH, Hsu JH, Lin CH, Liang HW. Carpal tunnel syndrome in male visual display terminal (VDT) workers. Am J Ind Med. 2007 Jan;50(1):1-7.

·      Lewańska M, Wagrowska-Koski E, Walusiak-Skorupa J. [Etiological factors for developing carpal tunnel syndrome in people who work with computers]. Med Pr. 2013;64(1):37-45.

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