Page 74 - Occupational Health & Safety, June 2018

ERGONOMICS
Carpal Tunnel Syndrome: What We Know
BY BLAKE MCGOWAN Carpal tunnel syndrome (CTS) is one of the most common work-related musculoskele- tal disorders (MSDs) and is a widely recog- nized condition. Chances are, you probably know someone who suffers from it, had surgery to al- leviate the painful symptoms of it, or has it but doesn’t know it yet. Even though the incidence is so great and could be one of the most talked about ailments at din- ner parties, most people might not know or under- stand its etiology. To fully understand the disorder, it’s important to know how the arm works. Tendons, blood vessels, and the median nerve pass through the carpal tunnel (at the wrist) as they make their way from the forearm to the fingers. The median nerve plays a significant role in how the hand functions. It controls the small muscles (which control movement) at the base of the thumb and enables the palm side of the thumb, index, middle, and part of the ring finger to feel sensations or touch. If the tendons and tendon sheaths running through the carpal tunnel become ir- ritated and begin to swell, the median nerve may be
affected, and carpal tunnel syndrome may result.
What Are the Symptoms?
Some people may not know they’re at risk or that they have CTS because the symptoms are so gradual. Tin- gling, frequent burning, itching, and numbness are some of the early reported signs and generally appear in one or both hands during the night. In fact, most people sleep with flexed wrists, and those who suffer might try to “shake out” the “pins and needles” sensa- tion. We all know what our foot or leg feels like when it is “asleep” or feels swollen from sitting in a pretzel- like position on the floor. Imagine feeling that often.
As the condition worsens, the sufferer may report more tingling, reduced grip strength, and the inability to grasp an object or perform certain tasks during the day. He or she may say his or her fingers feel useless. As the condition progresses, the muscle at the base of the thumb wastes away and the ability to distinguish hot from cold objects diminishes.
What is the Prevalence of CTS?
The prevalence of medically diagnosed and electro- diagnostic confirmed CTS is generally higher in the working population compared to the general popula- tion. The prevalence of CTS among manufacturing and meatpacking workers ranges from 5 to 21 percent. The prevalence in general populations ranges from 1 to 5 percent (Bonfiglioli et al., 2013; Dale et al., 2013; Fan et al., 2015; Harris-Adamson et al., 2015; Harris- Adamson et al., 2016; Kozak, et al., 2015; Violante, et al., 2016). The highest prevalence in the working
population is among grinders, butchers, grocery store workers, frozen-food factory workers, platers, and other workers whose jobs involve high-force, highly repetitive manual movements. Jobs with the highest CTS risk include those in meat and fish processing in- dustries, forestry work with chain saws, and electronic assembly work (Hagberg et al., 1992).
Incidence rates of CTS calculated from the Wash- ington state workers’ compensation records ranged from 0.8 to 14.8 per 1,000 person-years and varied by industrial and occupational classifications. Similar rates of 12.4 per 1,000 person-years were observed among 432 industrial and clerical workers using a case definition requiring electrodiagnostic confirma- tion. A pooled analysis of six prospective studies of 4,321 workers showed that:
■ the prevalence of hand symptoms of CTS is 15.2 percent,
■ the prevalence of CTS based on electrodiag- nostic method is 7.8 percent,
■ the incidence of CTS is 5.8 percent, and
■ the incidence rate of CTS is 2.3 per 100 person-years.
What is the Cost and Burden of CTS?
CTS is the most expensive upper-extremity MSD. Medical care cost estimates in the United States ex- ceed $2 billion annually and are primarily due to car- pal tunnel release surgery. The non-medical costs are estimated to be 1 to 4 times greater than the medical costs (Dale et al., 2013). In the United States, the me- dian lost work time resulting from work-related CTS is 27 days. This is longer than that of any other work- related disorder, except fractures. Furthermore, 18 percent of workers who develop CTS reported leaving their jobs within 18 months (Dale et al., 2013).
What are the Individual and
Occupational Risk Factors?
There are both individual and occupational risk factors associated with CTS (Bonfiglioli et al., 2013; Dale et al., 2013; Fan et al., 2015; Harris-Adamson et al., 2015; Harris-Adamson et al., 2016; Kozak, et al., 2015; Vio- lante, et al., 2016). Individual risk factors include age, gender, body mass index (BMI), pregnancy, medical conditions (e.g., diabetes and thyroid disorders), and musculoskeletal comorbidities (e.g., trigger finger, rota- tor cuff syndrome, cervical radiculopathy). Thus, aging, weight/obesity, gender (female), and existing medical conditions increase the risk of CTS.
A tremendous amount of effort and research has been conducted to better understand occupational risk factors for CTS. Many risk factors have been
70 Occupational Health & Safety | JUNE 2018
www.ohsonline.com