Work-Related Disorders of the Neck and Upper Extremity
Lawrence J.Fine and Barbara A.Silverstein
A 31-year-old, right-handed man had been employed in a variety of automobile manufacturing jobs for 13 years. Two years ago he switched to a new plant and was assigned to a job that required him to move a spot welding machine beneath cars moving overhead. He had a minute to complete four welds on each car. The spot welder, which had metal handles, required substantial force for appropriate positioning, and it had to be repositioned four times for each car. The worker’s wrists were in complete extension for a substantial portion of the job cycle.
When the worker started on this job, the weekday work shift was 9 hours long and Saturday work was required in most weeks. After 3 weeks on the job, he noted that he had pain in both wrists. He also noted numbness and tingling in the first four fingers on his left hand, first only at night, a few nights each week, after he had fallen asleep. When he awoke at night with the numbness, he would got up and walk around shaking his hands; in about ten minutes he would be able to go back to sleep. Gradually, over the next several months, the numbness and pain worsened both in frequency and intensity. His left hand would feel numb by the end of the work shift, and any time he was driving, his hands would become numb. Since he liked his job and did not want to be placed on restriction, which would mean he could not work overtime, he decided to visit his private physician rather than the company physician. He also was not sure that the company physician would be very sympathetic to his complaints.
His physician found on physical examination that he had decreased sensitivity to light touch in the left index and middle fingers and a positive Phalen’s test of the left hand. She suspected carpal tunnel syndrome (CTS) and believed that the disorder might be work-related because the patient was young, male, and had no other risk factors, such as diabetes, past history of wrist fracture, or recent trauma to the wrist. The physician discussed job changes with the patient. She also prescribed wrist splints to be used only at night.
The splints relieved some of the nighttime numbness for a period. However, over the next 6 months, the patient’s symptoms began to be present all of the time, and he thought that his left hand was becoming weaker. Similar symptoms also developed in his right hand.
The patient felt he could no longer do his job and returned to his physician. She noted that the Phalen’s test was now positive bilaterally. She referred him to a hand surgeon and ordered nerve conduction tests because she was concerned that some surgeons do not always have these tests done before surgery. The nerve conduction test showed slowing of sensory nerve impulse conduction in the median nerve in the region
Reprinted with permission from Occupational Health: Recognizing and Preventing Work-Related Disease, Levy and Wegman (eds.), 470–1, Copyright 1995, Little, Brown and Company.
of the carpal tunnel.
One year after the problem was first noted, he had surgery, first on the left hand and then on the right hand. Following surgery, the company placed him in a transitional work center for a 3-month period where he worked at his own pace and had no symptoms. He then returned to the assembly line with the restriction that he not use welding guns or air-powered hand tools. When he worked on the line, he occasionally had symptoms, but they were substantially less intense and less frequent than before.
He later transferred to a warehouse, because he felt that he would have a better chance of avoiding long layoffs there. He was placed on a job that required use of a stapling gun to seal packages. Three weeks after being placed in this job, his symptoms began to return with their former intensity. Through ordinary channels he immediately sought and was given a transfer to a position driving a fork lift truck. This change reduced, but did not eliminate, his symptoms. Currently he has numbness, tingling, and pain in the singers of both hands about twice a month. Playing volleyball usually triggers a severe attack. With the use of nighttime splints, he can sleep through most nights without awakening. While he feels that his hands are weaker than before he developed his symptoms, he is still able to perform his job. He has decided that as long as his symptoms remain at this level, he will continue working.
This case illustrates the intermittent and progressive nature of most work-related disorders of the upper extremity, and particularly of CTS, the best known of the common work-related disorders of the upper extremity. Other examples of these disorders that may be related to work include Quervain’s disease, epicondylitis, rotator (or rotor) cuff tendinitis (mainly supraspinatus), and tension neck syndrome. This family of disorders may involve muscles (tension neck syndrome), tendons (supraspinatus tendinitis disease), joints (degenerative joint disease), skin (calluses), nerves (CTS), or blood vessels (hand-arm vibration syndrome, or Raynaud’s phenomenon of occupational origin).