GM Releases Carpal Tunnel Test Results

The General Motors/Lasermedics press conference to release the results of the in-house study of carpal tunnel syndrome treated using the Lasermedics ML830 diode laser, was postponed from June 1994 until August. I was invited to attend this press briefing (the only outsider allowed) and reported on what I learned at the press briefing in this report, published in the September 1994 issue of Medical Laser Report.

GM Releases Carpal Tunnel Test Results

Irving J. Arons
Managing Director
Spectrum Consulting

Carpal tunnel syndrome (CTS), one of the repetitive stress injuries that strikes between 30% to 50% of workers involved in industries which have repetitive motion jobs (meat packing plants, automotive manufacturing, etc. -- see the Wall Street Journal of 7/14/94), is reportedly responsible for an estimated annual $29,000 per worker in lost job time for those workers so inflicted, according to the Bureau of Labor Statistics.

In an attempt to better understand the problem and to enable affected workers to return to work, General Motors Flint Assembly Plant, in 1989, began a program to deal with the approximately 10% of its work force getting CTS. What began as a means to track the injuries and redesign the work environment to alleviate the problem, turned into an 8 Phase program that has spread to an additional 7 GM assembly plants.

The study was coordinated by Dr. Wayne Good, medical director of the GM Flint plant and included a team of medical experts from various fields who studied the participants tool usage, designed physical therapy treatments to relieve the problem, and studied hand and wrist strength, motion, and blood flow, and the effects of low level laser light therapy in relieving the CTS symptoms.

Carpal tunnel syndrome is caused by a swelling or inflammation of the tendons leading to the thumb and first three fingers caused by repetitive motion, and the subsequent pressure and possible injury to the median nerve which are all contained in a tunnel-like structure (the carpal retinaculum) in the wrist area. In the later stages of the disease, the hands become wracked with pain, the fingers become numb, and the patient loses his/her ability to work with the afflicted hand (or hands).

About three years ago, Dr. Bryan Shumaker, director of the laser center at St. Joseph Mercy Hospital in Pontiac, MI, who had been working with Dr. Good on the GM CTS project, came across the biostimulation laser under development by Lasermedics (Stafford, TX) and suggested that perhaps this modality could be added to the GM project as a means of alleviating CTS. The laser therapy became Phase 8 of the program.

In conjunction with Lasermedics personnel, the GM CTS study group designed a double-blind study to evaluate the effects of physical therapy (PT) and physical therapy plus low level laser therapy on chronic CTS sufferers. The study included 116 out of work with CTS GM workers, who volunteered to undergo 5 weeks of treatment and testing. Half of the group were randomly assigned to receive physical therapy plus laser treatment, while the other half received PT and the use of a "sham" laser. (The Lasermedics Microlight 830 biostimulation laser has 3 diode lasers each delivering 30 mW of 830 nm infrared laser energy, which are peripherally located around a red emitting LED in the center of the battery-operated, hand-held device. In the "sham" laser, only the LED was operational, and since the infrared laser causes no discernable heating or sensation in use, neither the subjects nor the attending technicians delivering the laser treatment knew which coded device was real or the sham.)

The subjects were treated on a weekly basis for the five weeks of the program (which took place in late 1993), with the laser applied for a 33 second duty cycle to three spots on the wrist around the carpal tunnel. A baseline of blood flow, tactile sensation, and objective strength, grip, and motion measurements were taken, and also determined following the five week treatment program. 116 subjects were initially enrolled, but 17 dropped out during the screening process and an additional 10 dropped out during the program, leaving 89 subjects completing the testing (132 hands were treated). The median age of the subjects was 44, and slightly more females than males (54% vs. 46%) took part. About half of the subjects had previously had carpal tunnel release surgery, but the symptoms had re-occurred.

In the test results reported at the medical symposium sponsored by Lasermedics in Detroit on August 31, Dr. Tom Anderson, the GM spokesman for the study, revealed that there was improvement in almost every category of sensory perception, grip strength, and wrist motion for both the physical therapy alone and the PT plus laser treatment groups, with the only statistically significant improvement for those that received the laser treatment being in several categories of grip strength and in one category of range of wrist motion. More importantly, about 45% of both groups were able to return to work. However, this percentage is somewhat misleading and should be considered a bare minimum, because many more of those treated could have gone back to work if appropriate jobs had been available or if seniority allowed. Also, most of the subjects had been out of work because of CTS for more than three years and represented the worst case scenario, being chronic sufferers.

All of the research team agreed that the laser therapy was beneficial and could have been more so if used at an earlier stage of CTS development. In fact, according to one of the GM plant supervisors, the laser treatment continues to be used in all eight GM plants and to date several thousand workers who complain of CTS symptoms are regularly treated with the Lasermedics' laser alone, with a claimed success rate in alleviating the CTS symptoms of better than 85%!

It should also be noted that the cost savings of low level laser therapy compared to either open or endoscopic CTS release surgery can be substantial. Dr. Tracy Standridge of Owasso, OK, one of the Lasermedic clinical investigators for the Microlight 830 laser, supplied the information shown in the table below, based on data provided him by the Oklahoma Workman's Compensation Board, and what a CTS laser treatment program would cost in his office. As shown, including the costs of surgery and bringing another worker on board to replace the individual effected with RSI or CTS in those industries where it is prevalent, the difference could amount to as much as $20,000 more per worker to replace the surgery patient compared to the patient who receives laser treatment and can return to productive work.