The findings, made by a team of researchers with the University of Michigan Health System, the VA Ann Arbor Healthcare System, show that nighttime splinting can effectively improve hand and wrist discomfort for active workers with early symptoms of carpal tunnel syndrome (CTS).
The results from the study are published in the January issue of the Archives of Physical Medicine and Rehabilitation.
While carpal tunnel syndrome is a common work-related disorder and a major cause of impairment and disability in the workplace, the use of initial medical treatment protocols for the disorder -- wrist splints, modification of hand activity, non-steroidal anti-inflammatory medication, diuretics and steroid injections -- have widely varied across the United States and Western Europe, according to lead author Robert A. Werner, M.D., MS, professor in the Department of Physical Medicine and Rehabilitation at the University of Michigan Health System.
"Workers with carpal tunnel syndrome have more lost work time than any other work-related injury," said Werner, who is the chief of physical medicine and rehabilitation at the VA Ann Arbor Healthcare System and an associate research scientist with the University of Michigan Center for Ergonomics. "Additionally, CTS is frequently misdiagnosed and there's very little scientific research to show which initial treatments are actually the most effective for those with symptoms of carpal tunnel syndrome."
The first line of conservative treatment for CTS, both from doctors and self-prescribed, is typically nocturnal splinting. Splinting, Werner said, reduces stress on the peripheral nerve in the wrist, allowing it to heal and avoiding awkward wrist positions as a person sleeps. It is not recommended for daytime use when workers are active because it may cause additional strain on the wrist.
To determine the effectiveness of nocturnal splinting, Werner and his colleagues studied 112 active workers at a Midwestern automotive assembly plant with symptoms consistent with CTS but who had not sought medical treatment.
Subjects were selected if they experienced numbness, tingling, burning or pain in the median nerve of the hand for more than a week or for more than three times in the past six months. Werner noted that automotive assembly workers are five to 10 times more likely to develop CTS than people in the general population and people who type for a living. On average, automotive assembly workers miss a month of work, especially those who seek surgical intervention for advanced symptoms of CTS.
About Half of Splinted Group Sees Positive Results
As part of the randomized controlled study, 63 study participants were fitted with a custom wrist-hand splint that maintained the wrist in a neutral posture overnight and were instructed to wear the splint at night for a period of six weeks. This group, along with the remaining 49 participants, also viewed a 20-minute video on CTS and how to reduce ergonomic stressors at work and home.
After the six week trial, about half of the splinted group reported significant improvement in their symptoms, with one participant reporting complete relief of symptoms. Compared to the group assigned to just watch the video, the splinted group had significantly decreased hand, wrist, elbow and forearm discomfort after three months.
After 12 months, the improvement seen in each group was greatly dependent on the individual's level of hand/wrist nerve damage. Of those in the non-splinted group, participants with healthy nerves noted reduced hand/wrist discomfort, while those with injured nerves felt no improvement over time.
Those who used the splint -- both with healthy and injured nerves -- saw significant improvement in hand/wrist discomfort, and participants who initially reported higher levels of discomfort at the start of the study saw the greatest improvements with splint use. Additionally, 10 percent of the participants in this group continued to wear the splint at night beyond the initial six-week trial.
Prior to the study, nearly half of the participants used non-steroidal anti-inflammatory drugs and ice/heat treatments to treat their hand and wrist discomfort, while less than 25 percent had previously sought physical therapy for their carpal tunnel symptoms.
Despite relief from NSAIDs and other home remedies, Werner said using a custom fit or store-bought splint for nighttime use is the best first line of defense when symptoms of carpal tunnel begin. Splinting, however, has minimal effect on those with advanced carpal tunnel, he added.
"Early intervention with splinting is key to effective management of carpal tunnel syndrome," Werner said. "It's very cost-effective and the odds are very good that you will feel the benefits."
Werner said he hopes to build on the findings from this study by conducting a larger study to determine the cost-effectiveness of splinting and its long-term benefits for patients.
In addition to Werner, the study was co-authored by Alfred Franzblau, M.D., associate professor in the University of Michigan Health System Department of Emergency Medicine, associate research scientist at the University of Michigan Center for Ergonomics and professor in the Department of Environmental Health Sciences at the University of Michigan School of Public Health; and Nancy Gell, MPH, PT, a research associate in the University of Michigan Health System Department of Physical Medicine and Rehabilitation and the University of Michigan School of Public Health's Department of Environmental Health Sciences.
The UAW-GM National Joint Committee on Health and Safety funded the study.