A single corticosteroid injection in the wrist can offer at least a month of relief to people suffering from severe carpal tunnel syndrome, according to an updated review of studies by Canadian researchers.
Local injections are the most effective nonsurgical remedy for carpal tunnel, said Shawn Marshall, M.D., a specialist in physical medicine and rehabilitation at the University of Ottawa and lead author of the review. “One of the goals is to avoid surgery,” he said.
The review appears in the current issue of The Cochrane Library , a publication of The Cochrane Collaboration, an international organization that evaluates research in all aspects of health care. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing trials on a topic.
Carpal tunnel syndrome is irritation of the nerve that passes from the wrist to the hand by way of the carpal tunnel. Repetitive stress commonly causes the syndrome, especially in industrial or manufacturing settings with vibrating tools. The most frequent symptoms are pain and numbness in the fingers. Severe carpal tunnel syndrome can cause permanent loss of feeling and partial paralysis in the thumb.
This is the second update that Marshall and his co-authors have made since the initial publication of the review in 2000, which comprised three studies. Since then, there have been many more studies. For this update, the authors looked at a dozen studies with 671 participants.
They found that a single local corticosteroid injection provided clinical improvement in symptoms at one month when compared to a single systemic injection. In two studies, patients showed significant improvement in less than one month after receiving a local corticosteroid injection when compared to receiving a placebo. Another study that compared receiving a local corticosteroid injection to taking an oral corticosteroid found greater improvement among those who received the injection as long as three months after treatment.
“There's building evidence to suggest that it works beyond one month,” Marshall said.
Injections to treat severe carpal tunnel syndrome are more common in Europe than in North America, Marshall said.
Sometimes patients with very severe carpal tunnel syndrome receive corticosteroid injections although they also require future surgery. “It can work immediately,” Marshall said.
However, although they were more effective than oral medications, after two months, injections were no more effective than anti-inflammatory medicine, wrist splints or helium-neon laser therapy.
For many years, physicians avoided local corticosteroid injections for fear of causing nerve damage, said Robert Werner, M.D., chief of physical medicine at the Ann Arbor Veterans Administration Medical Center in Michigan.
“I think [injections are] underutilized,” said Werner, who was not involved with the study. Injections should be part of systematic approach to treating carpal tunnel syndrome, beginning with a wrist splint, he said, and if the splint does not provide relief, injections should become an option, followed finally by surgery, if necessary.
Studies suggest that anti-inflammatory medicines provide little, if any, relief for the irritation symptoms, Werner said.
The review did not look at the effectiveness of surgery compared to injections or the benefit of injections for treating less-than-severe carpal tunnel syndrome.
Regardless of the medical or surgical treatment received, the overall treatment plan should include an ergonomic assessment of the workplace with the goal of reducing the risk of a repetitive stress injury, Marshall said. “It's a very complex picture, with many different angles.”
The Cochrane Collaboration is an international nonprofit, independent organization that produces and disseminates systematic reviews of health care interventions and promotes the search for evidence in the form of clinical trials and other studies of interventions. Visit http://www.cochrane.org for more information.
Marshall S, Tardif G, Ashworth N. Local corticosteroid injection for carpal tunnel syndrome (Review). Cochrane Database of Systematic Reviews 2007, Issue 2.