Every year, just more than four out of every thousand Swedish women are diagnosed with carpal tunnel syndrome, a painful condition caused by a pinched nerve in the wrist.

That’s according to a new study that finds fewer Swedes end up with carpal tunnel than Americans.

For men, the number of new cases hovered just under two per 1,000 per year, according to new findings, in the Archives of Internal Medicine.

“This study adds to our observations that there are differences in the incidence of medically-attended carpal tunnel syndrome and surgical treatment between countries,” Dr. Russell Gelfman of the Mayo Clinic in Rochester, Minnesota, told Reuters Health by email. He was not involved in the study.

In previous work, he and his colleagues found about twice as many people in Olmsted County, Minnesota were diagnosed with carpal tunnel, compared to the rates seen in Sweden.

What accounts for these differences is still unclear, but both medical and social factors could be at play, said Dr. Isam Atroshi, of Hassleholm Hospital in Sweden, who led the new work.

For instance, he added in an email, it could be related to obesity or to different types of work.

Carpal tunnel is often a result of repetitive motions that cause the ligaments in the wrist to become inflamed and pinch a nerve.

Gelfman said as many as 15 percent of the population may have symptoms, but only about five percent or fewer have a diagnosis of carpal tunnel syndrome.

He added that the symptoms of carpal tunnel syndrome - pain and numbness in the arm and hand - are similar to those of tendonitis, a less serious but common inflammation of the tendons.

Carpal tunnel syndrome sometimes goes away by itself, but may require treatment. If wrist splints or corticosteroid hormone injections fail, surgery can take pressure off the pinched nerve and provide pain relief.

SOURCE: Archives of Internal Medicine, May 23, 2011.