Treatments for genital pain no better than placebo

Two standard therapies for a type of genital pain in women may be no more effective than a placebo, a new clinical trial suggests.

The study, reported in the journal Obstetrics & Gynecology, tested the effectiveness of two treatments for vulvodynia - pain in the external genital area that can either be chronic or arise from contact, such as during sex, tampon insertion or exercise that puts pressure on the area, like bike riding.

The condition may affect up to 14 million U.S. women at some point in their lives. Vulvodynia is diagnosed when other potential causes of the pain, such as infection, are ruled out.

The precise cause of vulvodynia is not clear, but researchers speculate that various factors may contribute to the disorder in different women - including injury to the nerves that supply the vulva; abnormal activity in the hormone receptors on cells that make up the vulvar tissue; and dysfunction in the muscles of the pelvic floor.

Among the therapies for vulvodynia are a class of depression medications known as tricyclic antidepressants and topical pain-numbing medications such as lidocaine.

Although both treatments are widely prescribed, there have been no clinical trials testing their effectiveness against a placebo. Such clinical trials are considered the "gold standard" for proving that a therapy does, in fact, produce results.

Despite the lack of evidence for their use, tricyclic antidepressants and topical lidocaine have become widely used for vulvodynia based largely on doctors' experience and the fact that the therapies are effective for other pain conditions, said Dr. David C. Foster, a professor of obstetrics and gynecology at the University of Rochester in New York.

For the new study, Foster and his colleagues randomly assigned 133 women who had had vulvodynia for at least three months to one of four treatment groups: one that received the antidepressant desipramine (Norpramin) and lidocaine cream; one given the antidepressant plus a placebo cream that only contained moisturizing ingredients; a third given placebo pills identical in appearance to the antidepressant, plus lidocaine cream; and a fourth that received only placebo pills and cream.

All of the women had "localized" vulvodynia (confined to the area surrounding the opening to the vagina) that arose from contact.

After 12 weeks, the researchers found, women in all four groups reported improvements in their pain symptoms.

On average, women taking both desipramine and lidocaine cream reported a 36 percent reduction in pain during a tampon-insertion test. But those using both placebo pills and placebo cream showed a similar improvement - a 33 percent reduction in pain, on average.

The improvements in the other two groups were somewhat less but still significant, according to the researchers: a 20 percent reduction in pain during tampon insertion in the lidocaine-only group, and a 24 percent decline in the antidepressant-only group.