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.

The groups also showed similar improvements on other measures of pain, including a cotton-swab test and a standard survey that gauges pain related to nerve damage. The only advantage seen with active treatment over placebo was when it came to the women’s satisfaction with their sex life: those on the antidepressant reported a bigger gain.

The findings, according to Foster, could indicate that the benefits of desipramine and topical lidocaine for vulvodynia pain reflect the “placebo effect” - where people feel better simply because they believe they are being treated.

But that is not necessarily the case, Foster told Reuters Health.

“What could be going on,” he explained, “is that there is a natural history of the condition where, if you give people enough time, many will get better.”

Another possibility, according to Foster, is that some women benefited from using moisturizing placebo cream.

His advice to women with vulvodynia symptoms is to try to find a doctor with experience in treating the condition who will take careful measurements of the pain - which ideally would include simple tests like the cotton-swab test of the vagina - and then monitor how that pain changes over time.

Foster noted that the National Vulvodynia Association (http://www.nva.org) is one resource women can use to find local doctors experienced in managing the condition.

In general, it would be best for women to start with the most conservative therapy options to limit the risks of side effects, according to Foster.

Like any drug, those used to treat vulvodynia carry some risks. In the current study, between one-fifth and one-quarter of women on desipramine reported dry mouth, hot flashes or dizziness. The most concerning side effects included tachycardia (a rapid heartbeat), seen in 16 percent of women on the medication; one woman developed mildly elevated liver enzymes, which can signal liver damage, and one developed elevated blood pressure and rapid heartbeat.

Non-drug approaches to relieving vulvodynia include physical therapy for the pelvic floor muscles, biofeedback to learn how to control the vaginal muscles, and cognitive-behavioral therapy to learn better ways to deal with symptoms. Studies suggest that these therapies are effective for some women.

Some women also find that cutting down on foods that contain compounds called oxalates - including greens, chocolate, beans and nuts - can make their urine less irritating and help ease vulvodynia pain.

When non-drug therapies and medications fail, surgery - called vestibulectomy - to remove the painful tissue is an option for women who have discomfort limited to that area.

Earlier this year, the British Society for the Study of Vulval Disease issued guidelines underlining the need for a combination of therapies in managing vulvodynia. It said that an individual woman’s pain should be carefully assessed, and she should be offered a range of treatment options depending on her personal situation - including pain medication, physical therapy, psychological therapy and, “if all else fails,” surgery.

Foster agreed that treatment has to be individually tailored. He pointed out that a 16-year-old girl who recently developed symptoms could well need different management from a woman in her 30s who has suffered pain for years.

As far as research implications, Foster said that going forward, it will be important to keeping testing vulvodynia medications against a placebo to weed out their true effectiveness.

Besides tricyclic antidepressants and topical anesthetics, certain anti-seizure medications, like gabapentin, are sometimes prescribed for vulvodynia.

SOURCE: Obstetrics & Gynecology, September 2010.