Studies suggest that some of the improvement in vaginal and urinary symptoms produced by postmenopausal estrogen therapy might be due to increased sensory responsiveness. Foster and colleagues investigated whether topical estradiol cream increases vulvovaginal responsiveness and the strength of circumvaginal muscles in women more than 60 years of age with urinary tract conditions such as incontinence, urgency or frequency.

Women in the study ranged from 60 to 72 years of age; their duration of menopause ranged from 21 to 26 years. The initial assessment included a comprehensive gynecologic examination, including evaluation of pelvic support and bulbocavernous reflex, vaginal atrophy and perineal sensation. Vaginal cytology assessment included maturation index. Serum estradiol levels were also obtained.

The 39 women enrolled in the study were randomly allocated to one of four treatment groups: (1) a group using 2 g of estradiol topical cream on the vulvar vestibule and vagina every night plus pelvic muscle biofeedback training, (2) a group using topical estradiol cream but no biofeedback training, (3) a group using placebo cream plus biofeedback training, and (4) a group using placebo cream plus sham biofeedback training. Patients were reassessed at four and six weeks. Thirty of the 39 patients completed the study.

Topical estradiol cream was associated with significantly improved sensitivity of the vulvar vestibule. This effect was most pronounced in women who were more than 70 years of age. Use of estradiol cream had no effect on the strength of circumvaginal muscles. The number of subjects did not permit analysis of changes in muscle strength by age. Use of estradiol cream also significantly improved the vaginal atrophic index, but serum estradiol levels did not correlate with changes in sensitivity.

The authors conclude that topical estradiol cream improves sensation in the vulvar vestibule through a direct local action of rapid onset. Such effects could improve sexual function. No effect on muscle strength of the circumvaginal muscles was noted. The authors call for further studies to confirm that estrogen acts on the peripheral nervous system as well as the central nervous system.