Vagino-levator reflex: description of a reflex and its role in sexual performance.

A new reflex, termed the 'vagino-levator reflex', was studied in 17 healthy women (mean age 36.6 years). The vagina was distended with up to 300 ml air in a condom tied to a catheter, and the levator ani response was determined by means of needle electrode introduced into the muscle. The test was repeated after anesthetizing the vagina and the levator muscle, respectively. The levator EMG activity rose when the vagina was distended; the amplitude and duration of activity increased in parallel with vaginal distension. The levator response did not occur after successive repetition of vaginal distension due probably to levator muscle fatigue; nor did it occur after anesthetizing the vagina or the levator muscle. The mean latency of the reflex was 39.5 ms. The vagino-levator reflex seems to play a role in the sexual act. Levator contraction upon penile thrusting leads to genital responses that could facilitate sexual performance. These responses comprise widening of the vaginal introitus, vaginal elongation and ballooning of the upper vagina as well as uterine elevation. Vagino-levator reflex dysfunction may result in disorders of sexual act.