Differential effects of exogenous estrogen versus a estrogen-progesterone combination on auditory evoked potentials in menopausal women.

The study was undertaken to determine the differential effects of estrogen and progestin on auditory evoked responses in postmenopausal women receiving hormone replacement therapy (HRT). Forty-seven women between 45 and 70 years of age attending menopause and HRT clinic were divided into two groups. Group I included 32 women who attained natural menopause and receiving combined estrogen progestin therapy. While group II included 15 surgically menopausal women receiving only estrogen. Evoked potentials were recorded in form of auditory brainstem response (ABR), middle latency response (MLR) & slow vertex response (SVR). There was improvement of conduction in auditory pathways at the level of brainstem and thalamocortical projections as indicated by the decrease in latencies of most of the waves of ABR and/MLR after 6 months of HRT in both the groups. The conduction in association areas, as indicated by SVR, did not show a significant change. The intergroup comparison after therapy revealed a decrease in latency of wave V and I-V interpeak latency in group II indicating that only estrogen users are benefited more. Thus HRT facilitates the process of sensory conduction, which may form one of the mechanisms of improved neuropsychological functions in menopausal women on HRT. The addition of progestin to estrogen does not have a negative or potentiating effect on it.