Auditory brainstem response in postmenopausal women treated with hormone replacement therapy: A pilot study

Objective: To research the nongenital audiological target for gonadal steroids in postmenopausal women who are treated with hormone replacement therapy. Design: Fifty postmenopausal volunteers were treated with hormone replacement therapy. Women with an intact uterus had sequential weekly transdermal estradiol plus nomegestrole acetate 5 mg orally for 12 days per month or a continuous daily oral dose of conjugated estrogen 0.625 mg and medroxyprogesterone acetate 5 mg tablet. Eighteen surgically postmenopausal women received a weekly transdermal estradiol system. Twenty-five postmenopausal volunteers-5 with a natural menopause and 10 with a surgical menopause-and 20 premenopausal normally cycling women were used as a control group. Each woman performed auditory brainstem response by auditory-evoked potentials for waves I, III, and V and for interpeak I-III, I-V, and III-V intervals. Results: Women who were treated with hormone replacement therapy showed wave latencies and interpeak latencies shorter than those for postmenopausal women in the control group (p ≤ 0.05), overlapping those of the premenopausal women (p > 0.05). Women who were treated with estrogen replacement therapy showed shorter time latencies than those treated with combined hormone replacement therapy (p ≤ 0.05). Conclusions: Our data suggest that fluctuating hormone levels cause changes in auditory brainstem response waves, even if the exact mechanism of activity of the gonadal steroids is not clear. However, we believe that estrogen may influence the neuronal plasticity, the metabolic levels of neurotransmitters, and thus the neuronal conduction time into the audiological system