Effects of patch or gel estrogen therapies on auditory brainstem response in surgically postmenopausal women: a prospective, randomized study

Abstract

Objective To study the effects of gonadal steroids on the nongenital audiological target in surgically postmenopausal women treated with patch or gel transdermal estrogen therapy (ET). Design Prospective randomized study. Setting Research Group for Sexology, University of Catania, Italy. Patient(s) One hundred twenty-two surgically postmenopausal women. Intervention(s) Transdermal E 2 by patch or gel, and evaluation of auditory brainstem response by auditory-evoked potentials for waves I, III, and V latencies, and for interpeak I–III, I–V, and III–V intervals. Main outcome measure(s) Changes in auditory wave latencies and in interpeak intervals during treatment with ET with respect to baseline levels. Result(s) One hundred two women completed the study. Forty-eight subjects used E 2 patches and 54 E 2 gel. No significant difference was observed in plasma E 2 improvement and in auditory brainstem response values with the two estrogen (E) formulations. The wave latencies and the interpeak intervals showed lower values during the E treatment than at baseline. Conclusion(s) Auditory brainstem response seems to depend on the type of E given. Our data suggest that fluctuating E levels act on waves, even if the exact mechanism of the gonadal steroids is not clear. However, we believe that E could influence neuronal plasticity, the metabolic levels of neurotransmitters, and thus, the neuronal conduction time into the audiological system.