Learning Objectives: Translational research concerning a syndrome with new information added stepwise.

Background: In Turner syndrome (loss of one X-chromosome) a female fenotype is presented with ear and hearing problems. These women lack ovaries and do not produce any estrogen. Both the outer, the middle and the inner ear are commonly affected in this syndrome. These women have massive otitis media problems, middle ear problems and a rapid hearing decline already at the age of 35. Males in general have a slow decline over time (from age 20), while females in general have a god hearing until time for menopause, when estrogen levels are low. What impact does estrogen have on hearing?

A Turner mouse, lacking one x-chromosome, has been developed and underlying immunological causes to explain the frequent otits media problems have been ruled out. Estrogen receptors, a prerequisite for estrogen acting in the inner ear, have been demonstrated in mice, rats, pigs and humans in the hearing nuclei where the hearing pathways are switched. There are two estrogen receptors present, an alfa and a beta receptor in the inner ear and if the beta receptor is knocked-out, mice gets deaf early at the age of 1 year.

A rapid decline in hearing is seen just at the time for menopause in the general population of women and hearing decline can improve if estrogen substitution is given. Estrogen substitution given to rats after ovaries having been surgically removed, hear better.

Methods: Experimental animal studies using immunhistochemistry, ABR measurements, genetic manipulations and hormone substitution have been performed as well as human longitudinal studies following hearing over time.

Results and Conclusion: It has been proven in animal and human studies that estrogen has an impact on hearing and can be regulated. Prednisolone does not show any receptors in the inner ear. Would it be possible to stimulate selective receptors with estrogen substitution to diminish the infections and hearing problems in the future?