[Pathogenesis and treatment of presbyacusis. Current status and future perspectives]

Factors responsible for presbyacusis include physiological ageing processes as well as endogenous or exogenous causes. In the industrial countries, two main exogenous causes are exposure to loud noise and obesity. Pathomechanisms contributing to presbyacusis are hypoxia/ischemia, reactive species formation and oxidative stress, apoptotic and necrotic death of hair cells and spiral ganglion cells as well as inherited and acquired mutations in the mitochondrial DNA. Important for the successful treatment of presbyacusis is a timely fitting of hearing aids on both ears to improve communication and provide the auditory system with acoustic information. Using the hearing aids will also elevate the detection threshold of an existing tinnitus signal. At present, several therapeutic strategies based on pharmacological intervention are under discussion. The application of antioxidants or caloric restriction are considered to prevent or reduce oxidative stress-induced damage. Animal experiments evidenced that superoxide dismutase 2 (SOD2) strongly decreases in age; thus, a further approach may be the overexpression or modulation of the SOD2 within the cochlea. Adenoviral-mediated gene transfer technology would be a tempting approach to address this type of therapy. Finally, hair cell regeneration could be a possible treatment of presbyacusis in the future.