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Abstract:
The anatomy of cochlear blood vessels is described and reference is made to the adrenergic innervation and its possible importance for the cochlear function. The effects of blood pressure changes due to various sympathetic influences upon the cochlear circulation and cochlear pO2 are also emphasized. Both general rules governing the microcirculation as well as anatomic and functional analyses of the cochlear blood vessels indicate that the capillary system possesses a remarkable ability for compensation so that a severe impairment of hearing function can occur either after obstruction of the larger afferent or efferent cochlear blood vessels or by general unbalance of the cochlear microcirculation. It is reported further on methods and results concerning the susceptibility of the cochlear microcirculation to various influences. According to the current scientific knowledge, the inner ear circulation has at its disposal a marked ability of autoregulation, its microcirculation however correlates with the aortic pressure better than the brain circulation. When the blood pressure is low, sympathetic stimulation leads to a decrease and sympathectomy to an increase of cochlear circulation. It has been shown that the inhalation of mixtures containing high doses of CO2 and the intravenous infusion of hyperosmolar solutions can also induce a significant increase of the cochlear blood circulation.