Sympathetic Stimulation and Otic Blood Flow

Abstract

The radioactive microsphere technique was used in dogs to assess the effect of sympathetic stimulation on temporal bone blood flow. The stellate, caudal cervical and superior cervical ganglia, and the vertebral and cervical sympathetic nerves were stimulated. In a large majority of the animals, stimulation had no effect on temporal bone blood flow although nasal tissue was greatly affected. In a minority of animals, a small effect was seen in temporal bone tissue. Similarly, norepinephrine infusion usually did not produce evidence of reduced blood flow in the temporal bone. It was concluded that the sympathetic innervation of otic blood vessels was not capable of controlling otic blood flow, only modulating it. A sympathetic vasospasm does not seem possible. Mention is made of the dual sympathetic innervation of the cochlea described by Spoendlin and Ross. The possible mediation of sympathetic effects in the cochlea by cyclic AMP is suggested.