Cochlear blood circulation studied with microspheres.

The cochlear blood flow was studied with the microsphere method in guinea pigs, rats and cats. Results from experiments using different sizes of microspheres were compared and the effect of middle ear infection or perforation of the otic capsule on the cochlear microcirculation was investigated. Neither the opening of the cochlear bony wall nor the middle ear infection influenced the blood flow in the cochlea. 9- and 15-micrometer spheres were given simultaneously and the results were equivalent, indicating no more shunting of the smaller ones than of the bigger ones. Thus, the smaller spheres are to be preferred, since the smaller ones can be used in a larger number without negative effects on the general circulation. In cats, the cochlear blood circulation was determined before and during cervical sympathetic stimulation. Sympathetic stimulation caused a reduction of 25% of the cochlear blood flow.