Pharmacological effects on cochlear blood flow measured with the Laser-Doppler technique

Studies of the cochlear blood flow (CBF) have been hindered by the relative inaccessibility of the vasculature deep in the temporal bone. However, well before the development of modern techniques for blood flow measurements and vital microscopy, clinicians made attempts to treat inner ear disorders by pharmacological means, e.g. by performing surgery on the cervical symphathetics in order to reduce a supposed vasoconstriction caused by norepinephrine or trying to cause cochlear vasodilation by injections of Novacin. The results of these treatments seemed positive, but were difficult to evaluate because of the high percentage of spontaneous recovery or remissions among the diseases treated. This problem continues today in evaluation of the effects of Dextran therapy or Carbogen inhalation. Current medical treatment however, is based on an increasing body of knowledge about the regulatory mechanisms controlling CBF. This knowledge has been gained by use of a variety of techniques with different approaches.