Percutaneous Recording of Cochlear Microphonics in Cats

Abstract

A NONSURGICAL approach to the recording of cochlear microphonics (CM) can have important clinical application. In the St. Joseph's Research Laboratory a method has been developed using cats as the experimental animal. Transference of the method to humans is in process. The method, using skin electrodes, has evolved from the following investigations. Material and Method Comparative recordings are made from anesthetized (sodium pentobarbital [Diabutal]), healthy, adult cats. In each animal readings are taken from a mature^* round window electrode, a tympanic membrane electrode, and skin electrodes. The skin electrodes are conventional hypodermic needles. Placement for optimal amplitude of the CM is shown in Fig 1. In recording from the tympanic membrane a ball-tipped copper wire is used as the active electrode with a hypodermic needle for reference in the skin. Stimuli are delivered through a polyethylene tube fitted into the animal's external canal and coupled with the phone by machined