THE EFFECT OF ELECTRODE POSITION IN ELECTROCOCHLEOGRAPHY

This study assessed the effect of needle electrode position on the hum an cochlear summating potential (SP) obtained by transtympanic electro cochleography (ECochG). Electrocochleography was performed on 10 subje cts with large central tympanic membrane perforations with good cochle ar function, and in whom a needle electrode could be accurately placed in a series of five pre-determined positions in the middle ear. A com parison of the electrocochleograms revealed a wide scatter of results between different positions in the same patient and between similar po sitions in different patients. Only when the needle was repositioned a t an almost identical recording site in the same subject, was good rep roducibility achieved. Such a wide and unpredictable variation in resu lts would suggest great caution is needed when comparing traces obtain ed using a transtympanic technique which precludes a view of the elect rode tip.