Cochlear Microphonics for Hearing Preservation in Vestibular Schwannoma Surgery

Abstract

The cochlear microphonic detection threshold predicts not only hearing preservation but also hearing improvement in patients with vestibular schwannomas.

Cochlear microphonic audiometry: a new hearing test for objective diagnosis of deafness

“…But, in that situation, the CMP lacks clinical utility because of its low derived potential. However, the CMP recording has some applications [10,13,14] including surgical monitoring of cochlear implantation [15]. Specific CMP recording, with surface electrodes and its applications, has been described previously [6Á8,16].…”

Intraoperative neuromonitoring techniques in the surgical management of acoustic neuromas

“…9,22,39,40,46,54,82,94,125,126 The operative EMG device consists of a stimulator probe and a "sensor" that detects contractions of the facial muscles. Most operations use a minimum of 2 channels to observe the activity of the orbicularis oris and orbicularis oculi muscles, 12,46,77,82,90,115 although the use of additional channels to observe other facial muscles may provide further benefit.…”

“…5,12,16,36,49,52,62,75,88,94,99,103,112,115,116,120,130,132,139,147 Although this discrepancy may highlight the need for improvement in IONM of CN VIII, 99 it may also reflect the inherent difficulty in preserving auditory function, as large tumors are more highly associated with postoperative deficits, 1,11,20,23,88,89,103,116 and tumors with extensive infiltration into the cerebellopontine angle render acoustic preservation an arduous task. 23,89,147 Operative damage to the vestibulocochlear nerve can be induced in various ways.…”

“…8,14,17,19,48,54,79,120,131,142,145,146 Further electrical waveforms are seen in ECOG, thus differentiating it from a direct CNAP reading. The cochlear microphonics and summation potential are both electrical responses generated from the organ of Corti, 54,94,113,120 and lower cochlear microphonic detection thresholds may be involved in prognosticating postoperative hearing function. 94 In the overall context of ECOG monitoring, however, cochlear microphonics and summation potentials are generally considered less important than the N1 peak.…”

“…The cochlear microphonics and summation potential are both electrical responses generated from the organ of Corti, 54,94,113,120 and lower cochlear microphonic detection thresholds may be involved in prognosticating postoperative hearing function. 94 In the overall context of ECOG monitoring, however, cochlear microphonics and summation potentials are generally considered less important than the N1 peak. 64,120 The primary advantages of ECOG and direct CNAPs are derived from their near-field designation.…”