Article
Differences and supplemental use of transtympanic electrocochleography and auditory brainstem response audiometry for intraoperative neuromonitoring
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Published: | June 4, 2012 |
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Objective: Resection of lesions within the cerebellopontine angle is widely performed using auditory brainstem response audiometry (ABR) for intraoperative neuromonitoring (IOM). Detection of those potentials via transtympanic electrocochleography (ECochG) is also routinely used but particularly for ear and cochlear surgery. Thus, this study evaluates the value of the combined use and differences between both modalities concerning pre- and postoperative hearing impairment.
Methods: Between 2006 and 2011 we performed 125 consecutive surgeries within the cerebellopontine angle under IOM by ABR and ECochG. The monitoring data were reviewed and related to pre- and postoperative hearing deficit.
Results: MEP monitoring was successful in 114 cases (91.2%). Postoperatively, 42.0% of patients showed any degree of new hearing deficit while 3.7% even improved. We recognized a higher variability and oscillation of EChoG potentials. Moreover, amplitudes of EChochG monitoring were significantly higher (0.18 ± 0.04 µV) compared to ABR potentials (0.08 ± 0.006 µV). (p < 0.05).
Conclusions: ABR and ECochG monitoring of the hearing system show significant differences. However, for optimal monitoring it seems feasible to combine the more stable ABR with the better detectable ECochG.