[Evaluation of the cochlear efferent system in patients with cerebello-pontine angle tumor]

The aim of the study was to estimate a cochlear efferent system in the group of patents with cerebello-pontine angle tumor (CPA). The size of an efferent effect was defined as the difference of the amplitudes in click evoked otoacoustic emissions (CEOAEs) during without contralateral acoustic stimulation (CAS) and with broad-bond noise (BBN) was estimated. The research was also conducted on the influence of tumor dimensions, age, sex, and the hearing level in tonal audiometry on the size of the efferent effect. The research was carried out on a group of 14 patients with cerebello-pontine angle tumor and on an appropriate fourteen-person test group. Having our results analyzed we were able to state that, compared with the test group, in the group of patients with CPA tumor significant reduce suppressions of otoacoustic emission response during CAS occurred both in an ear on the tumor side and in an ear on the healthy side. However, the tumor dimensions, sex, and the hearing level in tonal audiometry seemed not to affect significantly the size of the efferent effect.