摘要:

In a prospective study, 60 patients who underwent surgery for unilateral acoustic neuromas had the hearing on the contralateral ear tested before and several times after surgery. In 40 patients, a threshold increase was found during the following 9 days. The changes were greatest in the low frequencies immediately after surgery, but after 1 week the treble also became involved. After 3 months, the hearing was normalized. The elder patients more than 50 years of age were more often affected, whereas sex, tumor size, surgical approach or duration of surgery had no influence. The pathophysiological mechanisms are discussed and an intracochlear fluid dysfunction caused by the loss of cerebrospinal fluid is suggested.

ISSN:1420-3030    

DOI:10.1159/000259208

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Hearing loss has been reported following leakage of cerebrospinal fluid (CSF). The etiology has been attributed to an induced imbalance in the intracochlear hydrodynamics. The present study reports a guinea pig model with surgically induced loss of CSF. In 18 anesthetized animals, CSF was drained by a suboccipital incision in the dura. Eighteen animals were used as controls. The compound action potentials were recorded by an ear canal silver electrode. The animals with CSF loss showed a small increase in threshold and latency, while the control group was unchanged. The concept of an induced inner ear fluid dysfunction after CSF leak is supported by these findings.

ISSN:1420-3030    

DOI:10.1159/000259209

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Numerical estimation of pitch was performed by 8 adult subjects implanted with cochlear prostheses manufactured by Cochlear Limited. The electrode arrays had been inserted into the scala tympani to between one and one and a half turns of the cochlea. Using bipolar stimulation, the pitch estimates for each subject showed an overall reduction with insertion depth of the stimulated electrode. However, for several subjects, after decreasing regularly for the more basal electrodes, pitch estimates showed an abrupt decrease, followed in some cases by a region of low pitch. Two of the subjects, implanted with a modified electrode array, the ‘20 + 2’ which allowed monopolar in addition to bipolar stimulation, exhibited an abrupt decrease in pitch estimate with bipolar but not with monopolar stimulation. In these two subjects, for stimulating electrodes inserted more deeply than about three quarters of a turn, bipolar stimuli produced lower pitch sensations, and presumably more apical neural excitation patterns, than monopolar stim

ISSN:1420-3030    

DOI:10.1159/000259210

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Results for forward masking and numerical estimation of pitch were compared in a group of 6 adult subjects implanted with cochlear prostheses manufactured by Cochlear Limited. Data were collected for bipolar + 1 stimulation in all subjects, and for stimulation in one other mode, either common ground or monopolar, for all subjects but one. The pitch data show various irregularities and in each case can be seen to be broadly consistent with the corresponding forward masking data. It is shown that a ‘centre of gravity’ of the forward masking distribution varies with masker electrode in a manner that is qualitatively very similar to the variation of pitch estimate. It is suggested that, while pitch estimation results are consistent with those from forward masking, the latter contain more detailed information that may be useful in understanding intersubject variations in speech comprehens

ISSN:1420-3030    

DOI:10.1159/000259211

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

A model of auditory performance and a model of ganglion cell survival in postlinguistically deafened adult cochlear implant users are suggested to describe the effects of aetiology, duration of deafness, age at implantation, age at onset of deafness, and duration of implant use. The models were compared with published data and a composite data set including 808 implant users. Qualitative agreement with the model of auditory performance was found. Duration of deafness had a strong negative effect on performance. Age at implantation had a slight negative effect on performance, increasing after age 60 years. Age at onset of deafness had little effect on performance up to age 60. Duration of implant use had a positive effect on performance. Aetiology had a relatively weak effect on performance.

ISSN:1420-3030    

DOI:10.1159/000259212

出版商:S. Karger AG    

年代:1996

数据来源: Karger

ISSN:1420-3030    

DOI:10.1159/000259213

出版商:S. Karger AG    

年代:1996

数据来源: Karger