摘要:

ABSTRACTThis is a review of our studies of the labyrinthine fluid pressure in cats subjected to pressure changes in the middle ear (implosive routes) and the cerebrospinal fluid compartment (explosive routes) as well as to changes in vascular and ambient pressures. The perilymph, cerebrospinal fluid (CSF), middle ear, venous and arterial pressures were measured with the cochlear aqueduct (CA) patent as well as surgically blocked. Experiments on explosive pressure changes revealed that the perilymph pressure was regulated by the CSF in case of CA patency. The CSF influence was dominant enough to obscure any direct effect on the labyrinth from other sources. With the CA obstructed the CSF influence on the labyrinth was apparently mainly via the endolymphatic sac and duct although limited and much delayed. Systemic arterial pressure changes had a pronounced influence on the perilymph pressure, but this effect was revealed only when the CSF influence was reduced by CA obstruction. Experiments on implosive and ambient pressure changes suggested that there was no fundamental difference in the perilymph response to equivalent levels of implosive versus hypobaric pressure. Three factors determined the effect of implosive and hypobaric pressure: the patency of the CA, the rate of the pressure change, and the eustachian tube function.

ISSN:0192-9763    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTIn an effort to better define the effectiveness of the use of posturography in the preoperative diagnosis of perilymphatic fistula (PLF), a prospective investigation of the use of platform pressure posturography was performed. Six different protocols used atmospheric pressure change applied to the external auditory canal. Postural sway, monitored as the output parameter, was evaluated relative to its sensitivity and specificity in five different patient groups. Two independent surgeon groups were used to establish the final diagnosis of perilymphatic fistula. Results within a given surgeon group demonstrate varying sensitivity from 53 to 100 percent and specificity from 56 to 89 percent. Results across the two surgeon groups show nonstatistically significant changes in sensitivity and specificity, yet statistically significant differences exist between the surgeon groups for rate of surgery performed given a suspected patient group, and for rate of positive identification of PLF during surgery. We conclude that although the platform pressure test (PPT) shows promise as a test to raise preoperative suspicion for PLF, actual test performance figures cannot be calculated until a more definitive, objective, test is available to confirm the final diagnosis. The variability of selection criteria and diagnosis by surgical observation is too great to draw clear conclusions relative to test performance. Additionally, the use of vestibular rehabilitation techniques is suggested as a presurgical management strategy for a selected group of suspect patients.

ISSN:0192-9763    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTExperiment I investigated the effects of sample size (500 to 1500 stimulus repetitions) on the auditory brainstem response as a function of intensity (20 to 80 dB nHL) on a group of 10 normally hearing subjects. There was little change in identifiability, reliability, latencies, or amplitudes of Waves I, III, and V as the sample size increased from 500 or 750 to 1500 repetitions. These results suggest that 500 to 750 repetitions may be adequate when methods similar to those in the present study are used, and that the common clinical practice of employing ∼1500 repetitions may unnecessarily prolong testing. Experiment II employed 12 hearing-impaired subjects who were tested at 10 to 40 dB SL using sample sizes from 250 to 4500 stimulus repetitions. Identifiability of all waves increased as sample size increased from 250 to 4500 repetitions. The largest changes in identifiability occurred when sample size increased from 250 to 1500 or 3000 repetitions, with little improvement as sample size increased from 3000 to 4500 repetitions. Examiners should monitor averaged responses and terminate testing as soon as a wave is identified. Contrary to expectation, there was no systematic change in the standard error of measurement for latency (∼0.07 ms) as sample size increased from 250 to 4500 repetitions. The standard error of measurement for amplitude decreased from ∼100 nV with 500 repetitions to ∼45 nV at 3000 repetitions. The improvement in reliability with increasing sample size may be explained by a decrease in the variability of background noise. A systematic decrease in amplitude also was observed as sample size increased. This observation may be explained by a reduction in the residual noise levels or because of time jitter or adaptation within the auditory pathways. Nonetheless, investigators who wish to use ABR amplitude measures for diagnosis may benefit from using a relatively large sample size.

ISSN:0192-9763    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTThe nondeafened guinea pig model was utilized in this study to assess the functional and morphologic effects of cochlear implantation and electrical stimulation. Auditory brainstem responses (ABRs) were recorded prior to and following intrascalar implantation of a 3M-House cochlear electrode (n = 41 ears), as well as after electrical stimulation (n = 23 ears). The experimental population was divided into the following groups according to implantation and stimulation parameters: 200 μA for 3 hours (group I); 200 μA for 24 hours (group II); 400 μA for 3 hours (group III); implanted, but not stimulated (group IV); and nonimplanted, not stimulated ears (group V). Of those cochleae that sustained the trauma of implantation, 32 percent had no detectable ABR to 110 dB SPL clicks, while only 7 percent additionally failed to respond to 130 dB SPL clicks. No significant difference (one-way ANOVA with repeated measures at the 95 percent confidence limit) could be detected when comparing those ears that retained ABRs according to experimental grouping.Morphologic analysis was performed on 29 cochleae. Spiral ganglion “packing densities” were not found to be significantly different among the groups (ANOVA). The status of the organ of Corti was significantly better in groups II and V in comparison to the other groups (Kruskal-Wallis test with pairwise comparisons,p< 0.05); there was no discernible dose-response relationship. Morphologic and electrophysiologic changes correlated with insertion trauma and infection rather than with electrical stimulation at the levels tested in this study. Future research will attempt to develop a computer algorithm that can quantify cochlear morphologic changes in response to implantation and electrical stimulation to improve the analysis of these effects.

ISSN:0192-9763    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTFour patients with cholesteatoma were shown to have a large area of eroded tegmen tympani on computed tomography (CT). Magnetic resonance imaging (MRI) in the coronal and sagittal plane showed temporal lobe herniation in three cases and cholesteatoma with abscess elevating the dura in one case. In the patient with a cholesteatoma and an eroded tegmen tympani on CT, MRI is indicated to rule out brain herniation into the middle ear.

ISSN:0192-9763    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTLocating the facial nerve is an essential step in most mastoid procedures. A constantly occurring, easily identifiable, arterial bleeding point has been identified arising on the posterosuperior-lateral eminence of the posterior genu of the nerve, passing posterosuperiorly. The vessel permits exact siting of the genu before the nerve is seen, and provides a timely warning of the nerve's presence.

ISSN:0192-9763    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTGunshot injuries in the periauricular region can result in massive tissue distortion and destruction. The soft tissue effects can be so dramatic that otologic abnormalities can be initially overlooked, especially by non-otolaryngologists. Delayed stenosis or complete closure of the external auditory canal can occur. We present two cases of post-traumatic ear canal atresia that were initially overlooked by non-otolaryngologists, until secondary plastic reconstructive operations were performed in which preauricular skin incisions entered into large canal cholesteatomas. These canal cholesteatomas resulted from total obstruction of the external auditory canal after trauma.

ISSN:0192-9763    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTGenetic alterations that involve the inner ear and other systems may present well-defined clinical differences. We present two oriental sisters, age 34 and 26 years, with a picture of primary amenorrhea and “infantile” uterus associated with progressive hearing loss begun in infancy in the older sister, and after 20 years of age in the younger sister. The gynecologic evaluation showed uterine hypoplasia and gonadal dysgenesis in both sisters. The audiologic study showed bilateral sensorineural hearing loss with a flat-type curve in both cases, with an average threshold of 500, 1000 and 2000 Hz (PTA) in 80 dB (older sister) and 60 dB (younger sister), with recruitment measured by stapedial reflex in the second case. Vocal discrimination was 30 percent and 80 percent, respectively. The clinical picture fits Perrault's syndrome: recessive autosomal genetic alteration, with XX gonadal dysgenesis and sensorineural hearing loss.

ISSN:0192-9763    

出版商:OVID    

年代:1992

数据来源: OVID

ISSN:0192-9763    

出版商:OVID    

年代:1992

数据来源: OVID

摘要:

ABSTRACTPerilymph fistula is a potentially disabling leakage of perilymphatic fluid from the otic capsule. The occurrence of perilymph fistula is now attributed to a wide variety of causes and the diagnosis is frustrated by a lack of characteristic signs or symptoms. A brief review of the literature and the University of North Carolina philosophy for the diagnosis and management of perilymph fistula is presented. Emphasis on timely evaluation and surgical technique is provided.

ISSN:0192-9763    

出版商:OVID    

年代:1992

数据来源: OVID