ISSN:0192-9763    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

A series of 101 patients with Meniere's disease treated surgically with an intramastoid endolymphatic shunt operation and with a minimum follow-up of 2 years is reported. The results included success in 76 percent and failure in 22 percent. Thirteen of these patients maintained a hearing level of 15 dB or better, while 11 patients experienced hearing gains of 25 dB or better.These results are compared to other reports, and the difficulty of making such comparisons is illustrated. A derived “efficacy ratio” is defined, and its use is suggested to aid in making statistical inference. The conclusion is reached that more knowledge is required about the natural history of Meniere's disease so that appropriate staging may be carried out on these study populations.

ISSN:0192-9763    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Cerebral angiography has become essential in the evaluation and management of extensive skull-base lesions. However, with a 2.6 percent incidence of neurologic complications and a 0.3 percent incidence of permanent neurologic deficits associated with cerebral angiography, the procedure is not without risk.1 Recent advances in magnetic resonance angiography (MRA), allow one to visualize the skull-base vasculature without need of intravenous contrast injection or radiation exposure.Our initial experience in visualizing the normal vascular anatomy and pathology at the base of skull with this new imaging modality is presented. Two different MRA techniques were used: (1) thin-slice two-dimensional gradient echo pulse sequence acquisition with three-dimensional projection reconstruction, and (2) two-dimensional phase contrast angiography. The specifics of these techniques and their usefulness in the evaluation of lesions involving the skull base are discussed and demonstrated.

ISSN:0192-9763    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

For patients with a totally empty middle ear a total alloplastic middle ear prosthesis (TAM) has been developed consisting of a macroporous hydroxyapatite canal-wall segment as a foundation system from which a dense hydroxyapatite ossicular chain is suspended. To connect the ossicular chain, we developed an alloplastic tympanic membrane made from a polymer.Light microscopy, morphometry, and autoradiography as well as various electron microscopy techniques were used in this study to evaluate the biocompatibility of Polyactive(R), a polyether polyester copolymer, after implantation in the rat middle ear.After between 2 and 4 weeks, implants were completely covered by tympanic-membrane epidermis and epithelium. Polyactive provoked a mild foreign-body reaction, showed a degradation rate of 54 percent after 1 year, and was nontoxic. Growth of fibrous tissue and bone into Polyactive copolymer indicated appropriate implant fixation by mechanical interlocking. The fixation of Polyactive by ingrowth of bone is promising, not only in terms of the amount of bone but also in terms of the bone/polymer interface. The latter is indicative of bonding osteogenesis in a way similar to that reported for hydroxyapatite implants.The results of this study showed that Polyactive copolymer is suitable as a degradable alloplastic tympanic membrane, both as a temporary scaffolding for the repair of tympanic membrane perforations and as a tympanic membrane in the TAM.

ISSN:0192-9763    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

In patients with Meniere's disease, the possibility of developing Meniere's disease in the uninvolved ear is of great concern. In this study, the incidence of bilateral Meniere's disease (BMD) in medically treated patients was found to be 17 percent, while in surgically treated patients it was significantly lower, 5.9 percent (p<0.01). The incidence of BMD for each surgical procedure was as follows: 9 percent after endolymphatic subarachnoid shunt (n=101), 7 percent after cochleovestibular neurectomy (n=100), 6 percent after cochleosacculotomy (n=18), and 0 percent after vestibular nerve section (n=73). The average duration of disease prior to surgery was 6.3 years. Seventy-two percent of the patients who developed BMD did so within 5 years of the onset of their symptoms. Proper patient selection is the most likely explanation for the low incidence of BMD among surgically treated patients.

ISSN:0192-9763    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Auditory brainstem response is now widely employed as a screening test for acoustic neuromas because it is equally sensitive when standardized against computed tomography. We have detected eight small (<10 mm) acoustic neuromas using gadolinium enhanced magnetic resonance imaging. In three of these cases, the auditory brainstem response was falsely negative. In contrast, 19 patients with larger tumors (>10 mm) were found to have no false negative auditory brainstem responses. Auditory brainstem response appears to be less sensitive for detecting smalI, symptomatic acoustic neuromas.

ISSN:0192-9763    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

A more practical method of reporting the neurotologic test results became desirable in the course of preparing case reports. This need grew out of the necessity to organize neurotologic test results in a simple, easily understandable, nonredundant manner. Tests organized in this manner were vestibular and auditory tests. Vestibular tests included electronystagmography, rotational testing, and posturography. Auditory tests included pure-tone testing, speech testing, impedance testing, and auditory brainstem responses.

ISSN:0192-9763    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

This investigation studied the electrical auditory brainstem response (EABR) inputoutput functions in three groups of patients: individuals with normal auditory neural systems; patients with acquired, profound sensorineural hearing loss; and patients with congenital, profound sensorineural hearing loss. Each input-output function was obtained in the operating room under general anesthesia and with the patient paralyzed to eliminate myogenic contamination. In contrastto the acoustically elicited ABR, the EABR waveforms were characterized by a dominant early wave corresponding in latency to wave II. This wave was much larger and often appeared at lower stimulus intensities than wave V. The results, plotted according to rate of growth for waves II and V, showed that normal subjects generally had larger, more robust early waves than either hearing impaired group. Little difference was noted in the amplitudes or rates of growth for wave V among the three groups. Based on these observations, we concluded that the EABR demonstrated differences in the way normal and impaired systems respond to electrical stimulation. In addition, the EABR may be useful in providing a qualitative prediction of neural survival into broad categories of many surviving neurons versus a marked reduction in ganglion/neuronal density.

ISSN:0192-9763    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

Possible age-related effects of speech competition in one ear on the late auditory (LAEP) and P300 event-related potentials recorded at the other ear were investigated with female volunteers. In each of the age categories of 20 to 34, 35 to 49, 50 to 64, and 65 to 80 years, 10 subjects were tested. While contralateral speech competition produced no significant amplitude or latency changes in the earlier auditory brainstem or middle latency responses, several age- and competition-related effects were observed with the later-occurring LAEP and P300 responses. With contralateral competition, the two oldest groups exhibited significantly larger reductions in the N1-P2 peak-to-peak amplitude of the LAEP than did the two youngest groups. While significant decreases in P300 amplitude also occurred with the competition, the magnitude of this effect was not age-related. In addition, small but statistically significant increases in the latency of all three major components, N1 and P2 of the LAEP, and P300, occurred in the presence of contralateral competition. These effects also did not differ among the four age groups. Thus, the LAEP appears to be sensitive to some form of age-related change in binaural processing or attention, although the P300, while sensitive to contralateral competition, did not reflect an age-related component in this effect.

ISSN:0192-9763    

出版商:OVID    

年代:1991

数据来源: OVID

摘要:

In the preceding report in this journal, the authors presented evidence for an electrophysiologic correlate of impaired binaural processing or attention in elderly listeners. In the present experiment, the subjects tested in the earlier study were administered a Dichotic Digits Recognition task in which they were required, in separate sessions, to repeat all digits heard in both ears (channel capacity measure), or to report the digits in one ear while ignoring the digits in the opposite ear (selective attention measure). With both measures, older subjects performed significantly poorer than did younger subjects. Although similar age-related decrements in performance were observed with the behavioral and electrophysiologic tests, no significant correlations were found in the performances on the two types of tests. This suggests that, while both behavioral and electrophysiologic tests can reveal age-related decrements in binaural processing, they do not necessarily reflect the same underlying neural processes.

ISSN:0192-9763    

出版商:OVID    

年代:1991

数据来源: OVID