摘要:

Objective:The aim of this study was to illustrate and discuss management of cochlear implant infections.Study Design:The study design was a retrospective case review.Setting:This study was performed at a tertiary referral center with an associated Veterans Administration Hospital.Patients:Postlingually deafened adults who had revision surgery for delayed cochlear implant infections were included in this study.Intervention:Medical and surgical management of device infection without explantation.Main Outcome Measures:Eradication of infection without loss of speech reception.Results:All four patients were successfully managed without explantation.Conclusions:Explantation of an infected but functioning multichannel implant is not mandatory in the absence of systemic sepsis.

ISSN:0192-9763    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:This study aimed to determine the maximum dose of radiation the CLARION 1.2 cochlear implant can withstand safely.Introduction:Cochlear implants restore functional hearing to patients with sensorineural deafness. Because some patients may need radiation therapy, it is important to investigate the influence of ionizing radiation on cochlear implant function.Methods:This study tested the function of four CLARION 1.2 implants (Advanced Bionics, Sylmar, CA, U.S.A.) after varying radiation treatments with gamma rays. The first implant received a cumulative dosage of 69 Gy over nine treatments (single doses between 0.1-30 Gy). The second was irradiated with a total of 90 Gy, receiving three treatments of 30 Gy each. The third and fourth received doses more typical of patient therapy (i.e., 2 Gy) approximately 30 times, for a cumulative dosage of approximately 60 Gy. Implant function was tested after every treatment; the CLARION implant incorporates a back-telemetry system, allowing impedance and current output testing.Results:Despite the type of treatment, the results were quite consistent: difficulties in function occurred when the cumulative dosage inside the implant was approximately 60 Gy. The first implant recovered completely and the second recovered partially.Discussion:The CLARION 1.2 cochlear implant seems to safely withstand approximately 60 Gy of radiation before experiencing functional difficulties. In a clinical situation, the implant would not likely be in the target volume irradiated, and thus the patient's therapeutic cumulative dosage might be higher.

ISSN:0192-9763    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:This study aimed to investigate the relationship of electrode insertion length and speech recognition in patients using Nucleus-22 cochlear implants.Study Design:The study design was a retrospective review of a consecutive clinical seriesSetting:The study was conducted at an academic medical center.Patients:Thirty-one postlingually deafened adults with at least 6 months' experience with a Nucleus-22 cochlear implant using Spectra-22 processor and SPEAK strategy participated.Main Outcome Measures:Open-set speech recognition scores for words and sentences were measured.Results:Insertion length ranged from 22 rings (estimated 17 mm) to 32 rings (estimated 25 mm). Mean word recognition score was 35%. Mean sentence score was 69.6%. Statistical analysis showed no correlation between insertion depth and word or sentence scores.Conclusion:Insertion of the Nucleus-22 array beyond 22 rings does not improve performance in speech recognition. This finding cannot be generalized to other electrodes or processing strategies.

ISSN:0192-9763    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:This study compares auditory performance between original and replacement cochlear implants.Study Design and Setting:Data from 18 U.S. cochlear implant programs were obtained by retrospective chart review. Patients received and returned subjective questionnaires.Patients:Twenty-eight adults with once-functioning Nucleus 22 cochlear implants that failed received replacement Nucleus 22 cochlear implants in the same ears.Main Outcome Measures:Objective measures included sentence (CID Everyday Sentences or Iowa Sentences) and monosyllabic word (NU-6 Words or CNC Words) speech discrimination scores. Patients also rated and compared performance using subjective scales.Results:Thirty-seven percent of patients had significantly higher sentence or word scores with their replacement cochlear implants than with their original implants, 26% had no significant change, and 37% had significantly poorer scores. Subjectively, 57% of patients reported that the performance of their replacement device was better or the same and 43% reported that it was poorer. There was no correlation between performance with the replacement cochlear implant and cause of the original device failure, duration of original device use before failure, surgical complications with either implantation, changes in electrode insertion depths, or preoperative variables, such as age, etiology, or duration of deafness.Conclusions:Speech recognition ability with a replacement cochlear implant may significantly increase or decrease from that with the original implant. Experienced cochlear implant patients facing reimplantation must be counseled regarding the possibility of differences in sound quality and speech recognition performance with their replacement device.

ISSN:0192-9763    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Hypothesis:The differing clinical behavior of acoustic neuroma (AN) may be explained by the presence of specific biological features involved in tumorigenesis and growth.Background:Transforming growth factor (TGF) β1 is known to participate in the regulation of peripheral nerve tumors, modulating cell proliferation and differentiation with mechanisms different from those of glial growth factors (GGF) and fibroblastic growth factors (FGF), which are responsible for Schwann cells' mitogen activity.Methods:Surgically removed human AN specimens were fixed in formalin and embedded in paraffin for immunohistochemistry studies. Expression and localization of TGF-β1 in different tumor regions were assessed after incubation of paraffin sections with a mouse monoclonal anti-TGF β1 antibody (DBA, Milan, Italy). Clinically, the time elapsed between the beginning of symptomatology and AN size as shown by preoperative computed tomography, magnetic resonance imaging, or both was calculated as rough value of growth rate, which enabled slow-growing and fast-growing ANs to be distinguished.Results:Eighty-four percent of AN specimens expressed TGF-β1 positivity at the level of the cytoplasm of the Schwann cells. TGF-β1 reactivity was also shown in the blood vessel walls (96.15%) and the tumor capsule (80.86%). TGF β1reaction appeared higher in Antoni A regions than in Antoni B regions. No significant relationship was found between TGF-β1positivity and AN growth rate in the two groups.Conclusions:TGF-β1 could participate in the biological behavior of AN, particularly as an important factor of tumor growth prediction by allowing rapidly progressive or potentially recurrent tumors to be differentiated from slow-growing tumors that are unlikely to recur. The clinical course of patients with AN is currently still of little help in predicting the rate of AN growth.

ISSN:0192-9763    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:The purpose of this study was to use multiplanar high-resolution magnetic resonance imaging (MRI) to detail the patterns of tumor spread in nasopharyngeal carcinoma (NPC) and to correlate the findings with the presence of an effusion in the middle ear and mastoid.Materials and Methods:Magnetic resonance imaging was performed in 51 patients with newly diagnosed NPC, providing 102 individual sides for analysis.Results:Fifty-nine lateral walls of the nasopharynx were involved by NPC. Tumor involved the lateral recess (55), eustachian tube orifice (41), levator palatini (LP) (32), torus tubarius (TT) (21), pharyngobasilar fascia (38), tensor palatini (TP) (17), parapharyngeal fat space (PFS) (19), main body of the cartilaginous eustachian tube (CET) (13), bony eustachian tube (0), middle ear (0), and inner ear (0). Effusions were present in 32 (54%) of the 59 involved sides. Effusions were found to be associated with the following patterns of spread: tumor causing major displacement of the CET without invasion (3 of 4), tumor invading TT or LP with minor displacement of the TT (4 of 7) or major displacement of the CET (7 of 7) and advanced invasion involving the TP, PFS, or CET with major displacement of CET (18 of 19). Effusions were not seen in tumors without invasion that were restricted to the lateral recess or eustachian tube orifice either with no displacement (0 of 11) or with minor displacement (0 of 11) of the TT. Effusions were present in 28 of 30 cases with major displacement of the main body of the CET, 4 of 18 with minor displacement of the TT, and 0 of 11 with no displacement. Displacement of the eustachian tube was a significant factor in the production of an effusion (p /0.00001) and remained significant even after exclusion of all cases of advanced invasion (p /0.0001).Conclusion:The cause of an effusion in NPC is multifactorial. Magnetic resonance imaging has shown invasion of the tensor palatini muscle in patients with an effusion, suggesting a functional cause. However, displacement of the eustachian tube is a significant factor in patients with middle ear and mastoid effusions.

ISSN:0192-9763    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:The aim of this study was to assess the performance of clinical methods, viz. otoscopy, pure-tone audiometry, and tympanometry in diagnosing middle ear effusions (MEEs) using magnetic resonance imaging as a reference standard.Study Design:A retrospective study of 46 patients with newly diagnosed nasopharyngeal carcinoma was performed comparing clinical evaluation and audiometry results with magnetic resonance imaging findings obtained before radiation therapy.Results:Twenty-two (25%) of the temporal bones imaged had both MEE and mastoid effusions, 24 (27%) had only middle ear fluid, and 29 (33%) had mastoid fluid alone. The sensitivity for tympanometry, audiometry, and otoscopy in detecting fluid in the middle ear was 96%, 92%, and 80%, respectively. Although tympanometry was most sensitive in diagnosing MEE, there was no statistically significant difference when comparing the overall accuracy of pure-tone audiometry air-bone gap and tympanometry (p=0.7, chi-square test). Flat curve tympanograms (type B) only achieved a sensitivity of 45% but were of high specificity (92%). Forty-nine percent with negative pressure tympanograms (mean air pressures >-100 daPa) had no MEE.Conclusions:Using magnetic resonance imaging as a reference standard, tympanometry is the most sensitive audiologic test in detecting the presence of MEE. The overall accuracy of tympanometry, pure-tone audiometry air-bone gap, and otologic examination was, however, not significantly different.

ISSN:0192-9763    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Hypothesis:Topical application of 3% papaverine hydrochloride in the cerebellopontine angle (CPA) produces reversible conduction block of the facial nerve.Background:A case of loss of spontaneous and evoked facial muscle activity, and transient postoperative facial paralysis, after topical application of papaverine in the CPA during surgery for an acoustic neuroma using intraoperative cranial nerve monitoring is reported. Other cases of transient neurologic dysfunction after use of this drug have been reported.Methods:A rabbit model of CPA surgery via suboccipital craniectomy, with intraoperative monitoring of the facial nerve, was used in this experiment.Results:No significant difference in facial muscle stimulation thresholds was identified after application of varying concentrations of papaverine to the facial nerve in the CPA.Conclusion:Although the intraoperative event described in the report is suggestive of an effect of papaverine on facial nerve function, this effect could not be reproduced in an established animal model of CPA surgery.

ISSN:0192-9763    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Objective:This study was designed to determine whether stapes movement is pistonlike or complex.Background:The literature provides conflicting information on whether stapes footplate motion is only pistonlike or has other types of movement, such as hingelike or rocking.Methods:Using 10 freshly harvested human cadaver temporal bones, 3 targets were placed on the stapes footplate through an extended facial recess approach. The targets were 0.5-mm pieces of reflective adhesive material positioned on the long axis of the footplate at the anterior cms, central footplate, and posterior crus. Displacement and phase of the three targets were measured from 0.2 to 10 kHz at a 90dB sound pressure level input at the tympanic membrane. The measuring system was a sophisticated laser Doppler vibrometer (LDV). A computer program (Tymptest) calculated footplate displacement and relative phase at the three sites and the ratio of anterior-posterior rocking movement of the footplate long axis to displacement at the center.Results:Below 2.0 kHz, stapes vibration is predominately pistonlike. Above 2.0 kHz, anterior-posterior rocking motion increases logarithmically with frequency, and, near 4.0 kHz, rocking and pistonlike motion are approximately equal.Conclusions:Stapes footplate vibration is primarily pistonlike up to 2.0 kHz but becomes more complex at higher frequencies because of an increase in anterior-posterior rocking motion. Hingelike movements were not observed. This information may be helpful in the design of ossicular replacement prostheses that mimic or improve upon normal stapes vibration.

ISSN:0192-9763    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Hypothesis:Cochleostomy followed by intracochlear infusion, as a model system for continuous drug delivery, may be well tolerated by the auditory system with preservation of hearing.Background:The infusion of therapeutic agents, such as neurotrophins, growth factors, anti-inflammatory drugs, and viral gene therapy vectors, into the cochlea over a prolonged period of time may be desirable to reduce cochlear damage after auditory insult. However, the effects of continuous cochlear infusion have not been studied adequately.Methods:Eight Hartley guinea pigs underwent left cochleostomy with infusion of artificial perilymph (n=7) or 0.85% saline (n=1). The artificial perilymph or 0.85% saline was administered by an osmotic minipump (Alza, Palo Alto, CA, U.S.A., model 2002; infusion rate 0.5 uL/hr, mean pumping duration of 2.5 weeks) connected to the cochlea by a fine plastic cannula (Inner Diameter=0.28 mm, Outer Diameter=0.61 mm) that enters the scala tympani via a cochleostomy. Hearing was assessed by determining auditory brain stem response (ABR) thresholds before surgery and on postoperative days 3 and 7 for artificial perilymph infused animals and before surgery and on postoperative days 3, 7, 14, 21, and 28 for the single saline-infused animal. The ABR thresholds were determined with a click and at the following frequencies: 1 kHz, 2 kHz, 4 kHz, 8 kHz, 16 kHz, 20 kHz, and 30 kHz.Results:There was a preservation of preoperative ABR thresholds in the lower frequencies (1,2 kHz), mild elevation (≥10 dB) in the midfrequencies (4, 8 kHz), and marked rise (≤30 dB) in the ABR thresholds at higher frequencies (≤16 kHz). Surprisingly, the single long-term animal showed recovery of hearing in midfrequencies and high frequencies with the passage of time.Conclusions:Cochleostomy and intracochlear infusion result in auditory insult limited largely to the region of surgical trauma. Demonstration of hearing preservation after surgical breach of the cochlea should encourage further development of potential diagnostic and therapeutic intervention into the inner ear.

ISSN:0192-9763    

出版商:OVID    

年代:1999

数据来源: OVID