Expert opinion on the diagnosis of acoustic tumors.

Ideally, clinicians recommend diagnostic tests when the patient's risk of disease is sufficient to justify putting numerous similar patients through the morbidity required to diagnose disease in one patient. In the case of acoustic tumor diagnosis, there are few published data available to the clinician to help assess risk in an individual patient. The purpose of this study was to obtain information by an opinion poll of a group of experts. We used the Delphi method to poll clinicians trained at the House Ear Clinic. We asked these experts 20 questions related to acoustic tumor diagnosis. Some of the expert opinion presented herein is the only data related to acoustic tumor diagnosis available to clinicians. These data are a first step in elevation of decision-making for tumor diagnosis above the level of speculation. However, the experts' responses displayed a pattern of inaccuracy that limits the clinical application of their opinion. Exposing this pattern was instructive for identifying desirable features of protocols for diagnosing tumors. We recommend that protocols not depend on clinicians estimating probability of tumor. Instead, protocols may list specific findings, such as unilateral distortion on the telephone, to indicate, when present, that the risk of tumor is sufficient to order a diagnostic test.

Reducing footplate complications in small fenestra microdrill stapedotomy.

Some surgeons have altered their technique for small fenestra stapedotomy in order to avoid footplate complications. This study aimed to determine what surgical step changes reduced footplate complications and improved hearing results. Operative reports provided data on surgical technique and complications in 151 consecutive primary stapes surgery patients. Comparisons of preoperative and postoperative audiograms provided hearing results of surgery. Fenestrating the footplate after, rather than before, stapes arch removal and fracturing the stapes arch after dividing one crus with a nipper were two surgical steps that reduced fractures. Hearing results were better after fenestration of the footplate with a microdrill compared to results with a hand drill.

Indications for hearing preservation in acoustic tumor surgery.

This study addresses the problem of how to counsel patients with acoustic tumors concerning the issue of hearing preservation. Rather than the traditional yes or no answer, we wish to give the patient the probability that hearing can be preserved given the size of the tumor and the patient's preoperative hearing level. The subjects were 77 patients of the Seattle Ear Clinic who underwent total removal of unilateral acoustic tumors with attempted hearing preservation using a suboccipital approach. Other criteria for inclusion in the study were: tumor size, measured from a preoperative diagnostic image, and availability of pre- and postoperative hearing test results. We reviewed published data from other centers using similar inclusion criteria to determine if our findings were representative of the experience of surgeons at other institutions. We found a significant relationship between hearing preservation success and tumor size, but not between success and preoperative hearing level. The probability of success varied from 78 percent for 0.5-cm tumors to about 15 percent for tumors 2.0 cm and larger. If surgery was successful, 82 percent of patients had hearing that was the same or better than their preoperative hearing level.

Composite tragal perichondrial/cartilage autografts vs cartilage or bone paste grafts in tympanoplasty.

Extrusion of plastic or ceramic implants is a significant cause of failure in ossiculoplasty for chronic ear disease. This paper reports the use of a composite tragal cartilage and perichondrial autograft compared to cartilage or bone paste between the graft and tympanic membrane. At 2 years, there were no extrusions in the group with the composite graft (n = 18) and 5 extrusions in the cartilage/bone paste group (n = 18) (P = 0.02). The mean average air-bone gap was significantly better for the composite grafts at 2 years (15 dB vs 24 dB) (P less than 0.05). Extrusions were eliminated and hearing results better at 2 years using the composite graft.

Hearing threshold difference between ears and risk of acoustic tumor.

This study addresses the question, what difference in hearing between ears puts a patient at sufficient risk of acoustic tumor to warrant further diagnostic tests? The subjects were 210 patients with surgically confirmed unilateral acoustic tumors and a control group comprised of 112 patients referred for audiometry. Hearing thresholds were determined at octave intervals from 250 Hz to 8 kHz. The threshold in the nonsuspect ear was subtracted from the threshold in the suspect ear. The rank order in effectiveness for threshold difference was: 2 kHz, 4 kHz, 1 kHz, 8 kHz, 500 Hz, and 250 Hz. We found that the most effective diagnostic strategy was to refer patients for magnetic resonance imaging if their average threshold difference at 1 to 8 kHz was 20 dB or greater and refer patients for auditory brainstem response testing if their average threshold was 5 to 20 dB.

Ceravital versus plastipore in tympanoplasty: a randomized prospective trial.

The hearing results and extrusion rates for ossicular chain reconstruction using a new material called Ceravital, a bioactive glass ceramic, were compared with those for Plastipore, a porous polyethylene that is our standard for synthetic materials. Our null hypothesis was that the results of the two materials were similar. A Ceravital or a Plastipore prosthesis was randomly assigned to 112 consecutive patients. We had 6-month follow-up on 100 patients and 3-year follow-up on 80 patients. The average air-bone gap at 4,000 Hz was 6 dB less with Plastipore than with Ceravital (p = .036). Patients were twice as likely to have an air-bone gap of 15 dB or less with Plastipore than with Ceravital (40% versus 21%; p = .061). Two of the 38 patients with Ceravital prostheses had a late hearing-result failure due to resorption of the prosthesis material. The materials had similar extrusion rates. We rejected our null hypothesis. The Plastipore group had better hearing results than did the Ceravital group.

Open-set minimum auditory capability scores for House and Nucleus cochlear prostheses.

This study addresses the following questions: Is there a difference in open-set recognition among patients using House and Nucleus devices? How many subjects are needed to determine statistically significant differences between devices? The subjects were 12 patients, six with House and six with Nucleus cochlear prostheses. Using open-set tests from the Minimum Auditory Capabilities Battery, the Nucleus group had significantly better scores than the House device group. Our sample size was adequate in part because the House device group scored near zero. To determine moderate differences between groups with scores of 10% or better, approximately 20 paired or 60 unpaired subjects would be needed in each group.

Complications of translabyrinthine vs. suboccipital approach for acoustic tumor surgery.

This study presents the operative results of surgeons with experience in both the translabyrinthine and suboccipital approaches to acoustic tumor removal for the purpose of resolving some of the controversy among centers favoring one approach over the other. The subjects were 171 patients with acoustic tumors who were treated at Virginia Mason Clinic from 1975 to 1986. The translabyrinthine approach was used in 64% of cases, the suboccipital approach in 35%, and the middle fossa approach in 1%. There were minor differences in morbidity and mortality between approaches. These data did not favor one approach over another. In an exploratory analysis, we found that the morbidity with a planned two-stage translabyrinthine-suboccipital removal was greater than the morbidity with a one-stage removal.

Analysis of the glycerin test for Menière's disease.

The glycerin test has low sensitivity for Menière's disease using present published criteria. The purpose of this study is to compare the efficacy of standard empirical criteria with our theoretically based criteria. Subjects were 47 patients with Menière's disease and 45 patients with other causes of hearing loss and dizziness. Pure-tone thresholds and word-identification scores were determined before and 3 hours after administration of glycerin. The results were submitted to decision and multivariate discriminate analyses. The theoretically based criterion applied to pure-tone threshold testing alone was the most effective protocol for glycerin testing. Combining pure-tone thresholds and word-identification increased the false-positive rate without adequately increasing the true-positive rate, and provided no advantage over testing thresholds alone.

Decision analysis of auditory brainstem responses and rotational vestibular tests in acoustic tumor diagnosis.

This study addresses the problem of the escalation of the costs of medical care which make diagnosis of acoustic tumor expensive. Specifically, we examined the hypothesis that a test protocol of the auditory brainstem response (ABR) in parallel with sinusoidal harmonic acceleration (SHA) is more cost-effective in identification of the risk of tumor than ABR alone. The subjects were 74 patients with acoustic tumors and 78 controls. ABR and SHA data from these subjects were submitted to decision analysis. ABR was more cost-effective than the protocol of ABR in parallel with SHA. Using these data, we outlined a "decision tree" for acoustic tumor diagnosis that fit the goals of high sensitivity when earlier probability of tumor was high, and high specificity when earlier probability of tumor was low.

Vagal body tumors: diagnosis and treatment.

This presentation includes a report of four vagal body tumors bringing the total number in the English literature to approximately 80. The diagnosis and treatment of this lesion, its familial incidence and the propensity for multiple secreting or nonsecreting chemodectomas, and appropriate clinical and pathologic studies required will be reviewed in some detail. Appropriate differential diagnostic features will be illustrated by comparison of these tumors with other primary vagal tumors from our experience such as neurofibromas, neurilemmomas, and cystic degeneration of neurilemmomas.

Intraoperative auditory brain stem response monitoring during ultrasonic aspiration of posterior fossa tumors.

The use of an ultrasonic aspirator may decrease the morbidity associated with the surgical removal of intracranial tumors by reducing the duration of surgery. In this study we monitored the auditory brain stem response (ABR) during ultrasonic surgical aspiration of 20 posterior fossa tumors. Twelve subjects had a transient decrement in the ABR during use of the ultrasonic aspirator; one had a temporary sensorineural hearing loss contralateral to the side of the surgery. Monitoring of the ABR during use of the ultrasonic aspirator in the posterior fossa helped minimize the risk of injury to normal structures. Changes in latency, amplitude, and interpeak interval of the ABR waves alert the surgeon to the need to adjust the aspirator settings or the conditions in the operative field before continuing to use the tool.

The cochlear prosthesis. Bringing the world of sound to the deaf.

The complexity of coding in the auditory nerve makes it unlikely that a prosthesis for deaf persons can exactly duplicate the normal function of the ear. With recent advances, however, cochlear prostheses can perform some of the frequency-analysis functions of the normal ear. Cochlear prostheses are effective aids to lipreading and allow recognition of some sounds without visual cues, thus enhancing the profoundly deaf person's communication skills substantially.

Intra-aural reflexes elicited by a cochlear prosthesis in monkeys.

Objective audiological tests are needed for pre- and postsurgical evaluation of cochlear prosthesis patients who are unable to give reliable subjective responses. In this study we demonstrated that contralateral intra-aural reflexes were elicited by a cochlear prosthesis in the monkey. Reflex variables measured include threshold, latency and amplitude. These findings indicate that the electrically elicited intra-aural reflex response may be useful to evaluate the peripheral auditory system in subjects with sensory deafness.

Evaluation of tensor tympani muscle dominance in the biphasic acoustic reflex.

The Acoustic reflex frequently causes a biphasic change in impedance at onset. Understanding the cause of the biphasic response is important for establishing a physiological basis for the clinical measurement of reflex latency. The decrease in impedance at onset may be due to uncoupling of impedance contributed by the cochlea. Subsequent increases in impedance predominantly reflect stapedius muscle activity. The clinical implications of this physiologic model are discussed.