A clinical, genetic and audiological study of patients and families with unilateral vestibular schwannomas. II. Audiological findings in 93 patients with unilateral vestibular schwannomas

The Diagnostic Accuracy of Pure-Tone Audiometry Screening Protocols for Vestibular Schwannoma in Patients with Asymmetrical Hearing Loss-A Systematic Review and Meta-Analysis

(1) Background: Magnetic resonance imaging (MRI) is the gold standard investigation for all patients who present with asymmetrical hearing loss (AHL) and a high index of suspicion for vestibular schwannoma (VS). However, pure-tone audiometry (PTA) is an investigation that can be used for the screening of these patients in order to reduce the costs. The aim of this systematic review and meta-analysis was to evaluate the diagnostic accuracy of different PTA protocols for VS in patients with ASHL, when compared with MRI; (2) Methods: Medline, Embase, and Cochrane databases were used to find relevant studies. All prospective and retrospective observational studies that evaluated the accuracy of PTA protocols for the screening of VS were assessed, according to the international guidelines; (3) Results: We analyzed seven studies (4369 patients) of poor-to-moderate quality. Their pooled sensitivity was good (0.73-0.93), but their specificity was low (0.31-0.60). All protocols were located in the right lower quadrant on the likelihood scattergram, and the post-test probabilities for positive and negative diagnosis of these protocols were extremely low; (4) Conclusions: PTA protocols cannot be used for a proper screening or diagnosis of vestibular schwannoma despite their good sensibility, and MRI remains the gold standard for this purpose.

Evaluation of pure-tone audiometric protocols in vestibular schwannoma screening

The objective was to evaluate the pure-tone audiogram-based screening protocols in VS diagnostics. We retrospectively analyzed presenting symptoms, pure tone audiometry and MRI finding from 246 VS patients and 442 controls were collected to test screening protocols (AAO-HNS, AMCLASS-A/B, Charing Cross, Cueva, DOH, Nashville, Oxford, Rule3000, Schlauch, Seattle, Sunderland) for sensitivity and specificity. Results were pooled with data from five other studies, and analysis of sensitivity, specificity and positive likelihood ratio (LR+) for each protocol was performed. Our results show that protocols with significantly higher sensitivity (AMCLASS-A/B, Nashville) show also significantly lowest specificity, and tend to have low association (positive likelihood ratio, LR+) to the VS. The highest LR+ was found for protocols AAO-HNS, Rule3000 and Seattle. In conclusions, knowing their properties, screening protocols are simple decision-making tools in VS diagnostic. To use the advantage of the highest sensitivity, protocols AMCLASS-A + B or Nashville can be of choice. For more reasonable approach, applying the protocols with high LR+ (AAO-HNS, Rule3000, Seattle) may reduce the overall number of MRI scans at expense of only few primarily undiagnosed VS.

Prevalence of Acoustic Neuroma Associated with Each Configuration of Pure Tone Audiogram in Patients with Asymmetric Sensorineural Hearing Loss

Objectives

The criteria have not yet been established for identifying the configuration of a pure tone audiogram constituting abnormal results that warrant further investigation. The purpose of this study was to determine the prevalence of acoustic neuroma associated with each configuration of the pure tone audiogram in patients with asymmetric sensorineural hearing loss (SNHL).

Methods

We performed a retrospective chart review of 500 patients 15 years of age or older who had asymmetric SNHL and had undergone magnetic resonance imaging.

Results

The prevalence of acoustic neuroma in these patients was 2.6% (13 of 500). The prevalence of acoustic neuroma in each audiometric configuration was as follows: 7.1% (3 of 42) for a basin-shaped loss (odds ratio [OR] versus overall prevalence, 2.88; p =0.23; 95% confidence interval [CI], 0.79 to 10.54),4.7% (5 of 107) for a flat loss, 3.4% (2 of 58) for total deafness, 2.9% (l of 34) for a high-frequency sloping audiogram, and 2.5% (2 of 81) for a high-frequency steep audiogram. The prevalence in patients with nonimproving idiopathic sudden deafness was 8.1% (OR, 3.29; p = 0.06; 95% CI, 1.13 to 9.55).

Conclusions

In conclusion, 2.9% to 8.1% of patients with a characteristic configuration of the pure tone audiogram and symptoms of nonimproving or progressive idiopathic sudden deafness may have acoustic neuroma.

Audiological correlates of tumor parameters in acoustic neuromas

The objective of this study was undertaken to evaluate a correlation of pure tone audiometry, speech audiometry with tumor size, the presence of intrameatal extension, contralateral pure tone audiometry, and contralateral speech audiometry results at acoustic neuroma (AN) patients. Seventy-six patients with a unilateral-cerebellopontine angel tumor with/without internal acoustic canal (IAC) were included in this study. Data on pure tone audiometry, speech discrimination scores (SDS), speech reception thresholds (SRT), tumour size, and extension to IAC were analyzed retrospectively. As a result, patients with unilateral ANs had an asymmetric sensorineural hearing loss and had an asymmetric finding on the results of speech audiometry was present. We could not find any correlation between the size of the tumor and the hearing levels at each frequency. In addition, there appeared to be no significant correlation between the extension of tumor to the IAC and the audiological findings.

Clinical decision support systems and computer-aided diagnosis in otology

OBJECTIVES

We reviewed the progress of the implementation of expert diagnostic systems in the field of otology.

STUDY DESIGN AND SETTING

We conducted a review of the literature at a research institute.

RESULTS

The utilization of expert diagnostic systems in otology is very limited. Previous applications focused primarily upon the diagnosis of vertiginous disorders with the use of deterministic algorithms and, more recently, with adaptive algorithms such as neural networks.

CONCLUSION

Expert systems provide greater diagnostic accuracy to physicians across a wide range of medical specialties. The success of such a system depends upon the strength of its reasoning algorithm, the validity of its knowledge base, and its ease of use.

SIGNIFICANCE

There have been no attempts to develop an adaptive expert system for the full range of otological conditions. Such a tool may be of great use to physicians as a diagnostic aid and educational resource, particularly for those located in isolated sites.

Vestibular schwannoma: when to look for it?

OBJECTIVES

(1) To compare audiometric parameters in patients with vestibular schwannoma and in those with asymmetric hearing loss from other causes; and (2) to assess proposed screening criteria by comparing published protocols.

METHODS

Audiometric data from 199 vestibular schwannoma patients and 225 non-tumour patients were compared. Eight screening protocols were tested on these 424 patients.

RESULTS

Vestibular schwannoma and non-tumour patients with little or no hearing loss in the unaffected ear were inseparable; however, vestibular schwannoma patients with hearing loss in the unaffected ear had greater audiometric asymmetry, compared with non-tumour patients with the same pattern of hearing loss. The sensitivity of screening protocols varied from 73 to 100 per cent; parallelism was observed between sensitivity and screening rate.

CONCLUSION

As regards vestibular schwannoma screening protocols, the best compromise between sensitivity and screening rate was offered by a criterion comprising either: (1) > or =20 dB asymmetry at two neighbouring frequencies, or unilateral tinnitus, or (2) > or =15 dB asymmetry at two frequencies between 2 and 8 kHz.

The effects of midazolam on pure tone audiometry, speech audiometry, and audiological reaction times in human volunteers

Auditory evoked potentials are effected by benzodiazepines, as is cortical processing of auditory stimuli. The effect of benzodiazepines on auditory sensitivity has not, however, been studied. We designed the present study to investigate the effect of sedative doses of midazolam on pure tone and speech audiometry and on audiological reaction times in healthy volunteers. Thirty volunteers underwent baseline audiological assessment for pure tones and speech and had their audiological reaction times measured at 10 and 50 dB above their threshold hearing level at a frequency of 1 kHz. Subjects were then randomly assigned to one of two groups. Group A (n = 15) received midazolam (0.04 mg/kg) IV, and Group B (n = 15) received a similar volume of placebo IV. The audiological tests were repeated 5 min later, and performance was compared with baseline data. Scheffé post hoc tests were used to assess the significance of changes in each group. There was no pre- to posttest change in audiological performance in either the placebo group (P = 0.194) or the midazolam group (P = 0.957). Speech audiometry performance was likewise unaffected by midazolam (P = 0.154). Reaction time at the 10-dB and 50-dB sensation levels were both significantly prolonged after midazolam administration (P = 0.023 and P = 0.012, respectively). In this study, we demonstrate that sedation with midazolam (0.04 mg/kg) does not alter pure tone or speech audiometric thresholds, but it does significantly delay the reaction time to auditory stimuli. Medical practitioners should advise midazolam-sedated patients of their impaired reaction to auditory warning signals (e.g., traffic and car horns) as part of the day-ward discharge recommendations.

IMPLICATIONS

In this study, we demonstrate that sedation of healthy volunteers with the benzodiazepine midazolam, in the common clinical dosage, does not affect their hearing capability as measured by pure tone and speech audiometry. However, one's ability to react to auditory signals is impaired after midazolam, which may have implications for patients after day-case procedures.