The sensitivity of auditory brainstem response testing for the diagnosis of acoustic neuromas

Red flags alerting a posterior cranial fossa tumor from audiovestibular perspectives - a review

BACKGROUND

There is no comprehensive and up-to-date overview of audiovestibular approach to the posterior fossa tumors in the literature.

OBJECTIVE

This paper reviewed the literature relating to tumors at the posterior cranial fossa to find red flags alerting a posterior fossa lesion from audiovestibular perspectives.

METHODS

This review was developed from articles published in those journals listed on the journal citation reports. Through the PubMed database, Embase, Google Scholar, and Cochrane library, 60 articles were finally obtained based on the PRISMA guidelines for reporting reviews.

RESULTS

The presence of one red flag indicates a positive predictive value of 33% for detecting a posterior fossa lesion. Clinical features, namely, 1) mid-frequency sudden sensorineural hearing loss (SNHL), 2) bilateral sudden SNHL, and 3) rebound nystagmus may indicate a posterior fossa lesion, representing one, two, and three red flags, respectively.

CONCLUSION

Those with 1) mid-frequency sudden SNHL, 2) bilateral sudden SNHL, and 3) rebound nystagmus trigger one, two, and three red flags, respectively, alerting clinicians the possibility of a posterior fossa lesion, which warrant MR imaging to exclude life-threatening or treatable conditions.

SIGNIFICANCE

Patients with posterior fossa tumors may have potential life-threatening outcome.

Mismatch negativity as a marker of music perception in individual cochlear implant users: A spike density component analysis study

OBJECTIVE

Ninety percent of cochlear implant (CI) users are interested in improving their music perception. However, only few objective behavioral and neurophysiological tests have been developed for tracing the development of music discrimination skills in CI users. In this study, we aimed to obtain an accurate individual mismatch negativity (MMN) marker that could predict behavioral auditory discrimination thresholds.

METHODS

We measured the individual MMN response to four magnitudes of deviations in four different musical features (intensity, pitch, timbre, and rhythm) in a rare sample of experienced CI users and a control sample of normally hearing participants. We applied a recently developed spike density component analysis (SCA), which can suppress confounding alpha waves, and contrasted it with previously proposed methods.

RESULTS

Statistically detected individual MMN predicted attentive sound discrimination ability with high accuracy: for CI users 89.2% (278/312 cases) and for controls 90.5% (384/424 cases). As expected, MMN was detected for fewer CI users when the sound deviants were of smaller magnitude.

CONCLUSIONS

The findings support the use of MMN responses in individual CI users as a diagnostic tool for testing music perception.

SIGNIFICANCE

For CI users, the new SCA method provided more accurate and replicable diagnostic detections than preceding state-of-the-art.

Auditory brainstem responses obtained with randomised stimulation level

OBJECTIVE

To present randomised stimulation level (RSL) - a stimulation paradigm in which the level of the stimuli is randomised, rather than presented sequentially as in the conventional paradigm.

DESIGN

The value of RSL was evaluated by (i) comparing the morphology of auditory brainstem responses (ABRs) elicited by the conventional and RSL paradigms, and by (ii) an online survey investigating the hearing comfort of the stimulus sequence.

STUDY SAMPLE

ABRs were obtained from 11 normal-hearing adults (8 females, 25-29 years). The online survey was administered to 238 adults from the general community.

RESULTS

Results showed that (i) both stimulation paradigms elicit ABR signals of similar morphology, (ii) RSL provides a faster comprehensive representation of the ABR session, and that (iii) the general population found RSL stimuli to be more comfortable.

CONCLUSIONS

The simultaneous evaluation of all ABR traces of the session provided by RSL has potential to improve the identification of ABR components by enabling clinicians to make use of the response tracking strategy from the start of the test, which is critical in situations where ABRs present an abnormal morphology. New research opportunities and the clinical potential of RSL are discussed.

Clinical usefulness of labyrinthine three-dimensional fluid-attenuated inversion recovery magnetic resonance images in idiopathic sudden sensorineural hearing loss

PURPOSE OF REVIEW

Literature on the use of current magnetic resonance imaging (MRI) for patients with idiopathic sudden sensorineural hearing loss (ISSNHL) is reviewed, emphasizing the role of three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) MRI. The discussion focuses on the diagnostic role of temporal bone MRI using 3D-FLAIR and the relationship between MRI findings, clinical symptoms, and hearing outcome.

RECENT FINDINGS

The currently suggested MRI protocol for SSNHL includes a 3D T2-weighted steady-state free procession sequence or its equivalent, pre and postcontrast T1-weighted, and pre and postcontrast 3D-FLAIR sequences. The 3D-FLAIR image identifies an underlying labyrinthine condition in 24-57% of patients with ISSNHL, contributing to understanding the pathophysiologic mechanisms (e.g., labyrinthitis or labyrinthine hemorrhage). Recent studies demonstrated consistent results that initial hearing loss could be related to the signal change on the 3D-FLAIR image. Various results on 3D-FLAIR image value prediction for the final hearing outcome were shown.

SUMMARY

3D-FLAIR MRI application identifies an underlying labyrinthine condition. Abnormal MRI findings correlate with initial hearing loss and accompanying symptoms and hearing outcome. Performing temporal bone MRI with 3D-FLAIR sequence may clarify probable ISSNHL pathophysiology, improve diagnostic accuracy, provide prognostic information to physicians, and possibly guide toward a more specific treatment.

Clinical Practice Guideline: Sudden Hearing Loss (Update)

OBJECTIVE

Sudden hearing loss is a frightening symptom that often prompts an urgent or emergent visit to a health care provider. It is frequently but not universally accompanied by tinnitus and/or vertigo. Sudden sensorineural hearing loss affects 5 to 27 per 100,000 people annually, with about 66,000 new cases per year in the United States. This guideline update provides evidence-based recommendations for the diagnosis, management, and follow-up of patients who present with sudden hearing loss. It focuses on sudden sensorineural hearing loss in adult patients aged ≥18 years and primarily on those with idiopathic sudden sensorineural hearing loss. Prompt recognition and management of sudden sensorineural hearing loss may improve hearing recovery and patient quality of life. The guideline update is intended for all clinicians who diagnose or manage adult patients who present with sudden hearing loss.

PURPOSE

The purpose of this guideline update is to provide clinicians with evidence-based recommendations in evaluating patients with sudden hearing loss and sudden sensorineural hearing loss, with particular emphasis on managing idiopathic sudden sensorineural hearing loss. The guideline update group recognized that patients enter the health care system with sudden hearing loss as a nonspecific primary complaint. Therefore, the initial recommendations of this guideline update address distinguishing sensorineural hearing loss from conductive hearing loss at the time of presentation with hearing loss. They also clarify the need to identify rare, nonidiopathic sudden sensorineural hearing loss to help separate those patients from those with idiopathic sudden sensorineural hearing loss, who are the target population for the therapeutic interventions that make up the bulk of the guideline update. By focusing on opportunities for quality improvement, this guideline should improve diagnostic accuracy, facilitate prompt intervention, decrease variations in management, reduce unnecessary tests and imaging procedures, and improve hearing and rehabilitative outcomes for affected patients.

METHODS

Consistent with the American Academy of Otolaryngology-Head and Neck Surgery Foundation's "Clinical Practice Guideline Development Manual, Third Edition" (Rosenfeld et al. Otolaryngol Head Neck Surg. 2013;148[1]:S1-S55), the guideline update group was convened with representation from the disciplines of otolaryngology-head and neck surgery, otology, neurotology, family medicine, audiology, emergency medicine, neurology, radiology, advanced practice nursing, and consumer advocacy. A systematic review of the literature was performed, and the prior clinical practice guideline on sudden hearing loss was reviewed in detail. Key Action Statements (KASs) were updated with new literature, and evidence profiles were brought up to the current standard. Research needs identified in the original clinical practice guideline and data addressing them were reviewed. Current research needs were identified and delineated.

RESULTS

The guideline update group made strong recommendations for the following: (KAS 1) Clinicians should distinguish sensorineural hearing loss from conductive hearing loss when a patient first presents with sudden hearing loss. (KAS 7) Clinicians should educate patients with sudden sensorineural hearing loss about the natural history of the condition, the benefits and risks of medical interventions, and the limitations of existing evidence regarding efficacy. (KAS 13) Clinicians should counsel patients with sudden sensorineural hearing loss who have residual hearing loss and/or tinnitus about the possible benefits of audiologic rehabilitation and other supportive measures. These strong recommendations were modified from the initial clinical practice guideline for clarity and timing of intervention. The guideline update group made strong recommendations against the following: (KAS 3) Clinicians should not order routine computed tomography of the head in the initial evaluation of a patient with presumptive sudden sensorineural hearing loss. (KAS 5) Clinicians should not obtain routine laboratory tests in patients with sudden sensorineural hearing loss. (KAS 11) Clinicians should not routinely prescribe antivirals, thrombolytics, vasodilators, or vasoactive substances to patients with sudden sensorineural hearing loss. The guideline update group made recommendations for the following: (KAS 2) Clinicians should assess patients with presumptive sudden sensorineural hearing loss through history and physical examination for bilateral sudden hearing loss, recurrent episodes of sudden hearing loss, and/or focal neurologic findings. (KAS 4) In patients with sudden hearing loss, clinicians should obtain, or refer to a clinician who can obtain, audiometry as soon as possible (within 14 days of symptom onset) to confirm the diagnosis of sudden sensorineural hearing loss. (KAS 6) Clinicians should evaluate patients with sudden sensorineural hearing loss for retrocochlear pathology by obtaining magnetic resonance imaging or auditory brainstem response. (KAS 10) Clinicians should offer, or refer to a clinician who can offer, intratympanic steroid therapy when patients have incomplete recovery from sudden sensorineural hearing loss 2 to 6 weeks after onset of symptoms. (KAS 12) Clinicians should obtain follow-up audiometric evaluation for patients with sudden sensorineural hearing loss at the conclusion of treatment and within 6 months of completion of treatment. These recommendations were clarified in terms of timing of intervention and audiometry and method of retrocochlear workup. The guideline update group offered the following KASs as options: (KAS 8) Clinicians may offer corticosteroids as initial therapy to patients with sudden sensorineural hearing loss within 2 weeks of symptom onset. (KAS 9a) Clinicians may offer, or refer to a clinician who can offer, hyperbaric oxygen therapy combined with steroid therapy within 2 weeks of onset of sudden sensorineural hearing loss. (KAS 9b) Clinicians may offer, or refer to a clinician who can offer, hyperbaric oxygen therapy combined with steroid therapy as salvage therapy within 1 month of onset of sudden sensorineural hearing loss.

DIFFERENCES FROM PRIOR GUIDELINE

Incorporation of new evidence profiles to include quality improvement opportunities, confidence in the evidence, and differences of opinion Included 10 clinical practice guidelines, 29 new systematic reviews, and 36 new randomized controlled trials Highlights the urgency of evaluation and initiation of treatment, if treatment is offered, by emphasizing the time from symptom occurrence Clarification of terminology by changing potentially unclear statements; use of the term sudden sensorineural hearing loss to mean idiopathic sudden sensorineural hearing loss to emphasize that >90% of sudden sensorineural hearing loss is idiopathic sudden sensorineural hearing loss and to avoid confusion in nomenclature for the reader Changes to the KASs from the original guideline: KAS 1-When a patient first presents with sudden hearing loss, conductive hearing loss should be distinguished from sensorineural. KAS 2-The utility of history and physical examination when assessing for modifying factors is emphasized. KAS 3-The word "routine" is added to clarify that this statement addresses nontargeted head computerized tomography scan that is often ordered in the emergency room setting for patients presenting with sudden hearing loss. It does not refer to targeted scans, such as temporal bone computerized tomography scan, to assess for temporal bone pathology. KAS 4-The importance of audiometric confirmation of hearing status as soon as possible and within 14 days of symptom onset is emphasized. KAS 5-New studies were added to confirm the lack of benefit of nontargeted laboratory testing in sudden sensorineural hearing loss. KAS 6-Audiometric follow-up is excluded as a reasonable workup for retrocochlear pathology. Magnetic resonance imaging, computerized tomography scan if magnetic resonance imaging cannot be done, and, secondarily, auditory brainstem response evaluation are the modalities recommended. A time frame for such testing is not specified, nor is it specified which clinician should be ordering this workup; however, it is implied that it would be the general or subspecialty otolaryngologist. KAS 7-The importance of shared decision making is highlighted, and salient points are emphasized. KAS 8-The option for corticosteroid intervention within 2 weeks of symptom onset is emphasized. KAS 9-Changed to KAS 9A and 9B. Hyperbaric oxygen therapy remains an option but only when combined with steroid therapy for either initial treatment (9A) or salvage therapy (9B). The timing of initial therapy is within 2 weeks of onset, and that of salvage therapy is within 1 month of onset of sudden sensorineural hearing loss. KAS 10-Intratympanic steroid therapy for salvage is recommended within 2 to 6 weeks following onset of sudden sensorineural hearing loss. The time to treatment is defined and emphasized. KAS 11-Antioxidants were removed from the list of interventions that the clinical practice guideline recommends against using. KAS 12-Follow-up audiometry at conclusion of treatment and also within 6 months posttreatment is added. KAS 13-This statement on audiologic rehabilitation includes patients who have residual hearing loss and/or tinnitus who may benefit from treatment. Addition of an algorithm outlining KASs Enhanced emphasis on patient education and shared decision making with tools provided to assist in same.

Location of Small Intracanalicular Vestibular Schwannomas Based on Magnetic Resonance Imaging

Vestibular schwannomas (VSs) were proposed to arise from the glial-Schwann cell junction within the internal auditory canal (IAC). However, otopathology studies indicate that VS may arise anywhere along the course of the vestibular nerve. Recent studies suggested that the majority of tumors are located centrally within the IAC with an equal distribution near the porus acusticus and the fundus. However, these studies analyzed tumors of all sizes, obscuring their precise origin. Herein, we aim to quantify the position of small intracanalicular tumors (<5 mm), assessing hearing outcomes and growth patterns in relation to tumor position. Of the 38 small intracanalicular tumors analyzed, 61% originated closest to the fundus, 34% at the midpoint, and only 5% closest to the porus acusticus. Tumors were observed with serial magnetic resonance imaging for 3.37 ± 2.65 years (mean ± SD) without intervention. Our findings indicate a lateral predominance of small VS within the IAC, an independence between tumor location and hearing outcomes, and further support the slow natural progression of VS.

Audiological Evaluation of Vestibular Schwannoma Patients with Normal Hearing

Objective: To evaluate the audiological aspects of vestibular schwannoma (VS) patients with normal hearing. Study Design: Retrospective study. Setting: Quaternary referral center for skull base pathologies. Patients: The records on 4,000 patients who had been diagnosed with VS between 1986 and December 2017 were retrospectively reviewed. The patients included in the study were the ones who complied with the strict audiological normality criteria, as follows: a pure tone hearing threshold (at the 6-octave-spaced frequencies from 250 to 8,000 Hz) ≤25 dBHL; a word recognition score >90%; and interaural differences ≤10 dB at each frequency. Interventions: Auditory brainstem response (ABR) testing and radiological imaging. Main Outcome Measures: The incidence of normal objective hearing among VS patients, and the diagnostic utility of the ABR and the effect of tumor size and site on the response. Results: The incidence of normal hearing among VS patients was 4.2%. Tinnitus and vertigo were the most common symptoms across tumor grades; 5.6% of the tumors were large and giant tumors. The ABR yielded a sensitivity of 73.6%, with a false negative rate of 26.3% using a cutoff point of 0.2 ms for interaural latency differences. Conclusions: The diagnosis of VS should not be based on audiometric thresholds alone. Alarming signs of VS should be clear to the physician in order not to miss or delay the diagnosis of the disease. The ABR is useful in the diagnosis of VS, but normal results do not exclude the occurrence of the disease in patients with normal hearing.

[Early acoustic evoked potentials in patients with "small" vestibular schwannomas]

BACKGROUND

The prognostic potential of click-evoked early acoustic evoked potentials (EAEP) for vestibular schwannoma (VS) diagnostics is considered insufficient for tumors small than approximately <1.5 cm in diameter. However, up until now, the derivations at higher sound pressure levels have mainly been used for EAEP evaluation. The aim of this study was to examine whether registered EAEP are more sensitive to pathological changes at low sound pressure levels and with smaller tumors.

METHODS

Comparative examinations (pair-matched) were conducted with 34 patients. An appropriate patient with an identical hearing level threshold - either a purely cochlear hearing deficiency or a normal hearing level - was matched to each tumor patient. EAEP were registered at 80, 60, and 40 dB HL. The characteristic parameters where assessed visually and evaluated statistically, both in respect to patient groups and in bilateral comparisons. Furthermore, the relationship between the level-dependent wave V latency differences in bilateral comparison and tumor size were evaluated.

RESULTS

Low-level cochlear hearing deficiencies did not cause a change in wave V latency, such that the pathological side differences at 40 dB HL in patients with VS can be considered a "purely" retrocochlear hearing deficiency. The sensitivity of EAEP registered at 40 dB HL decreases only with tumors under about <5 mm in diameter. Combining the values of wave V latency and interaural wave V latency difference effectively reduces false-positive findings at 40 dB HL to zero.

CONCLUSION

Beyond the suprathreshold derivations, potential registrations at 40 dB HL can also be diagnostically useful to differentiate cochlear from retrocochlear lesions. In the case of small VS and good hearing levels, these registrations may also be used for intraoperative monitoring to allow better evaluation of level-dependent changes in the auditory nerve.

Assessing the efficacy of asynchronous telehealth-based hearing screening and diagnostic services using automated audiometry in a rural South African school

Background

Asynchronous automated telehealth-based hearing screening and diagnostic testing can be used within the rural school context to identify and confirm hearing loss.

Objective

The aims of the study were to evaluate the efficacy of an asynchronous telehealth-based service delivery model using automated technology for screening and diagnostic testing as well as to describe the prevalence, type and degree of hearing loss.

Method

A comparative within-subject design was used. Frequency distributions, sensitivity, specificity scores as well as the positive and negative predictive values were calculated. Testing was conducted in a non-sound-treated classroom within a school environment on 73 participants (146 ears). The sensitivity and specificity rates were 65.2% and 100%, respectively. Diagnostic accuracy was 91.7% and the negative predictive values (NPV) and positive predictive values (PPV) were 93.8% and 100%, respectively.

Results

Results revealed that 23 ears of 20 participants (16%) presented with hearing loss. Twelve per cent of ears presented with unilateral hearing impairment and 4% with bilateral hearing loss. Mild hearing loss was identified as most prevalent (8% of ears). Eight ears obtained false-negative results and presented with mild low- to mid-frequency hearing loss. The sensitivity rate for the study was low and was attributed to plausible reasons relating to test accuracy, child-related variables and mild low-frequency sensory-neural hearing loss.

Conclusion

The study demonstrates that asynchronous telehealth-based automated hearing testing within the school context can be used to facilitate early identification of hearing loss; however, further research and development into protocol formulation, ongoing device monitoring and facilitator training is required to improve test sensitivity and ensure accuracy of results.

Diagnosis of retrocochlear lesions with emphasis on expansion of the cerebellopontine angle

The correct diagnosis of CPA tumours is a relatively common issue in both neurological and ENT practice, the omission of which can have serious consequences for the patient. Properly set clinical guidelines and diagnostic protocols are key aspects of good clinical practice. In the case of CPA tumours, two options are available: the first is diagnosis with the help of an ABR as the primary tool for determining the group of patients with a possible tumour; the second is an MRI scan of the posterior cranial fossa. With an appropriately set diagnostic protocol in place, and despite the 40% chance of failure of the ABR to detect tumours less than or equal to 1 cm, similar treatment results can be achieved with much higher cost efficacy in case of primary ABR testing.

Current audiological diagnostics

Today's audiological functional diagnostics is based on a variety of hearing tests, whose large number takes account of the variety of malfunctions of a complex sensory organ system and the necessity to examine it in a differentiated manner and at any age of life. The objective is to identify nature and origin of the hearing loss and to quantify its extent as far as necessary to dispose of the information needed to initiate the adequate medical (conservative or operational) treatment or the provision with technical hearing aids or prostheses. Moreover, audiometry provides the basis for the assessment of impairment and handicap as well as for the calculation of the degree of disability. In the present overview, the current state of the method inventory available for practical use is described, starting from basic diagnostics over to complex special techniques. The presentation is systematically grouped in subjective procedures, based on psychoacoustic exploration, and objective methods, based on physical measurements: preliminary hearing tests, pure tone threshold, suprathreshold processing of sound intensity, directional hearing, speech understanding in quiet and in noise, dichotic hearing, tympanogram, acoustic reflex, otoacoustic emissions and auditory evoked potentials. Apart from a few still existing gaps, this method inventory covers the whole spectrum of all clinically relevant functional deficits of the auditory system.

Predictors of hearing outcomes following low-dose stereotactic radiosurgery in patients with vestibular schwannomas: A retrospective cohort review

OBJECTIVES

Hearing deterioration is a major concern for hearing-preserved patients with vestibular schwannomas who are treated with stereotactic radiosurgery (SRS). Thus, determining which patients are more likely to have worse hearing outcomes following SRS may facilitate clinicians in deciding whether conservative policy should be applied in the interest of hearing preservation. This study aimed to define the predictors of hearing outcomes following SRS.

PATIENTS AND METHODS

This retrospective study included 100 patients who underwent low-dose SRS (12- to 13-Gy marginal dose) for vestibular schwannomas between January 2004 and January 2014. Clinical factors and hearing outcomes following radiosurgery were reviewed.

RESULTS

All patients had serviceable hearing at diagnosis and prior to SRS. The median follow-up period was 6.5years (range, 3-10years). The hearing preservation rate in the first, third, and fifth year after radiosurgery was 89%, 68%, and 63%, respectively. A mean cochlear dose lower than 4Gy was a favorable predictor of hearing outcome. Maximal cochlear dose, patient age, pre-treatment pure-tone average, and imaging characteristics were not associated with post-treatment hearing preservation. Our study showed an accelerated rate of deterioration of serial pure-tone average in the first 3years, followed by a more gradual decline after radiosurgery.

CONCLUSION

Our results suggest that cochlear dose constraint is the most crucial factor for hearing preservation. This study provides insight into the rate of hearing preservation and the pattern of hearing deterioration following radiosurgery and can help clinicians advise patients of hearing outcomes following SRS.

Acoustic neuroma: An investigation of associations between tumor size and diagnostic delays, facial weakness, and surgical complications

We conducted a retrospective case review to ascertain the clinical characteristics associated with acoustic neuromas and their treatment. Our study population was made up of 96 patients-41 men and 55 women, aged 17 to 84 years (mean: 54)-who had undergone treatment for acoustic neuromas and for whom necessary data were available. We compiled data on presenting symptoms, the interval from symptom onset to diagnosis, tumor size at diagnosis, facial weakness, the interval from diagnosis to surgery, the type of surgical approach, and surgical complications. Our primary goals were to determine if tumor size was correlated to (1) the interval from symptom onset to diagnosis, (2) the degree of preoperative facial weakness, and (3) surgical complications. We also sought to document various other clinical characteristics of these cases. The mean interval from the first symptom to diagnosis was 4.5 years; the time to diagnosis did not correlate with tumor size. Nor was tumor size correlated with the degree of preoperative facial weakness as determined by facial electroneurography. Surgical complications occurred in 15 of the 67 patients who underwent surgery (22.4%), and they did correlate with tumor size. The most common complications were postoperative facial weakness (13.4% of operated patients), cerebrospinal fluid leak (6.0%), and infection (3.0%). Since tumors typically grow about 2 mm per year and since larger tumors are associated with more severe symptoms and surgical complications, we expected that the time to diagnosis would correlate with tumor size, but we found no significant association.

Comparison of 3 ABR Methods for Diagnosis of Retrocochlear Hearing Impairment

BACKGROUND The purpose of this study was to compare the effectiveness of methods for screening for retrocochlear pathologies based on auditory evoked brainstem responses (ABRs). The study compared the sensitivity, specificity, and effectiveness of these 3 techniques. MATERIAL AND METHODS The methods were: (i) standard ABR utilizing click-evoked responses, (ii) stacked ABR based on derived-band responses, and (iii) ABRs evoked by tone-pips (ABR TP). The methods were tested on patients with retrocochlear pathologies confirmed by MRI-Gd, normal-hearing subjects, and patients with cochlear hearing loss. The system and software used in the tests was NavPro AEP v.6.2.0 (BioLogic - Natus). Prior to testing, all subjects were given comprehensive audiologic and otologic examinations, including MR imaging. Sensitivity and specificity functions and predictive values of methods were determined. RESULTS The stacked ABR method as realized in the NavPro system exhibited high sensitivity but specificity was very low, due to the high variability of stacked ABR amplitudes. The standard ABR method had good specificity, but low sensitivity in cases of small tumors (below 1 cm in diameter). Best sensitivity and specificity was obtained with the ABR TP method. CONCLUSIONS The stacked ABR method allows small acoustic tumors to be detected, but produces high percentage of false positive results. The ABR TP method offers good sensitivity and specificity, and relatively high predictive value. The best option would be to use a two-stage screening, consisting of a standard ABR in the first stage and an ABR TP test in the second.

Otologic manifestations of acoustic neuroma

CONCLUSION

Many patients with acoustic neuroma (AN) experience hearing loss and tinnitus. Time from first symptoms to diagnosis can be considerable. AN should be suspected, and MRI scans performed, in patients with hearing loss accompanied by asymmetry, tinnitus, low speech discrimination score (SDS), and abnormal auditory brainstem response (ABR).

OBJECTIVES

To determine the otorhinolaryngological factors associated with AN by analyzing the clinical manifestations and diagnostic test results of patients with AN before MRI scanning.

METHODS

This study enrolled 114 patients definitively diagnosed with AN after visiting the Ear-Nose-and-Throat and Neurosurgery Departments of Kyung Hee University Medical Center from 2001 to 2013. Factors retrospectively analyzed included patient age, gender, major symptoms, accompanying symptoms, symptom duration, pure-tone audiometry, SDS, asymmetry, tinnitogram, ABR, and MRI scan results.

RESULTS

The main symptom of AN was hearing loss, and the most frequent accompanying symptom was tinnitus. More severe deafness correlated significantly with lower SDS (p < 0.05). Asymmetric hearing was observed in 75 of 116 patients (64.6%), and mean SDS was 73.1 ± 34.1%. Of patients with latencies of waves I, III, and V on ABR tests, 56.1%, 92.4%, and 92.4%, had interaural latency differences ≥0.2 ms. However, audiometry results did not correlate with lesion site or tumor size (p > 0.05).

Audiovestibular Characteristics of Small Cochleovestibular Schwannomas in Neurofibromatosis Type 2

OBJECTIVE

Describe the relationship between cochleovestibular schwannoma (CVS) volume, audiovestibular characteristics, and magnetic resonance imaging (MRI) findings in patients with neurofibromatosis type 2 (NF2).

STUDY DESIGN

Subgroup analysis of NF2 prospective natural history study from 2008 to 2011.

SETTING

Quaternary medical research institute.

SUBJECTS AND METHODS

NF2 patients with small treatment-naive CVSs (volume <1000 mm(3)) by ear; N = 49 ears (32 patients). Cross-sectional analysis of the following parameters was performed: tumor size, auditory brainstem response (ABR), 4-frequency pure-tone average (4f-PTA; 0.5, 1, 2, and 4KHz), cervical vestibular evoked myogenic potential (cVEMP), caloric testing, 240° velocity step test (VST), and MRI findings.

RESULTS

For all physiologic measures but the 4f-PTA, larger tumors correlated with abnormal responses (P < .05). For abnormal ABR, mean tumor volume was 405 vs 151 mm(3) (P = .0007) for normal ABR. Similarly, larger tumors correlated with weak caloric responses (mean 521 vs 165 mm(3); P = .0007) and weak cVEMP (mean 357 vs 192 mm(3); P = .0262). Tumor volume was not significantly correlated with 4f-PTA. Elevated intralabyrinthine protein on MRI fluid-attenuated inversion recovery sequences was correlated with larger tumor volume (mean 333 vs 55 mm(3); P = .001) and abnormal ABR and 4f-PTA (P < .05) but did not correlate with cVEMP, VST, or caloric responses.

CONCLUSION

In our cohort, ABR, caloric response, cVEMP, and elevated intralabyrinthine protein correlated with tumor volume, but 4f-PTA did not. Abnormal ABR and 4f-PTA correlated with elevated intralabyrinthine protein. These findings may provide insight on the effect of small CVS on the inner ear and cochleovestibular nerves, which may aid in their optimal management.

The role of current audiological tests in the early diagnosis of hearing impairment in infant

This study aims to compare the various audiological tests that are currently available as screening tools for infant hearing assessment. In developing countries, which have limited resources, it is imperative to design a screening programme that is easy to perform, gives accurate results, has good patient acceptability and is cost effective. Fifty infants, 3-12 months of age, were subjected to BOT for hearing, transient-evoked oto-acoustic emissions (TEOAEs), automated auditory brainstem response (AABR) test, auditory brainstem evoked response (ABR) testing and auditory steady state response (ASSR). The sensitivity and specificity of the various tests was calculated, with ABR test as the gold standard. We also compared them for average time taken, cost factors, ease of performance, number of repeat tests required and patient acceptability. All the screening tests, TEOAE, AABR and behavioral observation test had reasonably high sensitivity. Specificity was highest for behavioral observation testing (67.7 %) and AABR (64.5 %), but low for OAE test (48.3 %). The cost and time taken for each test was least for the behavioral observation test, which also did not require any repeat testing. TEOAE and AABR incur a recurring cost of approximately one dollar per test. However, in 12 and 28 % of the babies had to be called back for repeat testing, respectively. ASSR, as a diagnostic test, has a 100 % sensitivity and high specificity but scores down on the cost involved, time taken and the number of repeat tests required. Overall parent acceptability was the highest for behavioral observation test, as it was non-invasive and easy to perform. Behavioral observation combined with TEOAE/AABR, can be fairly accurate as screening tests for hearing loss in infants. Considering its ease of performance and low cost, behavioral observation could be used as a screening test for detection of hearing loss in infants, in those countries/places where universal neonatal hearing screening is not yet available.

Preoperative characteristics of auditory brainstem response in acoustic neuroma with useful hearing: importance as a preliminary investigation for intraoperative monitoring

We classified the results of preoperative auditory brainstem response (ABR) in 121 patients with useful hearing and considered the utility of preoperative ABR as a preliminary assessment for intraoperative monitoring. Wave V was confirmed in 113 patients and was not confirmed in 8 patients. Intraoperative ABR could not detect wave V in these 8 patients. The 8 patients without wave V were classified into two groups (flat and wave I only), and the reason why wave V could not be detected may have differed between the groups. Because high-frequency hearing was impaired in flat patients, an alternative to click stimulation may be more effective. Monitoring cochlear nerve action potential (CNAP) may be useful because CNAP could be detected in 4 of 5 wave I only patients. Useful hearing was preserved after surgery in 1 patient in the flat group and 2 patients in wave I only group. Among patients with wave V, the mean interaural latency difference of wave V was 0.88 ms in Class A (n = 57) and 1.26 ms in Class B (n = 56). Because the latency of wave V is already prolonged before surgery, to estimate delay in wave V latency during surgery probably underestimates cochlear nerve damage. Recording intraoperative ABR is indispensable to avoid cochlear nerve damage and to provide information for surgical decisions. Confirming the condition of ABR before surgery helps to solve certain problems, such as choosing to monitor the interaural latency difference of wave V, CNAP, or alternative sound-evoked ABR.

Audiologic and vestibular assessment in patients with β-thalassemia major receiving long-term transfusion therapy

BACKGROUND

Life-long transfusion therapy with chelators is a treatment choice for patients with β-thalassemia major. Some investigators have proposed auditory impairment related to the use of deferoxamine, but the mechanisms remain unclear and whether or not deferiprone has similar side effects needs to be evaluated.

PROCEDURE

Thirty-seven patients with β-thalassemia major who received regular transfusion in our hospital were enrolled. Chelation agents, including deferoxamine and deferiprone, were used. To assess audiologic function, otoscopy, pure tone audiometry (PTA), tympanometry, transient evoked oto-acoustic emission (TEOAE), and auditory brainstem response (ABR) were conducted. Bithermal caloric test was performed to evaluate vestibular function.

RESULTS

All of the 37 patients had normal findings on otoscopic evaluation and their tympanograms were type A. Thirteen patients (35.1%) had hearing impairment at one or more frequencies as detected by PTA. Compared to those without hearing impairment, patients with hearing impairment had lower serum ferritin levels (P = 0.01). Seven of 21 patients (33.3%) failed to pass the TEOAE, while 13 (61.9%) had abnormal ABR findings. Sixteen patients (80%) had canal paresis in the caloric test.

CONCLUSIONS

The incidence of auditory impairment and vestibular dysfunction was high in patients with β-thalassemia major receiving long-term transfusion therapy. Potential lesions of auditory impairment may exist anywhere along the auditory pathway, from the inner ear to the brainstem. Lower serum ferritin levels may be associated with hearing impairment. Therefore, regular check-ups of serum ferritin levels and periodic audiologic assessment are mandatory.

ABR in the diagnosis of vestibular schwannomas: a meta-analysis

PURPOSE

The aim of this study is to rigorously evaluate the role of auditory brainstem response (ABR) testing in the diagnosis of vestibular schwannomas (VS).

MATERIALS AND METHODS

Searches were conducted in multiple online databases, supplemented by hand searches. From the studies chosen for final inclusion, relevant data were extracted and meta-analysis of pooled data was performed.

RESULTS

623 studies were identified from which 43 met inclusion criteria for analysis (1978 to 2009) including 3314 patients. Pooled sensitivity for ABR detection of vestibular schwannomas was 93.4% (95% CI 92.6-94.3, P=0.0000). For tumors less than 1cm (8 studies, 176 patients) sensitivity was 85.8% (95% CI 80.6-90.1, P=0.0116). For tumors greater than 1cm (6 studies, 251 patients) pooled sensitivity was 95.6% (95% CI 93.1-98.2, P=0.0660). Sensitivity of ABR to detect extracanalicular tumors was higher than for intracanalicular tumors, though pooled data were not statistically valid. Pooled specificity (8 studies, 2432 patients) was 82.0% (95% CI 80.5-83.6, P=0.0000).

CONCLUSIONS

Although MRI remains the gold standard, emerging trends towards more conservative management coupled with limited financial resources may prompt many clinicians to review the role of ABR testing in screening for retrocochlear pathology. In light of the high sensitivity and specificity of ABR testing for VS, we strongly urge its reconsideration as a useful diagnostic tool for patients with clinically suspected VS.

Clinical Practice Guideline

Objective. Sudden hearing loss (SHL) is a frightening symptom that often prompts an urgent or emergent visit to a physician. This guideline provides evidence-based recommendations for the diagnosis, management, and follow-up of patients who present with SHL. The guideline primarily focuses on sudden sensorineural hearing loss (SSNHL) in adult patients (aged 18 and older). Prompt recognition and management of SSNHL may improve hearing recovery and patient quality of life (QOL). Sudden sensorineural hearing loss affects 5 to 20 per 100,000 population, with about 4000 new cases per year in the United States. This guideline is intended for all clinicians who diagnose or manage adult patients who present with SHL.

Purpose. The purpose of this guideline is to provide clinicians with evidence-based recommendations in evaluating patients with SHL, with particular emphasis on managing SSNHL. The panel recognized that patients enter the health care system with SHL as a nonspecific, primary complaint. Therefore, the initial recommendations of the guideline deal with efficiently distinguishing SSNHL from other causes of SHL at the time of presentation. By focusing on opportunities for quality improvement, the guideline should improve diagnostic accuracy, facilitate prompt intervention, decrease variations in management, reduce unnecessary tests and imaging procedures, and improve hearing and rehabilitative outcomes for affected patients.

Results. The panel made strong recommendations that clinicians should (1) distinguish sensorineural hearing loss from conductive hearing loss in a patient presenting with SHL; (2) educate patients with idiopathic sudden sensorineural hearing loss (ISSNHL) about the natural history of the condition, the benefits and risks of medical interventions, and the limitations of existing evidence regarding efficacy; and (3) counsel patients with incomplete recovery of hearing about the possible benefits of amplification and hearing-assistive technology and other supportive measures. The panel made recommendations that clinicians should (1) assess patients with presumptive SSNHL for bilateral SHL, recurrent episodes of SHL, or focal neurologic findings; (2) diagnose presumptive ISSNHL if audiometry confirms a 30-dB hearing loss at 3 consecutive frequencies and an underlying condition cannot be identified by history and physical examination; (3) evaluate patients with ISSNHL for retrocochlear pathology by obtaining magnetic resonance imaging, auditory brainstem response, or audiometric follow-up; (4) offer intratympanic steroid perfusion when patients have incomplete recovery from ISSNHL after failure of initial management; and (5) obtain follow-up audiometric evaluation within 6 months of diagnosis for patients with ISSNHL. The panel offered as options that clinicians may offer (1) corticosteroids as initial therapy to patients with ISSNHL and (2) hyperbaric oxygen therapy within 3 months of diagnosis of ISSNHL. The panel made a recommendation against clinicians routinely prescribing antivirals, thrombolytics, vasodilators, vasoactive substances, or antioxidants to patients with ISSNHL. The panel made strong recommendations against clinicians (1) ordering computerized tomography of the head/brain in the initial evaluation of a patient with presumptive SSNHL and (2) obtaining routine laboratory tests in patients with ISSNHL.

Cost analysis of asymmetric sensorineural hearing loss investigations

OBJECTIVES/HYPOTHESIS

The purpose of this study is to critically evaluate the typical cost of asymmetrical sensorineural hearing loss (ASNHL) work-up, and to compare the positive predictive value from this common presenting symptom.

STUDY DESIGN

Retrospective chart review from two major otolaryngology centers.

METHODS

We reviewed charts from patients presenting to New York Eye and Ear Infirmary between January 1, 2006 and December 31, 2006, and the University of Minnesota between December 1, 2002 and November 30, 2007 with ASNHL. Diagnostic information included magnetic resonance imaging (MRI) and serum laboratory values (antinuclear antibodies, erythrocyte sedimentation rate, Lyme, rapid plasma reagin, and thyroid-stimulating hormone). We calculated positive rate according to each item of diagnosis. To estimate cost-benefit, we further calculated the average cost for identifying a patient with a positive result.

RESULTS

The total cost was $263,535, whereas the average cost for identifying a positive patient was $146,40.81. The total lab cost was $16,935 and the total imaging cost was $246,600. The average cost for identifying a positive patient based on MRI was $61,650 and $2,109 based on lab values. Of the 247 patients, only six patients (2.4%)-one patient with acoustic neuroma, two patients with syphilis, and three patients with Lyme--were identified with treatable pathology.

CONCLUSIONS

A comprehensive ASNHL work-up may not be applicable to all patients. Laboratory serologic tests are highly cost effective in diagnosing treatable causes of ASNHL, such as syphilis and Lyme. Although radiographic imaging with MRI is not as cost effective, its value in detecting for acoustic neuroma is undeniable.

Ipsilateral and Contralateral Acoustic Brainstem Response Abnormalities in Patients With Vestibular Schwannoma

OBJECTIVE: To analyze auditory brainstem response (ABR) data in patients with vestibular schwannomas (VS) in an effort to identify correlations between abnormal ABR parameters and tumor size.

STUDY DESIGN: Cross-sectional study with chart review.

SETTING: Tertiary referral hospital.

SUBJECTS AND METHODS: Retrospective chart review and analysis of bilateral ABR records in patients with VS. Interaural latency differences of interpeak I-V (ILD-I-V) and ILD-V longer than 0.2 ms were used as abnormal criteria.

RESULTS: Thirty patients with a mean age of 50 ± 14 years were included in this study. The most frequent changes in ABR parameters included those of ILD-I-V (100%), wave V latency (96.7%), ILD-V (93.3%), and interpeak I-V latency (90%). Average VS tumor size was 2.48 ± 1.31 cm. For patients with VS greater than or equal to 2 cm, the prevalences of abnormal ipsilateral interpeak III-V latency, contralateral wave V latency, and interpeak III-V latency showed statically significant differences ( P = 0.0035, P = 0.0267, and P = 0.0273, respectively) compared to those in patients with VS less than 2 cm. Tumor size was positively correlated with pure-tone average ( P = 0.0106) and with the total number of bilateral abnormal ABR parameters ( P = 0.004).

CONCLUSIONS: We identified a correlation between ABR parameters and VS tumor size. An ipsilateral ILD-I-V greater than 0.2 ms was sensitive for detecting VS. Abnormal contralateral wave V and interpeak III-V latency indicated a tumor size potentially larger than 2 cm. Further studies are needed to confirm these findings.

Is the nerve origin of the vestibular schwannoma correlated with vestibular evoked myogenic potential, caloric test, and auditory brainstem response?

CONCLUSIONS

The results of the caloric test, vestibular evoked myogenic potential (VEMP), and auditory brainstem response (ABR) in patients with vestibular schwannoma (VS) did not show clear correlation with the nerve origin of the tumor but with tumor size. When we focused on patients with VS within the internal acoustic canal (IAC), neither the nerve origin of the tumor nor the tumor size showed clear correlation with the results of these tests.

OBJECTIVES

This study examined the correlation of the nerve origin of VS, superior or inferior vestibular nerve, with the results of function tests.

SUBJECTS AND METHODS

Subjects comprised 109 consecutive patients diagnosed as having unilateral VS. Each test was performed before surgery. Tumor size was measured with preoperative MRI.

RESULTS

The nerve origin of the tumor was identified in 63 of the 109 patients. The percentage of patients showing abnormal responses in each test was not different between 37 patients with superior VS and 26 patients with inferior VS. Also, no difference was observed for patients with VS within the IAC. Mean tumor size in patients showing abnormal responses was larger than that in patients showing normal responses on each test. However, this tendency was not observed for patients with VS within the IAC.

Diagnosis and therapy of vestibular schwannoma

MRI studies are of paramount importance for diagnosis and follow-up measurements during conservative and postinterventional management of vestibular schwannomas (VS). MRI findings that convey important information for hearing-preservation VS surgery are: length of tumor-cochlear nerve contact, involvement of the internal auditory canal, incomplete filling of internal auditory canal, tumor size less than 15 mm and the intralabyrinthine signal intensity on 3DFT-CISS gradient-echo images. Functional neuro-otologic studies of facial nerve function, hearing and vestibular/balance function provide a valuable means of assessment of the actual impairment of the functional status of the VS patient. Intraoperative monitoring of facial nerve function and hearing has been refined, resulting in improved final postoperative facial nerve and hearing outcomes in VS patients treated with microsurgery. Long-term results reported by teams practicing stereotactic radiosurgery or fractionated stereotactic radiotherapy have been very encouraging. On the other hand, conservative management appears to be a viable option for a select group of VS patients. The refinement of surgical technique has rendered surgery safer and less invasive, resulting in better functional outcomes. Steroid use is currently used postinterventionally to improve final hearing outcome, although with questionable effectiveness. Physical rehabilitation programs are applied to accelerate vestibular functional recovery postoperatively and there is weak evidence that early physical rehabilitation may improve the final facial nerve outcome. Quality-of-life measures have emerged as important determinants of final therapeutic decision-making. More studies with high levels of evidence are needed to support clinical decisions.

The diagnostic value of vestibular-evoked myogenic potential in patients with vestibular schwannoma

OBJECTIVE

This study examined the diagnostic value of the vestibular-evoked myogenic potential (VEMP) in comparison with the caloric test in patients with vestibular schwannoma (VS).

METHODS

Data were retrospectively collected from 803 consecutive patients who visited our vertigo clinic and underwent vestibular tests. Amongst them, 78 patients were diagnosed as having untreated unilateral VS. VEMP was performed using click and short-tone burst stimulation. The caloric test was performed using ice water. The sensitivity and specificity of each test were evaluated.

RESULTS

Of the 78 patients with VS, 63 had abnormal VEMPs as well as abnormal caloric responses. Of the 725 patients without VS, 382 had normal VEMPs and 416 had normal caloric responses. The sensitivity and specificity of VEMP were 80.8% (95% CI: 72.0-89.5%) and 52.7% (95% CI: 49.1-56.3%), respectively; those of the caloric test were 80.8% (95% CI: 72.0-89.5%) and 57.4% (95% CI: 53.8-61.0%), respectively.

CONCLUSIONS

The sensitivity and specificity of VEMP and the caloric test showed no significant differences.

SIGNIFICANCE

In patients with VS, although the specificity of VEMP was not very high, its sensitivity was high and comparable to that of the caloric test.

Diagnostic value of auditory brainstem responses in cerebellopontine angle tumours

CONCLUSION

Auditory brainstem responses (ABRs) associated with other audio-vestibular examinations and a thorough clinical examination should allow detection of the majority of cerebellopontine angle (CPA) lesions (99.2-100%).

OBJECTIVE

The increasing quality of MRI in the detection of CPA lesions, and the reports of false negative ABRs have raised issues concerning the value of ABR in the diagnosis and preoperative assessment of CPA lesions. The aim of this work was to assess the value of the ABR in the diagnosis of vestibular schwannomas (VS) and other CPA lesions.

PATIENTS AND METHODS

This retrospective study included 676 solitary VS (548 operated on and 128 followed up) and 70 other CPA tumours (72% meningiomas, 11% cholesteatomas, 3% ependymomas, 15% miscellaneous) managed between 1990 and 2001. All patients underwent clinical examination, audiometry, ABR, vestibular caloric tests and MRI.

RESULTS

ABRs were normal in 4.8% of VS. Association of normal ABR, vestibular caloric tests and audiometry (AAO-HNS class A) represented only 0.7% of VS. In other CPA lesions, ABR were normal in 15% of cases and the association of the three above-mentioned examinations was encountered in 10%. However, in the latter cases the clinical examination showed an abnormality in all cases.

Auditory Brainstem Response Threshold Differences in Patients with Vestibular Schwannoma: A New Diagnostic Index

Auditory brainstem response (ABR) testing is less sensitive in detecting small vestibular schwannomas than medium-size tumors. Magnetic resonance imaging (MRI) is more sensitive than ABR alone for small and large tumors, but it carries with it increased cost and issues of unavailability and patient discomfort. We conducted a prospective pilot study of 7 patients with untreated MRI-proven, unilateral vestibular schwannoma to determine if we could increase the sensitivity of ABR testing in detecting small tumors. Our method involved the use of a new ABR index that is based on threshold differences. All patients underwent pure-tone audiometry followed by a determination of behavioral threshold and neurodiagnostic threshold ABR in the normal ear, which was used as a control, and in the diseased ear. Analysis of results revealed that all 7 patients had an abnormal ABR threshold difference, and 5 patients displayed abnormal traditional ABR indices. The mean difference between the ABR and behavioral click thresholds was 41.4 dB in the diseased ears (with the ABR threshold being higher than the click threshold) and 15.8 dB in the normal ears. None of the control ears had a threshold difference >30 dB.

Correlating the cochleovestibular deficits with tumor size of acoustic neuroma

CONCLUSION

The tumor size of acoustic neuroma correlates with cochleovestibular deficits. Those tumors with global frequency hearing loss, bilateral gaze nystagmus, or absent caloric and VEMP responses may indicate a tumor size >2.5 cm.

OBJECTIVE

This study aimed to investigate the correlation between cochleovestibular deficits and the size of acoustic neuroma.

PATIENTS AND METHODS

A total of 44 patients with acoustic neuroma were enrolled in this study. Pure tone audiometry, electronystagmography, caloric test, vestibular evoked myogenic potential (VEMP) test, and MRI were conducted.

RESULTS

There is a trend of correlation between tumor size and audiographic configuration, with small-sized tumor in normal and rising types, medium-sized tumor in mid- and high-frequency hearing loss, and large-sized tumor in flat and deafness types. Five patients with bilateral gaze nystagmus had significantly larger tumor size than those without nystagmus. When 1 and 0 are used to represent abnormal and normal responses, respectively, the relationship between tumor size and vestibular function can be expressed as: tumor size (cm)=1.43 (caloric response)+1.35 (VEMP response), indicating that the estimated tumor size for those with abnormal caloric or VEMP responses increased by 1.43 or 1.35 cm, respectively.

Ipsilateral and contralateral vestibular schwannomas in unilateral long-term deaf ears

In the past decade, we have encountered two patients with unilateral long-term deaf ear having vestibular schwannoma. One was on the deaf ear in a 53 years' woman and the other was on the contralateral hearing ear in a 62 years' woman. These two patients had total deafness on the right ear since childhood, associated with absent auditory brainstem response (ABR) and caloric responses, whereas normal ABR and caloric responses were shown on the left ear. Although similar physiological findings were disclosed on the deaf ears, MRI scan demonstrated vestibular schwannoma on the different side, that is, one in deaf ear and the other in hearing ear. For the former, absent ABR and caloric results indicate that the tumor originates from the superior vestibular nerve. In contrast with the latter, normal ABR and caloric responses, but absent vestibular-evoked myogenic potentials on the hearing ear imply that the tumor originates from the inferior vestibular nerve. The ipsilateral tumor on the deaf ear underwent intracranial surgical excision, followed by radiosurgery due to tumor recurrence 10 years later, while the contralateral one on the only hearing ear received radiosurgery only. Both patients were rather well, 3 years after last treatment.

The stacked ABR: a sensitive and specific screening tool for detecting small acoustic tumors

The failure of standard ABR measures to detect small (< or =1 cm) acoustic tumors has led to the use of enhanced magnetic resonance imaging (MRI) as the standard to screen for small tumors. This study investigates the suitability of the stacked ABR as a sensitive screening alternative to MRI for small acoustic tumors (SATs). The objective of the study was to determine the sensitivity and specificity of the stacked ABR technique for detecting SATs. A total of 54 patients with acoustic tumors identified by MRI that were either < or =1 cm in size or undetected by standard ABR methods, irrespective of size, were studied. A control population of 78 nontumor normal-hearing subjects was also tested. For comparison, two standard ABR measures (IT5 and I-V delay) were also analyzed. The stacked ABR demonstrated 95% sensitivity and 88% specificity; 100% sensitivity was obtained at 50% specificity. Standard ABR measures were much poorer in detecting these tumors. In conclusion, the stacked ABR can be used as a sensitive, widely-available, cost-effective, and comfortable tool for screening SATs.

Vinpocetine inhibits the epileptic cortical activity and auditory alterations induced by pentylenetetrazole in the guinea pig in vivo

Here we investigate the effect of the neuroprotective drug, vinpocetine on the epileptic cortical activity, on the alterations of the later waves of brainstem auditory evoked potentials (BAEPs) and on the hearing decline induced by the convulsing agent, pentylenetetrazole (PTZ). Vinpocetine at doses from 2 to 10 mg/kg inhibits the tonic-clonic convulsions induced by PTZ (100 mg/kg). Vinpocetine injected at a dose of 2 mg/kg 4 h before PTZ completely prevents the characteristic electroencephalogram (EEG) changes induced by PTZ for the ictal and post-ictal periods. Vinpocetine also abolished the PTZ-induced changes in the amplitude and latency of the later waves of the BAEPs in response to pure tone burst monoaural stimuli (frequency 8 or 4 kHz intensity 100 dB), and the PTZ-induced increase in the BAEP threshold. These results show the antiepileptic potential of vinpocetine and indicate the capability of vinpocetine to prevent the changes in the BAEP waves associated with the hearing loss observed during generalized epilepsy.

[Magnetic resonance: first choice test in the screening of internal auditory canal and cerebellopontine angle tumors]

Although internal auditory canal (IAC) and cerebellopontine angle (CPA) tumors are rare, their clinical suspicion is quite common in the otolaryngology office. MRI is the imaging modality of choice in diagnosing these tumors. Perceived high costs may prevent clinicians from using it as a screening tool. A protocol designed to improve cost-effectiveness in such diagnosis results in a more rationale clinical practice. Our aim was to evaluate the usefulness of MRI as screening tool in diagnosis of IAC and CPA tumors in our population. Between March 1998 and March 2000, a prospective series of 200 cases had a MRI screening requested. MRI were performed following Fast Spin Echo technique, providing T2-weighted images. Gadolinium enhanced MRI was reserved for selected cases. We report on 190 MRI done. We found 7 neuromas (3.5%), one CPA metastasis, one epidermoid cyst and 9 IAC vascular anomalies. Only 138 cases (69%) had normal MRI images. When used following a designed protocol, MRI is our procedure of choice while screening IAC and CPA tumors because it is a cost-effective tool.