Diagnostic yield of MRI for audiovestibular dysfunction using contemporary referral criteria: correlation with presenting symptoms and impact on clinical management

Incidence of Vestibular Schwannoma in Patients with Unilateral Tinnitus: A Systematic Review and Meta-Analysis

OBJECTIVES

Vestibular schwannoma (VS) is a tumor of the vestibulocochlear nerve. Current literature indicates that 1.6% of patients undergoing magnetic resonance imaging of the internal auditory meatus (MRI IAM) for audiovestibular symptoms are diagnosed with a VS. However, there is limited research reporting on patients who present with unilateral tinnitus without asymmetrical hearing loss. This study is a systematic review and meta-analysis evaluating how many of those patients had a VS diagnosed on MRI IAM.

DATABASES USED

Online searches of PubMed, Medline, and Embase databases were performed up to October 2022.

METHODS

This meta-analysis was undertaken aligning with PRISMA guidelines. Articles reporting on patients having MRI IAM for unilateral tinnitus without asymmetrical hearing loss were included. Outcomes measures were patient demographics, VS cases, incidental findings, size, and management of tumor. A meta-analysis of proportions was performed using a random-effects model with the restricted maximum likelihood method. Quality assessment was performed using the Joanna Briggs Institute critical appraisal checklist.

RESULTS

Seven case series were included in the review: a total of 1,394 patients. Seven patients had a VS, with a median size of 4 mm. The pooled detection rate for VS was 0.08% (95% confidence interval = 0.00-0.45). Subsequent management was reported in six cases of which four were actively monitored and two surgically excised. The most common incidental finding was sinus disease (49 patients).

CONCLUSION

Our findings indicate that MRI IAM has a low diagnostic yield for VS detection in patients presenting with unilateral tinnitus without asymmetrical hearing loss, with mostly small tumors that are conservatively managed.

Neuroaudiological Considerations for the Auditory Brainstem Response and Middle Latency Response Revisited: Back to the Future

The auditory brainstem response (ABR) and middle latency response (MLR) are two sets of evoked potentials that have made major contributions to the field of diagnostic audiology. Many of these contributions were guided by clinical research audiologists. Though many of these auditory evoked potentials (AEPs) are still being used diagnostically by audiologists, there has been a steep decline in their popularity both clinically and in the research laboratory. This is indeed most unfortunate because these AEPs could and should be advancing our field and benefitting many patients. In this article, some critical research is overviewed that addresses some of the reasons why these AEPs (ABR and MLR) are not being utilized as frequently as they should be for neuroauditory assessments. Reflecting on our past when ABR and MLR were more commonly used can serve as a model for our future. Multiple applications and the diagnostic value of these AEPs are presented in an effort to convince audiologists that these electrophysiologic procedures should be revisited and reapplied in the clinic and research settings. It is argued that the dwindling use of ABR and MLR (and AEPs in general) in the field of audiology is not only remarkably premature but also lacks good scientific grounding. While on the other hand, if applied clinically, the value of these AEPs is both substantial and promising.

Imaging of the Vestibular Schwannoma: Diagnosis, Monitoring, and Treatment Planning

Appropriate imaging strategies for the detection, treatment planning, and posttreatment monitoring of vestibular schwannomas will be discussed. The typical and variant imaging appearances of vestibular schwannomas, as well as the imaging features that should prompt consideration of differential diagnoses, will be illustrated. Understanding the natural history of vestibular schwannomas, optimal measurement and definition of tumour growth helps the radiologist evaluate for the failure of conservative management and requirement for surgery or radiotherapy. In order to determine the success of conservative management, the radiologist is required to understand the natural history of vestibular schwannomas and how tumour growth is defined. Finally, the imaging features which help guide appropriate treatment with surgery or radiotherapy will be highlighted, and the expected posttreatment imaging changes will be described.

Development of a diagnostic model to identify patients at high risk for cerebellopontine angle lesions

Purpose

To develop a diagnostic model to identify patients at high risk of a CPA lesion.

Methods

A consecutive cohort of patients with AAD referred by a general practitioner, who underwent their first MRI examination of the CPA between 2005 and 2015 was included. Demographics, symptoms, findings during physical examination, and pure-tone audiometry were used as potential predictors. The presence of a CPA lesion was used as outcome.

Results

We analyzed data of 2,214 patients, detecting 73 CPA lesions in 69 (3.1%) patients. The final model contained eleven variables, namely gender [male] [OR 1.055 (95% CI 0.885–1.905)], sudden onset of hearing loss [OR 0.768 (95% CI 0.318–0.992)], gradual onset of hearing loss [OR 1.069 (95% CI 0.500–1.450)], unilateral tinnitus [OR 0.682 (95% CI 0.374–0.999)], complaints of unilateral aural fullness [OR 1.006 (95% CI 0.783–2.155)], instability [OR 1.006 (95% CI 0.580–2.121)], headache [OR 0.959 (95% CI 0.059–1.090)], facial numbness [OR 2.746 (95% CI 0.548–11.085)], facial nerve dysfunction during physical examination [OR 1.024 (95% CI 0.280–3.702)], and asymmetry in BC at 1 kHz [OR 1.013 (95% CI 1.000–1.027)] and 4 kHz [OR 1.008 (95% CI 1.000–1.026)].

Conclusion

The proposed diagnostic model is a first step in selecting patients with a high risk of a CPA lesion among those with AAD. It needs to be externally validated prior to its implementation in clinical practice.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00405-021-06778-6.

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.

Diagnostic yield of MRI of the brain and IAC in patients with neurotologic complaints

OBJECTIVES

Quantify number of MRI scans obtained in a tertiary neurotology practice and identify likelihood of pathologic findings.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary neurotology center.

SUBJECTS AND METHODS

A retrospective analysis of all adult patients over 20 months (3/2012-10/2013) where MRI was deemed necessary for evaluation of neurotologic complaints. Demographics, clinical history, physical examination, and audiometric findings were used to categorize new patients into 7 groups: definite Meniere's disease (MD), probable MD, possible MD, vague dizziness, tinnitus only, asymmetric hearing loss (HL), and other symptoms to stratify risk for retrocochlear tumor and other relevant pathology.

RESULTS

1537 MRI scans were performed, 932 of these were for a new diagnosis. Discovering retrocochlear tumors was rare (1.4%). Patients with HL had a 0.3% (1/314) chance of retrocochlear tumor and 3.2% (10/314) chance of relevant pathology. Patients with only unilateral tinnitus had no evidence of retrocochlear tumors, and 3.8% chance of finding relevant pathology. Patients with "definite" or "probable" MD had no evidence of retrocochlear tumor or other relevant findings. All discovered acoustic neuromas were in the "possible MD" category, which had a 9.3% chance of finding all relevant pathology.

CONCLUSIONS

In a tertiary neurotology center, the likelihood of finding a retrocochlear tumor on MRI is rare. In the current study, unilateral tinnitus exclusively, "definite MD," and "probable MD" failed to yield a single example of retrocochlear tumor. Patients with "possible MD" had the highest probability of finding retrocochlear tumors and other relevant pathology.

Incidental findings on magnetic resonance imaging of the internal auditory meatus performed to investigate audiovestibular symptoms

OBJECTIVE

To determine the frequency of incidental findings found on magnetic resonance imaging scans of the internal auditory meatus performed to investigate audiovestibular symptoms, and to determine how to best manage these when found.

METHOD

A retrospective review was conducted of internal auditory meatus magnetic resonance imaging scans during a three-month period in the radiology department at a UK district general hospital.

RESULTS

A total of 109 scans were reviewed. Of these, 92.7 per cent showed no retrocochlear pathology, 0.9 per cent showed vestibular schwannoma, 6.4 per cent revealed vascular loops, and 2.8 per cent showed incidental findings that warranted further action and investigation. Of the scans, 40.4 per cent showed other incidental pathologies such as age-related ischaemic changes, and sinus disease that required no further intervention. Of the magnetic resonance imaging scans reviewed, 49.5 per cent were entirely normal.

CONCLUSION

Almost half of the scans investigating audiovestibular symptoms showed incidental findings. Otolaryngologists should have an understanding of the significance of the most commonly encountered incidental findings, and should counsel patients appropriately and refer them onward when necessary.

Cerebellopontine angle and intracanalicular masses mimicking vestibular schwannomas

OBJECTIVE

To describe the clinical and radiographic characteristics in a series of patients with non-vestibular schwannoma cerebellopontine angle (CPA) and intracanalicular (IAC) masses, who underwent microsurgery for presumed vestibular schwannoma (VS).

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary neurotologic referral center.

PATIENTS

One thousand five hundred ninety-three patients underwent microsurgery for apparent VS from 2002 to 2013. Of these, 53 patients (3%) were discovered to have a diagnosis other than VS.

INTERVENTIONS

Middle fossa, translabyrinthine, and retrosigmoid craniotomy.

MAIN OUTCOME MEASURES

Clinical presentation, radiologic analysis, and histopathology examination.

RESULTS

There were 17 facial schwannomas, 15 meningiomas, 9 hemangiomas, 6 lipochoristomas, 3 inflammatory reactions, and one each of lymphoma, glial heterotopia, solitary fibrous tumor, ependymoma, and a non-diagnostic mass. Excluding facial schwannomas, 23 cases were misdiagnosed as VS in the first half of the study period, compared to only 15 cases in the latter half (p = 0.09). Ninety-six percent of patients presented with some combination of sensorineural hearing loss, balance disturbance, and tinnitus. In the subset of patients with available preoperative MRI scans for retrospective review, only 4 of 28 patients had radiologic findings suggestive of pathology other than VS. The most common missed radiologic diagnoses were facial schwannoma, lipochoristoma, and meningioma.

CONCLUSION

A subgroup of patients with CPA and IAC masses who present with radiologic findings diagnostic of VS will have an alternative histopathologic diagnosis. Optimal radiologic imaging and experienced interpretation can improve diagnostic accuracy. The most common tumors that mimic VS despite ideal radiologic imaging are facial schwannomas, meningiomas, and hemangiomas.

Less common neuro-otologic disorders

PURPOSE OF REVIEW

A systematic approach to the history and examination allows the physician to diagnose the most common vestibular disorders of the brain or inner ear. However, some less common disorders require a specific familiarity so that they are not misdiagnosed as one of the more common disorders,treated inappropriately, or misattributed to a psychogenic etiology. This article describes four of the less common disorders that can present with a primary problem of dizziness and imbalance: (1) mal de débarquement syndrome, (2) bilateral vestibulopathy, (3) cerebellar ataxia, and (4) vestibular schwannomas (ie, acoustic neuromas).

RECENT FINDINGS

Associated clinical features of mal de débarquement syndrome have recently been investigated to clarify the spectrum of the syndrome. The combination of cerebellar ataxia, neuropathy, and vestibular areflexia (bilateral vestibulopathy) has been summated into a new syndrome. Further refinement of ocular motor features of cerebellar ataxia can narrow genetic testing requirements. Vestibular schwannomas remain an uncommon etiology for isolated dizziness; recent imaging studies have helped quantify the low yield of screening MRI protocols for the evaluation of undefined dizziness.

SUMMARY

A working knowledge of these less common disorders will help the physician make the diagnosis efficiently by gathering key elements of the history and fine-tuning diagnostic testing.

Prospective evaluation of the clinical profile and referral pattern differences of vestibular schwannomas and other cerebellopontine angle tumors

OBJECTIVE

To evaluate the clinical profile, referral pattern, delay in diagnosis, and impact of tumor size of cases involving vestibular schwannomas (VS) versus other cerebellopontine angle (CPA) tumors in an Egyptian population.

STUDY DESIGN

Case series study.

SETTING

Tertiary referral center.

PATIENTS

A prospective study of possible retrocochlear lesions was conducted from 2008 to 2010.

INTERVENTION(S)

Patients were subjected to a full clinical history, complete otorhinolaryngological examination, a basic audiologic evaluation, auditory brainstem response assay, and gadolinium-enhanced magnetic resonance imaging. According to the findings of magnetic resonance imaging, patients with retrocochlear lesions were divided into 2 groups: those with VS (n = 17) and those with other CPA lesions (n = 14).

MAIN OUTCOME MEASURE(S)

Diagnostic delay and criteria of VS and CPA tumors.

RESULTS

Unilateral hearing loss and tinnitus were presented in 52.9% of VS cases with a diagnostic delay of 15.5 months. For cases involving other CPA lesions, a combination of otologic symptoms was observed in 9 (64%) of 14 cases, and a diagnostic delay of 47.5 months was experienced. An absence of auditory brainstem response waves was identified significantly (p < 0.05) for the affected ears of both groups. Only differences in Wave V latency were significant between the 2 groups (p < 0.05).

CONCLUSION

A longer diagnostic delay was associated with cases involving other types of CPA lesions versus cases of VS, and tumor size and volume did not affect the diagnostic delay of the former. Moreover, the only significant difference in clinical presentation for these 2 groups of intracranial tumor involved Wave V latency.