Findings on 7000 MRI of the IAM: To scan or not to scan?: A retrospective cohort study

Incidental findings on magnetic resonance imaging of the internal auditory meatus for vestibular schwannoma: a systematic review

OBJECTIVE

Magnetic resonance imaging of the internal auditory meatus is a highly sensitive and specific way to diagnose vestibular schwannoma. However, the rate of incidental findings with this method is believed to be high and can lead to increased patient anxiety and health interventions with unclear benefit.

METHOD

A systematic review of the literature was performed using the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines to identify incidental findings from magnetic resonance imaging of the internal auditory meatus; 12 studies were identified for inclusion within this review.

RESULTS

A total of 10 666 patients were included within the review. The overall rate of diagnosis of vestibular schwannoma was 0.87 per cent; 21 per cent of the study population had incidental findings on magnetic resonance imaging of the internal auditory meatus, and 9.56 per cent had clinically significant incidental findings.

CONCLUSION

Standardised pre-scan counselling may mitigate the risks of overdiagnosis, but future work should be undertaken to assess the benefits of such a strategy as well as the exact significance of some incidental findings.

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.

An observational study of T2-weighted white matter hyperintensities on magnetic resonance imaging of the internal auditory meatus and brain: ignore or not?

BACKGROUND

Magnetic resonance imaging of the internal auditory meatus frequently detects incidental white matter hyperintensities. This study investigated the association between these and the risk of stroke and transient ischaemic attack, or myocardial infarction.

METHODS

The records of patients with incidental white matter hyperintensities were reviewed, and data were collected on: age, sex, cardiovascular risk factors, and incidence of stroke and transient ischaemic attack, or myocardial infarction, five years later. The risk factors associated with vascular events were explored.

RESULTS

Of 6978 patients, 309 (4.4 per cent) had incidental white matter hyperintensities. Of these, 20 (6.5 per cent) had a stroke or transient ischaemic attack within five years, and 5 (1.7 per cent) had a myocardial infarction. The number of cardiovascular risk factors was significantly associated with the incidence of stroke and transient ischaemic attack (p = 0.004), and myocardial infarction (p = 0.023).

CONCLUSION

The number of cardiovascular risk factors predicts the likelihood of vascular events; appropriate risk factor management is recommended for patients with incidental white matter hyperintensities of presumed vascular origin.

The use of magnetic resonance imaging in the investigation of patients with unilateral non-pulsatile tinnitus without asymmetrical hearing loss

BACKGROUND

Tinnitus is a common condition presenting to the ENT out-patient clinic. Vestibular schwannomas are benign cerebellopontine angle tumours that usually present with unilateral sensorineural hearing loss. Magnetic resonance imaging of the internal auditory meatus is the definitive investigation in their detection. The current recommendation is for unilateral tinnitus patients to undergo magnetic resonance imaging of the internal auditory meatus to exclude vestibular schwannoma.

OBJECTIVE

To evaluate magnetic resonance imaging in the investigation of patients with unilateral non-pulsatile tinnitus without asymmetrical hearing loss.

METHOD

A retrospective case series was conducted of all patients who underwent magnetic resonance imaging of the internal auditory meatus to investigate unilateral non-pulsatile tinnitus without asymmetrical hearing loss, from 1 January 2014 to 1 January 2019.

RESULTS

Of 2066 scans, 566 (27 per cent) were performed to investigate patients (335 female, 231 male) with unilateral non-pulsatile tinnitus without asymmetrical hearing loss. Three vestibular schwannomas were detected on imaging, and 134 incidental findings were discovered.

CONCLUSION

The detection rate of vestibular schwannoma in this group was just 0.3 per cent. This paper questions the utility of magnetic resonance imaging evaluation in these patients.