Brazilian Society of Otology task force - Vestibular Schwannoma ‒ evaluation and treatment

OBJECTIVE

To review the literature on the diagnosis and treatment of vestibular schwannoma.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on vestibular schwannoma were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The topics were divided into 2 parts: (1) Diagnosis - audiologic, electrophysiologic tests, and imaging; (2) Treatment - wait and scan protocols, surgery, radiosurgery/radiotherapy, and systemic therapy.

CONCLUSIONS

Decision making in VS treatment has become more challenging. MRI can diagnose increasingly smaller tumors, which has disastrous consequences for the patients and their families. It is important to develop an individualized approach for each case, which highly depends on the experience of each surgical team.

Sudden sensorineural hearing loss as the initial symptom in patients with acoustic neuroma

Background

Previous studies have shown that patients with acoustic neuroma (AN) sometimes present with sudden sensorineural hearing loss (SSNHL) as an initial symptom. The purpose of this research was to investigate the clinical characteristics, diagnosis, and treatment of AN in patients initially diagnosed with SSNHL.

Materials and methods

We reviewed retrospectively the medical records of all patients who were treated as SSNHL initially and were later diagnosed with AN after undergoing magnetic resonance imaging (MRI) at our hospital between 2008 and 2021. Patient demographics, associated complaints (mostly tinnitus and vertigo), the severity of hearing loss, audiogram configurations, auditory brainstem response (ABR), and MRI examination were reviewed and analyzed. In addition, treatment outcomes and management protocols were also included in this study.

Results

A total of 10 (0.7%, 10/1,383) patients presented with SSNHL as the initial symptom and were diagnosed as AN by MRI finally. Of the 10 patients enrolled in this study, four were men and six were women. The average age at the time of diagnosis of SSNHL was 46.2 ± 13.16 years. These patients exhibited varying severity of hearing loss and a variety of audiogram configurations. All patients showed an abnormal ABR. According to the Koos grading standard, there were 5 grade I (intracanalicular [IAC]) tumors, 3 grade II tumors, and 2 grade III tumors. The treatment outcome revealed that 2 patients exhibited recovery of the average hearing of impaired frequency by more than 15 dB, and 6 patients showed no recovery. Furthermore, four patients were referred to undergo surgical treatment after being diagnosed with AN, 1 patient accepted stereotactic radiation therapy, and the remaining 5 patients were on a “wait and scan” strategy.

Conclusion

The hearing loss of patients with AN presented with SSNHL may improve with drug treatment. Hearing recovery for SSNHL does not exclude the presence of AN, and all patients initially diagnosed with SSNHL should undergo MRI and ABR to prevent misdiagnosis and delays in potential treatment.

Assessment of epidermoid cyst with trigeminal neuralgia before neuroendoscopy: A high-resolution MR study based on 3D-FIESTA and MR angiography

PURPOSE

To assess the value of preoperative 3D-FIESTA and MR angiography (MRA) in endoscopic resection of epidermoid cysts presenting with trigeminal neuralgia (TN).

METHODS

3D-FIESTA and MRA were performed before neuroendoscopy in 32 cases of epidermoid cysts with TN, and the tumors were grouped into types A, B, C, and D according to the relationship between the tumor and adjacent nerves and arteries (Hitoshi Kobata's classification). Evaluation of the neuroendoscopic resectability of different types of tumors, included gross total tumor removal (GTR), subtotal tumor removal (STR), and partial tumor removal (PTR). During the 5-year follow-up, symptoms were assessed based on facial pain relief using the Barrow Neurological Institute (BNI) score.

RESULTS

The coincidence rate between MRI classification of the tumor and the operation was 100%. Type B tumors were the most common (18/32, 56.3%). Type A tumors showed the highest resectability (9/9, 100%), followed by type B tumors (14/18, 77.8%). Moreover, microvascular decompression was performed in all 4 cases of type C and 1 case of type D tumors. During follow-up, 23 patients showed marked improvement in symptoms (15, 8 of BNI I or II), 8 cases showed partial improvement (BNI III), and only 1 case of type C tumor was associated with poor facial pain relief, which recurred 5 years later (BNI IV).

CONCLUSIONS

Preoperative high-resolution MR can accurately analyze the relationship between epidermoid cysts and adjacent nerves and arteries. It could act as a powerful tool in the evaluation of tumor resectability and the prognosis of surgery.

Current imaging tools for vestibular schwannoma

PURPOSE OF REVIEW

Of the tumors found in the cerebellopontine angle (CPA), vestibular schwannomas are by far the most common. Modern diagnostic imaging enables excellent visualization of the CPA and detection of very small tumors while optimizing patient comfort and time. This review addresses the current imaging tools available for diagnosis of vestibular schwannomas.

RECENT FINDINGS

The current gold-standard imaging study for vestibular schwannomas is a gadolinium-enhanced T1-weighted MRI. The yield of this expensive study is only about 3-4% given the low incidence of vestibular schwannomas, thus there is utility in screening with noncontrast T2-weighted MRI, which is a quicker and more economical study.

SUMMARY

Vestibular schwannomas are best evaluated with gadolinium-enhanced T1-weighted MRI, which can detect tumors as small as 2-3 mm. Recent studies have found that the reported sensitivity and specificity of noncontrast MRI is almost equivalent to that of gadolinium-enhanced T1-weighted MRI. As such, this modality is increasingly being adopted by institutions for both diagnosis and surveillance of vestibular schwannomas and shows promise for broader implementation. Newer protocols, such as FLAIR and DTI may provide additional information and further aid preoperative counseling and surgical planning in the future.

A preliminary study of deep learning-based reconstruction specialized for denoising in high-frequency domain: usefulness in high-resolution three-dimensional magnetic resonance cisternography of the cerebellopontine angle

PURPOSE

Deep learning-based reconstruction (DLR) has been developed to reduce image noise and increase the signal-to-noise ratio (SNR). We aimed to evaluate the efficacy of DLR for high spatial resolution (HR)-MR cisternography.

METHODS

This retrospective study included 35 patients who underwent HR-MR cisternography. The images were reconstructed with or without DLR. The SNRs of the CSF and pons, contrast of the CSF and pons, and sharpness of the normal-side trigeminal nerve using full width at half maximum (FWHM) were compared between the two image types. Noise quality, sharpness, artifacts, and overall image quality of these two types of images were qualitatively scored.

RESULTS

The SNRs of the CSF and pons were significantly higher with DLR than without DLR (CSF 21.81 ± 7.60 vs. 15.33 ± 4.03, p < 0.001; pons 5.96 ± 1.38 vs. 3.99 ± 0.48, p < 0.001). There were no significant differences in the contrast of the CSF and pons (p = 0.225) and sharpness of the normal-side trigeminal nerve using FWHM (p = 0.185) without and with DLR, respectively. Noise quality and the overall image quality were significantly higher with DLR than without DLR (noise quality 3.95 ± 0.19 vs. 2.53 ± 0.44, p < 0.001; overall image quality 3.97 ± 0.17 vs. 2.97 ± 0.12, p < 0.001). There were no significant differences in sharpness (p = 0.371) and artifacts (p = 1) without and with DLR.

CONCLUSION

DLR can improve the image quality of HR-MR cisternography by reducing image noise without sacrificing contrast or sharpness.

Clinical Practice Guideline: Ménière's Disease

OBJECTIVE

Ménière's disease (MD) is a clinical condition defined by spontaneous vertigo attacks (each lasting 20 minutes to 12 hours) with documented low- to midfrequency sensorineural hearing loss in the affected ear before, during, or after one of the episodes of vertigo. It also presents with fluctuating aural symptoms (hearing loss, tinnitus, or ear fullness) in the affected ear. The underlying etiology of MD is not completely clear, yet it has been associated with inner ear fluid (endolymph) volume increases, culminating in episodic ear symptoms (vertigo, fluctuating hearing loss, tinnitus, and aural fullness). Physical examination findings are often unremarkable, and audiometric testing may or may not show low- to midfrequency sensorineural hearing loss. Conventional imaging, if performed, is also typically normal. The goals of MD treatment are to prevent or reduce vertigo severity and frequency; relieve or prevent hearing loss, tinnitus, and aural fullness; and improve quality of life. Treatment approaches to MD are many and typically include modifications of lifestyle factors (eg, diet) and medical, surgical, or a combination of therapies.

PURPOSE

The primary purpose of this clinical practice guideline is to improve the quality of the diagnostic workup and treatment outcomes of MD. To achieve this purpose, the goals of this guideline are to use the best available published scientific and/or clinical evidence to enhance diagnostic accuracy and appropriate therapeutic interventions (medical and surgical) while reducing unindicated diagnostic testing and/or imaging.

Inner ear MRI: is it always useful to manage intravenous contrast?

OBJECTIVE

To evaluate the added value of administering intravenous contrast (IVC) routinely to the MRI of patients with audiovestibular symptoms in the assessment of a neuroradiologist and a resident.

MATERIALS AND METHODS

Retrospective study including patients who had an inner ear MRI for two months. Two radiologists reviewed independently and blinded the images. A first assessment was made analyzing just the sequences acquired without contrast and then a second evaluation of all the sequences, including post-contrast T1 sequences. The interobserver correlation and the correlation between MRI findings and the reason for requesting the study were calculated.

RESULTS

40 patients were included. The range age was 36-80 years. The most frequent reason for request the MRI was hearing loss (52.5%). Neuroradiologist without IVC found 82.5% of extraotic pathology and 17.5% of otic pathology, highlighting the neurinoma of the VIII pair (7.5%); ossifying labyrinthitis, retrofenestrated otosclerosis and cholesteatoma. After IVC administration, findings were similar. The resident identified otic pathology in 5% in baseline sequences and 20% using CIV. The interobserver correlation using IVC was excellent (0.97), but weak without IVC (0.52). There was a correlation between the reasons for request the MRI and the findings in the ears, both in protocols without IVC (p = 0.004) and in protocols with IVC (p = 0.002).

CONCLUSION

Inner ear MRI without contrast gives relevant information to assess audiovestibular symptoms. The use of IVC increases the degree of confidence in a novel radiologist, while in the expert its use is less relevant. A protocol should be proposed in which gadolinium is used in selected patients.