Intralabyrinthine Schwannoma: Distinct Features for Differential Diagnosis

Evolution of Vestibular Findings During and Between the Attacks of Meniere Disease: Update

Purpose of Review

The diagnosis of Meniere disease (MD) has based on characteristics of vertigo and findings of audiologic evaluation. This review focuses on the recent findings of the evolution of vestibular function and their underlying physiology during and between the attacks of MD and thus aims to help identify this common disorder with many faces according to the phase.

Recent Findings

During the attacks, the direction of spontaneous nystagmus changes over time, beating initially toward the affected ear (irritative nystagmus), then toward the healthy ear (paretic nystagmus), and finally back toward the affected ear again (recovery nystagmus). Apart from these direction changes, atypical forms of spontaneous nystagmus, such as downbeat, discordant horizontal-torsional, and aperiodic alternating nystagmus, can be observed. Head impulse tests (HITs) are mostly normal during the irritative/recovery phases, but positive in more than half of patients during the paretic phase. By contrast, caloric tests are usually abnormal irrespective of the phases, although paradoxical caloric hyper-responsiveness can be observed in 18% of patients during the irritative/recovery phases. Thus, dissociation in the findings of caloric tests-HITs can be observed during and between the attacks. Horizontal head shaking tends to augment spontaneous nystagmus during each phase, while skull vibration mostly induces nystagmus beating toward the healthy ear irrespective of the phases. During the attacks, ocular vestibular-evoked myogenic potentials (VEMPs) may be enhanced, whereas cervical VEMPs are usually decreased during stimulation of the involved ear.

Summary

Recognizing these evolutions of vestibular findings during and between the attacks of MD would provide insights into its pathophysiology and aid in treatments and diagnosis.

Does Location of Intralabyrinthine Vestibular Schwannoma Determine Objective and Subjective Vestibular Function?

BACKGROUND AND OBJECTIVE

The incidence of intralabyrinthine schwannomas is increasing, and a growing attention is given to the detrimental effects on hearing function. On the contrary, the vestibular profile of intralabyrinthine vestibular schwannomas (VSs) is still not well understood. We aimed to investigate and report the observed relationships between the intralabyrinthine location of the schwannomas and objective and subjective vestibular profile of the patients.

METHODS

Retrospective cohort study of 20 consecutive individuals with sporadic intralabyrinthine schwannomas and grouped according to the intralabyrinthine location of the schwannomas. Vestibular testing consisted of the video head impulse test of all three semicircular canals, the caloric test, cervical and ocular vestibular evoked myogenic potentials, and the dizziness handicap inventory. A nonparametric unpaired t test was performed to compare groups, and Fisher's exact test was used for categorical data.

RESULTS

The median video head impulse test gains (lateral, anterior, posterior) were 0.40, 0.50, and 0.75 for intravestibular schwannomas and 0.93, 1.52, and 0.91 for intracochlear schwannomas ( p = 0.0001, p = 0.009, p = 0.33), respectively. Caloric unilateral weakness had a median of 100% for intravestibular schwannomas and 14% for intracochlear schwannomas ( p = 0.0001). The mean dizziness handicap inventory was 21 for intravestibular schwannomas and 1 for cochlear schwannomas ( p = 0.02). There were no significant differences in vestibular evoked myogenic potentials according to intralabyrinthine location.

CONCLUSION

By both objective and subjective measures, intralabyrinthine schwannomas with an intravestibular component has significantly worse vestibular function than schwannomas with purely cochlear involvement.

Audiovestibular Findings in Patients with Concurrent Superior Canal Dehiscence and Vestibular Schwannoma

OBJECTIVE

To describe the clinical-instrumental findings in case of concurrent superior canal dehiscence (SCD) and ipsilateral vestibular schwannoma (VS), aiming to highlight the importance of an extensive instrumental assessment to achieve a correct diagnosis.

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

Five patients with concurrent SCD and VS.

INTERVENTION

Clinical-instrumental assessment and imaging.

MAIN OUTCOME MEASURE

Clinical presentation, audiovestibular findings, and imaging.

RESULTS

The chief complaints were hearing loss (HL) and unsteadiness (80%). Other main symptoms included tinnitus (60%) and pressure-induced vertigo (40%). Mixed-HL was identified in three patients and pure sensorineural-HL in 1, including a roll-over curve in speech-audiometry in two cases. Vibration-induced nystagmus was elicited in all cases, whereas vestibular-evoked myogenic potentials showed reduced thresholds and enhanced amplitudes on the affected side in three patients. Ipsilesional weakness on caloric testing was detected in three patients and a bilateral hyporeflexia in one. A global canal impairment was detected by the video-head impulse test in one case, whereas the rest of the cohort exhibited a reduced function for the affected superior canal, together with ipsilateral posterior canal impairment in two cases. All patients performed both temporal bones HRCT scan and brain-MRI showing unilateral SCD and ipsilateral VS, respectively. All patients were submitted to a wait-and-scan approach, requiring VS removal only in one case.

CONCLUSION

Simultaneous SCD and VS might result in subtle clinical presentation with puzzling lesion patterns. When unclear symptoms and signs occur, a complete audiovestibular assessment plays a key role to address imaging and diagnosis.

Full Endoscopic Resection of Intralabyrinthine Schwannomas: A Case Series

Objective: To investigate the technique and efficacy of fully endoscope resection of intralabyrinthine schwannomas (ILS) by transcanal transpromontorial endoscopic approach (TTEA). Study Design: Retrospective case review. Setting: Hospital. Patients: All patients who were affected by ILS, without extension to the internal auditory canal and underwent surgery with TTEA in our hospital in 2020. Intervention(s): Therapeutic. Main Outcome Measure(s): Recovery status, postoperative complications and remaining symptoms after surgery. Results: Three patients were included, all of which underwent gross total resections. The follow-up period was from 10 months to 2 years. No intraoperative and postoperative major complications were observed. There was no facial paralysis or cerebrospinal fluid leakage postoperatively. The hospitalization time of TTEA was 5 days. Three patients' vertigo was relieved after 1 week without receiving vestibular therapy. Only 1 patient complained of transient episodes of vertigo when climbing or holding heavy objects. Conclusions: TTEA has the advantages of clear vision to identify the anatomical structure, enabling complete tumor resection, reduced operation time, and faster postoperative recovery.Level of Evidence: IV.

Intralabyrinthine schwannomas: a two-case series and literature review with a focus on hearing rehabilitation

PURPOSE

Intralabyrinthine schwannomas (ILSs) are an uncommon finding. Diagnosis is challenging and no gold standard treatment exists yet. In this article, we present a two-cases series and review the latest available literature to assess the best diagnostic and therapeutic scheme.

METHODS

We reviewed the latest available literature assessing most frequent and relevant sets of symptoms, clinical features of the disease, diagnostic tests and imaging, possible treatments and after-surgery hearing rehabilitation techniques. We then compared literature data to our own series ones.

RESULTS

ILSs clinical presentation and development may overlap with other, more common otological conditions. Full audiometric battery test, electrophysiological study of VEMPS and MRI with contrast enhancement all appear to be critical to correctly diagnose these tumors. Several treatments exist: radiological follow-up, radiation therapy, full or partial surgical excision. Hearing rehabilitation is mostly accomplished through simultaneous cochlear implantation.

CONCLUSIONS

Our case-series data matches the available literature. ILSs are a rare type of vestibular schwannomas. Diagnosis in challenging and delayed in time as all the diagnostic tests, yet sensitive, are not specific for ILSs. The most suitable treatment seems to be surgical excision of these tumors followed by simultaneous cochlear implantation to restore hearing.

The Natural History of Primary Inner Ear Schwannomas: Outcomes of Long-Term Follow-Up

OBJECTIVE

To describe the natural history of primary inner ear schwannomas over a long follow-up period.

STUDY DESIGN

Retrospective case series.

SETTING

Tertiary referral center.

PATIENTS

Patients with primary inner ear schwannomas with serial audiometric and radiologic follow-up.

MAIN OUTCOME MEASURES

Patterns of hearing loss, rate of hearing decline, presence of vestibular symptoms, and rate of tumor growth.

RESULTS

A total of 12 patients with 13 tumors were identified. The mean duration of follow-up was 7 years. Forty-six percent of tumors were intracochlear, 15% were intravestibular, 23% were transmodiolar, and 15% were intravestibular-cochlear. Hearing loss was the most common presenting symptom, occurring in all patients. Among patients with serviceable hearing (American Academy of Otolaryngology-Head and Neck Surgery Class A or B) at the time of presentation, the average time to decline to a nonserviceable hearing level was 57.3 months (range, 21-117 mo). Hearing loss was sudden in 31% of patients, progressive in 61% and fluctuating in 8%. No patients had intractable vertigo; however, two required vestibular physiotherapy. On initial magnetic resonance imaging, the mean largest tumor dimension was 3.1 mm (standard deviation, 1.2 mm), and the mean largest dimension on most recent magnetic resonance imaging was 4.4 mm (standard deviation, 1.1 mm). Two tumors exhibited no growth over a follow-up of 11.3 and 2.8 years, respectively. Overall, the mean growth was 0.25 mm per year followed. Two patients underwent cochlear implantation with simultaneous tumor resection and had favorable outcomes.

CONCLUSION

Long-term follow-up suggests a conservative approach, with possible hearing rehabilitation at the time of deterioration, is a safe management strategy for primary inner ear schwannomas.

Schwannoma of the radial nerve: a case report

Schwannomas are the most common benign tumors of the peripheral nerves, but represents only 5%-8% of all soft tissue tumors. Their diagnosis is usually delayed due to their slow growth and the nervous adaptation to their increased volume. Ultrasound sonography and magnetic resonance imaging (MRI) images usually ease the diagnosis. Correct enucleation offers very good postoperative outcomes and avoids recurrences. We report an unusual case of schwannoma of the radial nerve (RN) that remained asymptomatic for one year and a half, and treated well, had good outcomes.

Case report: Concurrent intravestibular schwannoma mimicking Ménière's disease and cochlear hydrops detected via delayed three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging

Objective

To present a case of intralabyrinthine schwannoma (ILS) presenting as Ménière's disease diagnosed via 4-h delayed gadolinium-enhanced three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI) and treated successfully using the translabyrinthine approach.

Patient

A patient who was diagnosed with intravestibular ILS.

Interventions

The patient underwent comprehensive preoperative neurological examinations and MRI. The tumor was resected using the translabyrinthine approach and was pathologically confirmed as schwannoma based on the surgical specimen.

Main outcome measures

Preoperative audiogram and vestibular test findings and MRI images.

Results

Preoperatively, pure-tone audiogram showed progressive sensorineural hearing loss only on the affected side. The video head impulse test and vestibular evoked myogenic potential test showed vestibular dysfunction on the affected ear. Immediate gadolinium-enhanced T1-weighted MRI revealed an enhanced region in the vestibule. Meanwhile, magnetic resonance cisternography showed a filling defect. Delayed 3D-FLAIR MRI revealed a signal void in the scala media of the cochlea indicative of cochlear hydrops, and a strong signal in the perilymph at the basal cochlea suggestive of impaired blood–labyrinthine barrier.

Conclusion

Delayed 3D-FLAIR MRI is useful in diagnosing concurrent ILSs and endolymphatic hydrops.

Challenges of Cochlear Implantation in Intralabyrinthine Schwannoma Patients: Surgical Procedures and Auditory Outcome

Intralabyrinthine schwannoma (ILS) is a rare benign tumor of the inner ear potentially causing unilateral sensorineural hearing loss and vertigo. This study evaluated the outcome of one surgical session comprising microsurgical ILS resection and cochlear implantation in terms of surgical feasibility, complications, and auditory outcome. Ten clinically and histologically confirmed ILS patients included in this study (three women and seven men; mean age 56.4 ± 8.6) underwent surgery between July 2015 and February 2020. Eight patients had intracochlear tumor location; the remaining two had vestibulocochlear and intravestibular ILS. One of the three following methods was used for tumor removal: an extended cochleostomy, subtotal cochleoectomy, or a translabyrinthine approach. Although negligible improvement was observed in two of the patients, two patients were lost to follow-up, and one opted out from using CI, the speech perception of the five remaining ILS patients improved as per the Freiburg Monosyllable Test (FMT) from 0% before surgery to 45– 50% after the implantation. Our study supports the presented surgical approach’s feasibility and safety, enabling tumor removal and hearing restoration shortly after surgery.

Four-Hour Delayed Gadolinium-Enhanced 3D-FLAIR MR Imaging Highlights Intralabyrinthine Micro-Schwannomas

OBJECTIVE

To demonstrate the clinical significance of 4-hour delayed gadolinium-enhanced three-dimensional fluid-attenuated inversion recovery (delayed 3D-FLAIR) in patients with intralabyrinthine schwannoma (ILS).

PATIENTS

Three patients who were clinically diagnosed with ILS.

INTERVENTIONS

All patients underwent audiological examinations and magnetic resonance imaging (MRI) scans. The MR-protocol included axial MR cisternography, immediate gadolinium-enhanced T1-weighted sequence, and heavily T2-weighted 3D-FLAIR prior to and 4 hours after the intravenous administration of gadolinium contrast medium.

MAIN OUTCOME MEASURES

All MR images were visually inspected.

RESULTS

In all three patients with ILS, delayed 3D-FLAIR MRI demonstrated a strong signal of cochlear fluid surrounding the tumor, which highlighted a tumor region that lacked signals.

CONCLUSIONS

Delayed 3D-FLAIR MRI may serve as a novel diagnostic tool for the early detection of intralabyrinthine micro-schwannoma. The findings also shed light on the pathophysiology of ILS.

Cervical and Ocular Vestibular-Evoked Myogenic Potentials in Patients With Intracochlear Schwannomas

Objective: To evaluate ocular and cervical vestibular evoked myogenic potentials (oVEMPs and cVEMPs) in patients with solely intracochlear localization of an intralabyrinthine schwannoma (ILS).

Study Design: Retrospective analysis of a series of cases.

Setting: Monocentric study at a tertiary referral center.

Patients: Patients with intracochlear schwannoma (ICS) and VEMP measurements.

Outcome Measures: Signed asymmetry ratio (AR) of cVEMPs and oVEMPs to air conducted sound with AR cut-offs considered to be asymmetrical when exceeding ±30% for cVEMPs and ±40% for oVEMPs with respect to the side affected by the tumor (reduced amplitudes on the affected side indicated by negative values, enhanced amplitudes by positive values); VEMP amplitudes and latencies; tumor localization in the cochlear turn and scala.

Results: Nineteen patients with a solely intracochlear tumor (ICS patients) [10 males, 9 females, mean age 57.1 (SD: 13.4) years] were included in the study. On the affected side, cVEMPs were absent or reduced in 47% of the patients, normal in 32%, and enhanced in 21%. Ocular VEMPs on the affected side were absent or reduced in 53% of the patients, normal in 32% and enhanced in 15%. Latencies for cVEMPs and oVEMPs were not significantly different between the affected and non-affected side. In all patients with enhanced VEMPs, the tumor was located in the scala tympani and scala vestibuli.

Conclusions: As a new and unexpected finding, VEMP amplitudes can be enhanced in patients with intracochlear schwannoma, mimicking the third window syndrome.

Diagnostic assessment of magnetic resonance imaging for patients with intralabyrinthine schwannoma: A systematic review

OBJECTIVES

Recent advancements in high-resolution imaging have improved the diagnostic assessment of magnetic resonance imaging (MRI) for intralabyrinthine schwannoma (ILS). This systematic review aimed to evaluate the diagnostic performance of MRI for patients with ILS.

METHODS

Ovid-MEDLINE and EMBASE databases were searched for related studies on the diagnostic performance of MRI for patients with ILS published up to February 10, 2020. The primary endpoint was the diagnostic performance of MRI for ILS. The quality of the enrolled studies was assessed using tailored questionnaires and the Quality Assessment of Diagnostic Accuracy Studies-2 criteria.

RESULTS

Overall, 6 retrospective studies that included 122 patients with ILS from a parent population of 364 were included. The sample size, parent population and its composition, reference standard, detailed parameters of MRI, and even the diagnostic methods varied between the studies. The studies had moderate quality. The sensitivity of combination of T2WI and CE-T1WI was over 90%. Relative sensitivity of T2WI comparative to CE-T1WI ranged from 62% to 100%, and the specificity were 100%.

CONCLUSIONS

MRI has acceptable diagnostic performance for ILS. There is a need for well-organized research to reduce the factors causing heterogeneity.

Ictal downbeat nystagmus in Ménière disease: A cross-sectional study

OBJECTIVE

To determine the mechanism of ictal downbeat nystagmus in Ménière disease (MD), we compared the head impulse gain of the vestibulo-ocular reflex (VOR) for each semicircular canal between patients with (n = 7) and without (n = 70) downbeat nystagmus during attacks of MD.

METHODS

We retrospectively analyzed the results of video-oculography, video head-impulse tests, and cervical vestibular-evoked myogenic potentials (VEMPs) in 77 patients with definite MD who were evaluated during an attack.

RESULTS

Pure or predominant downbeat nystagmus was observed in 7 patients (9%) with unilateral MD during the attacks. All 7 patients showed spontaneous downbeat nystagmus without visual fixation with a slow phase velocity ranging from 1.5 to 11.2°/s (median 5.4, interquartile range 3.7-8.5). All showed a transient decrease of the head impulse VOR gains for the posterior canals (PCs) in both ears (n = 4) or in the affected ear (n = 3). Cervical VEMPs were decreased in the affected (n = 2) or both ears (n = 2) when evaluated during the attacks. Downbeat nystagmus disappeared along with normalization of the VOR gains for PCs after the attacks in all patients. During the attacks, the head impulse VOR gains for the PC on the affected side were lower in the patients with ictal downbeat nystagmus than in those without (Mann-Whitney U test, p < 0.001), while the gains for other semicircular canals did not differ between the groups.

CONCLUSION

Downbeat nystagmus may be observed during attacks of MD due to an asymmetry in the vertical VOR or saccular dysfunction. MD should be considered in recurrent audiovestibulopathy and ictal downbeat nystagmus.