Intralabyrinthine schwannoma affecting the low but not high frequency function of the vestibulo-ocular reflex: implications for the clinical diagnosis of chronic peripheral vestibular deficits

A Case Report Demonstrating Preservation of Vestibular Receptor Function after Transcochlear Removal of an Intracochlear Schwannoma with Extension to the Fundus of the Internal Auditory Canal

Preservation of function is an important goal during surgical management of cochleovestibular schwannomas. We here demonstrate the relief of vertigo and the preservation of function of all five vestibular receptors after removal of an intracochlear schwannoma with extension to the fundus of the internal auditory canal. A 61-year-old male with a five-year history of left-sided deafness, tinnitus, vertigo attacks, and an MRI consistent with an intracochlear schwannoma with limited extension through the modiolus to the fundus of the internal auditory canal (IAC) underwent transcanal, transcochlear total tumor removal and-due to a cerebrospinal fluid leak from the fundus of the IAC-revision surgery with lateral petrosectomy and blind sac closure of the external auditory canal. Despite complete removal of the cochlear partition of the inner ear (total cochlectomy), the patient's vestibular receptors remained functional, and the vertigo symptoms disappeared. These results show that vestibular labyrinthine function may not only be preserved after partial or subtotal cochlectomy but also after complete cochlear removal. This further confirms the vestibular labyrinth's robustness and encourages surgical management of transmodiolar schwannomas with limited extension to the fundus of the IAC.

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.

Vestibular Schwannoma: Long-term Outcome of the Vestibular Function After Stereotactic Radiosurgery

Objective

Evaluation at long term of the impact of the stereotactic surgery (SRS) on the vestibular function in vestibular schwannoma (VS) patients.

Study design and setting

Retrospective study in a tertiary referral center.

Patients

Fifty-one VS patients were included (34 females;17 males), aged from 41 to 78 years treated exclusively with SRS.

Intervention

Vestibular function was assessed before SRS and with median time interval of 14 (FU1) and 25 (FU2) months after treatment. Vestibular evaluation included: history, clinical vestibular examination, videonystagmography, head impulse test (v-HIT) and cervical vestibular evoked myogenic potentials (c-VEMPS).

Results

Before SRS, caloric testing (Caloric) was impaired in 77%; after treatment, in 92% (FU1) and 77% (FU2). Lateral HIT was decreased in 22% before SRS, in 39% at FU1 and FU2. C-VEMPS were absent in 50% before SRS, in 76% at FU1 and, FU2. Before SRS, no statistically significant association was found between asymptomatic and symptomatic patients with respect to the results of Caloric, v-HIT and c-VEMPS. This lack of association was also seen after SRS, at FU1 and FU2.

Conclusion

Our study showed that the impairment of the vestibular function might be attributed to the VS itself as well as to the radiation of the inner ear during SRS. The lateral SSC at low frequencies and the saccular function seem to be more involved with the time.

Risk of acute brain lesions in dizzy patients presenting to the emergency room: who needs imaging and who does not?

The usefulness of brain imaging studies in dizzy patients presenting to the emergency department (ED) is controversial. We aimed to assess the ‘real-world’ probability of ischemic stroke and other acute brain lesions (ABLs) in these patients to create an algorithm that helps decision-making on whether which and when brain imaging is needed. By reviewing medical records, we identified 610 patients presenting with dizziness, vertigo or imbalance to our university hospital’s ED and receiving neurological workup. We collected timing/triggers of symptoms, ABCD² score, focal neurological abnormalities, HINTS (head impulse, nystagmus, test-of-skew) and other central oculomotor signs. ABLs were extracted from CT/MRI reports. Uni-/multivariate logistic regression analyses investigated associations between clinical parameters and ABLs. Finally, the likelihood of ABLs was assessed for different clinically defined subgroups (‘dizziness syndromes’). Early CT (day 1) was performed in 539 (88%) and delayed MR imaging (median: day 4) in 299 (49%) patients. ABLs (89% ischemic stroke) were revealed in 75 (24%) of 318 patients with adequate imaging (MRI or lesion-positive CT). The risk for ABLs increased with the presence of central oculomotor signs (odds ratio 2.8, 95% confidence interval 1.5–5.2) or focal abnormalities (OR 3.3, 95% CI 1.8–6.2). The likelihood of ABLs differed between dizziness syndromes, e.g., HINTS-negative acute vestibular syndrome: 0%, acute imbalance syndrome with ABCD²-score ≥ 4: 50%. We propose a clinical pathway, according to which patients with HINTS-negative acute vestibular syndrome should not receive brain imaging, whereas imaging is suggested in dizzy patients with acute imbalance, central oculomotor signs or focal abnormalities.

Intralabyrinthine Schwannoma: Distinct Features for Differential Diagnosis

Objectives: The aim of this study was to delineate the clinical and laboratory features suggestive of intralabyrinthine schwannoma (ILS). Methods: We compared the clinical features of 16 patients with ILS, who had been diagnosed at the Seoul National University Bundang Hospital from 2003 to 2018, with those of 18 patients with symptomatic unilateral intracanalicular schwannoma and randomly selected 20 patients with definite or probable unilateral Meniere's disease (MD). Results: Patients with ILS presented with either recurrent spontaneous dizziness/vertigo combined with auditory symptoms (n = 8), isolated auditory symptoms without dizziness/vertigo (n = 7), or recurrent spontaneous dizziness/vertigo without auditory symptoms (n = 1). Most patients reported no improvement (n = 11) or worsening (n = 1) of the symptoms despite medical treatments including intratympanic (n = 5) or intravenous steroids (n = 2). Conventional brain MRIs failed to detect ILS in about a half of the patients (7/16, 44%). However, ILS showed a filling defect on 3-dimensional (3D) heavily T2-weighted MRIs (n = 12), and nodular enhancement on 3D contrast-enhanced T1 (n = 15) or FLAIR MRIs (n = 13) targeted for the inner ear. Compared to MD or intracanalicular schwannoma, ILS showed mostly abnormal head-impulse tests (HITs, p = 0.001). In contrast, the incidence of canal paresis did not differ among the groups (p = 0.513). Conclusion: ILS may mimic MD by presenting recurrent dizziness/vertigo and auditory symptoms. ILS should be suspected in patients with recurrent audiovestibulopathy especially when (1) the duration of the dizziness is not typical for MD, (2) the patients do not respond to medical treatments, or (3) HITs are abnormal.

Current diagnostic procedures for diagnosing vertigo and dizziness

Vertigo is a multisensory syndrome that otolaryngologists are confronted with every day. With regard to the complex functions of the sense of orientation, vertigo is considered today as a disorder of the sense of direction, a disturbed spatial perception of the body. Beside the frequent classical syndromes for which vertigo is the leading symptom (e.g. positional vertigo, vestibular neuritis, Menière’s disease), vertigo may occur as main or accompanying symptom of a multitude of ENT-related diseases involving the inner ear. It also concerns for example acute and chronic viral or bacterial infections of the ear with serous or bacterial labyrinthitis, disorders due to injury (e.g. barotrauma, fracture of the oto-base, contusion of the labyrinth), chronic-inflammatory bone processes as well as inner ear affections in the perioperative course. In the last years, diagnostics of vertigo have experienced a paradigm shift due to new diagnostic possibilities. In the diagnostics of emergency cases, peripheral and central disorders of vertigo (acute vestibular syndrome) may be differentiated with simple algorithms. The introduction of modern vestibular test procedures (video head impulse test, vestibular evoked myogenic potentials) in the clinical practice led to new diagnostic options that for the first time allow a complex objective assessment of all components of the vestibular organ with relatively low effort. Combined with established methods, a frequency-specific assessment of the function of vestibular reflexes is possible. New classifications allow a clinically better differentiation of vertigo syndromes. Modern radiological procedures such as for example intratympanic gadolinium application for Menière’s disease with visualization of an endolymphatic hydrops also influence current medical standards. Recent methodical developments significantly contributed to the possibilities that nowadays vertigo can be better and more quickly clarified in particular in otolaryngology.

Association of posterior semicircular canal hypofunction on video-head-impulse testing with other vestibulo-cochlear deficits

OBJECTIVES

The video-head-impulse test (vHIT) provides a functional assessment of all six semicircular canals (SCC). Occasionally isolated loss of the posterior canal(s) (ILPC) is diagnosed, though this finding is poorly characterized. Here we assessed how accurate that diagnosis is by measuring the co-occurrence of abnormalities on caloric irrigation, vestibular-evoked myogenic-potentials and audiometry.

METHODS

We identified 52 patients with ILPC (unilateral=40, bilateral=12). We determined vHIT-gains and saccade-amplitudes and correlated vHIT-findings with other vestibulo-cochlear tests.

RESULTS

The most frequent diagnoses were history of vestibular neuritis (13/52), Menière's disease (12/52) and vertigo/dizziness of unclear origin (13/52). Unilateral ILPC on vHIT was accompanied by a deficient horizontal canal on calorics, saccular and/or utricular deficits ipsilesionally in 33/40 (83%), while ipsilesional hearing-loss was noted in 24/40 (60%). Involvement of other sensors was highest for vestibular schwannoma (100%) and history of vestibular neuritis (92%). Bilateral deficits in ≥1 vestibulo-cochlear sensor(s) were noted in 2/12 cases with bilateral ILPC.

CONCLUSIONS

>80% of patients with unilateral ILPC had additional deficits of other parts of the vestibular organ, while this rate was ≤20% for patients with bilateral ILPC.

SIGNIFICANCE

Dizzy patients should receive testing of the posterior canals and if abnormalities are observed, additional vestibulo-cochlear testing should be obtained.

Video head impulse in comparison to caloric testing in unilateral vestibular schwannoma

CONCLUSIONS

Although there was a statistically significant relationship between the results of the vHIT and the caloric test, the limited strength of this relationship suggests that, for unilateral vestibular schwannoma (UVS), caloric testing and vHIT may provide complementary information on vestibular function.

OBJECTIVE

There is limited information that can be used to determine which of the video head impulse test (vHIT) and caloric test might be better used in the diagnosis and management of UVS. In this study, a group of participants with un-operated UVS was studied using both methods.

METHODS

The subjects' vestibular function was assessed using the vHIT and caloric testing. Tumour size was quantified using MRI and their balance disturbance assessed using the Jacobsen Dizziness Handicap Inventory (DHI).

RESULTS

Twenty of 30 subjects had an abnormal canal paresis according to the Jongkees' criterion (> 0.25); however, only 10/30 had an ipsilesional vHIT gain of <0.79. Canal paresis could be predicted from the ipsilesional and contralesional vHIT gains. Tumour size could also be predicted from the ipsilesional vHIT gain and canal paresis. However, DHI scores could not be predicted from the degree of canal paresis, vHIT gain, or the MRI measures.

Audiovestibular Function Deficits in Vestibular Schwannoma

Introduction. Vestibular schwannomas (VS) are benign tumours of the vestibular nerve and can lead to hearing loss, tinnitus, vertigo, facial palsy, and brainstem compression. Audiovestibular diagnostic tests are essential for detection and treatment planning. Methods. Medline was used to perform a systematic literature review with regard to how audiovestibular test parameters correlate with symptoms, tumour size, and tumour location. Results. The auditory brainstem response can be used to diagnose retrocochlear lesions caused by VS. Since hearing loss correlates poorly with tumour size, a retrocochlear lesion is probably not the only cause for hearing loss. Also cochlear mechanisms seem to play a role. This can be revealed by abnormal otoacoustic emissions, despite normal ABR and new MRI techniques which have demonstrated endolymphatic hydrops of the inner ear. Caloric and head impulse tests show frequency specific dynamics and vestibular evoked myogenic potentials may help to identify the location of the tumour regarding the involved nerve parts. Conclusion. In order to preserve audiovestibular function in VS, it is important to stop the growth of the tumour and to avoid degenerative changes in the inner ear. A detailed neurotological workup helps to diagnose VS of all sizes and can also provide useful prognostic information.

Clinical presentation of intralabyrinthine schwannomas: a multicenter study of 110 cases

OBJECTIVE

To describe the presentation of intralabyrinthine schwannomas (ILSs).

STUDY DESIGN AND SETTING

Retrospective multicenter study involving 12 European skull base surgery tertiary referral centers.

PATIENTS

One hundred ten patients with the diagnosis of ILS, either labyrinth confined or extending into the internal auditory meatus for less than 50% of their volume.

MAIN OUTCOME MEASURES

Data collected were age, sex, nature and timing of presenting symptoms, hearing (according to the AAO-HNS grading system), results of vestibular tests (caloric tests and cervical vestibular-evoked myogenic potentials [c-VEMPs]), and tumor localization. Presenting symptoms and laboratory test results were studied according to the extension of the lesion into the cochlea (C) and vestibule (V), on one hand, and according to unifocal (L1) or plurifocal (L2) extension into the labyrinth, on the other.

RESULTS

Intracochlear type was more common (50%) than vestibular (19.1%) and more diffuse forms (30.9%). The mean delay for diagnosis was long (72.5 mo; SD, 76.6). Mean age was 53.9 years (SD, 13.2). Deafness was the most common symptom (77.8 dB HL [SD, 33.6], with only 24.6% of patients keeping viable hearing. Caloric tests (65.5% of patients) were abnormal in 77.8% of cases. c-VEMPs were abnormal in 65.7% of the 36 cases analyzed. In V forms, hearing was significantly better (class A + B in 21.1% in C and 45.8% in V forms) (p = 0.03), and vestibular function was more altered (C: 57%, V: 100%, p = 0.0009*). L2 forms were diagnosed later (L1: 59.1 mo, L2: 104.5 mo; p = 0.004*) and were associated more frequently with a dead ear (L1: 13.1%, L2: 41.2%, p = 0.002*) than L1 forms.

CONCLUSIONS

This series, which is the largest in the literature, demonstrates that even very small and localized ILSs heavily compromise labyrinthine functions.

Meta-analysis on the clinical outcomes in patients with intralabyrinthine schwannomas: conservative management vs. microsurgery

The objective of this review is to compare the symptomatological evolution following conservative management (CM) or microsurgery (MS) in patients with intralabyrinthine schwannomas (ILS). A thorough systematic review of the English and French literature from 1948 to February 2014 was performed using Ovid Medline. An ancestor search was also completed. The major inclusion criterion consisted of a diagnosis of ILS with magnetic resonance imaging. Patients with a classic vestibular schwannoma, cases of incidentaloma during surgery or an autopsy were the main exclusion criteria. Thirty-one studies met our selective criteria. Descriptive data were collected from the articles. Clinical outcomes regarding the hearing loss, tinnitus, vertigo, dizziness and aural fullness were stated as improved, unchanged or worse at the last follow-up. All data were then separated into two different groups according to the management option: CM and MS. The data were analyzed using a Pearson χ (2) test and Fisher's exact test. This meta-analysis suggests that MS has a statistically significant favorable outcome regarding symptom relief compared to CM in patients with ILS suffering from tinnitus, vertigo and dizziness. Hearing level was not compared between treatment groups, as MS leads to anacusis. An indicative bias was the main limitation of this study, as patients suffering from intractable vertigo with moderate-to-severe hearing loss were referred to MS. Therefore, in the presence of a serviceable hearing, we suggest that CM should be the treatment of choice.

Economic management of vertigo/dizziness disease in a county hospital: video-head-impulse test vs. caloric irrigation

The video-head-impulse test (vHIT) is an important test for examining unilateral vestibular hypofunction. Alternatively, one can test for vestibular hypofunction with the caloric irrigation test. Various studies have shown that both tests may not always identify vestibular hypofunction; instead, the results of the tests might be contradictory. This retrospective study reproduces those finding in a much larger group of patients at a county hospital. 1063 patients were examined with the vHIT and bithermal caloric irrigation on the same day and analyzed with respect to side differences. Of those patients 13.3% had pathological vHIT and a caloric irrigation test, 4.6% a pathological vHIT only and 24.1% a pathologic caloric test only. As both tests might be necessary, we calculated the optimal sequence of the two examinations based on savings in time for the different disease groups. Especially in vestibular failure using the vHIT first and only applying the caloric irrigation in case of an unremarkable vHIT saves time and optimizes the diagnostic work up. In contrast, in Menière's disease and vestibular migraine testing caloric irrigation first might be more efficient.

Horizontal VOR function shows frequency dynamics in vestibular schwannoma

The objective of this retrospective study was to investigate the horizontal vestibulo-ocular reflex (hVOR) pathway with caloric test (low-frequency hVOR) and video head impulse test (vHIT) (high-frequency hVOR) in patients with sporadic vestibular schwannoma (69 patients, 27-86 years, mean age 58.1 years) and to compare both test methods in terms of their sensitivity and specificity to detect a retrocochlear lesion. Test results with a unilateral weakness (UWCaloric) >25 % (caloric test) or a Mean-GainvHIT <0.79/asymmetry ratio of Gain (AR-GainvHIT) >8.5 % and accompanied refixation saccades (vHIT) were considered abnormal. The overall sensitivity of the caloric test was 72 %. The evaluation of AR-GainvHIT detected more abnormal cases than did Mean-GainvHIT (44 vs. 36 %). In up to 4 %, a normal caloric test result was related to an abnormal vHIT. There was only a moderate correlation of UWCaloric and AR-GainvHIT (r = 0.54, p < 0.05) with a linear regression line intercept/slope of 32.2/0.9 (p < 0.05). Receiver operating characteristics curve analysis exhibited at a UWCaloric of 50 % a vHIT sensitivity/specificity/positive predictive value/negative predictive value of 0.45/0.9/0.94/0.42. Vestibular testing at varying frequencies provides deeper insights into hVOR function and is helpful in detecting a cerebello-pontine lesion. Whereas caloric test yields a high sensitivity for nerve dysfunction, vHIT test reveals a remaining function of hVOR in the high-frequency range.

Intralabyrinthine schwannomas: a case series with discussion of the diagnosis and management

OBJECTIVE

By extracting cases of intralabyrinthine schwannomas (ILS) from the sum of all vestibular schwannomas, we aim to identify and analyze unique features of its presentation. This allows us to refine the management protocol of this rare condition.

DESIGN

This is a retrospective study of all patients seen in the Department of Otorhinolaryngology-Head and Neck Surgery, Rouen University Hospital, with either ILS or ILS with intracanalicular extension (ILS-IAC) between 2001 and 2011. A literature search was performed and results combined to draw conclusions on management strategies.

METHOD

Three patients with ILS and 6 patients with ILS-IAC were identified. We retrieved data on age, sex, symptoms, audiometry, imaging, and management. Pure tone audiometry and speech discrimination score were assessed and hearing classification recorded. Facial nerve function and vestibular function were documented throughout. The diagnostic and surveillance imaging (MRI with or without CT) were reviewed.

RESULTS

The average age at presentation was 62.8 years and the sex ratio was (male: female) 4:5. An ipsilateral hearing loss was observed in all patients. Eight of 9 patients had tinnitus at presentation, 2 had rotatory vertigo, and 1 patient had a facial palsy and hemifacial spasm. In 2 cases, the labyrinthine extension was initially missed. The patient presenting with a large tumor and facial palsy was operated on without delay. The others underwent MRI surveillance, with 4 requiring surgery at a later stage. No postoperative facial palsies were encountered other than the one that had been present preoperatively.

CONCLUSION

Frequency of ILS is underestimated because of poor diagnostic criteria. These tumors have often been described as having features, which resemble Ménière's disease, which is not found in our series. In the absence of tumor progression or disabling symptoms, their management is surveillance/medical, and when surgery is considered, facial paralysis and recurrence rates seem low. The treatment of IAC-ILS differs from that of ILS.

Relation of video-head-impulse test and caloric irrigation: a study on the recovery in unilateral vestibular neuritis

The head-impulse test (HIT) is an important test for examining unilateral vestibular hypofunction. The new video-head-impulse test (vHIT) is more sensitive and specific than the clinical bedside-head-impulse test. Alternatively, one can test for vestibular hypofunction with the caloric irrigation test. Various studies have shown that both tests may not always identify vestibular hypofunction; instead, the results of the tests might be contradictory. To further explore the question, of whether vHIT and caloric irrigation test the same part of the angular horizontal vestibulo-ocular reflex (VOR), we examined patients with unilateral vestibular neuritis at different points in time. The tonic vestibular imbalance (e.g., subjective-visual-vertical, ocular torsion and spontaneous nystagmus) and dynamic dysfunction of VOR (vHIT and bithermal caloric irrigation) were measured and quantified. While parameters of the tonic vestibular imbalance were well described by single exponential decay functions, dynamic parameters were less well defined. Therefore, to better compare the time course of pairs of two different parameters, we used a linear regression analysis. No linear correlation was found in the group and individually for the gain asymmetry and the ipsilesional gain of the vHIT with the unilateral weakness of the bithermal caloric irrigation tests. Linear correlation was found for most parameters of tonic vestibular imbalance. These findings are further evidence that vHIT and caloric irrigation test different parts of the angular VOR.

Caloric test and video-head-impulse: a study of vertigo/dizziness patients in a community hospital

The head-impulse test (HIT) is an important test for examining unilateral vestibular hypofunction. The new video-head-impulse test (vHIT) is more sensitive and specific than the clinical bedside-head-impulse test (bHIT). Alternatively, one can test for vestibular hypofunction with the caloric irrigation test. Various studies showed that both tests may not always identify vestibular hypofunction; instead, the results of the tests might be contradictory. To evaluate the diagnostic value of these tests, we routinely measured patients exhibiting vertigo or dizziness at our community hospital with bithermal caloric irrigation, the bHIT and the vHIT. Only those patients (n = 172) with a pathological caloric irrigation test of more than 25 % unilateral weakness in the Jongkee's formula were included. Out of these patients, 41 % had a pathologic vHIT. Among the subgroup with acute symptoms (symptom onset within 5 days), 63 % had a pathological video-head-impulse, whereas only 33 % of the non-acute group (symptom onset more than 5 days) tested pathological. A pathological HIT depended on the disease stage, the amount of unilateral weakness in caloric examination and on the test itself.