Atypical periodic alternating nystagmus responding to high-dose intravenous immunoglobulins: a case report.

BACKGROUND: Acquired periodic alternating nystagmus (PAN) is a rare but well-defined syndrome that consists of a horizontal nystagmus that cyclically reverses its direction. PAN can be caused by degenerative, neoplastic, or toxic diseases of the cerebellum and, in a few cases, by subacute cerebellar ataxia of immune origin. CASE PRESENTATION: A 44-year-old man came to our attention because of rapidly progressive gait instability and blurred vision. Clinical examination showed PAN and a mild pancerebellar syndrome. Eye movement recordings disclosed a short cycle PAN with significant slow-phase velocity only in darkness. Under the effect of a γ-aminobutyric acid type B (GABAB) agonist, PAN was not modified. Right after treatment with intravenous immunoglobulin (IVIg) was started, PAN was essentially eliminated. Three months after last dose of IVIg, this nystagmus reappeared. CONCLUSIONS: IVIg resolved PAN in this patient. This finding may point to an autoimmune mechanism underlying this patient's nystagmus. This case suggests that the usefulness of IVIg at treating PAN might be worth a consideration in similar clinical settings.

Vestibular impairment in Charcot-Marie-Tooth disease type 4C.

Charcot-Marie-Tooth disease type 4C (CMT4C) is a hereditary neuropathy with prominent unsteadiness. The objective of the current study is to determine whether the imbalance in CMT4C is caused only by reduced proprioceptive input or if vestibular nerve involvement is an additional factor. We selected 10 CMT4C patients and 10 age-matched and sex-matched controls. We performed a comprehensive evaluation of the vestibular system, including video Head Impulse Test, bithermal caloric test, galvanic stimulation test and skull vibration-induced nystagmus test. None of the patients experienced dizziness, spontaneous or gaze-evoked nystagmus, but all had significant vestibular impairment when tested when compared to controls. Seven had completely unexcitable vestibular systems and abnormal vestibuloocular reflex. There was no correlation between the degree of vestibulopathy and age or clinical severity. Significant vestibular impairment is a consistent finding in CMT4C and is present early in disease evolution. The profound imbalance that is so disabling in these patients may result from a combination of proprioceptive loss and vestibular neuropathy, and this would modify the recommended rehabilitation strategies.

Allelic variants in TLR10 gene may influence bilateral affectation and clinical course of Meniere's disease.

Toll-like receptors trigger the innate immune response by activating various cell types such us macrophages and lymphocytes. We genotyped SNV of TLR3, TRL7, TLR8 and TLR10 in 863 Spanish and 150 Italian patients with Meniere's disease (MD) and 1,013 controls by using Taqman assays. Real-Time qPCR was used to measure the expression level of TLR10 in peripheral blood leukocytes. The overall dataset showed that the C allele and the CC genotype of rs11096955 in TLR10 gene were more commonly observed in controls than patients (corrected p = 1 × 10(-3), OR = 0.68 [95 % confidence interval, 0.54-0.84] for CC genotype; corrected p = 1.5 × 10(-5), OR = 0.75 [0.66-0.85] for allele C). Moreover, the CC genotype was more frequent in patients with uni- (19 %) than bilateral sensorineural hearing loss (SNHL) (13 %). Logistic regression demonstrated that the time since the onset of MD, Tumarkin crises, hearing stage and rs11096955 were independent factors influencing the risk of bilateral SNHL. In addition, rs11096955 influenced hearing loss progression in patients with bilateral MD. No change in expression of TLR10 was observed according to CC, CA or AA genotypes. Our data suggest that allelic variants of TLR10 gene may influence the susceptibility and time-course of hearing loss of MD in the European population.

Functional variants of MIF, INFG and TFNA genes are not associated with disease susceptibility or hearing loss progression in patients with Ménière's disease.

Variability in acute immune response genes could determine susceptibility or prognosis for Ménière's disease (MD). The cytokines tumor necrosis factor α (TNFα), macrophage migration inhibitory factor (MIF) and interferon γ (INFγ) are proinflammatory cytokines of the innate immune response. These cytokines mediate inflammation and have been previously associated with the inflammatory process in several autoimmune diseases. We investigated the association between functional allelic variants of MIF (rs35688089), IFNG (rs2234688) and TNFA (rs1800629) in patients with MD. In addition to testing these variants for an association with disease, we also tested for an association with clinical aspects of disease progression, such as persistence of vertigo and the sensorineural hearing loss. A total of 580 patients with diagnosis of definite MD, according to the diagnostic scale of the American Academy of Otolaryngology-Head and Neck Surgery, and 552 healthy controls were included. DNA samples from a set of 291 American patients were used to confirm the results obtained in the MIF gene in our Spanish cohort. Although we found a significant association with the allele containing five repeats of CATT within the MIF gene in patients with MD in the Spanish cohort [corrected p = 0.008, OR = 0.69 (95 % CI, 0.54-0.88)], this finding could not be replicated in the American set. Moreover, no genetic associations for variants in either the TNFA or IFNG genes and MD were found. These results support the conclusion that functional variants of MIF, INFG, and TFNA genes are not associated with disease susceptibility or hearing loss progression in patients with MD.

Evolution of symptoms in Ménière's disease.

OBJECTIVE: To investigate the sequence and correlation of symptoms of Ménière's disease (MD) depending on their order of manifestation. METHODS: Descriptive, longitudinal study of the symptoms in 237 tertiary hospital patients who had been diagnosed with definite MD according to the criteria of the American Academy of Otolaryngology. Patients were followed for 1-31 years. RESULTS: Disease began with the three classic symptoms in only 40% of the patients. We recorded the mean, median and maximum time needed to complete the symptoms as well as the time elapsed in some patients from disease onset in one ear to bilateral involvement. CONCLUSIONS: We reckon that this study may be of great help in ruling out a diagnosis of MD when the patient presents with only one or two symptoms of the triad. Furthermore, regarding the planning of treatment, the time interval between unilateral and bilateral involvement (5-7 years) is very important since bilateral involvement has great repercussions on treatment, especially surgical treatment.

Polymorphisms of CD16A and CD32 Fcγ receptors and circulating immune complexes in Ménière's disease: a case-control study.

BACKGROUND: Autoimmune diseases with elevated circulating autoantibodies drive tissue damage and the onset of disease. The Fcγ receptors bind IgG subtypes modulating the clearance of circulating immune complexes (CIC). The inner ear damage in Ménière's disease (MD) could be mediated by an immune response driven by CIC. We examined single-nucleotide polymorphism (SNPs) in the CD16A and CD32 genes in patients with MD which may determine a Fcγ receptor with lower binding to CIC. METHODS: The functional CD16A (FcγRIIIa*559A > C, rs396991) and CD32A (FcγRIIa*519A > G, rs1801274) SNPs were analyzed using PCR-based TaqMan Genotyping Assay in two cohorts of 156 mediterranean and 112 Galicia patients in a case-control study. Data were analyzed by χ2 with Fisher's exact test and Cochran-Armitage trend test (CATT). CIC were measured by ELISA for C1q-binding CIC. RESULTS: Elevated CIC were found in 7% of patients with MD during the intercrisis period. No differences were found in the allelic frequency for rs396991 or rs1801274 in controls subjects when they were compared with patients with MD from the same geographic area. However, the frequency of AA and AC genotypes of CD16A (rs396991) differed among mediterranean and Galicia controls (Fisher's test, corrected p = 6.9 × 10-4 for AA; corrected p = 0.02 for AC). Although genotype AC of the CD16A receptor was significantly more frequent in mediterranean controls than in patients, [Fisher's test corrected p = 0.02; OR = 0.63 (0.44-0.91)], a genetic additive effect for the allele C was not observed (CATT, p = 0.23). Moreover, no differences were found in genotype frequencies for rs396991 between patients with MD and controls from Galicia (CATT, p = 0.14). The allelic frequency of CD32 (rs1801274) was not different between patients and controls either in mediterranean (p = 0.51) or Galicia population (p = 0.11). CONCLUSIONS: Elevated CIC are not found in most of patients with MD. Functional polymorphisms of CD16A and CD32 genes are not associated with onset of MD.

Novel mutations in the USH1C gene in Usher syndrome patients.

PURPOSE: Usher syndrome type I (USH1) is an autosomal recessive disorder characterized by severe-profound sensorineural hearing loss, retinitis pigmentosa, and vestibular areflexia. To date, five USH1 genes have been identified. One of these genes is Usher syndrome 1C (USH1C), which encodes a protein, harmonin, containing PDZ domains. The aim of the present work was the mutation screening of the USH1C gene in a cohort of 33 Usher syndrome patients, to identify the genetic cause of the disease and to determine the relative involvement of this gene in USH1 pathogenesis in the Spanish population. METHODS: Thirty-three patients were screened for mutations in the USH1C gene by direct sequencing. Some had already been screened for mutations in the other known USH1 genes (myosin VIIA [MYO7A], cadherin-related 23 [CDH23], protocadherin-related 15 [PCDH15], and Usher syndrome 1G [USH1G]), but no mutation was found. RESULTS: Two novel mutations were found in the USH1C gene: a non-sense mutation (p.C224X) and a frame-shift mutation (p.D124TfsX7). These mutations were found in a homozygous state in two unrelated USH1 patients. CONCLUSIONS: In the present study, we detected two novel pathogenic mutations in the USH1C gene. Our results suggest that mutations in USH1C are responsible for 1.5% of USH1 disease in patients of Spanish origin (considering the total cohort of 65 Spanish USH1 patients since 2005), indicating that USH1C is a rare form of USH in this population.

Effects of betahistine on patient-reported outcomes in routine practice in patients with vestibular vertigo and appraisal of tolerability: experience in the OSVaLD study.

This was a 3-month multicentre, open-label post-marketing surveillance study of betahistine (24 mg b.i.d. or 16 mg t.i.d.) in patients with vertigo of peripheral vestibular origin. Study endpoints comprised on-treatment changes in the Dizziness Handicap Index (DHI), Hospital Anxiety and Depression Score (HADS) and the Short-Form (SF)-36v2. Total DHI score improved 37.2 points (of a 100-point scale) following betahistine treatment. Corresponding improvements occurred in all three DHI scale domains (all p < 0.001 vs baseline). Betahistine therapy was also accompanied by progressive, significant improvements in both HADS-A and HADS-D scores (p < 0.001), and improvements in the distribution profiles of anxiety and depression scores. Significant improvements in the Physical Component Summary and Mental Component Summary scores of the SF-36v2 were recorded during betahistine treatment. Betahistine was generally well tolerated. A total of 76 adverse drug reactions (ADRs) were recorded in 49 patients (2.4%), of which 75 were classified as mild or moderate and 54 were possibly related to betahistine. ADRs led to study drug discontinuation in 17 patients. These data illustrate that treatment with betahistine 48 mg/day in patients with recurrent peripheral vestibular vertigo is associated with improvements in objective measures of health-related quality of life and satisfactory tolerability.

The role of vertical semicircular canal function in the vertical component of skull vibration-induced nystagmus.

Background: Generally, vertical component of the skull vibratory nystagmus (VCN) is ignored in the clinical practise. Thus, the relative contribution of the vestibular organs in the presence of VCN remains unknown.Objectives: To determine the association between vertical semicircular canal (vSCC) function and the presence of VCN.Material and methods: Comparisons were made between Video Head Impulse Test and SVINT (100 Hz) results at the time of the acute peripheral vestibular lesion (PVL) and at the post-acute phase in patients diagnosed PVL. Later on, a paired analysis was performed restricting the assessments to patients with vestibular explorations in both the acute and post-acute phases.Results: In an univariable analysis, larger mean total gain differences (TGD) between vSCC VOR gains, significantly related with the appearance of VCN in nystagmography in the acute phase (p = .001), unlike the post-acute phase (p = .46). After a multivariate analysis, mean TGD was the only predictive factor of the VCN (p = .013). In the paired analysis, we found an increase in the post-acute phase mean TGD, approaching zero value.Conclusions and significance: Global relation between all vertical canals has at least a contributory role in the presence of the vertical component of nystagmus in SVINT.

[Clinical symptoms of equilibrium disorders in patients with whiplash syndrome]. / Expresión clínica de las alteraciones del equilibrio en pacientes con síndrome de latigazo cervical.

INTRODUCTION AND OBJECTIVE: There are many entities that cause equilibrium disorders. Whiplash syndrome is becoming an important entity as a trigger of equilibrium disorders because of an increase in traffic accidents. There are many hypotheses on the generation of vertigo and dizziness in whiplash syndrome. The objective of this study is to describe and analyze the clinical symptoms of patients who suffered whiplash. MATERIAL AND METHOD: Thirty six patients with equilibrium disorders who suffered whiplash syndrome were studied prospectively. None of these subjects had cranial trauma or a history of vestibular pathology prior to the traffic accident. We conducted an exhaustive anamnesis, videonystagmography and cervical magnetic resonance. Patients were classified by type of equilibrium symptom and degree of cervical lesion. RESULTS: 55.5 % of patients had a sensation of dizziness associated with postural and cephalic movements, 38.8 % had disequilibrium continuously, and 16.7 % (6 cases) had vertigo. Three of this last group had a diagnosis compatible with benign positional vertigo but this diagnosis was confirmed in only 2 patients; two patients had labyrinth commotion and one patient had vertigo of unknown origin. CONCLUSIONS: In patients with whiplash, the most frequent equilibrium symptom is the sensation of fleeting dizziness associated with head movements, while only a small group suffer from vertigo. Although vestibular tests are normal in most patients, we cannot rule out the existence of otolithic lesions.

[Contribution of the vestibular evoked myogenic potentials to the study of the vestibular neuritis]. / Aportación del potencial vestibular miogénico evocado al estudio de la neuritis vestibular.

INTRODUCTION: Until recently, the only tests available to provide information about vestibular function were caloric and kinetic tests, which only give us information about the external semicircular canal and the superior vestibular nerve. In recent years the development of vestibular evoked myogenic potentials has allowed us to assess the saccule and the inferior vestibular nerve. Our aim is, by studying the caloric test results as well as the vestibular evoked myogenic potentials in patients with Vestibular Neuritis, to determine whether they have involvement of the superior, inferior or both vestibular nerves. MATERIAL AND METHODS: Retrospective study of 9 patients with Vestibular Neuritis admitted to a tertiary care hospital. We studied them by means of anamnesis, otoneurological clinical examination, caloric test and vestibular evoked myogenic potentials. Their clinical progress after admission and any residual instability were also studied. RESULTS: Women were more affected (66.6 %) than males. The mean age for presentation of the disease was 53.8 +/- 14.0 years. Hospital stays lasted for 5.7 +/- 3.2 days. After their crises, they suffered from instability for 122 +/- 114 days. Four cases were diagnosed as Complete Vestibular Neuritis and five as Superior Vestibular Neuritis. P13 wave latency was normal in all cases. There were no differences between the groups in terms of the length of hospital stay nor residual instability. CONCLUSIONS: Nowadays, vestibular evoked myogenic potentials make it possible to advance further in the study of Vestibular Neuritis. Complete and superior vestibular neuritis are much more frequent than inferior vestibular neuritis. Clinical behaviour is similar in the sub-types found.

Valencia's Cathedral Church Bell Acoustics Impact on the Hearing Abilities of Bell Ringers.

Studies on the effect of occupational noise have been widely performed for occupations such as construction workers, workers of factories or even musicians and workers of nightclubs. However, studies on the acoustics of church bells are very scarce and usually reported in languages other than English. In Spain, although the tradition of bell ringers is progressively getting lost, some bell ringers that continue transmitting the tradition remain. Church bells create sound with a large sound pressure level that can be heard from a great distance. However, despite the characteristics of the sound of church bells, bell ringers do not present symptoms of occupational hearing loss unlike musicians and construction workers. To determine the effects of the sound of the church bells on bell ringers, in this paper, an acoustic study of the church bells and a physiological study of the hearing abilities of bell ringers. Results show sound pressure levels reaching 120 dB inside the bell tower. The resulting hearing loss in bell ringers is small considering the great intensity of the sound produced by the bells. This is likely due to the short amount of time that bell ringers are exposed to the sound even if it reaches high sound pressure levels.

Benign paroxysmal vertigo secondary to placement of maxillary implants using the alveolar expansion technique with osteotomes: a study of 4 cases.

The osteotome method is an often-used technique of great utility in certain patients with maxillary bone atrophy. However, it has been associated with the provocation of benign paroxysmal positional vertigo (BPPV), which has been described as a consequence of working the implant bed with osteotomes. During the placement of maxillary dental implants using the osteotome technique, the trauma induced by percussion with the surgical hammer, along with hyperextension of the neck during the operation, can displace otoliths and induce BPPV. Four cases of BPPV occurring after the preparation of maxillary implant beds are presented. Treatment consists fundamentally of maneuvers to move the calcium carbonate crystals from their anomalous location in the semicircular canal to their correct place in the utricle.

Screening of the USH1G gene among Spanish patients with Usher syndrome. Lack of mutations and evidence of a minor role in the pathogenesis of the syndrome.

The Usher syndrome (USH) is an autosomal recessive hereditary disorder characterized by the association of sensorineural hearing loss, retinitis pigmentosa (RP) and, in some cases, vestibular dysfunction. The USH1G gene, encoding SANS, has been found to cause both Usher syndrome type I and atypical Usher syndrome. 109 Spanish unrelated patients suffering from Usher syndrome type I, type II, type III and unclassified Usher syndrome were screened for mutations in this gene, but only eight different changes without a clear pathogenic effect have been detected. Based on these results as well as previous studies in other populations where mutational analysis of this gene has been carried out, one can conclude that USH1G has a minor involvement in Usher syndrome pathogenesis.

HLA-DRB1*1101 allele may be associated with bilateral Méniére's disease in southern European population.

OBJECTIVE: To analyze the associations of HLA-DRB1* and DQB1* Class II alleles in patients with bilateral Méniére's disease (MD). PATIENTS AND METHODS: Eighty patients from two ethnically defined groups with definite bilateral MD, according to the diagnostic scale of the American Academy of Otolaryngology-Head and Neck Surgery, were compared with normal controls from the same origin in a prospective multicenter study. We performed an allele-specific amplification for HLA-DRB1* and DQB1* genes of the major histocompatibility complex. RESULTS: The allele HLA-DRB1*1101 was associated with bilateral MD in the Mediterranean population (odds ratio, 3.65 [95% confidence intervals, 1.5-9.1], corrected p = 0.029); however, this allele was not associated in the group from Galicia (northwest of Spain). No differences were found in the distribution of alleles for the gene HLA-DQB1* between patients and controls. CONCLUSION: The allele HLA-DRB1*1101 and the allelic group HLA-DRB1*11 may determine an increased susceptibility to develop bilateral MD in a southern European population.

Effect of the stringency of conditions on caloric test results in healthy subjects. / Efecto de la rigurosidad de las condiciones sobre los resultados de la prueba calórica en sujetos sanos.

The caloric test is widely used to assess vestibular function, but the conditions in which it is performed can vary. Caloric nystagmus obtained in 57 healthy subjects were compared: 24 subjects studied in ideal conditions and 33 subjects in non-ideal conditions. A statistically significant decrease in the slow phase velocity of the 4 irrigations performed on the subjects in non-ideal conditions was observed. This must be considered, especially in subjects with suspected bilateral involvement. Stringent conditions reduce the risk of misdiagnosis with bilateral deficit.

Ipsilesional Nystagmus Induced by Vibration in Subjects With Ménière's Disease or Vestibular Schwannoma.

OBJECTIVE: To analyze the frequency in which vibration-induced nystagmus (VIN) with ipsilesional direction appears in subjects with Ménière's disease (MD) or vestibular schwannoma (VS). STUDY DESIGN: Cross-sectional study. SETTING: Tertiary referral center. PATIENTS: Fifty-two subjects with MD and 21 subjects with vestibular schwannoma. INTERVENTION: Videonystagmographic recordings of VIN at 30, 60, and 100 Hz. MAIN OUTCOME MEASURES: Direction and slow phase velocity of VIN at 30, 60, and 100 Hz. RESULTS: Ipsilesional Nystagmus was observed in 8 of 52 subjects with MD (15.4%) and in 11 of 21 subjects affected of unilateral VS (52.4%). Ipsilesional nystagmus was significantly higher in patients with VS (p = 0.003). The frequency of appearance of ipsilesional nystagmus in the subjects with VS who has not been treated was significantly higher than those who underwent radiosurgery (84.6% vs 0%, p = 0.046). CONCLUSION: Ipsilesional vibration-induced Nystagmus can be present in subjects with vestibular deficits caused by MD and VS.

Audiological Findings in Charcot-Marie-Tooth Disease Type 4C.

OBJECTIVE: Charcot-Marie-Tooth disease type 4C (CMT4C) is a hereditary demyelinating early onset neuropathy with prominent unsteadiness and occasional cranial nerve involvement. Vestibulopathy caused by the dysfunction of cranial nerve VIII has been demonstrated in a high percentage of these patients, but the presence and degree of auditory neuropathy are unknown. The aim of the study was to characterize the hearing abnormalities of a series of patients with CMT4C and to determine the presence and severity of auditory neuropathy (AN) in these patients. MATERIALS AND METHODS: Ten patients with genetically confirmed CMT4C underwent comprehensive clinical and audiological testing. The results were compared among patients in different age groups and also to the results of vestibular testing that had already been performed. RESULTS: Only 3 patients had hearing problems, but 9 had hearing abnormalities on ancillary testing that were compatible with different degrees of auditory nerve dysfunction. In the mildest cases, only the abnormality of the stapedial reflex and distortion of wave I in auditory brainstem responses could be detected. In the more severe cases, tonal audiometry revealed asymmetric hearing loss. These findings were more severe in older patients, even after correcting for age-related hypoacusia. In these patients, vestibular dysfunction could also be detected and seemed to be more profound and symmetric than hearing loss. CONCLUSION: This report confirms and defines the presence of different degrees of auditory neuropathy in all patients with CMT4C, being detectable, usually unilaterally, during infancy, and worsening with disease progression.

Regulation of Fn14 Receptor and NF-κB Underlies Inflammation in Meniere's Disease.

Meniere's disease (MD) is a rare disorder characterized by episodic vertigo, sensorineural hearing loss, tinnitus, and aural fullness. It is associated with a fluid imbalance between the secretion of endolymph in the cochlear duct and its reabsorption into the subarachnoid space, leading to an accumulation of endolymph in the inner ear. Epidemiological evidence, including familial aggregation, indicates a genetic contribution and a consistent association with autoimmune diseases (AD). We conducted a case-control study in two phases using an immune genotyping array in a total of 420 patients with bilateral MD and 1,630 controls. We have identified the first locus, at 6p21.33, suggesting an association with bilateral MD [meta-analysis leading signal rs4947296, OR = 2.089 (1.661-2.627); p = 1.39 × 10-09]. Gene expression profiles of homozygous genotype-selected peripheral blood mononuclear cells (PBMCs) demonstrated that this region is a trans-expression quantitative trait locus (eQTL) in PBMCs. Signaling analysis predicted several tumor necrosis factor-related pathways, the TWEAK/Fn14 pathway being the top candidate (p = 2.42 × 10-11). This pathway is involved in the modulation of inflammation in several human AD, including multiple sclerosis, systemic lupus erythematosus, or rheumatoid arthritis. In vitro studies with genotype-selected lymphoblastoid cells from patients with MD suggest that this trans-eQTL may regulate cellular proliferation in lymphoid cells through the TWEAK/Fn14 pathway by increasing the translation of NF-κB. Taken together; these findings suggest that the carriers of the risk genotype may develop an NF-κB-mediated inflammatory response in MD.

Response Over Time of Vertigo Spells to Intratympanic Dexamethasone Treatment in Meniere's Disease Patients.

OBJECTIVE: To assess the effectiveness and response over time of intratympanic dexamethasone on the symptoms of Meniere's disease. MATERIALS AND METHODS: We performed a matched cohort study of 24 patients with Meniere's disease who were unresponsive to initial treatment and underwent 3 sessions of weekly intratympanic dexamethasone injections using a concentration of 16 mg/mL and 24 matched controls with the same characteristics with regard to vertigo spells. RESULTS: Compared with control subjects, intratympanic dexamethasone injections resulted in a decrease in the frequency of vertigo spells in the first 6-month period. In the dexamethasone-treated group, a ≥60% decrease in vertigo spells was achieved by 70.8% of patients in the first 6 months. Total remission was achieved by 20.8% of patients in the first 8 months, but after this, the effect tapered. A slight improvement in Tinnitus loudness and no changes in hearing levels were found. The stage of Meniere's disease, years from disease onset, and mean number of vertigo spells per month did not have any effects on the percentage of decrease in vertigo spells. CONCLUSION: Intratympanic dexamethasone temporarily reduces the frequency of vertigo spells during the initial months but does not remove the probability of having further spells in the future. This therapy provides a valuable tool to accomplish a rapid decrease in vertigo spells in subjects with Meniere's disease, and it is considered an alternative to chemical or surgical labyrinthectomy.