Post-irradiation endolymphatic hydrops vs. post-irradiation sudden deafness.

BACKGROUND: Increasing numbers of acute sensorineural hearing loss (SNHL) are recently experienced in irradiated nasopharyngeal carcinoma (NPC) survivors. AIM: This study adopted MR imaging to differentiate between post-irradiation sudden deafness (PISD) and post-irradiation endolymphatic hydrops (PIEH) in long-term NPC survivors with acute SNHL. METHODS: From 2012 to 2021, consecutive 10 irradiated NPC survivors with acute SNHL were enrolled. All patients underwent an inner ear test battery and MR imaging using HYDROPS-Mi2 technique. Six patients (11 ears) with positive cochlear hydrops on MR images were diagnosed as PIEH, while another 4 patients (4 ears) without cochlear hydrops on MR images were referred to PISD. RESULTS: The interval from the onset of NPC to acute SNHL did not significantly differ between the PIEH (10 ± 6 years) and PISD (8 ± 2 years). No significant difference was found between the two disorders from any of the symptomatic, radiotherapeutic, audiological, or vestibular perspective. Interestingly, most (5/6) patients with PIEH had bilateral involvement, while all (4/4) patients with PISD showed unilateral affliction. A significantly declining sequence of abnormality rates in the inner ear test battery was noted in the PIEH patients, running from the audiometry (100%), cervical vestibular-evoked myogenic potential (VEMP) test (100%), ocular VEMP test (73%), to the caloric test (36%). However, such declining trend was not observed in patients with PISD. CONCLUSION: When facing an NPC survivor who had acute SNHL over a prolonged period after irradiation, MR imaging using HYDROPS-Mi2 technique should be performed to differentiate the PIEH from the PISD, since both disorders have various treatment modalities and hearing outcome.

Spironolactone Ameliorates Cochlear Implant Induced Endolymphatic Hydrops.

BACKGROUND: Endolymphatic hydrops (EH) has been observed in both animal and human cochleae following cochlear implant (CI) surgery. We tested whether EH could be eliminated by administration of mineralocorticoid steroid antagonist spironolactone and explored the electrophysiological consequences of this. METHODS: Sixty-four adult guinea pigs underwent cochlear implantation with a dummy electrode. Animals then survived either 2, 7, or 28 days. Auditory function was monitored by recording electrocochleography from the round window membrane preimplantation, and on the last day of the experiment. Spironolactone or control solution was added to animals' feed for 7 days (if they survived that long) beginning immediately prior to surgery. The presence of EH was determined using thin-sheet laser imaging microscopy. RESULTS: Treatment with spironolactone resulted in significant reduction in EH in the second cochlear turn 7 days postimplantation. In all animals, the compound action potential (CAP) threshold was elevated 2 days postimplantation, but for most frequencies had recovered substantially by 28 days. There was no treatment effect on CAP thresholds. SP/AP ratios were elevated at day 2. The amplitude growth of the CAP did not differ between test and control groups at any time after implantation. CONCLUSIONS: EH can be suppressed by antagonism of mineralocorticoid receptors in the week after cochlear implantation. Reduction in EH did not lead to any change in hearing, and there was no indication of synaptopathy signalled by reduced CAP amplitude at high sound intensities. We found no electrophysiological evidence that EH early after implantation impacts negatively upon preservation of residual hearing.

Pathogenesis and Etiology of Ménière Disease: A Scoping Review of a Century of Evidence.

IMPORTANCE: Ménière disease is a rare chronic benign disorder of the inner ear with a natural history of multiple clinical phenotypes of variable severity and a tendency to burnout with time. Although multiple treatment modalities have been shown to improve the disease process-some adversely affecting cochleovestibular function-it remains uncertain whether one, several separate, or a combination of pathophysiologic mechanisms affect the disease process. A scoping review of the evidence underlying proposed pathophysiologic mechanisms of Ménière disease is needed to determine which processes are most likely to be etiopathogenic factors. OBSERVATIONS: Of the 4602 relevant articles found through Embase, Ovid, and PubMed, 444 met inclusion criteria. The most common reported causes of Ménière disease were autoimmune or immune-mediated, genetic, or structural dysfunction of the inner ear. During the study period from inception to March 2021, etiologic theories shifted from structural dysfunction to autoimmune and genetic causes of Ménière disease. CONCLUSIONS AND RELEVANCE: This scoping review found that Ménière disease is a multifactorial disease with lifelong comorbidities and loss of quality-associated life-years whose most commonly reported causes were structural dysfunction, immunologic damage, and genetic susceptibility. Recent studies have examined how autoinflammatory processes and vestibular migraine may be associated with Ménière disease. Large heterogeneity among studies may be explained by historical differences in the clinical understanding of the disease, as well as evolving intervention methodologies and practitioner expertise. Ménière disease is a multifactorial disease with lifelong comorbidities and loss of quality-associated life-years; therefore, future studies of reliable biomarkers of endolymphatic hydrops and real-time imaging are warranted to improve understanding and treatment.

MRI of endolymphatic hydrops in patients with intralabyrinthine schwannomas: a case-controlled study using non-enhanced T2-weighted images at 3 T.

OBJECTIVE: Like other vestibular schwannomas developing in the internal auditory canal, intralabyrinthine schwannomas (ILS) may present with similar symptoms as in endolymphatic hydrops. Two different studies have described MR saccular hydrops in ~ 30% of internal auditory canal vestibular schwannomas, but this association has never been studied in ILS before. The aim of this work is to study the prevalence of a saccular dilation in ILS, on a T2-weigthed sequence at 3 T, compared to a control group. MATERIAL AND METHODS: All patients presenting with typical ILS between January 2008 and October 2018 were included (n = 28, two patients with bilateral tumors) and compared to a control group (n = 53). All underwent a high-resolution T2-weighted 3D sequence (FIESTA-C). The height and width of the saccule were measured on a coronal plane by two radiologists. RESULTS: The saccule was dilated on the side of the schwannoma in 47% of the cases (p = 0.0006 for the height, p = 0.0487 for the width). Bilateral saccular dilation was observed in 37% of the cases. There was a statistically significant correlation between the presence of a saccular hydrops and balance disorders (p = 0.02) as 50% of the patients with an intralabyrinthine schwannoma who presented with such symptoms had a saccular dilation. CONCLUSION: Forty-seven percent of ILS are associated with homolateral saccular dilation, which is an MR sign of endolymphatic hydrops (bilateral in 37%) and it appears related to the presence of balance disorders. This opens new therapeutic potentialities with the possible use of anti-vertiginous drugs, which could have a beneficial effect on their clinical symptomatology.

Assessment of the Progression of Vertical Semicircular Canal Dysfunction and Increased Vestibular Endolymphatic Hydrops in Patients With Early-Stage Ménière Disease.

Importance: Vertical semicircular canals and endolymphatic hydrops play important roles in the pathophysiological mechanisms of Ménière disease. However, their characteristics and associations with disease progression during medical treatment have not been determined. Objective: To examine the function of both the horizontal and vertical semicircular canals in patients with Ménière disease and to evaluate the change in endolymphatic hydrops volume during medical treatment, including treatment with diuretic therapy, over a 2-year period. Design, Setting, and Participants: This prospective longitudinal observational cohort study included 55 patients with definite unilateral Ménière disease and was performed in a tertiary care hospital in Japan. Participants were enrolled between April 1, 2017, and January 31, 2018, and those with vestibular migraine were excluded. All participants received education regarding diet and lifestyle modifications and treatment with betahistine mesylate (36 mg daily) and/or an osmotic diuretic (42-63 mg daily). Patients were followed up for vertigo and hearing evaluations at least once per month for more than 12 months and were instructed to record episodes of vertigo in a self-check diary. Audiometry was performed monthly, video head impulse testing and caloric testing were performed every 4 months, and magnetic resonance imaging was conducted annually. Data were analyzed from May 15, 2017, to January 31, 2020. Main Outcomes and Measures: Neurootological testing to evaluate vestibuloocular reflex gain over time, magnetic resonance imaging to evaluate the change in endolymphatic hydrops volume over time, and monthly vertigo and hearing evaluations for more than 12 months. Results: Among 55 participants with definite Ménière disease, 32 patients (58.2%) were female, and the mean (SD) age was 59.0 (15.1) years. The median disease duration was 2 years (interquartile range, 0-4 years), with 43 patients (78.2%) having an early stage (ie, disease duration ≤4 years) of Ménière disease. Over the 2-year study period, the vestibuloocular reflex gain decreased from 0.76 to 0.56 in the superior semicircular canals, for a difference of 0.20 (95% CI, 0.14-0.26) and from 0.68 to 0.50 in the posterior semicircular canals, for a difference of 0.18 (95% CI, 0.14-0.22). The maximum slow-phase velocity and vestibuloocular reflex gain in the horizontal semicircular canals were maintained. The volume ratio of vestibular endolymphatic hydrops increased from 19.7% to 23.3%, for a difference of 3.6% (95% CI, 1.4%-5.8%). The frequency of vertiginous episodes decreased, and the hearing level over the study period worsened from 40.9 dB to 44.5 dB, for a difference of 3.5 dB (95% CI, 0.7-6.4 dB). Conclusions and Relevance: In this study, during a 2-year period of medical treatment among patients with Ménière disease, vestibuloocular reflex gain decreased in the vertical semicircular canals but was maintained in the horizontal semicircular canals; the endolymphatic hydrops volume ratio increased, and the frequency of vertiginous episodes decreased. These findings describe the pathological progression of chronic Ménière disease and expand the understanding of its pathophysiological characteristics during the early stage of disease.

Gadolinium-enhanced MRI reveals dynamic development of endolymphatic hydrops in Ménières disease / Ressonância magnética com gadolínio revela o desenvolvimento dinâmico da hidropsia endolinfática na doença de Ménière

Abstract Introduction: Meniere's disease is associated with impaired hearing, tinnitus, vertigo, and aural fullness. Many anatomical studies have suggested idiopathic endolymphatic hydrops as the pathological basis of Meniere's disease, which now can be visualized by using gadolinium -enhanced magnetic resonance imaging of the inner ear. Objective: To investigate the development of endolymphatic hydrops in Meniere's disease by monitoring the vestibules and cochleae of affected patients. Methods: Inner ears of 178 patients with definite unilateral Meniere's disease diagnosis were visualized by 3-dimensional fluid-attenuated inversion recovery and three-dimensional real inversion recovery magnetic resonance imaging following bilateral gadolinium intratympanic injection. The scans were used to evaluate the presence and degree of endolymphatic hydrops in the vestibules and cochlear structures, including the cochlear apical turn, the cochlear middle turn, and the cochlear basal turn. The correlation of endolymphatic hydrops occurrence between the various parts of the inner ear was determined. Results: Symptomatic endolymphatic hydrops was detected on the affected side in all patients, whereas asymptomatic endolymphatic hydrops was detected on the unaffected contra-lateral side in 32 patients (18.0%). On the affected side, the cochlear apical turn and the cochlear middle turn demonstrated significantly higher rates of endolymphatic hydrops than the cochlear basal turn and the vestibule. The severity of endolymphatic hydrops gradually decreased from the cochlear apical turn to the cochlear basal turn. On the contra lateral side, the incidence and degree of the detected asymptomatic endolymphatic hydrops were significantly greater in the cochleae than in the vestibules (p < 0.05), with no significant difference detected between the cochlear turns. Conclusion: Progression of endolymphatic hydrops appears to be directional, initiated in the cochlea. The order of endolymphatic hydrops severity gradually decreases from the cochlear apical turn to the cochlear basal turn and then to the vestibule. Endolymphatic hydrops in the vestibule is associated with symptomatic Meniere's disease.

Resumo Introdução: A doença de Ménière está associada a deficiência auditiva, zumbido, vertigem e plenitude auricular. Muitos estudos anatômicos sugerem hidropsia endolinfática idiopática como a base patológica da doença, que agora pode ser visualizada através de estudo por imagem da orelha interna por ressonância magnética com gadolínio. Objetivo: Investigar o desenvolvimento da hidropsia endolinfática na doença de Ménière com monitoramento dos vestíbulos e das cócleas dos pacientes afetados. Métodos: Orelhas internas de 178 pacientes com diagnóstico definitivo de doença de Ménière unilateral foram visualizados através de imagem de recuperação de inversão atenuada por fluidos em ressonância magnética tridimensional, 3-D FLAIR, e por inversão real após injeção intratimpânica bilateral de gadolínio. Os exames foram usados para avaliar a presença e o grau de hidropsia endolinfática nos vestíbulos e nas estruturas cocleares, inclusive o giro coclear apical, o giro coclear médio e o giro coclear basal. A correlação da ocorrência de hidropsia endolinfática entre as várias partes da orelha interna foi determinada. Resultados: Hidropsia endolinfática sintomática foi detectada no lado afetado em todos os pacientes, enquanto hidropsia endolinfática assintomática foi detectada no lado contralateral não afetado em 32 pacientes (18,0%). No lado afetado, o giro apical da cóclea e o giro coclear médio demonstraram taxas significativamente mais altas de hidropsia endolinfática do que o giro basal e o vestíbulo. A gravidade da hidropsia endolinfática diminuiu gradualmente do giro apical da cóclea para o giro basal. No lado contralateral, a incidência e o grau da hidropsia endolinfática assintomática detectada foram significantemente maiores nas cócleas do que nos vestíbulos (p < 0,05), sem diferença significante entre os giros cocleares. Conclusões: A progressão da hidropsia endolinfática parece ser direcional, iniciando-se na cóclea. A sua ordem da gravidade diminui gradualmente do giro apical da cóclea para o giro basal e, em seguida, para o vestíbulo. A hidropsia endolinfática no vestíbulo está associada à doença de Ménière sintomática.

Pathophysiologic Findings in the Human Endolymphatic Sac in Endolymphatic Hydrops: Functional and Molecular Evidence.

BACKGROUND: The endolymphatic sac (ES) is a cystic structure situated on the posterior fossa dura and is connected to the luminal space of the vestibular organ through the endolymphatic duct, which branches into the utricular and saccular ducts. Unlike the cochlea and vestibule, the ES does not contain sensory epithelium in its luminal space, and a single layer of epithelial cells line the luminal surface area. The ES in the inner ear is thought to play a role in the regulation of inner ear homeostasis, fluid volume, and immune reaction. If these functions of the ES are disrupted, dysfunction of the inner ear may develop. The most well-known pathology arising from dysfunction of the ES is endolymphatic hydrops, characterized by an enlarged endolymphatic space due to the accumulation of excessive endolymphatic fluid. Although, molecular identities and functional evidence for the roles were identified in animal studies, basic studies of the human ES are relatively uncommon compared with those using animal tissues, because of limited opportunity to harvest the human ES. METHODS: In this study, molecular and functional evidence for the role of the human ES in the development of endolymphatic hydrops are reviewed. RESULTS AND CONCLUSIONS: Although evidence is insufficient, studies using the human ES have mostly produced findings similar to those of animal studies. This review may provide a basis for planning further studies to investigate the pathophysiology of disorders with the finding of endolymphatic hydrops.

MRI of endolymphatic hydrops in patients with vestibular schwannomas: a case-controlled study using non-enhanced T2-weighted images at 3 Teslas.

OBJECTIVE: Vestibular schwannomas (VS) may present with similar symptoms endolymphatic hydrops. Association between hydrops and internal auditory canal VS has been described by Naganawa et al. (Neuroradiology 53:1009-1015, 2011), but has never been confirmed since. The aim of this work was to study the prevalence of a saccular dilation on a T2-weighted sequence at 3 T MRI in VS compared to a control group. MATERIALS AND METHODS: All patients presenting with typical VS between May 2009 and July 2018 were included (n = 183) and compared to a control group (n = 53). All underwent a high-resolution T2-weighted 3D sequence (FIESTA-C). The height and width of the saccule were measured on a coronal plane by two radiologists. RESULTS: The saccule was dilated on the side of the schwannoma in 28% of the cases (p = 2.81 × 10- 5), with 15.7% of bilateral dilation. Saccular dilation was correlated to sensorineural hearing loss (OR 3.26, p = 0.02). There was also a significant correlation between saccular hydrops on the normal contralateral side of patients with VS and vertigo (p = 0.049), and between saccular hydrops on the side of the tumour and tinnitus (p = 0.006). CONCLUSION: A third (29%) of VS are associated with a saccular dilation on the side of the tumour, which is an MR sign of endolymphatic hydrops (bilateral in 15.7% of the cases) and it appears related to sensorineural hearing loss and tinnitus, as well as vertigo if a contralateral dilation is present. This opens new therapeutic potentialities with the use of anti-vertiginous drugs, which could have a beneficial effect on the clinical symptoms.

Clinical features and management of Meniere's disease patients with drop attacks.

PURPOSE: The aims of the present study are to investigate the variations in clinical features, including medical history, hearing function, vestibular function, and degree of endolymphatic hydrops (EH), in Meniere's disease (MD) patients with and without drop attacks (DAs), and to examine the efficacy of intratympanic gentamicin (ITG) treatment in alleviating DAs. METHODS: In total, 177 unilateral definite MD patients, including 16 patients with DAs and 161 patients without DAs, were enrolled. The results of hearing test, vestibular-evoked myogenic potentials (VEMPs), and magnetic resonance imaging (MRI) were analyzed. Thirteen patients with DAs received a single ITG treatment and were followed up. RESULTS: The disease course of MD in the DA group was significantly longer than that in the control group (p = 0.007). MD patients with DAs had significantly greater hearing loss and worse EH than MD patients without DAs (p < 0.05). However, there was no between-group difference in vestibular function. In the study, 92.31% of refractory definite MD patients with DAs achieved satisfactory control of DAs after ITG treatment. CONCLUSIONS: MD patients with DAs tend to suffer from severe hearing loss and a significant degree of EH in the inner ear. However, the vestibular function of MD patients with DAs may not be completely abolished, but be sensitive to stimulating signals. ITG treatment, which helps to decrease vestibular sensitivity, was an effective treatment to control DAs.

Intraoperative Electrocochleography: A Window Into Endolymphatic Hydrops in a Patient With an Endolymphatic Sac Tumor.

OBJECTIVES: Intraoperative electrocochleography (ECochG) provides valuable information regarding inner ear function during surgical procedures. Here, we report findings from ECochG collected at three time intervals during the management of a patient with symptoms of inner ear hydrops. PATIENTS: A 38-year-old man with an endolymphatic sac tumor who demonstrated classic Ménière's symptoms. INTERVENTIONS: Endolymphatic shunt, tumor biopsy, and definitive resection of an endolymphatic sac tumor. MAIN OUTCOME MEASURES: Intraoperative ECochG measurements at three time intervals, using frequency-specific tone bursts and clicks. RESULTS: Across time intervals, the amplitude of ECochG summation potential (SP) responses decreased for tone bursts of all frequencies. On the other hand, the SP response to the click stimulus, and the ratio of the SP to action potential (AP), basically remained unchanged across time points. CONCLUSIONS: Results suggest that the absolute amplitude of the SP response to frequency-specific tone bursts may be more sensitive to inner ear hydrops than the traditionally used SP/AP ratio as a response to click stimuli.

Clinical features of delayed endolymphatic hydrops and intralabyrinthine schwannoma : An imaging-confirmed comparative case series. English version.

BACKGROUND: The aim of this study was to compare the clinical history and audiovestibular function test results of patients suffering from intralabyrinthine schwannoma or delayed endolymphatic hydrops (DEH). PATIENTS AND METHODS: Five patients diagnosed with intralabyrinthine schwannoma by magnetic resonance imaging (MRI) and five patients diagnosed with DEH by locally enhanced inner ear MRI (LEIM) were retrospectively studied. RESULTS: All patients with intralabyrinthine schwannoma or DEH initially presented with hearing loss. Vertigo occurred in two patients with intralabyrinthine schwannoma and in all patients with DEH. While audiometry achieved poorer results for patients with intralabyrinthine schwannomas, vestibular function tests revealed normal results in about half of the patients in both groups. CONCLUSION: Patients with intralabyrinthine schwannomas may present with clinical symptoms similar to patients suffering from other inner ear disorders such as delayed endolymphatic hydrops and they may obtain similar findings in audiovestibular function tests. High-resolution magnetic resonance imaging with locally applied contrast agent may provide evidence of both underlying pathologies.

High Resolution MRI Shows Presence of Endolymphatic Hydrops in Patients Still Symptomatic After Endolymphatic Shunt Surgery.

OBJECTIVE: Endolymphatic hydrops has been well described in patients with Ménière's syndrome; however, causation has not been established. Decompression of the endolymphatic sac has been proposed as a means to relieve hydrops and improve vertigo symptoms, but the efficacy of the surgery is debated. Until recently, there have been few objective measures of efficacy other than patients' subjective symptoms. Recent archival human temporal bone studies have shown that patients continue to have hydrops after shunt surgery. We propose using high-resolution magnetic resonance imaging (MRI) to determine the efficacy of endolymphatic shunt surgery (ELS) in patients who continue to experience vertigo. PATIENTS: Four patients presented with continued vertigo after ELS. INTERVENTIONS: Magnetic resonance imaging sequences included "cisternographic" three-dimensional T2, and delayed intravenous-enhanced three-dimensional fluid-attenuation inversion recovery (DIVE-3D-FLAIR) sequences, performed with 2350 ms (bright perilymph) and 2050 ms (bright endolymph) inversion times. The bright endolymph images were subtracted from bright perilymph images to create a composite image with bright perilymph, dark endolymph, and intermediate bone signals. MAIN OUTCOME MEASURES: MRI finding of endolymphatic hydrops. RESULTS: In all five affected ears in four patients who continued to experience severe vertigo, hydrops was found on high resolution MRI on the operated ear. The appearance on MRI was no different than in patients with endolymphatic hydrops (EH) who have not had surgery. CONCLUSIONS: The present study demonstrates the persistence of endolymphatic hydrops in patients who have failed ELS. Future studies evaluating for the presence or absence of endolymphatic hydrops in patients who claim to obtain relief from ELS.

How Often Does Stapedectomy for Otosclerosis Result in Endolymphatic Hydrops?

OBJECTIVES: 1) To evaluate the long-term (≥10 year) clinical incidence of endolymphatic hydrops (EH) after stapedectomy for otosclerosis, using low-frequency sensorineural hearing loss (LFSNHL) as a marker for EH. 2) To determine the histologic incidence of EH in human temporal bone specimens (TBS) with a history of stapedectomy for otosclerosis. 3) To determine the histologic incidence of EH in a control group of human TBS. STUDY DESIGN: Retrospective review and temporal bone study. SETTING: Tertiary medical center and temporal bone pathology laboratory. PATIENTS: Patients with otosclerosis, human TBS with otosclerosis, and human TBS with presbycusis as the control group. INTERVENTION: Pure-tone audiometry, temporal bone pathology. MAIN OUTCOME MEASURES: 1) LFSNHL, defined as >10 decibel elevation of bone conduction thresholds at 250 and 500 Hz, after correcting for age-related hearing loss (per ISO 7029). 2) Histologic assessment of EH. RESULTS: In patients with otosclerosis, 8 of 110 (7.3%) operated patients versus 3 of 123 (2.4%) nonoperated patients developed LFSNHL (p = 0.08). No patients with LFSNHL had other symptoms of EH. In TBS with otosclerosis, 11 of 93 (11.8%) operated TBS versus 3 of 156 (1.9%) nonoperated TBS had evidence of EH (p <0.001). In the control group of TBS with presbycusis, 9 of 253 (3.5%) had EH. CONCLUSION: The long-term incidence of LFSNHL, a marker for EH, in patients with otosclerosis was not significantly higher in those who underwent stapedectomy. The histologic incidence of EH, however, was significantly higher in TBS that had undergone stapedectomy compared with nonoperated TBS or a control group of TBS.

[Menière's Disease]. / Morbus Menière.

Menière`s disease is one of the most common inner ear and vestibular disorders. It is defined as the idiopathic syndrome of endolymphatic hydrops (ELH). Despite the development of several different animal models of ELH, its etiology and pathogenesis is still unresolved. In humans, endolymphatic hydrops may occur spontaneously or as a consequence of specific disorders with distinct inner ear pathologies, e. g., infectious labyrinthitis, noise induced hearing loss or vestibular schwannoma. Recent imaging studies using MRI have shown that hydropic ear disease is associated not only with the full triad of vertigo, hearing, loss and tinnitus/aural pressure, but also with inner ear symptoms that do not fulfill the clinical criteria of definite Menière's disease as set forth by the AAO-HNS. Therefore, terms like "atypical" or "cochlear"/"vestibular" Menière's disease or "forme fruste" should be avoided and the term "Menière's disease" should universally be applied according only to these guidelines. Besides that, the recent possibility of visualizing endolymphatic hydrops on MRI and thereby ascertaining the diagnosis in difficult cases and new audiovestibular function tests for the indirect detection of endolymphatic hydrops show promising results. Evidenced based reviews of currently available therapeutic options still reveal many uncertainties with regard to efficacy, with the exception of the ablative therapies, e. g., intratympanic gentamicin application.

Endolymphatic hydrops is prevalent in the first weeks following cochlear implantation.

AIM: To explore morphological or electrophysiological evidence for the presence of endolymphatic hydrops (EH) in guinea pig cochleae in the first 3 months after cochlear implantation. METHODS: Dummy silastic electrodes were implanted atraumatically into the basal turn of scala tympani via a cochleostomy. Round window electrocochleography (ECochG) was undertaken prior to and after implantation. Animals survived for 1, 7, 28 or 72 days prior to a terminal experiment, when ECochG was repeated. The cochleae were imaged using micro-CT after post-fixing with osmium tetroxide to reveal the inner ear soft tissue structure. EH was assessed by visual inspection at a series of frequency specific places along the length of the cochlea, and the extent to which Reissner's membrane departed from its neutral position was quantified. Tissue response volumes were calculated. Using ECochG, the ratio of the summating potential to the action potential (SP/AP ratio) was calculated in response to frequencies between 2 and 32 kHz. RESULTS: There was minimal evidence of electrode trauma from cochlear implantation on micro-CT imaging. Tissue response volumes did not change over time. EH was most prevalent 7 days after surgery in implanted ears, as determined by visual inspection. Scala media areas were increased, as expected in cases of EH, over the first month after cochlear implantation. SP/AP ratios decreased immediately after surgery, but were elevated 1 and 7 days after implantation. CONCLUSIONS: EH is prevalent in the first weeks after implant surgery, even in the absence of significant electrode insertion trauma.

Endolymphatic hydrops in Ménière's disease: cause, consequence, or epiphenomenon?

OBJECTIVE: To determine the relationship of endolymphatic hydrops to Ménière's disease. DATA SOURCES: Comprehensive review of articles from 1938 through 2012 via Medline and Index Medicus. STUDY SELECTION: Articles discussing Ménière's disease and/or endolymphatic hydrops that include temporal bone autopsy data. DATA EXTRACTION: Fifty-three case reports and series were studied containing examination of 541 hydropic temporal bones and including 276 patients with Ménière's disease. These were divided into those meeting the 1995 American Academy of Otolaryngology-Head and Neck Surgery criteria for Ménière's disease and those that failed to meet these criteria. CONCLUSION: An individual meeting the 1995 criteria for Ménière's disease has a near certain probability of having endolymphatic hydrops in at least 1 ear. Autopsy data do not support the view that the association of MD and EH is an epiphenomenon or that MD causes EH; this leaves us with the probability that EH causes MD. If it is causative, hydrops alone is insufficient to cause Ménière's disease, indicating that there must be one or more additional cofactors that cause asymptomatic hydrops to become symptomatic Ménière's disease. Vascular risk factors should be studied as possible cofactors.