The periductal channels of the endolymphatic duct, hydrodynamic implications

Four-Hour-Delayed Gadolinium 3D REAL IR and SPACE FLAIR MRI Correlated to Meniere Disease Histology

Objectives: This study aims to showcase the complementary nature of utilizing both histopathology and magnetic resonance imaging (MRI) in understanding the otologic pathophysiology of Meniere disease. In addition, it seeks to raise awareness of the value of preserving and curating historical temporal bone collections which continue to inform our understanding of otologic diseases. Methods: The essential anatomical feature of Meniere disease-the distended membranous labyrinth-is explored through a comparison of early temporal bone studies with contemporary MRI techniques. The histopathologic photomicrographs are of inner ear specimens from deceased patients with symptoms consistent with Meniere disease. The MRI sequences from living patients exhibiting classic Meniere disease symptoms during life are captured 4 hours post-administration of gadolinium. Results: Both histopathologic examination and MRI imaging reveal consistent distention of the saccule, utricle, and scala media in patients with Meniere disease. The study shows the histologic photomicrographs of actual Meniere patients compared to the MRIs and successfully demonstrates the correlation between postmortem histological findings and MRI evidence of distension in living patients. Conclusions: A corresponding distension of the membranous labyrinth is seen in both the histologic specimens and the Meniere MRIs. This correlation suggests the potential utility of utilizing MRI to aid in diagnosing atypical Meniere disease and distinguishing it from other disease processes, such as migraine equivalent vertigo. The integration of historical temporal bone studies with modern MRI techniques offers valuable insights into the pathophysiology of otologic diseases. In addition, it emphasizes the importance of preserving and curating historical temporal bone collections for continued research and medical education purposes. Previous studies of delayed MRIs did not use Meniere disease temporal bone histopathology images.

Temporal bone marrow of the rat and its connections to the inner ear

Calvarial bone marrow has been found to be central in the brain immune response, being connected to the dura through channels which allow leukocyte trafficking. Temporal bone marrow is thought to play important roles in relation to the inner ear, but is still largely uncharacterized, given this bone complex anatomy. We characterized the geometry and connectivity of rat temporal bone marrow using lightsheet imaging of cleared samples and microCT. Bone marrow was identified in cleared tissue by cellular content (and in particular by the presence of megakaryocytes); since air-filled cavities are absent in rodents, marrow clusters could be recognized in microCT scans by their geometry. In cleared petrosal bone, autofluorescence allowed delineation of the otic capsule layers. Within the endochondral layer, bone marrow was observed in association to the cochlear base and vestibule, and to the cochlear apex. Cochlear apex endochondral marrow (CAEM) was a separated cluster from the remaining endochondral marrow, which was therefore defined as "vestibular endochondral marrow" (VEM). A much larger marrow island (petrosal non-endochondral marrow, PNEM) extended outside the otic capsule surrounding semicircular canal arms. PNEM was mainly connected to the dura, through bone channels similar to those of calvarial bone, and only a few channels were directed toward the canal periosteum. On the contrary, endochondral bone marrow was well connected to the labyrinth through vascular loops (directed to the spiral ligament for CAEM and to the bony labyrinth periosteum for VEM), and to dural sinuses. In addition, CAEM was also connected to the tensor tympani fossa of the middle ear and VEM to the endolymphatic sac. Endochondral marrow was made up of small lobules connected to each other and to other structures by channels lined by elongated macrophages, whereas PNEM displayed larger lobules connected by channels with a sparse macrophage population. Our data suggest that the rat inner ear is surrounded by bone marrow at the junctions with middle ear and brain, most likely with "customs" role, restricting pathogen spread; a second marrow network with different structural features is found within the endochondral bone layer of the otic capsule and may play different functional roles.

Comparison of vestibular aqueduct visualization on computed tomography and magnetic resonance imaging in patients with Ménière's disease

BACKGROUND

The vestibular aqueduct (VA) serves an essential role in homeostasis of the inner ear and pathogenesis of Ménière's disease (MD). The bony VA can be clearly depicted by high-resolution computed tomography (HRCT), whereas the optimal sequences and parameters for magnetic resonance imaging (MRI) are not yet established. We investigated VA characteristics and potential factors influencing MRI-VA visibility in unilateral MD patients.

METHODS

One hundred patients with unilateral MD underwent MRI with three-dimensional sampling perfection with application optimized contrasts using different flip angle evolutions (3D-SPACE) sequence and HRCT evaluation. The imaging variables included MRI-VA and CT-VA visibility, CT-VA morphology and CT-peri-VA pneumatization.

RESULTS

The most frequent type of MRI-VA and CT-VA visualization was invisible VA and continuous VA, respectively. The MRI-VA visibility was significantly lower than CT-VA visibility. MRI-VA visibility had a weak positive correlation with ipsilateral CT-VA visualization. For the affected side, the MRI-VA visualization was negatively correlated with the incidence of obliterated-shaped CT-VA and positively with that of tubular-shaped CT-VA. MRI-VA visualization was not affected by CT-peri-VA pneumatization.

CONCLUSION

In patients with MD, the VA visualization on 3D-SPACE MRI is poorer than that observed on CT and may be affected by its osseous configuration. These findings may provide a basis for further characterization of VA demonstrated by MRI and its clinical significance.

Endolymphatic Duct and Sac Decompression: A New Life for an Old Technique

BACKGROUND

Ménière's disease is an inner ear disorder causing recurrent vertigo, hearing loss, and tinnitus. Diagnosis is based on the variability of the symptoms over time and absence of radiological abnormalities. Medical therapy is effective only in a small percentage of patients. Surgical strategies remain controversial. In this article, we revisit a surgical technique neglected over the years: endolymphatic sac surgery.

METHODS

Fifty-four patients affected by Ménière's disease underwent endolymphatic duct and sac decompression. According to the American Academy of Otolaryngology-Head and Neck Surgery criteria, vertigo control was evaluated with follow-up at 6 months, 1 year, and 2 years from the intervention. Hearing results were evaluated before the surgery and at 2 years of follow-up using the pure tone average. The results were compared with similar techniques of endolymphatic sac surgery described in the literature.

RESULTS

According to the American Academy of Otolaryngology-Head and Neck Surgery criteria classification, 2 years after surgery, 87% patients achieved complete control of vertigo (class A). The hearing remained stable in 93.5% of patients. The results appear compatible with other publications data regarding endolymphatic sac surgeries.

CONCLUSION

The duct and endolymphatic sac decompression allows the control of vertigo and preserves hearing from the pathological effects of Ménière's disease. The revised technique allows the functional restoration of endolymphatic homeostasis.

Comparison of radiological abnormalities between the jugular bulb and the vestibular aqueduct in patients with Ménière's disease

Objective

Anatomical variations of the inner ear may contribute to the development of Ménière's disease (MD), which is a complex inner ear disorder histopathologically characterized by idiopathic endolymphatic hydrops (ELH). Abnormalities of the vestibular aqueduct (VA) and the jugular bulb (JB) have been suggested as predisposing factors. Yet, few studies have investigated the correlation between JB abnormalities and VA variations as well as its clinical relevance in these patients. In this retrospective study, we investigated the differences in the incidence of radiological abnormalities of the VA and JB in patients with definite MD.

Methods

Anatomical variations of JB and VA were evaluated based on high-resolution CT (HRCT) in a series of 103 patients with MD (93 unilateral cases and 10 bilateral cases). JB-related indices included JB anteroposterior and mediolateral diameter, JB height, JB type regarding to Manjila classification system, and incidences of JB diverticulum (JBD), JB related inner ear dehiscence (JBID), and inner ear adjacent JB (IAJB). VA-related indices included CT-VA visibility, CT-VA morphology (funnel, tubular, filiform, hollow, and obliterated-shaped type), and peri-VA pneumatization. Radiological indices were compared between MD ears and control ears.

Results

Radiological JB abnormalities were comparable between MD ears and control ears. As for VA-related indices, the CT-VA visibility was lower in MD ears than in control ears (p = 0.004). The distribution of CT-VA morphology was significantly different between MD and control ears (p = 0.013), with a higher proportion of obliterated-shaped type in MD ears (22.1%) than in control ears (6.6%).

Conclusion

Compared with JB abnormalities, the anatomical variations of VA are more likely to be an anatomically predisposing factor for MD.

Endolymphatic duct and sac decompression: A new technique for Ménière’s disease treatment

Background:

The present article aims to introduce the endolymphatic duct and sac decompression technique (DASD) and to give a spotlight on its benefits in Ménière’s disease (MD) treatment.

Methods:

Eighty-two patients with intractable MD which met the inclusion criteria were recruited and underwent DASD. This technique allows a meningeal decompression of the duct and the sac from the posterior cranial fossa to the labyrinthine block. The authors considered as main outcomes, the change of the dizziness handicap inventory (DHI) results, with the evaluations of the three sub-scales (Functional scale, Physical scale, and Emotional scale); ear fullness and tinnitus change on the perceptions of the patient; and hearing stage with four-Pure Tone Average (500 hz-1000 hz-2000 hz-4000 hz). The differences between the preoperative and the postoperative score were evaluated. A comparison with the literature was conducted.

Results:

After a 14-month follow-up, patients that underwent DASD reported a remarkable improvement of the symptoms in all three functional scales, confirmed by the total DHI. The difference between preoperative and postoperative scores is statistically significant. The data describe an ear fullness and tinnitus improvement. The multi-frequency tonal average before and after the surgery does not suggest a worsening of the value for any of 82 patients.

Conclusion:

The modification of sac surgery includes the endolymphatic duct in the decompression area allowing inner ear functional improvement, vertigo control, ear fullness improvement with minimal risk of facial nerve paralysis, and hearing loss. DASD is an improved old surgical technique.

Anatomical variation of inner ear may be a predisposing factor for unilateral Ménière's disease rather than for ipsilateral delayed endolymphatic hydrops

Objective

Radiological anatomical variations, measured by magnetic resonance imaging (MRI), were evaluated in patients with ipsilateral delayed endolymphatic hydrops (DEH) and unilateral Ménière’s disease (MD). The role of anatomical variations in different subtypes of hydropic ear disease was investigated.

Methods

Twenty-eight patients with ipsilateral DEH, 76 patients with unilateral MD, and 59 control subjects were enrolled. The radiological indices included the distance between the vertical part of the posterior semicircular canal and the posterior fossa (MRI-PP distance) and the visibility of vestibular aqueduct (MRI-VA). These variations among patients with DEH, MD, and control subjects were compared. The correlation between radiological anatomical variations and clinical features or audio-vestibular findings was also examined.

Results

(1) MRI-PP distance in the affected side of unilateral MD was shorter than that in ipsilateral DEH (Z =  − 2.481, p = 0.013) and control subjects (Z =  − 2.983, p = 0.003), while the difference of MRI-PP distance between the affected side of ipsilateral DEH and control subjects was not statistically significant (Z =  − 0.859, p = 0.391). (2) There was no significant interaural difference of MRI-PP distance in patients with unilateral MD (Z =  − 0.041, p = 0.968) and ipsilateral DEH (t =  − 0.107, p = 0.915) respectively. (3) No significant interaural difference of MRI-VA visibility was observed in patients with unilateral MD (χ² = 0.742, p = 0.389) and ipsilateral DEH (χ² = 0.327, p = 0.567) respectively. (4) No correlation was found between these anatomical variables and clinical features or audio-vestibular findings in patients with unilateral MD and ipsilateral DEH respectively (p > 0.05).

Conclusions

Anatomical variations of inner ear may be a predisposing factor in the pathogenesis of unilateral MD rather than ipsilateral DEH.

Key Points

• Patients with ipsilateral delayed endolymphatic hydrops showed normal distance between the vertical part of the posterior semicircular canal and the posterior fossa.

• Compared to patients with ipsilateral delayed endolymphatic hydrops and control subjects, patients with unilateral Ménière’s disease exhibited shorter distance between the vertical part of the posterior semicircular canal and the posterior fossa.

• Anatomical variations of inner ear may be a predisposing factor in the pathogenesis of unilateral Ménière’s disease rather than ipsilateral delayed endolymphatic hydrops.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00330-021-08430-7.

A Micro-CT and Synchrotron Imaging Study of the Human Endolymphatic Duct with Special Reference to Endolymph Outflow and Meniere's Disease

Meniere’s disease remains enigmatic, and has no treatment with sufficient evidence. The characteristic histopathological finding is endolymphatic hydrops, suggesting either an overproduction or decreased reabsorption of endolymph in the human inner ear. This study presents the first analysis of the vascular plexus around the human endolymphatic duct using micro computed tomography and coherent synchrotron radiation with phase contrast imaging. Using a software program, data were processed by volume-rendering with scalar opacity mapping to create transparent three-dimensional reconstructions. A rich vascular plexus was discovered around the endolymphatic duct that drained into collecting channels, linked to the vestibular venous outflow system. This network is believed to make up the principal route for endolymph outflow, and its associated malfunction may result in endolymphatic hydrops and Meniere’s disease.

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.

FGF23 and its role in X-linked hypophosphatemia-related morbidity

Background

X-linked hypophosphatemia (XLH) is an inherited disease of phosphate metabolism in which inactivating mutations of the Phosphate Regulating Endopeptidase Homolog, X-Linked (PHEX) gene lead to local and systemic effects including impaired growth, rickets, osteomalacia, bone abnormalities, bone pain, spontaneous dental abscesses, hearing difficulties, enthesopathy, osteoarthritis, and muscular dysfunction. Patients with XLH present with elevated levels of fibroblast growth factor 23 (FGF23), which is thought to mediate many of the aforementioned manifestations of the disease. Elevated FGF23 has also been observed in many other diseases of hypophosphatemia, and a range of animal models have been developed to study these diseases, yet the role of FGF23 in the pathophysiology of XLH is incompletely understood.

Methods

The role of FGF23 in the pathophysiology of XLH is here reviewed by describing what is known about phenotypes associated with various PHEX mutations, animal models of XLH, and non-nutritional diseases of hypophosphatemia, and by presenting molecular pathways that have been proposed to contribute to manifestations of XLH.

Results

The pathophysiology of XLH is complex, involving a range of molecular pathways that variously contribute to different manifestations of the disease. Hypophosphatemia due to elevated FGF23 is the most obvious contributor, however localised fluctuations in tissue non-specific alkaline phosphatase (TNAP), pyrophosphate, calcitriol and direct effects of FGF23 have been observed to be associated with certain manifestations.

Conclusions

By describing what is known about these pathways, this review highlights key areas for future research that would contribute to the understanding and clinical treatment of non-nutritional diseases of hypophosphatemia, particularly XLH.

Mastoid and Inner Ear Measurements in Patients With Menière's Disease

OBJECTIVE

To determine the relationship between radiographic temporal bone anatomy of patients with Menière's disease in medically and surgically managed populations versus controls.

STUDY DESIGN

Retrospective chart review.

SETTING

Two tertiary referral centers.

PATIENTS

Adults older than 18 years with Menière's disease treated with endolymphatic sac decompression (ESD) or medical management (non-ESD) versus controls.

INTERVENTIONS

Magnetic resonance imaging and computed tomography imaging studies of the temporal bones were reviewed by blinded radiologists.

MAIN OUTCOME MEASURES

Radiographic temporal bone dimensions were measured in Menière's disease and control patients. Age, sex, symptoms, audiogram data, academy classification of Menière's disease, and follow-up were recorded. Statistical analysis was performed to compare outcome measures across groups and demographics.

RESULTS

A total of 90 imaging studies were reviewed (ESD = 22; non-ESD = 30; control = 38). ESD and non-ESD groups had similar pure-tone averages (33.9 ± 20.6 versus 41.6 ± 22.6 dB HL; p = 0.21) and frequency of definite Menière's disease (59.1% versus 53.3%; p = 0.68). There was no significant trend between groups for any measurement. One nonsignificant trend existed in mean vestibule length, increasing from the control (5.45 ± 0.54 mm), non-ESD (5.80 ± 0.97 mm), and ESD (5.94 ± 0.81 mm) group. In a combined Menière's group, mean vestibule length was significantly greater than controls (5.86 ± 0.89 versus 5.45 ± 0.54 mm; p = 0.008) and mean vestibule width significantly less (2.99 ± 0.46 versus 3.19 ± 0.39 mm; p = 0.024).

CONCLUSION

Medical and surgical Menière's patients were similar utilizing academy classification. There was no significant trend between medical and surgical Menière's patients versus controls for any measurement. In a combined Menière's group, the longer and narrower vestibule anatomy may suggest an anatomical basis for endolymphatic hydrops.

The Human Vestibular Aqueduct: Anatomical Characteristics and Enlargement Criteria

HYPOTHESIS

The human vestibular aqueduct (VA) shows great anatomical variations, and imaging can be difficult, so we need more data on the normal anatomy of the VA for better radiologic evaluation of large vestibular aqueduct syndrome (LVAS).

BACKGROUND

The normal anatomy of the human VA was analyzed in micro-dissected human temporal bones.

METHODS

The study is based on two sets of human temporal bones. One set of 32 human temporal bones was selected from a collection of 50 micro-dissected specimens. The outline of the intraosseous portion of the VA was drawn and digitized, and dimensions were assessed. The other set of 20 plastic molds were randomly selected from a collection of 324 specimens, and the VA dimensions were assessed.

RESULTS

Measurements from this study are presented in means, standard deviations, and ranges. The results from these measurements are considered normal and compared with previously published data. The variations in the normal anatomy of the VA are presented and discussed.

CONCLUSION

The VA courses sagittal in the human skull. Therefore, we recommend the lateral projection (reformatted) to demonstrate the VA in LVAS patients. We advocate assessing: 1) the width (or height) of the external aperture (EA), 2) the width at the half distance between the EA and the common crus (CC), and if possible 3) the width of the proximal portion of the VA. Based on the measurements, our criteria for enlargement are 2.0 mm or greater, 1.5 mm or greater, and more than 1 mm at these sites.

Long-term outcomes of endolymphatic sac shunting with local steroids for Meniere's disease

OBJECTIVES

To evaluate the long-term efficacy of endolymphatic sac shunt techniques with and without local steroid administration.

STUDY DESIGN

Retrospective case series and patient survey.

SETTING

Tertiary university hospital.

PATIENTS

Meniere's disease (MD) patients that failed medical therapy and subsequently underwent an endolymphatic sac shunt procedure. All patients had definitive or probable MD and at least 18-months of follow-up.

INTERVENTIONS

Three variations on endolymphatic sac decompression with shunt placement were performed: Group A received no local steroids, Group B received intratympanic dexamethasone prior to incision, and Group C received dexamethasone via both intratympanic injection and direct endolymphatic sac instillation.

MAIN OUTCOME MEASURE(S)

Vertigo control, hearing results, and survey responses.

RESULTS

Between 2002 and 2013, 124 patients with MD underwent endolymphatic sac decompression with shunt placement. 53 patients met inclusion criteria. Groups A, B, and C had 6 patients, 20 patients, and 27 patients, respectively. Mean follow-up was 56months. Vertigo control improved in 66%, 83%, and 93% of Groups A, B, and C. Functional level improved for Group B (-2.0) and Group C (-2.2) but was unchanged in Group A. Pure-tone average and speech discrimination scores changed by +22dB and -30%, +6dB and -13%, and +6dB and -5% in Groups A, B, and C. The long-term hearing results were significantly better with steroids (Groups B and C) according to the AAO-HNS 1995 criteria but did not meet significance on non-parametric testing.

CONCLUSIONS

Endolymphatic sac shunt procedures may benefit from steroid instillation at the time of shunt placement.

Claudin expression in the rat endolymphatic duct and sac - first insights into regulation of the paracellular barrier by vasopressin

Hearing and balance functions of the inner ear rely on the homeostasis of the endolymphatic fluid. When disturbed, pathologic endolymphatic hydrops evolves as observed in Menière’s disease. The molecular basis of inner ear fluid regulation across the endolymphatic epithelium is largely unknown. In this study we identified the specific expression of the tight junction (TJ) molecules Claudin 3, 4, 6, 7, 8, 10, and 16 in epithelial preparations of the rat inner ear endolymphatic duct (ED) and endolymphatic sac (ES) by high-throughput qPCR and immunofluorescence confocal microscopy. Further we showed that Claudin 4 in the ES is a target of arginine-vasopressin (AVP), a hormone elevated in Menière’s disease. Moreover, our transmission-electron microscopy (TEM) analysis revealed that the TJs of the ED were shallow and shorter compared to the TJ of the ES indicating facilitation of a paracellular fluid transport across the ED epithelium. The significant differences in the subcellular localization of the barrier-forming protein Claudin 3 between the ED and ES epithelium further support the TEM observations. Our results indicate a high relevance of Claudin 3 and Claudin 4 as important paracellular barrier molecules in the ED and ES epithelium with potential involvement in the pathophysiology of Menière’s disease.

Treatment of ear and bone disease in the Phex mouse mutant with dietary supplementation

HYPOTHESIS

Phosphorus and vitamin D (calcitriol) supplementation in the Phex mouse, a murine model for endolymphatic hydrops (ELH), will improve otic capsule mineralization and secondarily ameliorate the postnatal development of ELH and sensorineural hearing loss (SNHL).

BACKGROUND

Male Phex mice have X-linked hypophosphatemic rickets (XLH), which includes osteomalacia of the otic capsule. The treatment for XLH is supplementation with phosphorus and calcitriol. The effect of this treatment has never been studied on otic capsule bone and it is unclear if improving the otic capsule bone could impact the mice's postnatal development of ELH and SNHL.

METHODS

Four cohorts were studied: 1) wild-type control, 2) Phex control, 3) Phex prevention, and 4) Phex rescue. The control groups were not given any dietary supplementation. The Phex prevention group was supplemented with phosphorus added to its drinking water and intraperitoneal calcitriol from postnatal day (P) 7-P40. The Phex rescue group was also supplemented with phosphorus and calcium but only from P20 to P40. At P40, all mice underwent auditory brainstem response (ABR) testing, serum analysis, and temporal bone histologic analysis. Primary outcome was otic capsule mineralization. Secondary outcomes were degree of SNHL and presence ELH.

RESULTS

Both treatment groups had markedly improved otic capsule mineralization with less osteoid deposition. The improved otic capsule mineralized did not prevent the development of ELH or SNHL.

CONCLUSION

Supplementation with phosphorus and calcitriol improves otic capsule bone morphology in the Phex male mouse but does not alter development of ELH or SNHL.

Post Hybrid Cochlear Implant Hearing Loss and Endolymphatic Hydrops

OBJECTIVE

To evaluate for potential causes of delayed loss of residual hearing that variably occurs with hybrid cochlear implants.

STUDY DESIGN

Histopathological evaluation of 29 human temporal bone (HTB) with cochlear implant (CI).

SETTING

The Neurotology and House HTB Laboratory of UCLA (House-UCLA).

SUBJECTS AND METHODS

HTB from CI patients from the House-UCLA HTB Laboratory (n = 28) and one courtesy of Massachusetts Eye and Ear Infirmary (MEEI). Histopathological analysis to identify the location of cochleostomy, fibrosis, and bone formation in the scala vestibuli and tympani, and endolymphatic hydrops. Spiral ganglion neuron counts were obtained. Statistical analysis compared presence of cochleostomy and location with the histopathological findings.

RESULTS

Seventeen of 29 bones with fibrosis in the scala vestibule (SV) and tympani had evidence of a cochleostomy involving the SV containing the ductus reunions, all of which had hydrops. Ten of 11 bones had no SV fibrosis, and a cochleostomy limited to the scala tympani, of which all had no hydrops. One HTB had moderate SV fibrosis not involving the ductus reuniens, and was without hydrops. One HTB had a SV cochleostomy but the electrode ruptured Reissner's membrane, and was without hydrops. Cochleostomy was significantly associated with SV fibrosis and hydrops (p < 0.01), those without hydrops had no SV atrophy (p < 0.01). Round window insertion was associated with no fibrosis and no hydrops.

CONCLUSION

We hypothesize that cochleostomies involving scala vestibuli incite fibrosis, compromising the ductus reuniens, causing hydrops which may cause the delayed loss of residual low frequency hearing in CI.

Endolymph movement visualized with light sheet fluorescence microscopy in an acute hydrops model

There are a variety of techniques available to investigate endolymph dynamics, primarily seeking to understand the cause of endolymphatic hydrops. Here we have taken the novel approach of injecting, via a glass micropipette, fluorescein isothiocyanate-dextran (FITC-dex) and artificial endolymph into scala media of anaesthetized guinea pigs, with subsequent imaging of the inner ear using Light Sheet Fluorescence Microscopy (LSFM) as a means to obtain highly resolved 3D visualization of fluid movements. Our results demonstrate endolymph movement into the utricle, semicircular canals and endolymphatic duct and sac when more than 2.5 μl of fluid had been injected into scala media, with no apparent movement of fluid into the perilymphatic compartments. There was no movement of endolymph into these compartments when less than 2.5 μl was injected. The remarkable uptake of the FITC-dex into the endolymphatic duct, including an absorption into the periductal channels surrounding the endolymphatic duct, highlights the functional role this structure plays in endolymph volume regulation.

Endolymphatic duct blockage: quality of life assessment of a novel surgical technique for Ménière disease

The aim of this study is to evaluate the quality of life (QOL) of patients treated by endolymphatic duct blockage (EDB) for Ménière's disease with a dedicated questionnaire. This is a retrospective cross-sectional study which included 54 patients diagnosed with severe, refractory Ménière's disease according to the AAO-HNS criteria and treated with EDB between 2010 and 2013. Answers to the first 38 questions have assigned scores from 0 to 4 (0 corresponding to the poorest QOL). A preoperative score called S1 was calculated as follows: S1 = sum of preoperative question scores/maximum possible preoperative score ×100. The same formula was used to calculate the postoperative score S2. The change in QOL score, S3, was then calculated (S3 = S2-S1). All answers were analyzed anonymously. Statistical analysis was done using Student t test and Chi square test. A response rate of 89 % was obtained with the Ménière's disease outcome questionnaire. The preoperative (S1) score was 21.4 (±12.6) and the postoperative score (S2) was 64.6 (±21.6) with a change in QOL (S3) of 43.3 (p < 0.001). Postoperatively, 89.9 % reported no Ménière's attacks (p < 0.001). Seventy-nine percent (15/19) of the questions showed a significant improvement after surgery. These results show that EDB is associated with a significant improvement of the QOL of patients suffering from severe Ménière's disease.