Immunohistochemical localisation of aquaporin 2 and vasopressin type 2 receptor in the human endolymphatic sac

OBJECTIVE

This study aimed to determine the distribution and subcellular localisation of aquaporin 2 and vasopressin type 2 receptor in the human endolymphatic sac.

METHODS

Ten samples of human endolymphatic sac were collected during acoustic neurinoma removal using the translabyrinthine approach. Immunohistochemistry and immunofluorescence were performed using aquaporin 2 and vasopressin type 2 receptor monoclonal antibodies.

RESULTS

Confocal microscopy demonstrated that vasopressin type 2 receptor labelling was expressed in both the apical and basolateral plasma membranes, and in the cytoplasm of the endolymphatic sac epithelium, whereas aquaporin 2 was strongly expressed at the basolateral site of the endolymphatic sac epithelium, in both the intraosseous and extraosseous parts of the endolymphatic sac.

CONCLUSION

Both aquaporin 2 and vasopressin type 2 receptor were detected in the epithelial cells of the human endolymphatic sac, suggesting that this channel may be involved in inner-ear fluid homeostasis. However, strong basolateral expression of aquaporin 2 in endolymphatic sac epithelium suggested that the function of aquaporin 2 may differ between the endolymphatic sac and kidney.

Live Imaging of the Dehydration Effect of Isosorbide on the Normal and Hydropic Guinea Pig Cochleae Using Optical Coherence Tomography

OBJECTIVE

To investigate the isosorbide-induced dehydration effect on the endolymphatic space by intratympanic administration of isosorbide.

BACKGROUND

Isosorbide, an osmotic diuretic, is used orally as a typical conservative therapy for Menière's disease (MD) in Japan. The dehydration effect occurs 6 hours after isosorbide ingestion. Intratympanic administration of isosorbide resolves endolymphatic hydrops faster than oral ingestion. In addition, the dehydration effect has never been shown directly. Therefore, we investigated the dehydration effect of intratympanic administration of isosorbide on endolymphatic hydrops using optical coherence tomography.

METHODS

We used eight Hartley guinea pigs, divided into normal and hydrops groups. In the hydrops group, the animals underwent endolymphatic sac obliteration to create endolymphatic hydrops. We obtained midmodiolar section images of the cochleae using optical coherence tomography. Then, 50 to 70% isosorbide was sequentially administered intratympanically for 5 minutes, and the apical turn of the cochlea was observed. The relative midmodiolar cross-sectional area of the scala media was calculated for quantitative assessment of the endolymphatic space.

RESULTS

In the normal group, 50% isosorbide had a slight but significant dehydration effect on the scala media; at 55 to 70%, Reissner's membrane became flat. In the hydrops group, 50% isosorbide slightly reduced endolymphatic hydrops; 65% flattened Reissner's membrane, and 70% slightly concaved it toward the basilar membrane.

CONCLUSION

The results suggest that we could select the concentration of isosorbide according to the stage or severity of MD and relief from acute attack. Intratympanic administration of isosorbide may be a promising treatment for patients with MD.

Potential biomarkers in peripheral blood mononuclear cells of patients with sporadic Ménière's disease based on proteomics

BACKGROUND

Ménière's disease (MD) mainly refers to the endolymphatic hydrops in membranous labyrinth of the inner ear. Application of the mass spectrometry-based proteomics techniques has not been applied in the field of MD.

OBJECTIVES

To search for potential differential proteins to identify the disease biomarkers and reveal disease bioinformatics-related mechanisms through applying protein technology to analyze the expression changes of peripheral blood mononuclear cells (PBMCs) in sporadic MD patients.

MATERIAL AND METHODS

15 MD patients and 15 healthy individuals were enrolled. PBMCs from them were extracted, and their protein expression was identified and compared by LC-MS/MS and spectra analysis.

RESULTS

There was significant difference in protein expression between MD patients and the control group. GO and KEGG analysis showed that endocytosis was involved in MD patients. Western blot results of CHMP1A and MMP9 protein showed that the expression of CHMP1A was higher in the MD group than that in the control group, while MMP9 was down-regulated. Immunohistochemistry confirmed that CHMP1A and MMP9 were expressed in the endolymphatic sacs of MD patients and in the inner ear of adult mice.

CONCLUSIONS AND SIGNIFICANCE

Endocytosis may be involved in the pathogenesis of sporadic MD, furthermore CHMP1A, VPS4A, FCN3 and MMP9 could be considered as potential biomarkers.

Ductus Reuniens and Its Possible Role in Menière's Disease

OBJECTIVE

After 160 years the true underlying cause of Meniere's disease remains enigmatic. The aim of our study is to discuss the possible implication of an obstruction of the ductus reuniens as a cause in Menière's disease.

METHODOLOGY

We first conducted an historical study of the description of the ductus reuniens. We then reviewed the literature regarding ductus reuniens obstruction in animal experiments, human post-mortem studies and living ear imaging. We completed its description by modern microCT imaging. Limited knowledge on the fate of dislodged saccular otoconia is summarized. The possible implications for Meniere's attacks are discussed.

RESULTS

Victor Hensen was the first to describe the ductus reuniens in 1863. He described its length and width and predicted that saccular otoconia might enter the ductus and the cochlea. On microCT the narrowest width of the human ductus reuniens was 0.14 mm. The literature reports cochlear endolymphatic hydrops occurring after animal experimental obstruction of the duct. Human postmortem studies have confirmed saccular otoconial clumps entering the ductus and the cochlea. A postmortem study has shown sites of endolymphatic obstruction, and imaging speculates on blockages in ears with Meniere's disease. Dislodged utricular otoconia can be in clumps of otolithic membranes.

CONCLUSION

Blockages of the ductus reuniens and at other endolymphatic system sites appear to be a feature in Meniere's disease ears. The blockages have been postulated to be saccular otoconia either causing or aggravating hydrops. This could be consistent with observed nystagmus reversals during attacks as the endolymphatic sac attempts to clear the hydrops and the otoconia.

[Efficacy of cochlear implantation for bilateral severe Ménière's disease]

OBJECTIVE

To investigate the effecacy of cochlear implantation (CI) improving hearing of Lermoyez's syndrome, we retrospectively analyzed a case of Lermoyez's syndrome whose left ear was extremely severe sensorineural deafness and right ear was severe sensorineural deafness.

METHOD

The patient had completed preoperative audiological examination , vestibular function and imaging examination, then was carried out bilateral endolymphatic sac decompression and left side CI. Follow up after the surgery.

RESULT

The vertigo could be controlled very well after the bilateral endolymphatic sac decompression surgery, but the hearing loss couldn't be control, so CI was carried out to improve hearing and speech recognition rate. The contralateral hearing also improved significantly after the operation.

CONCLUSION

Endolymphatic sac decompression can effectively control. Ménière's disease in patients with vertigo attacks. CI can improve patients' hearing, and speech recognition rate and, also could improve the quality of life. CI was the first choice for the patient of 4 stage Ménière's disease.

[Endolymphatic sac tumor with von Hippel-Lindau disease: report of two cases with testing of von Hippel-Lindau gene]

OBJECTIVE

Endolymphatic sac tumors (ELSTs) are rare in the general population with much higher prevalence in von Hippel-Lindau(VHL) disease. The purpose of this study is to present two cases of endolymphatic sac tumor with VHL disease with analysis of VHL gene and to explore their association with VHL disease using molecular analysis.

METHODS

Clinical data of these two patients from different VHL families were studied. DNAs extracted from peripheral bloods were amplified by the polymerase chain reaction using oligonucleotide primers corresponding to the VHL gene, then compared the mutations with the Human Gene Mutation Database.

RESULTS

In case 1, 6 family members were enrolled in the study. Among them, three had been identified to have a germline missense point mutation at codon 194 of the VHL gene exon 1 (p.S65W). The little sister of the patient (case 1) underwent vitrectomy for retinal hemangioblastoma 5 years ago in another hospital. The mother of the patient (case 1) was further diagnosed to have a cerebellar hemangioblastoma and renal carcinoma in the following physical examination. Case 2 with her parents were also tested. Codon 499 of the VHL gene exon 3 (p.R167W) were detected in case 2 and her mother, but the mother refused further examination.

CONCLUSIONS

The genetic diagnosis plays an important role in early detection of symptomatic patients and suspected patients. Clinical screening for members of the VHL families, and close follow-up of carriers allow an early detection of tumors and the metastasis, which is the most common cause of death of these patients.

Surgical treatment of endolymphatic sac tumor

The objective of this study was to understand the clinical characteristics of endolymphatic sac tumor and to optimize its diagnosis and treatment. We carried out a retrospective review of 11 patients diagnosed as having endolymphatic sac tumor based on operative findings and pathological features, and their clinical manifestations, differential diagnosis, and surgical approaches are discussed in detail. The lesions of 10 cases were completely surgically resected, two cases via the mastoid approach, 8 cases via the oto-cervical or cranio-oto-cervical combined approach. In one case the tumor was partially removed and the patient received adjuvant radiotherapy. In operation, four cases had facial-hypoglossal neural anastomosis, two cases had great auricular nerve graft, and in four cases the facial nerve integrity remained. Survival follow-up data range from 14 months to 10 years. We conclude that endolymphatic sac tumor is very rare and easily misdiagnosed. Reasonable surgical treatment can provide a good prognosis.

Comparison of gentamicin distribution in the inner ear following administration via the endolymphatic sac or round window

OBJECTIVE/HYPOTHESIS

The distribution of gentamicin in the inner ear via the endolymphatic sac (ES) or round window (RW) routes was investigated.

STUDY DESIGN

Experimental study.

METHODS

A fluorescent gentamicin-Texas Red conjugate (GTTR) was adopted to visualize the gentamicin. Adult guinea pigs were treated with GTTR applied to the ES or RW, the animals were allowed to recover for 3 days, then confocal microscopy was used to observe and quantify GTTR distributions in cochlear and vestibular sensory epithelium.

RESULTS

When GTTR was applied via the ES, strong GTTR labeling was observed in the vestibule while little GTTR was detected in the cochlea (P < .0001). However, distinct GTTR fluorescence was observed in the cochlea and vestibule following RW application (P = .7967). There was less GTTR labeling in cochlea via ES application than through RW administration (P < .0001).

CONCLUSIONS

ES drug application may be preferable for the treatment of intractable Meniere's disease. Laryngoscope, 2010.

Neurologic manifestations of von Hippel-Lindau disease

von Hippel-Lindau disease (VHL) is an autosomal-dominant neoplasia syndrome that is the result of a germline mutation of the VHL tumor suppressor gene on the short arm of chromosome 3. Patients with VHL are predisposed to develop lesions of the central nervous system and viscera. Central nervous system lesions include hemangioblastomas (the most common tumor in VHL) and endolymphatic sac tumors (ELSTs). Visceral manifestations include renal carcinomas and cysts, pancreatic neuroendocrine tumors and cysts, pheochromocytomas, and cystadenomas of the reproductive adnexal organs. Despite their benign pathology, hemangioblastomas and ELSTs are a frequent cause of morbidity and mortality in patients with VHL. Recent molecular biologic investigations into these VHL-associated central nervous system lesions provide new insight into their origin and development. Emerging data from serial imaging and clinical surveillance protocols provide insight into the natural history of these lesions. Because of the dissimilar pathobiology and clinical course between hemangioblastomas and ELSTs, the optimal management strategies for these neurologic manifestations of VHL are very different.

Aggressive papillary tumor of the middle ear: a true entity or an endolymphatic sac neoplasm?

Aggressive papillary tumors of the middle ear are rare, and their true origin is not clear. We describe the clinical, radiologic, genetic, and histopathologic features of a papillary epithelial tumor filling the middle ear of a 68-year-old woman. Imaging revealed no evidence of petrous temporal bone apex involvement, nor did genetic studies demonstrate the von Hippel-Lindau mutation. A literature search revealed 24 previously reported cases of such a papillary epithelial tumor of the middle ear. All except 2 cases demonstrated apical petrous temporal bone invasion on imaging, and it has been suggested that they arose from a primary endolymphatic sac tumor, which has a similar papillary epithelial histology. Substantial numbers of cases of papillary epithelial tumors involving the middle ear are reported to be associated with von Hippel-Lindau disease, as are known cases of endolymphatic sac tumor. This is the third reported case of papillary epithelial tumor of the middle ear that does not show apical petrous temporal bone invasion on imaging, suggesting that such neoplasms do not always arise from a primary in the endolymphatic sac.

Contrasting behavior of endolymphatic sac tumors: a report of 2 cases and literature review

BACKGROUND

Endolymphatic sac is an established source of low-grade neoplasms, posing a difficult problem in local tumor control.

CASE DESCRIPTION

Two cases of endolymphatic sac tumors are described in detail with regard to their clinical presentation and radiological findings. Both cases had diametrically opposite clinical outcomes in spite of repeated surgical interventions. A case with severe paraneoplastic syndrome and death after "cancer cachexia" is described.

CONCLUSIONS

Although endolymphatic tumors are known for their low-grade aggressiveness, in occasional cases, they may behave in a highly malignant behavior. The present communication highlights the contrast in clinical outcome and makes the clinician cautious of this special subgroup of tumors with a highly aggressive nature.

Endolymphatic sac papillary tumor: a case report and review

Endolymphatic sac papillary tumor (endolymphatic sac adenoma, temporal-mastoid bone adenoma or adenocarcinoma, low-grade adenocarcinoma of potential endolymphatic sac origin, aggressive papillary tumor of the temporal bone, Heffner's tumor) is a rare lesion that involves the temporal bone. This tumor usually appears alone, but in 11-30% of afflicted individuals, it is accompanied by von Hippel-Lindau disease. Endolymphatic sac papillary tumors are destructive tumors that exhibit locally aggressive behavior. They slowly grow into the posteromedial section of petrous temporal bone. The main symptoms produced by these lesions include hearing loss and cranial nerve deficits. Endolymphatic sac papillary tumors develop in two principal patterns that histopathologically form follicular and papillary or solid structures. Those two patterns are usually manifested in the same tumor. Immunochemical analysis of these tumors usually reveals cytokeratin, vimentin, epithelial membrane antigen, and (less frequently) S-100 protein and neuron-specific enolase. Local excision is curative for endolymphatic sac papillary tumors. The currently favored method of treatment consists of excision and long-term follow-up. The role of adjuvant radiotherapy as treatment is controversial. This case report describes an endolymphatic sac tumor in a 22-year-old woman without von Hippel-Lindau disease who had a number of complaints, including deafness in her left ear, complete left-sided facial paralysis, and hoarseness of approximately 8 years' duration.

Endolymphatic sac tumor demonstrated by intralabyrinthine hemorrhage

✓ Endolymphatic sac tumors (ELSTs) are locally invasive neoplasms that arise in the posterior petrous bone and are associated with von Hippel–Lindau (VHL) disease. These tumors cause symptoms even when microscopic in size (below the threshold for detectability on imaging studies) and can lead to symptoms such as hearing loss, tinnitus, vertigo, and facial nerve dysfunction. While the mechanisms of audiovestibular dysfunction in patients harboring ELSTs are incompletely understood, they have critical implications for management. The authors present the case of a 33-year-old man with VHL disease and a 10-year history of progressive tinnitus, vertigo, and left-sided hearing loss. Serial T1-weighted magnetic resonance (MR) imaging and computed tomography scans revealed no evidence of tumor, but fluid attenuated inversion recovery (FLAIR) MR imaging sequences obtained after hearing loss demonstrated evidence of left intralabyrinthine hemorrhage. On the basis of progressive disabling audiovestibular dysfunction (tinnitus and vertigo), FLAIR imaging findings, and VHL disease status, the patient underwent surgical exploration of the posterior petrous region, and a small (2-mm) ELST was identified and completely resected. Postoperatively, the patient had improvement of the tinnitus and vertigo. Intralabyrinthine hemorrhage may be an early and the only neuroimaging sign of an ELST in patients with VHL disease and audiovestibular dysfunction. These findings support tumor-associated hemorrhage as a mechanism underlying the audiovestibular dysfunction associated with ELSTs.

Mechanisms of morbid hearing loss associated with tumors of the endolymphatic sac in von Hippel-Lindau disease

CONTEXT

Endolymphatic sac tumors (ELSTs) are associated with von Hippel-Lindau disease and cause irreversible sensorineural hearing loss (SNHL) and vestibulopathy. The underlying mechanisms of audiovestibular morbidity remain unclear and optimal timing of treatment is not known.

OBJECTIVE

To define the mechanisms underlying audiovestibular pathophysiology associated with ELSTs.

DESIGN, SETTING, AND PATIENTS

Prospective and serial evaluation of patients with von Hippel-Lindau disease and ELSTs at the National Institutes of Health between May 1990 and December 2006.

MAIN OUTCOME MEASURES

Clinical findings and audiologic data were correlated with serial magnetic resonance imaging and computed tomography imaging studies to determine mechanisms underlying audiovestibular dysfunction.

RESULTS

Thirty-five patients with von Hippel-Lindau disease and ELSTs in 38 ears (3 bilateral ELSTs) were identified. Tumor invasion of the otic capsule was associated with larger tumors (P = .01) and occurred in 7 ears (18%) causing SNHL (100%). No evidence of otic capsule invasion was present in the remaining 31 ears (82%). SNHL developed in 27 of these 31 ears (87%) either suddenly (14 ears; 52%) or gradually (13 ears; 48%) and 4 ears had normal hearing. Intralabyrinthine hemorrhage was found in 11 of 14 ears with sudden SNHL (79%; P < .001) but occurred in none of the 17 ears with gradual SNHL or normal hearing. Tumor size was not related to SNHL (P = .23) or vestibulopathy (P = .83).

CONCLUSIONS

ELST-associated SNHL and vestibulopathy may occur suddenly due to tumor-associated intralabyrinthine hemorrhage, or insidiously, consistent with endolymphatic hydrops. Both of these pathophysiologic mechanisms occur with small tumors that are not associated with otic capsule invasion.

Adenocarcinoma del saco endolinfático en la enfermedad de von Hippel-Lindau. A propósito de un caso

Tumors originating in the endolymphatic system are extremely rare, and very few articles have been published about this type of tumors. Up to 15% of cases are associated to von Hippel-Lindau disease. This article describes the case of a patient previously diagnosed with von Hippel-Landau disease that presented a sudden loss of hearing in the left ear. Specific imaging tests (computed tomography [CT] and magnetic resonance imaging [MRI]) showed the presence of a neoplasm originating in the left endolymphatic sac. Histological analysis of the surgical specimen determined it corresponded to an adenocarcinoma of the endolymphatic sac.

Spinal metastasis from endolymphatic sac tumor

We describe a case of endolymphatic sac tumor with drop metastasis to the spine. Our review of the literature showed that this is only the 2nd reported case of such an occurrence.

Cholesterol granuloma surrounding the endolymphatic sac

We report a unique case of cholesterol granuloma (CG) surrounding the endolymphatic sac (ES). A 49-year-old man presented with the left side of sensorineural hearing loss, tinnitus, and vertigo. Magnetic resonance and computed tomography imaging revealed a CG surrounding the left ES. The patient initially underwent left transmastoid surgical resection of the tumor. At the time of surgery, brown fluid was aspirated from the tumor, but no other tumors were found. Histopathological examination revealed that the tumor contained cholesterol crystals, confirming the diagnosis of CG. At his 12-month postoperative follow-up, there was no evidence of recurrence. We discuss the radiology, pathology, and surgical removal of CGs surrounding ES.

Endolymphatic sac tumor: a report of 3 cases and discussion of management

Patients with an endolymphatic sac tumor (ELST) typically present with palsy of cranial nerves VII and/or VIII; other presenting symptoms include hearing loss, otalgia, occipital headaches, cranial nerve palsies, vertigo, gait ataxia, tinnitus, and otorrhea. ELSTs are extremely vascular, and they can invade and destroy temporal bone. Because of these characteristics, they are often mistaken for glomus tumors of the skull base. We describe the clinical presentation, evaluation, and management of ELSTs based on our review of the limited literature and our experience with 3 adults who presented to our tertiary care referral center with large ELSTs. Although these patients presented late in the course of their disease, their symptoms were relatively minor. Preoperative tumor embolization was performed, anda near-complete resection was achieved via an extended transotic approach in all 3 patients. The facial nerve was preserved without transposition in the first patient, the second patient underwent a primary nerve anastomosis, and the third required a cable graft of the facial nerve. Postoperative radiation therapy was administered to 2 of these patients. Follow-up by MRI detected no evidence of recurrence in any of the 3 patients.

Endolymphatic Sac Tumours: Surgical Management

BACKGROUND

Endolymphatic sac tumours (ELSTs) have been known as an individual tumour entity only since 1984. ELSTs may occur either solitarily and sporadically or as a hereditary manifestation associated with von Hippel-Lindau (VHL) disease. The latter association was first observed in 1992 and confirmed by molecular genetic analysis of the VHL gene. No consensual diagnostic and treatment strategy of ELST exists at present.

METHODS

Based on imaging criteria in computed tomography, magnetic resonance imaging (MRI), and magnetic resonance angiography, we developed a staging system to classify ELST in a series of seven consecutive patients in an attempt to custom-tailor the surgical approach. Type A referred to tumours that were locally confined without temporal bone erosion or infiltration of the dura (n = 2); type B tumours showed evidence of bone infiltration of the osseous labyrinth and sensorineural hearing loss (n = 2); and in type C, the tumour further invaded the sigmoid sinus and jugular bulb (n = 3). Two patients suffered from VHL disease.

RESULTS

In all patients, the tumour was completely removed. Stage-adapted surgical approaches included various transpetrosal procedures, from the translabyrinthine to the infratemporal approaches. The functional integrity of the facial nerve was maintained in all tumour stages, whereas the vestibulocochlear nerve could be preserved only in patients with type A tumours. Follow-up MRI demonstrated no local tumour recurrence during a postoperative observation period ranging from 4 to 38 months.

CONCLUSION

Stage-based surgical strategy enables the complete removal of ELST with minor morbidity. Transmastoid approaches are most efficient for resection of the tumour matrix to prevent local recurrence.

Delayed Facial Nerve Palsy After Otologic Surgery

Delayed facial nerve palsy (DFP) is rarely experienced after otologic surgeries that do not directly touch the facial nerves, such as tympano-mastoidectomy, cochlear implants, and stapes surgery, and is troublesome to both surgeons and patients if it happens. Here, we report 7 cases of DFP, including one case that developed DFP after endolymphatic sac surgery. The ratios of occurrence were as follows: 0.7% (2/305) for tympano-mastoidectomy, 0.8% (3/354) for cochlear implant, 0.4% (1/260) for stapes surgery and 1.0% (1/98) for endolymphatic sac surgery. All otologic surgeries, except for endolymphatic sac surgery, exposed the chorda tympani, and all surgeries, except for stapes surgery, underwent drilling for a mastoidectomy. Furthermore, DFP was always observed ipsilaterally to the operated ear after otologic surgeries and was never seen after benign parotid tumor surgery or total laryngectomy. Therefore, there may be a strong relationship between DFP and the procedures, used during otologic surgeries.

Endolymphatic sac tumor metastatic to the spine

✓ Endolymphatic sac tumors (ELSTs) are aggressive papillary lesions of the temporal bone. Although histologically benign, they may exhibit invasive growth and destruction of the skull base. Patients generally present with symptoms referable to the lesion's location within the middle or posterior cranial fossa. Although well characterized as a distinct entity, ELSTs involved in metastatic dissemination have never been reported. In the present report the authors describe a case of ELST metastatic to the spine treated with resection.

Tumors of the endolymphatic sac in patients with von Hippel-Lindau disease: implications for their natural history, diagnosis, and treatment

OBJECT

Endolymphatic sac tumors (ELSTs), which often are associated with von Hippel-Lindau (VHL) disease, cause irreversible hearing loss and vestibulopathy. Clinical and imaging surveillance protocols provide new insights into the natural history, mechanisms of symptom formation, and indications for the treatment of ELSTs. To clarify the uncertainties associated with the pathophysiology and treatment of ELSTs, the authors describe a series of patients with VHL disease in whom serial examinations recorded the development of ELSTs.

METHODS

Patients with VHL disease were included if serial clinical and imaging studies captured the development of ELSTs, and the patients underwent tumor resection. The patients' clinical, audiological, and imaging characteristics as well as their operative results were analyzed. Five consecutive patients (three men and two women) with a mean age at surgery of 34.8 years and a follow-up period of 6 to 18 months were included in this study. Audiovestibular symptoms were present in three patients before a tumor was evident on neuroimaging. Imaging evidence of an intralabyrinthine hemorrhage coincided with a loss of hearing in three patients. Successful resection of the ELSTs was accomplished by performing a retrolabyrinthine posterior petrosectomy (RLPP). Hearing stabilized and vestibular symptoms resolved after surgery in all patients. No patient has experienced a recurrence.

CONCLUSIONS

Audiovestibular symptoms, including hearing loss, in patients with VHL disease can be the result of microscopic ELSTs. Once an ELST has been detected, it can be completely resected via an RLPP with preservation of hearing and amelioration of vestibular symptoms. Early detection and surgical treatment of small ELSTs, when hearing is still present, should reduce the incidence and severity of hearing loss, tinnitus, vertigo, and cranial nerve dysfunction, which are associated with these tumors.

[Cochlear implant in a patient with dilatation of the endolymphatic sac and vestibular aqueduct]

We present an 8 years patient old with a giant dilatation of the vestibular aqueduct associated with profound and progressive bilateral sensorineural hearing loss. The patient received a cochlear implant and during the surgery a pulsatile clear fluid via the cochleostomy was observed, without gusher. We present all the problems, and offer some advices for this kind of surgery.

Surgical Treatment of Endolymphatic Sac Tumor With Adjunctive Stereotactic Radiation Therapy

A 44-year-old man presented with an endolymphatic sac tumor (ELST) associated with von Hippel-Lindau disease, which required four surgical procedures within 10 years. The earlier two surgeries resulted in only partial removal of the tumor because of vigorous intraoperative bleeding. Stereotactic radiation therapy was performed twice. The intraoperative bleeding was easy to control in the third operation, and ultimately the tumor was totally extirpated in the fourth operation. Histological examination of the tumor specimen harvested in the final surgery showed that the tumor cells had clearly decreased in number, and the interstitial tissue had become fibrous with organization of the tumor vessels, compared with the tumor specimen from the first surgery. Preoperative radiotherapy may be effective to reduce the devastating intraoperative bleeding of ELST.

[Endolymphatic sac adenocarcinoma: case report]

A case of endolymphatic sac adenocarcinoma is reported and the literature is reviewed. The clinical picture was presented by vertigo and progressive hearing loss caused by a tumor of the endolymphatic sac. The surgical removal was complete, via a retro and translabyrinthine approach. Endolymphatic sac tumors are locally invasive, involve the petrous bone and the mastoid. The radical surgery presents good outcome.

Review of the literature]

This report describes a patient with Von Hippel-Lindau disease revealed by an endolymphatic sac tumor. Endolymphatic sac tumor (EST) was only recently recognized as a manifestation of Von Hippel-Lindau (VHL) disease. EST are vascular lesions that destroy and expand bone. We report a recently treated case of an EST. A 30-year-old woman presented with otalgia and hearing loss. Computed tomography and magnetic resonance imaging showed typical features of an EST. We checked for VHL and found this disease in the patient. VHL disease is a hereditary cancer syndrome caused by germline mutations of the VHL tumor suppressor gene. A molecular diagnosis of VHL is nowadays available, and this has change the clinical management of patients and their families. Diagnosis of VHL has to be suspected in patients with a VHL-related tumor without familial history and especially in those cases of hemangioblastoma or endolymphatic sac tumors. Such patients should be systematically investigated for clinical and molecular evidence of VHL disease.

Expression of inducible nitric oxide synthase (iNOS/NOS II) in the hydropic vestibule after injection of keyhole limpet hemocyanin into the endolymphatic sac of guinea pigs

This study was undertaken to examine the expression of inducible nitric oxide synthase (iNOS / NOS II) in the hydropic vestibule of guinea pigs. Animals were systemically sensitized with 500 microg of keyhole limpet hemocyanin. Two weeks after the first injection, keyhole limpet hemocyanin (100 microg/5 microl) was injected into the endolymphatic sac following the intradural approach, and the next day temporal bones were removed for the immunohistochemical examination. Endolymphatic hydrops was evidenced by the expansion of the Reissner's membrane in the cochlea after direct injection of keyhole limpet hemocyanin into the endolymphatic sac. Inducible nitric oxide synthase expression was increased in the sensory cells, supporting cells and vestibular ganglion cells, while temporal bones, where only phosphate buffered saline was injected, did not show any inducible nitric oxide synthase immunoreactivity. High levels of inducible nitric oxide synthase-catalyzed nitric oxide were detected prior to the development of the inner ear dysfunction. Our results suggest that the occurrence of inducible nitric oxide synthase immunoreactivity parallels the inner ear disturbance as seen in endolymphatic hydrops.

MR imaging, CT, and angiography features of endolymphatic sac tumors: report of two cases

Low-grade adenocarcinoma of endolymphatic sac origin is a rare tumor of the temporal bone. There are some difficulties in its differential diagnosis from other vascular and non-vascular tumors of the temporal bone. However its radiological differentiation from other tumors of the temporal bone is important for surgical planning. We present a report on two endolymphatic sac tumors with some specific radiological findings which can support a correct diagnosis.

Extraosseous endolymphatic sac low-grade adenocarcinoma mimicking posterior fossa meningioma

Low-grade adenocarcinoma arising from the endolymphatic sac is an uncommon tumor that is characterized clinically by hearing loss and radiologically by temporal bone destruction. The authors report a case of low-grade adenocarcinoma of endolymphatic sac origin that mimicked a posterior fossa meningioma in both clinical and neuroimaging examinations. In this case, the most unusual and interesting feature was the lack of auditory symptoms and temporal bone destruction. The lesion occurred in a 21-year-old man who presented with headaches that had been increasing in frequency for 6 months and was associated with blurring of vision, diplopia, occasional nausea and vomiting, and gait disturbance. On examination, this patient exhibited bilateral papilledema, left sixth cranial nerve palsy, and gait ataxia. Neuroimaging studies revealed a large right posterior fossa tumor. At surgery, a hemorrhagic papillary adenocarcinoma of endolymphatic sac origin was found.

[Retraction of the endolymphatic membranes in temporal bones of the Wittmaack and Tufts collections]

BACKGROUND

In histologic studies, the volumetric status of the intralabyrinthine fluids is judged by the position of the endolymphatic membranes. Bulging of the membranes, commonly known as endolymphatic hydrops, is assumed to be caused by excess of endolymph. The opposite situation, retraction of the membranes is, however, only incidentally described and relatively little attention has been paid to its significance. Almost one hundred years ago Wittmaack described retraction of the endolymphatic membranes, which has since been considered to be preparation artifact--a concept that essentially remains unchallenged. To test the validity of this long premise, we examined two sets of temporal bones from different centers.

MATERIAL AND METHODS

We studied the following collections: 1. The Wittmaack collection in Hamburg, Germany. The original material of 67 temporal bones (patient ages 0-92 years, average age 35.2 years) on which Wittmaack based his opinions. 2. For comparison and to exclude age related phenomena, 125 temporal bones from 73 children between the ages newborn to ten years (average age 13.4 months, median 1.5 months) from the temporal bone collection of the Department of Otolaryngology Tufts University School of Medicine. All specimens were studied by light microscopy. Retraction was defined as depression of Reissner's membrane toward the stria vascularis and the Organ of Corti in more than one cochlear turn and was graded into mild, moderate and severe. Additionally the saccule, utricle and semicircular ducts were examined for collapse.

RESULTS

The reevaluation of the 67 temporal bones described by Wittmaack, including those of 7 children below the age of 10 years, showed retraction of Reissner's membrane in 81% compared to 33% of the temporal bones from the Tufts collection. In contrast to the high incidence of retraction in the cochlear duct, fewer saccules (12%) and utricles (4%) were collapsed in the Tufts collection. In the Wittmaack collection no significant differences between the underlying diseases were found, however in the Tufts collection the group of children who suffered from extracochlear infections and malignancies had a higher frequency of retraction.

CONCLUSION

Mild retraction might be to some extent physiologic or even artifactual. Severe retraction, however, is a definitive finding that is a part of a local or regional otopathologic process. Of material, it is quite possible that Wittmaack's original observations of what he called "hypotonic collapse" was of viral origin (viruses were not known during Wittmaack's time), ototoxicity or even of genetic origin.

Somatic von Hippel-Lindau gene mutations detected in sporadic endolymphatic sac tumors

Endolymphatic sac tumors (ELSTs) occur sporadically or in association with an autosomal dominantly inherited tumor syndrome, von Hippel-Lindau (VHL) disease. In VHL disease, a germline mutation of the VHL tumor suppressor gene is inherited, and loss of function of the wild-type allele occurs through genetic deletion with subsequent development of neoplastic growth. Genetic alterations associated with sporadic ELSTs are less well understood. In this study, we used tissue microdissection to selectively analyze neoplastic cells from four sporadic ELSTs. In two cases, we detected somatic mutations involving VHL gene exons 1 and 2, respectively. Additionally, one of these cases revealed deletion of the VHL gene locus. Two cases did not reveal VHL gene mutation; one of these two cases showed VHL gene deletion. These results suggest that mutations and allelic deletions of the VHL tumor suppressor gene play a role in the tumorigenesis of sporadic ELSTs.

[Endolymphatic sac tumors]

Tumors of the endolymphatic sac are rare and can be found in patients with Von Hippel Lindau disease. They most often develop within the intrapetrosal part of the sac but can sometimes be located in the distal part. Their growth is slow and they spread in two directions: laterally toward the external and middle ear and in the direction of the jugular foramen and medially into the ponto-cerebellar angle. The symptoms are usually auditive, with a constant neurosensorial deafness of sudden onset in 50 % of cases and sometimes associated with a tinnitus and dizziness. The varieties with medial extension result in a cerebellopontine angle syndrome. Diagnosis is made by imaging (CT scan and MRI) that reveals a heterogeneous tumor between the lateral sinus and the internal auditory meatus, hypervascularized showing contrast, with cystic zones and associated with bone lysis. Histological examination of a papillary cystadenoma is performed and the differential diagnosis is essentially made with a papillary of the choroïd plexus. They require total surgical excision in order to avoid possible recurrence and can be performed by retrosigmoïd approach, or more ideally, by transpetrosal approach.

Central nervous system hemangioblastomas, endolymphatic sac tumors, and von Hippel-Lindau disease

Von Hippel-Lindau disease (VHL) is a hereditary cancer syndrome caused by germline mutations of the VHL tumor suppressor gene. Major progress has been made in the last decade in both clinical and fundamental aspects of VHL. The VHL gene product, pVHL, has major and multiple functions: pVHL regulates not only first angiogenesis but also extracellular matrix formation and the cell cycle. A molecular diagnosis of VHL is now available, leading to a transformation in clinical management of patients and their families. Diagnosis of VHL has to be suspected in patients with a VHL-related tumor without familial history and especially in case of hemangioblastoma or endolymphatic sac tumors. Such patients should be systematically investigated for clinical and molecular evidence of VHL disease. Treatment of symptomatic hemangioblastomas remains mainly neurosurgical, often in emergency, but stereotactic radiosurgery is emerging as an alternative therapeutic procedure. In the future, antiangiogenic drugs could represent a potential medical treatment of CNS hemangioblastomas in view of their highly vascular structure. Lastly, visceral manifestations of VHL disease are also of critical importance and require early detection for effective treatment.

Inner ear transgene expression after adenoviral vector inoculation in the endolymphatic sac

Gene transfer has been performed in a variety of organs. In the mammalian inner ear, viral vectors have been used to introduce exogenous reporter genes via the scala tympani into the cochlea. While scala tympani inoculation is clinically feasible, it is not without risks. Moreover, transgene expression has so far been restricted to the cochlear tissues in the perilymphatic spaces that are contiguous with the scala tympani. To achieve gene transfer of vestibular organs and cells surrounding the endolymphatic space, and to extend the clinical utility of inner ear gene therapy, we developed a new surgical approach for vector inoculation. A replication-deficient adenoviral vector, Ad.RSVntlacZ, was injected into the guinea pig endolymphatic sac. A large number of blue (LacZ-positive) cells was observed in the endolymphatic sac and duct, the vestibule, and the ampulla. Blue cells were also detected in the cochlea, mainly in cells bordering the endolymphatic space: marginal cells in the stria vascularis and supporting cells in the organ of Corti. These findings indicate that inoculation of viral vectors into the endolymphatic sac can provide efficient gene transfer into a variety of cell types that are not accessible via scala tympani inoculation.

Bilateral endolymphatic sac papillary carcinoma

We report a case of bilateral and almost symmetrical endolymphatic sac papillary adenocarcinoma. A 22-year-old male patient presented with bilateral sixth, seventh, eighth and lower cranial nerve paresis and ataxia. Radiological investigations revealed extensively vascular tumours in the region of both jugular bulbs. The literature on this rare entity is briefly discussed.

Endolymphatic sac tumors: report of three cases

OBJECTIVE AND IMPORTANCE

We present three cases of endolymphatic sac tumors and review the previously published cases. Despite frequent extension to the cerebellopontine angle, these rare tumors have only recently been recognized by neurosurgeons.

CLINICAL PRESENTATION

A 26-year-old man developed a progressive hearing loss, revealing an intrapetrous retrolabyrinthine tumor on the right side. A 28-year-old woman experienced a left cerebellopontine angle syndrome, with a lytic intrapetrous mass extending into the cerebellopontine angle. A 38-year-old woman presented with an intracranial hypertension syndrome caused by a tumor of the jugular foramen.

INTERVENTION

For the first and second patients, the tumors originated from the operculum of the endolymphatic sac. Total removal was achieved, via a transpetrosal approach, in these two cases. No recurrence was detected after a 20-month follow-up period. For the third patient, the tumor originated from the distal part of the sac. Recurrence was observed 8 years after subtotal removal via a retrosigmoid route. Histological analysis revealed a papillary-cystic adenocarcinomatous pattern in all cases, without features of aggressiveness.

CONCLUSION

Endolymphatic sac tumors are locally invasive neoplasms characterized by bipolar intrapetrous and posterior fossa involvement. The anatomic complexity of the endolymphatic sac may explain the distinct patterns of extension of these tumors. Early radical surgery is related to good outcomes.

von Hippel-Lindau disease

von Hippel-Lindau disease is a hereditary cancer syndrome characterized by the development of vascular tumors of the central nervous system and retina, clear cell renal carcinomas, pheochromocytomas, pancreatic islet cell tumors, endolymphatic sac tumors, and benign cysts affecting a variety of organs. VHL disease is caused by germline mutations of the von Hippel-Lindau tumor suppressor gene located on chromosome 3p25. Tumor development in this setting is due to inactivation or loss of the remaining wild-type allele in a susceptible cell. The highly vascular nature of VHL-associated neoplasms can be understood in light of the recent finding that the VHL gene product (pVHL) inhibits the accumulation of hypoxia-inducible mRNAs, such as the mRNA encoding vascular endothelial growth factor (VEGF), under normoxic conditions. This property of pVHL appears to be linked to its ability to bind to complexes containing elongin B, elongin C, and cullin 2 (Cul2). Elongin C and Cul2, based on their homology with Skp1 and Cdc53, respectively, are suspected of targeting certain proteins for covalent modification with ubiquitin and hence for degradation. One model, which remains to be tested, is that the binding of pVHL to elongins B/C and Cul2 affects the ubiquitination of RNA-binding proteins that regulate the stability of hypoxia-inducible mRNAs.