Whole-brain monosynaptic outputs and presynaptic inputs of GABAergic neurons in the vestibular nuclei complex of mice.

GABAergic neurons in the vestibular nuclei (VN) participate in multiple vital vestibular sensory processing allowing for the maintenance and rehabilitation of vestibular functions. However, although the important role of GABA in the central vestibular system has been widely reported, the underlying neural circuits between VN GABAergic neurons and other brain functional regions remain elusive, which limits the further study of the underlying mechanism. Hence, it is necessary to elucidate neural connectivity based on outputs and inputs of GABAergic neurons in the VN. This study employed a modified rabies virus retrograde tracing vector and cre-dependent adeno-associated viruses (AAVs) anterograde tracing vector, combined with a transgenic VGAT-IRES-Cre mice, to map the inputs and outputs of VN GABAergic neurons in the whole brain. We found that 51 discrete brain regions received projections from VN GABAergic neurons in the whole brain, and there were 77 upstream nuclei innervating GABAergic neurons in the VN. These nuclei were mainly located in four brain regions, including the medulla, pons, midbrain, and cerebellum. Among them, VN GABAergic neurons established neural circuits with some functional nuclei in the whole brain, especially regulating balance maintenance, emotion control, pain processing, sleep and circadian rhythm regulation, and fluid homeostasis. Therefore, this study deepens a comprehensive understanding of the whole-brain neural connectivity of VN, providing the neuroanatomical information for further research on the neural mechanism of the co-morbidities with vestibular dysfunction.

Modified Translabyrinthine Approach for Massive Petrous Bone Cholesteatoma Removal and Cochlear Preservation Using Latent Spaces Anterior to the Cochlea.

OBJECTIVE: Microsurgery is the reference standard treatment of petrous bone cholesteatoma (PBC). In most cases, radical removal of an extensive PBC can only be achieved at the cost of sacrificing the cochlea. Such treatment will result in the impossibility of future cochlear implantation for hearing rehabilitation purposes. To address this issue, a modification of the traditional translabyrinthine (TL) approach with endoscopic assistance has been developed for radical removal of extensive PBC with preservation of the cochlea. METHODS: From June 2017 to December 2017, 3 patients with a massive PBC underwent surgical removal using the modified TL approach by the senior author in our department. We reviewed the patient characteristics and retrospectively studied the surgical outcomes and postoperative complications. In the present report, we have described our modified TL approach in detail. RESULTS: Complete resection of the PBC and successful cochlea preservation were achieved in all 3 patients. No recurrence had developed during the follow-up period. However, various degrees of cochlear ossification were observed in 2 patients postoperatively. CONCLUSIONS: This modified TL approach provides the possibility of fully exposing the whole petrous apex without removing the cochlea in selected cases. However, the development of long-term cochlear ossification requires further investigation to allow for successful cochlear implantation.

Petrous bone cholesteatoma: our experience of 51 patients with emphasis on cochlea preservation and use of endoscope.

Background: Petrous bone cholesteatoma (PBC) is a rare but local aggressive lesion which can lead to severe complications. Surgery is the mainstay for its treatment. Objectives: To analyse the clinical characteristics and surgical outcomes in a series of patients with PBC, paying special attention to cochlea preservation and use of endoscope. Materials and methods: Retrospective study of 51 patients with PBC who underwent surgery at our centre. Results: Hearing loss (72.5%) and facial paralysis (58.8%) were the two most common symptoms. According to Sanna's classification, supralabyrinthine subtype (51.0%) was the most common subtype, followed by the massive subtype (33.3%). In most patients, PBC was radically removed using subtotal petrosectomy (80.4%). Endoscope was used for assistance in six cases. Various managements of facial nerve were used in different cases. Hearing rehabilitation was not emphasized (44 postoperative dead ear); however, cochlea was preserved as far as possible (45.3%). Recurrence was identified in five patients by MRI with diffusion weighted imaging (DWI) sequence. No recurrence was detected in patients underwent surgery with endoscope assistance. Conclusions and significance: radical excision and functional reconstruction constitute the framework of PBC surgery. Cochlea preservation is critical for possible cochlear implantation in the future. Use of endoscope has the potential to enhance surgical precision and reduce recurrence.

Neurorrhaphy for Facial Reanimation with Interpositional Graft: Outcome in 23 Patients and the Impact of Timing on the Outcome.

OBJECTIVE: Neurorrhaphy with interpositional graft is a practical technique to achieve facial reanimation when the continuity of the facial nerve is interrupted and a large gap between the proximal and distal stump exists. The aim of this study was to report long-term outcomes of neurorrhaphy for facial reanimation with interpositional graft. The roles of some variable factors in the outcome of neurorrhaphy with interpositional graft were also evaluated and compared. METHODS: A retrospective case series from a single tertiary referral center comprised 23 patients with facial nerve interruptions who underwent neurorrhaphy with interpositional graft using either end-to-end anastomosis or end-to-side hypoglossal-facial technique. Preoperative data (age, sex, primary lesion, interval from paralysis to surgery, facial nerve function), intraoperative data (surgical approach, graft and type of neurorrhaphy), and postoperative data (facial nerve function) were collected and analyzed. RESULTS: Mean follow-up time was 26.6 ± 11.9 months. Patients who underwent neurorrhaphy for facial reanimation within 1 year after onset of facial paralysis were more likely to achieve House-Brackmann grade ≤3 compared with patients who underwent neurorrhaphy >1 year after onset of facial paralysis (odds ratio = 23.85, P = 0.04). No other factors were associated with improved outcomes. CONCLUSIONS: Early neurorrhaphy with interpositional graft (≤1 year) for facial reanimation resulted in better final facial nerve function outcomes compared with a delayed procedure.

Cerebrospinal fluid otorrhea secondary to congenital inner ear dysplasia: diagnosis and management of 18 cases.

OBJECTIVE: To describe the characteristics of the clinical presentation, diagnosis, surgical methods, and outcomes of patients with otogenic cerebrospinal fluid (CSF) leakage secondary to congenital inner ear dysplasia. METHODS: A retrospective review was performed of 18 patients with otogenic CSF leakage secondary to inner ear dysplasia who underwent surgery in our group from 2007 to 2017 and had a follow-up of at least 4 months. The average length of follow-up was three years. The characteristics of the clinical presentations of all patients, such as self-reported symptoms, radiographic findings, surgical approaches and methods of repair, position of the leakage during surgery, and postoperative course, including the success rate of surgery, are presented. RESULTS: The patients presented mostly with typical symptoms of meningitis, severe hearing impairment, and CSF otorrhea or rhinorrhea. All 18 patients had at least one previous episode of meningitis accompanied by a severe hearing impairment. The preoperative audiograms of 17 patients showed profound sensorineural hearing loss, and one patient had conductive hearing loss. Twelve patients presented with an initial onset of otorrhea, and two had accompanying rhinorrhea. Six patients complained of rhinorrhea, two of whom were misdiagnosed with CSF rhinorrhea and underwent transnasal endoscopy at another hospital. High-resolution computed tomography (HRCT) images can reveal developments in the inner ear, such as expansion of a vestibular cyst, unclear structure of the semicircular canal or cochlea, or signs of effusion in the middle ear or mastoid, which strongly suggest the possibility of CSF otorrhea. The children in the study suffered more severe dysplasia than adults. All 18 patients had CSF leakage identified during surgery. The most common defect sites were in the stapes footplates (55.6%), and 38.9% of patients had a leak around the oval window. One patient had a return of CSF otorrhea during the postoperative period, which did not re-occur following a second repair. CONCLUSIONS: CSF otorrhea due to congenital inner ear dysplasia is more severe in children than in adults. The most common symptoms were meningitis, hearing impairment, and CSF otorrhea or rhinorrhea. HRCT has high diagnostic accuracy for this disease. The most common fistula site was around the oval window, including the stapes footplates and the annular ligament.

Preliminary study on the mechanism underlying the interaction of balance dysfunction and anxiety disorder.

This study aims to explore the anxiety-related behavioral changes and the concentration alterations of monoamine neurotransmitters in balance/anxiety-related nuclei of intratympanic gentamicin (GT)-induced balance disorder models. GT was administrated intratympanically in the adult male Sprague-Dawley rats to establish the vestibular impaired animal model. Rotarod was applied to test the vestibular function, and elevated plus maze and open field test were harnessed to evaluate the anxiety level. Monoamines and their metabolites were assayed by high-performance liquid chromatography. Rotarod test revealed that 6 days after GT administration, the average latency decreased significantly compared with the control group. Three days after GT administration, the travel distance and the central zone time obtained from open field and the duration of open arm stay and the times of open arm entries from elevated plus maze were apparently lower than those of the control group, whereas no significant differences were noted between 2-week group and the control group. Three days after GT administration, the concentration of norepinephrine (NE) and 5-hydroxyindoleacetic acid (5-HIAA) within medial vestibular nucleus (MVN); the concentration of NE, serotonin (5-HT), and 5-HIAA within locus coeruleus (LC); and the concentration of NE, 5-HT, 5-HIAA, and 3,4-dihydroxyphenylacetic acid within dorsal raphe nucleus (DRN) increased significantly compared with the control group. Two weeks after the administration, the concentrations of part of the neurotransmitters were lower than those of the 3-day group, indicating the rapid activation and slow deactivation of MVN-LC and MVN-DRN pathways. Vestibular impairment could lead to elevated anxiety level. The elevated anxiety levels might be attributed to increased monoamine concentrations within MVN, LC, and DRN.

Quantitative Analysis of Psychiatric Disorders in Intractable Peripheral Vertiginous Patients: A Prospective Study.

OBJECTIVE: To investigate the correlation between psychological disorder and vestibular dysfunction in patients suffering from intractable peripheral vertigo. STUDY DESIGN: Prospective study. SETTING: In-patients in a university hospital. METHODS: Prospective design of 26 intractable peripheral vertiginous patients with peripheral vestibular dysfunction and 20 controls recruited from the EENT hospital. Hospital Anxiety and Depression scale, Self-rating Anxiety scale, Self-rating Depression scale, Symptom Checklist-90 were used in this study. All vertigo patients received intratympanic gentamicin/dexamethasone administration or endolymphatic sac decompression. Pre- and posttreatment scores were collected and compared. All the results were statistically analyzed using Stata 8.0. t test or rank-sum test and paired-sample t test or rank-sum test were performed. RESULTS: The outcomes of Hospital Anxiety and Depression scale, Self-rating Anxiety scale, Self-rating Depression scale, Symptom Checklist-90 were significantly greater in vertiginous group than that in normal controls (p < 0.05). The pretreatment scores of these four scales were greater than the posttreatment scores in vertiginous patients, especially in Class A and B groups (p < 0.05). The scores of more scales were demonstrated to be statistically different in patients with over 5 years of the disorder and among patient in stages 1 to 3 than in stage 4 (p < 0.05). No significant difference was noted between male and female participants in all the questionnaires used (p > 0.05). CONCLUSION: Increased anxiety/depression levels were noted in peripheral vertiginous patients compared with normal controls through psychiatric questionnaires, and then a significant decrease after the effective treatment of vertigo, suggesting that vertigo attack may contribute to psychological dysfunction. The intervention seemed to be more effective in lowering anxiety/depression levels among patients in earlier stage of Ménière's disease marked by pure-tone audiometry results.

Preclinical and clinical studies of unrelieved aural fullness following intratympanic gentamicin injection in patients with intractable Ménière's disease.

OBJECTIVE: To clarify whether gentamicin affects vestibular dark cells in guinea pigs and relieves patients of aural fullness with intractable Ménière's disease following intratympanic administration. MATERIALS AND METHODS: Purified gentamicin-Texas Red (GTTR) was injected intratympanically in guinea pigs that were sacrificed at 1, 3, 7, 14 and 28 days. GTTR uptake was examined in hair cells, and transitional cells and dark cells in vestibular end-organs were examined. Specific attention was paid to its distribution in dark cells under confocal microscopy, and the ultrastructure of dark cells using electron microscopy, following intratympanic injection. RESULTS: Dark cells in the semicircular canals showed weak GTTR uptake at 1, 3, 7, 14 and 28 days after intratympanic injection, with no significant differences at various time points after injection. However, the adjacent transitional cells demonstrated intense GTTR uptake that was retained for at least 28 days. Ultrastructural studies demonstrated negligible characteristics associated with apoptosis or necrosis in these dark cells. The tight junctions between dark cells showed no signs of disruption at 7 or 28 days after injection. CONCLUSION: Intratympanic gentamicin has little direct impact on vestibular dark cells. CLINICAL APPLICATION: A modified low-dose titration intratympanic approach was used in 29 patients with intractable vertigo and the clinical outcomes were followed. Aural fullness following intratympanic gentamicin injection was not relieved based on our subjective scales, demonstrated by no statistically significant difference between preinjection (4.16 ± 3.08) and postinjection (3.58 ± 2.93; p > 0.05) aural fullness scores. Vertigo control was achieved in 88% of patients, with hearing deterioration identified in 16% of patients. Intratympanic gentamicin administration might not lead to relief of aural fullness in patients with intractable vertigo, although it can achieve a high vertigo control rate with some cochleotoxicity.

Surgical outcomes of 43 cases with adenoid cystic carcinoma of the external auditory canal.

PURPOSE: To evaluate surgical outcomes for adenoid cystic carcinoma (ACC) of the external auditory canal (EAC). METHODS: Forty-three patients with ACC of the EAC in Eye and ENT Hospital of Fudan University were analyzed retrospectively for survival. The patients were staged according to the modified Pittsburgh staging system. Thirteen patients with T1 stage underwent local resection (LR), 6 patients with T1 stage underwent lateral temporal bone resection (LTBR), and 8 patients with T1 stage underwent LTBR including superficial parotidectomy (SP). Two patients with T2 stage underwent LTBR, and 1 patient with T2 stage underwent LTBR+SP. Three patients with T3 stage underwent LTBR. One patient with T4 stage underwent LTBR, two patients with T4 stage underwent subtotal temporal bone resection (STBR), and 7 patients with T4 stage underwent LTBR+SP. RESULTS: Of all patients that underwent surgery, 13 died of their primary cancers during the follow-up time. The 5-year survival rates of patients with T stages 1 through 4 were 85%, 67%, 67%, and 30%, respectively. There was statistically significant difference in 5-year survival rate between T1 and other stages (T2, T3, T4) using the log-rank test (p<0.05). There was significant difference in 5-year survival rate between T4 and other stages using the log-rank test (p<0.05). The 5-year survival rates after LR, LTBR or LTBR plus SP for T1 were 77%, 87% and 100%, respectively. The 5-year survival rates after LTBR, STBR or LTBR plus SP for T4 were 0%, 50% and 29%, respectively. The 5-year survival rates for 19 patients with clear surgical margins and 24 patients with positive margins were 89% and 54%, respectively. The 5-year survival rates of patients with radiotherapy and without radiotherapy were 62% and 86%, respectively. CONCLUSION: An en bloc resection including superficial parotidectomy is favored in an effort to produce negative surgical margins for ACC of the EAC. Adjunctive radiotherapy is used for patients with positive margins and in advanced lesions.

Temporal and spatial distribution of gentamicin in the peripheral vestibular system after transtympanic administration in guinea pigs.

BACKGROUND AND OBJECTIVE: Transtympanic administration of gentamicin is effective for treating patients with intractable vertigo. This study explored the spatial and temporal distribution of gentamicin in vestibular end-organs after transtympanic administration. METHODS: Thirty guinea pigs were transtympanically injected with gentamicin conjugated to Texas Red (GTTR) and their vestibular end-organs examined after various survival periods. Another 9 guinea pigs received GTTR at different doses. Nine animals received Texas Red only and served as controls. We used confocal microscopy to determine the cellular distribution of GTTR in semicircular canal cristae, as well as the utricular and saccular maculae. RESULTS: The most intense GTTR labeling was present in the saccule compared to other vestibular end-organs. GTTR fluorescence was detected predominantly in type I hair cells, type II hair cells and transitional cells after a single transtympanic dose of GTTR (0.1 mg/ml, 0.05 ml), while only weak fluorescence was observed in non-sensory cells such as supporting cells, dark cells and lumenal epithelial cells. Transitional cells displayed intense GTTR fluorescence in the supra-nuclear regions 24 h after transtympanic injection that was retained for at least 4 weeks. A decreasing spatial gradient of GTTR fluorescence was observed sensory epithelial regions containing central type I to peripheral type I and then type II hair cells in the crista ampullaris, and from striolar to extra-striolar hair cells within the vestibular macula. GTTR fluorescence extended from being restricted to the apical cytoplasm at lower doses to the entire cell body of type I hair cells with increasing dose. GTTR fluorescence reached peak intensities for individual regions of interest within the cristae and maculae between 3 and 7 days after transtympanic injection. CONCLUSION: The saccular uptake of GTTR is greater than other vestibular end-organs after transtympanic injection in the semicircular canals.

Labyrinthine sequestrum: four case studies.

Labyrinthine sequestrum, a rare form of labyrinthitis, is highly distinct from the more commonly encountered labyrinthitis ossificans based on its unique clinical, radiologic, and histologic characteristics. The study included 4 such patients who had undergone clinical and laboratory investigations, computed tomography (CT), and magnetic resonance imaging (MRI) assessments followed by surgical procedures and pathological evaluation. Their major symptoms were otorrhea, otalgia, tinnitus, and profound hearing loss. Imaging studies showed an osteolytic soft mass with calcified debris in the inner ear, and the bony labyrinth was eroded partly or completely by granulation mass, with loss of bony morphology. Further pathological examination was coincident with inflammatory granulation tissue with some calcification or osseous tissue. The disease process is attributed to chronic osteomyelitis due to the presence of osteonecrosis. Prompt CT and MRI examinations and optimal therapeutic management facilitate definitive diagnosis and protect against fatal complications.

Uptake of gentamicin by vestibular efferent neurons and superior olivary complex after transtympanic administration in guinea pigs.

Transtympanic administration of gentamicin is a widely accepted and effective approach for treating patients with intractable vertigo. Previous studies have demonstrated the uptake, distribution and effects of gentamicin in peripheral vestibular and cochlear structures after transtympanic injection. However, little is known about whether transtympanically administered gentamicin is trafficked into more central auditory and vestibular structures and its effect on these structures. In this study, we used immunofluorescence to determine the distribution of gentamicin within the auditory and vestibular brainstem. We observed gentamicin immunolabeling bilaterally in the vestibular efferent neurons, and in the superior olivary complex, and ipsilaterally in the cochlear nucleus 24h after transtympanic administration of gentamicin, and that the drug could still be detected in these locations 30 days after injection. In contrast, no gentamicin labeling was detected in the vestibular nuclear complex. In the vestibular efferent neurons and superior olivary complex, gentamicin labeling was detected in the cytoplasm and cell processes, while in the cochlear nucleus gentamicin is mainly localized outside and adjacent to the cell bodies of neurons. Nerve fibers in cochlear nucleus, root of eighth nerve, as well as descending pathways from the superior olivary complex, are also immunolabeled with gentamicin continuously. Based on these data, we hypothesize that retrograde axonal transport of gentamicin is responsible for the distribution of gentamicin in these efferent nuclei including vestibular efferent neurons and superior olivary complex and anterograde axonal transport into the ipsilateral cochlear nucleus.

The relationship between age-related hearing loss and synaptic changes in the hippocampus of C57BL/6J mice.

To explore the relationship between age-related hearing loss (presbycusis) and synaptic degeneration in the hippocampal CA3 region of C57BL/6J mice, we investigated both cognitive performance and synaptic changes within the hippocampus of C57BL/6J mice from three age groups of 6-8, 24-26, and 42-44 weeks; CBA/CaJ mice served as controls. The auditory brainstem response was used as a measure of hearing threshold, and cognitive behavior was evaluated using the Morris water maze. The ultrastructure of synapses was observed with transmission electron microscopy, and the quantity and distribution of the synaptic markers synaptophysin and PSD-95 were observed with immunohistochemistry. The hearing threshold of C57BL/6J mice was significantly higher at 24-26 weeks than at 6-8 weeks, and hearing loss was profound at 42-44 weeks. This was accompanied by progressive degeneration of synapses within the auditory cortex. In contrast, the hearing threshold of CBA/CaJ mice was relatively unchanged at 24-26 weeks of age, and these mice developed only mild hearing loss at 42-44 weeks of age. Interestingly, C57BL/6J, but not CBA/CaJ mice clearly exhibited both decreased performance in the Morris water maze and degeneration of synapses within the hippocampus. We therefore conclude that age-related hearing loss is accompanied by the degeneration of synapses in the hippocampal CA3 region of C57BL/6J mice.

Survival outcomes in surgical treatment of 72 cases of squamous cell carcinoma of the temporal bone.

OBJECTIVE: To evaluate surgical outcomes for squamous cell carcinoma of the temporal bone. STUDY DESIGN: Retrospective study. SETTING: Eye and ENT Hospital. METHODS: Seventy-two patients with squamous cell carcinoma of the temporal bone were analyzed for survival. The patients were staged according to the modified Pittsburgh staging system. Five patients with T1 cancers underwent local resection (LR), and 10 patients with T1 cancers underwent lateral temporal bone resection (LTBR). Two patients with T2 cancers underwent LR, and 1 patient with T2 cancer underwent LTBR. One patient with T3 cancer underwent LR, 8 patients with T3 cancers underwent LTBR, and 10 patients with T3 cancers underwent subtotal temporal bone resection (STBR). Ten patients with T4 cancers underwent LTBR, and 25 patients with T4 cancers underwent STBR. RESULTS: Of all patients that underwent surgery, 18 died of their disease during the follow-up time. The 5-year survival rates of patients with T stages 1 through 4 were 100%, 67%, 21%, and 14%, respectively. There was no statistically significant difference in 5-year survival rate between T3 and T4 using the log-rank test (p > 0.05). The 5-year survival rates after LTBR and STBR for T3 were 26% and 16% (p > 0.05), respectively, and those for T4 were 17% and 11% (p > 0.05), respectively. CONCLUSION: An en bloc resection is favored in an effort to produce negative surgical margins for squamous cell carcinoma of the temporal bone. Adjunctive radiotherapy is used for advanced lesions.

Another etiology for vertigo due to idiopathic lateral semicircular canal bony defect.

Superior semicircular canal dehiscence syndrome (SSCDS) is a set of symptoms, related to vestibular and/or auditory, which dues to a dehiscence of bone at the superior semicircular canal. We reported an extremely rare case with idiopathic bony dehiscence at the lateral semicircular canal, which presents the similar symptoms with SSCDS, and performed a pertinent literature review. A 76-year-old male patient complained experiencing vertigo and autophony caused by loud noises, with a sign of horizontal eye movements for the stimuli of loud noise to his right ear. HRCT scanning presented a solitary 2.0mm bony defect at the right lateral semicircular canal. For a chief complaint of sound-/pressure-induced vertigo and/or oscillopsia and/or auditory symptoms, semicircular canal dehiscence syndrome should be considered. Then the doctor could presume the location of the dehiscence via the way of the oscillopsia. If the dehiscence lying the lateral semicircular canal, in clinical radiology, both axial and coronal images to be produced though the lateral semicircular canal plane in a parallel and perpendicular way should be carefully assessed for making diagnosis.

[Correlation between age-related hearing loss and impairment of cognition in C57BL/6J mice].

OBJECTIVE: To explore the correlation of age-related hearing loss and cognition impairment in C57BL/6J mice by observing hearing, cognitive function and synapses. METHODS: C57BL/6J and CBA/CaJ mice were divided into 3 groups. The hearing and cognitive functions of each animal was tested. And the ultrastructure of synapses was simultaneously observed for C57BL/6J mice. RESULTS: The 24-26-week-old C57BL/6J mice developed moderate hearing loss while the 42-44-week-old C57BL/6J counterparts suffered profound hearing loss. Whereas excellent hearing was maintained in 3 groups of CBA/CaJ mice within 44 weeks. During cognitive test, the performance of 42-44-week-old C57BL/6J mice was significantly worse than CBA/CaJ mice. During probe test, the number of platform crossing of 42-44-week-old C57BL/6J mice was smaller than that of CBA/CaJ mice (0.5 ± 0.6 vs 1.9 ± 1.6; P < 0.05). The 42-44-week-old C57BL/6J mice had a wider synaptic cleft and a thinner postsynaptic density than the 24-26-week-old C57BL/6J counterparts [synaptic cleft: (19.4 ± 0.5) nm vs (11.9 ± 0.7) nm; postsynaptic density: (15.2 ± 0.5) nm vs (27.8 ± 2.0) nm; both P < 0.05]. Furthermore, the degeneration of synapses in hippocampus CA3 area of C57BL/6J mice were clearly observed at 42 - 44 weeks of age, but not seen in CBA/CaJ mice. CONCLUSION: Age-related hearing loss might impact on the cognition impairment in C57BL/6J mice.

Use of the loud sound stimulation test in diagnosis of semicircular canal dehiscence syndrome.

Semicircular canal dehiscence (SCD) syndrome is rare, and its diagnosis is a significant challenge in clinical practice. Our aim was to explore application of the loud sound stimulation test for diagnosing SCD syndrome. Eight cases of superior semicircular canal dehiscence (SSCD), among them two patients had bilateral dehiscences and one case of lateral semicircular canal dehiscence (LSCD). A total of 11 dehiscences were studied retrospectively. Loud sounds (pure tones, 100 dB, 110 dB nHL) at frequencies of 500, 1,000, and 2,000 Hz were used to stimulate both ears for 5 s. A temporal bone computed tomography (CT) scan with semicircular canal reconstruction was performed in all patients. Vertigo was present in seven of nine cases following loud sound stimulation. In addition, the patient with LSCD demonstrated horizontal eye movement following loud sound stimulation, whereas six patients with SSCD showed rotational eye movement. Among them, two patients with bilateral superior canal dehiscence showed a positive response to the loud sound stimulation in only one ear. The diagnoses of all patients were confirmed with a high-resolution temporal bone CT with corresponding multi-planar reconstruction of the affected semicircular canals with various size dehiscences. We conclude that the characteristic eye movement following loud sound stimulation is valuable for diagnosing SCD syndrome. In addition, the loud sound stimulation test has unique advantages, especially for confirming the affected ear and the corresponding semicircular canal.

[Olfactory ensheathing cells promote the survival of newborn rat spiral ganglion cells in vitro].

The objective of this study is to explore whether olfactory ensheathing cells (OECs) can promote the survival of newborn rat spiral ganglion cells (SGCs) and the underlying possible mechanisms. Co-culture of OECs from adult rats with SGCs from newborn rat cochlea was established and single culture of SGCs acted as control. OECs were obtained and purified based on their special rate of attachment which was different from the other harvested cell types during culture. OECs and SGCs were immunocytochemically characterized and confirmed by expression of low-affinity nerve growth factor receptor p75 or positive label of neuron-specific betaIII-tubulin. To investigate the mechanisms of the role of OECs in survival of SGCs, brain derived neurotrophic factor (BDNF) and anti-BDNF antibody (IgY) were added into the media of the co-cultures respectively, and the surviving SGCs were examined after treatment. Single layer of OECs (92% pure) was seen seven days after plating. Surviving SGCs, which extended their primary neurites, were found on the surface of the layer in the co-cultures. When OECs and SGCs were co-cultured, the number of surviving SGCs was significantly greater than that in the single culture (P<0.01). Nine days after culture, there was even no change in the number of surviving SGCs in the co-culture while the number reduced to almost zero in the single culture. In comparison with co-culture without treatment, addition of BDNF (500 pg/mL) into the media had no obvious promoting effect on the survival of SGCs. The number of surviving SGCs reduced significantly when anti-BDNF antibody was applied into the media of co-cultures (P<0.01). These results suggest that OECs can promote the survival of SGCs when they are co-cultured in vitro. BDNF released from OECs, as one of the survival factors, plays an important role in the survival of SGCs.