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.

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.

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.

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.

Sound-induced vertigo due to bone dehiscence of the lateral semicircular canal.

Dehiscence of the lateral semicircular canal (LSCD) has been reported much but mainly in association with cholesteatoma and canal wall down mastoidectomy, while idiopathic LSCD was rarely reported. Bassim reported one case with lateral semicircular canal dehiscence, but presented no vestibular or auditory symptoms. The patient in this study complained significant sound-induced vertigo and autophony in his right ear. The axis of nystagmus was orthogonal to the lateral semicircular canal, and no torsional or vertical motions were observed, so pathology of the lateral semicircular canal was preferentially considered. Benign paroxysmal positional vertigo was excluded since vertigo attacks had no relation to the change of head position. The dehiscence of the right lateral semicircular canal was then confirmed through the high-resolution temporal bone computer tomography scan and the reconstructed images. The cause of the LSCD is poorly understood, since no history of head trauma, otological infection or surgery was documented.

[CT multiplane reconstruction images of superior semicircular canal dehiscence syndrome].

OBJECTIVE: To evaluate the clinical application of multi-planar reformation (MPR) for the diagnosis of superior semicircular canal dehiscence syndrome. METHODS: A retrospective study was conducted on 9 patients who were diagnosed with SSCD syndrome in the Otology and Skull Base Surgery group of Fudan University. Three radiologists analyzed all the patients' 0.75 mm-collimated axial and coronal images and 0.75 mm-collimated MPR images, and they came up with the same results. RESULTS: There were 18 superior semicircular canal in the 9 patients, of whom 9 were intact and 9 were defective. All the defective superior semicircular displayed a definite dehiscence in all the MPR images, which indicated the sensitivity was 100%; however, 7 of the 9 defective superior semicircular canal were diagnosed as dehiscence in axial images, while 8 of the 9 were diagnosed in coronal images, but the sensitivities were 77.8% and 88.9% respectively. The results of the other 9 with intact superior semicircular canal displayed in the MPR, axial, and coronal images were also different. In the MPR images, they all displayed definite intact roof over the superior semicircular canal. There were 2 dehiscence in all axial and coronal images, and the specificities were 77.8%. CONCLUSION: The MPR image is more useful in diagnosis of superior semicircular canal dehiscence syndrome than that of the routine axial and coronal images.

[Uptake and accumulation of gentamicin by mouse hair cells from the cochlear explants in vitro].

OBJECTIVE: To investigate the upstaging and accumulation of gentamicin by mouse hair cells in vitro. METHODS: Cochlear explants were prepared from the microdissected neonatal mouse cochlea. Cochlear explants were cultured with gentamicin-Texas-red conjunction (GTTR) for different time. Laser confocal microscopy was used to observe the distribution of GTTR in the cochlear sensory cells after labeling with phalloidin-alexa-488. RESULTS: Soon after culture, there was diffuse red staining all tissue cells in the explants. At later time the hair cells were more staining than other cells in the explants. There was no obviously accumulation of GTTR in the supporting cells. The peak level of fluorescent density was reached at 24 hours culture. The GTTR was seen in the infracuticular zone of the hair cells. There was still accumulation of GTTR in the hair cells of the explants after 7 days culturing. CONCLUSIONS: GTTR and cochlea explants were useful methods to investigate the pharmacokinetics and mechanisms of gentamicin accumulation over time.

[Diagnosis of superior semicircular canal dehiscence syndrome].

OBJECTIVE: To better understand superior semicircular canal dehiscence (SSCD) syndrome. METHODS: A retrospective study was conducted on 6 patients who were diagnosed with SSCD syndrome in the Otology and Skull Base Surgery group of Fudan University. The clinical presentations including symptoms, signs, auditory tests and high resolution temporal bone computed tomography were reviewed. RESULTS: Four patients presented with low frequency hearing loss while acoustic reflex responses were intact. Another patient was concomitance with chronic otitis media demonstrated profound sensorineural hearing loss. The sixth patient demonstrated normal hearing. Two patients also complained of autophony, but they were unable to tolerate their own voice. Five patients presented with vertigo while 2 patients were unable to tolerate the environmental noise. All patients showed slow component vertical torsional eye movement away from the effected eye which was induced by the presence of loud sound or pressure in the middle ear or valsalva maneuver. Four patients also demonstrated vertigo induced by the loud sound, 1 patient was induced head movement by 110 dB tone. All patients were revealed variable bone defect overlying on the SSC using high resolution temporal bone CT scan with SSC reformation. CONCLUSIONS: The diagnosis of SSCD syndrome was established on both the presence of bone defect overlying superior semicircular canal which was demonstrated using high resolution temporal bone CT scan, and the presence of associated vestibular and auditory symptoms and signs.

[Etiological factor analysis of facial nerve paralysis due to chronic inflammation of middle ear].

OBJECTIVE: To discuss the etiological factors of facial nerve paralysis due to chronic inflammation of middle ear. METHODS: This retrospective research included 41 patients operated for facial nerve paralysis due to chronic inflammation of middle ear. Careful exploration was made in facial canal in order to identify pathological tissue involvement. Pathological examination was performed in all operative specimens. RESULTS: Four intact fallopian canals were observed. There was a defect on the fallopian canal in 37 patients (90%) and it was most commonly located on the tympanic segment of the canal (89%). Pathological report was cholesteatoma, granulation and tuberculosis, which was found in 24 cases (59%) 14 cases (34%) and 3 cases (7%), respectively. CONCLUSIONS: Facial nerve paralysis due to chronic inflammation of middle ear was frequently relevant with cholesteatoma,the tympanic segment of the fallopian canal was most location to be involved in. Its major factor was the infection spreading along the nerve tissue, but not atrophy due to compression. The defect on the fallopian canal was not necessary for infection diffusion.

Reanimation of paralyzed laryngeal muscles by electrical stimulation synchronized with inspiration.

OBJECTIVE: To determine the effects of electrical stimulation on denervated cat posterior cricoarytenoid (PCA) muscle. STUDY DESIGN AND SETTING: This study was conducted on six cats with PCA muscle denervation. All animals were sacrificed 12 weeks after surgery and the glottal area in the live animals and the fiber diameters of PCA muscle were obtained. RESULTS: Signals synchronized with inspiration were recorded and transmitted to stimulate PCA muscle. The abduction of the paralyzed vocal cord during inspiration was observed; this allows enough flow of air through the larynx to maintain the respiration. The stimulated fiber diameters of PCA muscle were different from that of nonstimulated (P < 0.01). Although all denervated muscles were degenerated, electrical stimulation was used to prevent muscular atrophy. CONCLUSIONS: This study indicates that electrical stimulation of the PCA muscle synchronized with inspiration could restore the abduction of a paralyzed vocal cord and prevent the denervated muscles from atrophying. SIGNIFICANCE: Electrical stimulation synchronized with inspiration may lead to reanimation of paralyzed laryngeal muscles.

[Distribution of gentamicin in inner ear after intratympanic gentamicin injection].

OBJECTIVE: To investigate uptake and accumulation of gentamicin by cells in the guinea pig inner ear after intratympanic injection using a fluorescent probe--gentamicin-Texas-red conjunction (GTTR). METHODS: Adult guinea pigs (n = 80) were administered a single dose of GTrR to the middle ear cavity through the intact membrane and survived for 12 h, 24 h, 48 h, 3 d, 4 d, 7 d, 14 d and 28 d. The distribution of GTTR in the cochlear and vestibular cells was observed after staining with phalloidin-alexa-488. Texas Red and DMSO were injected into the tympanum as control. RESULTS: Diffuse staining of gentamicin in the labyrinth was observed initially after local drug administration. At later time point the outer hair cells and sensory cells of vestibular organ were staining more densely than the support cells in the inner ear. The peak level of fluorescent density was reached 3 days after local injection. The GTTR was observed in the infracuticular zone. CONCLUSIONS: GTTR was a potential fluorescent probe to investigate the pharmacokinetics and mechanisms of gentamicin accumulation in local application.