Background and ObjectivesZZOverexposure to intense sound can cause temporary or permanent hearing loss.Post-exposure recovery of thresholds has been assumed to indicate reversal of damage to the inner ear without persistent consequences for auditory function.However, there was a report that acoustic overexposures causing moderate temporary threshold shift caused acute loss of afferent nerve terminals and delayed degeneration of the cochlear ganglion cells while cochlear sensory cells were intact.The purpose of the study was to evaluate the numerical changes of ribbon synapses and efferents to the outer hair cells in ears with temporary noise-induced threshold shifts.Materials and MethodsZZFour-week old CBA mice with normal Preyer's reflexes were used.Mice were exposed to white noise of 110 dB SPL for one hour.Auditory brainstem response (ABR) and distortion-product otoacoustic emission (DPOAE) were recorded before exposure and at four different post-exposure times, 1, 3, 5, and 7 days after noise exposure.Ribbon synapses and efferents near cochlear nerve terminals were stained and calculated in the control group mice at two post-exposure times, 3 and 5 days after the exposure.ResultsZZIn the noise-exposed ears, there was no loss of hair cells, in either inner hair cells or outer hair cells.ABR and DPOAE showed maximum threshold shifts after noise-exposure; they returned to the normal pre-exposure values by at day 5.The number of ribbon synapses tended to decrease at 3 days after noise-exposure, but the number of efferent fibers was not statistically different from those of the control mice.ConclusionZZOur results suggest that the loss of ribbon synapses could be related with the recovery course of temporary threshold shift, even to the point of full hearing recovery.
There is a clinical need to develop a stent to treat obstructive and refractory Eustachian tube dysfunction (ETD) after balloon Eustachian tuboplasty. An animal model for stent placement in the Eustachian tube (ET) is needed to develop optimal designs and materials, as stents for ETD have not been clinically applied. The purpose of this study was to evaluate the technical feasibility of stent placement and histological changes in a porcine ET model. Six ETs were evaluated in three pigs. Cobalt–chrome alloy stents with two different diameters were placed in the left and right ET of each animal (right, 3.5 mm; left, 2.5 mm). The outcomes were assessed by endoscopic and fluoroscopic imaging during the procedure, computed tomography after the procedure, and by histological examinations. Stent placement was technically successful in all specimens after metallic guiding sheaths were located in the nasopharyngeal end of the ET. The mean luminal diameters of the proximal, middle, and distal portions of the larger stents in the right ETs were 3.48 mm, 2.54 mm, and 2.15 mm, respectively. In the left ETs using smaller stents, these values were 2.49 mm, 1.73 mm, and 1.42 mm, respectively. The diameters of the inserted stents differed by stent location and the original diameter. Histological findings showed tissue hyperplasia with severe inflammatory cell infiltration at 4 weeks after stent placement. In conclusion, stent placement into the porcine ET was technically feasible, and stent-induced tissue hyperplasia was significantly evident. The luminal configuration of the placed ET stent changed according to its non-elastic nature and anatomical features of the porcine ET. Using this model, ET stents of various materials and designs with anti-inflammatory or anti-proliferative drugs can be optimized for future treatments of ET dysfunction.
This paper addresses the performance of bit-interleaved coded multiple beamforming (BICMB) [1], [2] with imperfect knowledge of beamforming vectors. Most studies for limited-rate channel state information at the transmitter (CSIT) assume that the precoding matrix has an invariance property under an arbitrary unitary transform. In BICMB, this property does not hold. On the other hand, the optimum precoder and detector for BICMB are invariant under a diagonal unitary transform. In order to design a limited-rate CSIT system for BICMB, we propose a new distortion measure optimum under this invariance. Based on this new distortion measure, we introduce a new set of centroids and employ the generalized Lloyd algorithm for codebook design. We provide simulation results demonstrating the performance improvement achieved with the proposed distortion measure and the codebook design for various receivers with linear detectors. We show that although these receivers have the same performance for perfect CSIT, their performance varies under imperfect CSIT.
Immediate facial nerve substitution or graft technique has been used for the repair of facial nerve defects occurring as a result of tumour dissection. However, some patients report unsatisfactory outcomes, such as difficulty in maintaining resting or smiling symmetry, due to persistent flaccid facial palsy. Here we evaluated the functional outcomes of transferring the masseteric branch of the trigeminal nerve to the facial nerve adjunct to facial nerve graft.We reviewed the medical records of seven patients who underwent facial reanimation surgery between 2014 and 2016. The patients were divided into two groups according to the type of facial reanimation surgery: group A, masseteric nerve innervation with interposition graft; group B, interposition graft only. The postoperative resting symmetry and dynamic movement were compared.Facial contraction was first observed in group A at 4 months and in group B at 7.3 months. Most of the patients achieved reliable resting symmetry; however, one patient in group B exhibited unsatisfactory facial weakness on the affected side. Group A patients showed better dynamic movement than group B patients. Eye closure, oral excursion and oral continence were better in group A than in group B patients. Smile symmetry in both groups was similar due to hyperkinetic movement in group A patients and flaccidity in group B patients.Dual innervation of the masseteric branch of the trigeminal nerve improves the dynamic movement of paralysed facial muscles and shortens the recovery period in patients with iatrogenic facial palsy.
To investigate the long-term educational and occupational status of prelingually bilateral deaf children who received a cochlear implant (CI) before the age of 7, and to identify factors that influence these outcomes.Retrospective chart review.Single tertiary care center.Seventy-one children who underwent CI surgery from 2000 to 2007 were included. The latest education and occupation status and word recognition score (WRS) were analyzed.The mean age at the time of surgery and the current age was 3.9 and 22.4 years. The age at CI showed a negative correlation with WRS. All subjects had graduated from high school or obtained an equivalent educational qualification. General high school graduates showed a higher WRS than those who attended a special education high school. The college entrance rate of CI patients (74.6% %) was comparable to that of the general population (72.5%). Subjects who went to college had a significantly better WRS than those who did not (51.4% vs 19.3%). Excluding 30 subjects currently enrolled in college, 26 (62%) of the remaining 41 were currently employed and engaged in various vocational activities, of which most (21 out of 26, 81%) were employed through vocational training institutes, or via special recruitment policy for the disabled.The long-term use of CI in prelingually deaf children enables not only speech perception but also produces comparable levels of education and employment to those of the general population. A good WRS and supportive policy were related to these successful outcomes.
Abstract To assess the safety and efficacy of navigation-guided balloon Eustachian tuboplasty (BET) compared to medical management (MM) alone in patients with chronic Eustachian tube dilatory dysfunction (ETD). This is a prospective, multicenter, 1:1 parallel-group, randomized controlled trial (RCT). It aims to assess the efficacy of navigation-guided BET compared to MM alone in patients with chronic ETD. The primary outcome measure was an improvement in the Eustachian tube dysfunction questionnaire (ETDQ)-7 score at the 6-week follow-up compared with baseline. Secondary outcome measures included changes in the signs and symptoms during the follow-up, changes in the score for each subcategory of ETDQ-7, type of tympanometry, pure tone audiometry, and the availability of a positive modified Valsalva maneuver. Navigation-guided BET was safely performed in all patients. A total of 38 ears of 31 patients (19 ears of 16 patients in the BET group and 19 ears of 15 patients in the control group) completed the planned treatment and 6 weeks of follow-up. More patients in the BET group (1.99 ± 0.85) had less symptomatic dysfunction than in the control group (3.40 ± 1.29) at 6 weeks post-procedure ( P = 0.001). More patients experienced tympanogram improvement in the BET group at 6 weeks compared to the control group (36.5% vs. 15.8%) with a positive modified Valsalva maneuver (36.6% vs. 15.8%, P = 0.014). Additionally, air–bone gap change was significantly decreased in the BET group compared to the control group at the 6-week follow-up visit ( P = 0.037). This prospective, multicenter, RCT study suggests that navigation-guided BET is a safe and superior treatment option compared to MM alone in patients with chronic ETD.
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