Xueyuan Zhang

SIRT1 expression in the cochlea and auditory cortex of a mouse model of age-related hearing loss.

SIRT1 is a highly conserved NAD(+)-dependent protein deacetylase known to have protective effects against a variety of age-related diseases. However, there is a lack of information concerning SIRT1 expression in the cochlea and auditory cortex of C57BL/6 mice, a mouse model of age-related hearing loss. Using RT-PCR and immunohistochemistry, we show that SIRT1 is abundantly expressed in the inner hair cells, strial marginal cells, strial intermediate cells, type I and type IV fibrocytes of the spiral ligament and spiral ganglion neurons. In addition, moderate SIRT1 is also detected in the outer hair cells and neurons of the auditory cortex. Associated with elevated hearing thresholds and hair cells loss during aging, there is also a significant reduction of SIRT1 expression in the cochlea and auditory cortex. The expression pattern of SIRT1 in the peripheral and central auditory system suggests that SIRT1 may play an important role in auditory function and therefore may serve as a protective molecule against age-related hearing loss.

Evaluation of auditory cortical development in the early stages of post cochlear implantation using mismatch negativity measurement

Objective The aim of this study was to investigate auditory cortical development using mismatch negativity (MMN) in prelingual severe-to-profound hearing-impaired children from the stage of cochlear implant (CI) power-up to 6 months after power-up. Method Eighteen children were recruited and examined at the stage of CI initial power-up (M0), as well as several follow-up periods, that is, 1 month (M1), 3 months (M3), and 6 months (M6) after CI power-up. The MMN responses were measured using a 128-Channel Dense Array EEG System. The group average and individual MMN analysis were used to investigate the longitudinal changes of the MMN characteristics. The relationship between MMN characteristics and scores of categories of auditory performance (CAP) was also investigated. Results Although the MMN incidence was much lower at the periods of M0 and M1, significantly higher MMN incidence was found in M3 and M6. The MMN latencies decreased significantly from M3 to M6, but no significant difference in the amplitudes was found between these periods. There was a negative correlation between the increment of CAP scores and decrement of MMN latency from M3 to M6. Conclusion MMN incidence increment and latency decrement are likely to be the objective and noninvasive indicators for evaluating auditory central development at an early stage in children after cochlear implantation. Moreover, the latency decrement from M3 to M6 correlated significantly with the increment of the CAP scores, indicating a fast maturation period, which might be a key period for auditory rehabilitation.

The characteristic and changes of the event-related potentials (ERP) and brain topographic maps before and after treatment with rTMS in subjective tinnitus patients.

Objectives To compare the event-related potentials (ERPs) and brain topographic maps characteristic and change in normal controls and subjective tinnitus patients before and after repetitive transcranial magnetic stimulation (rTMS) treatment. Methods and Participants The ERPs and brain topographic maps elicited by target stimulus were compared before and after 1-week treatment with rTMS in 20 subjective tinnitus patients and 16 healthy controls. Results Before rTMS, target stimulus elicited a larger N1 component than the standard stimuli (repeating sounds)in control group but not in tinnitus patients. Instead, the tinnitus group pre-treatment exhibited larger amplitude of N1 in response to standard stimuli than to deviant stimuli. Furthermore tinnitus patients had smaller mismatch negativity (MMN) and late discriminative negativity (LDN)component at Fz compared with the control group. After rTMS treatment, tinnitus patients showed increased N1 response to deviant stimuli and larger MMN and LDN compared with pre-treatment. The topographic maps for the tinnitus group before rTMS -treatment demonstrated global asymmetry between the left and right cerebral hemispheres with more negative activities in left side and more positive activities in right side. In contrast, the brain topographic maps for patients after rTMS-treatment and controls seem roughly symmetrical. The ERP amplitudes and brain topographic maps in post-treatment patient group showed no significant difference with those in controls. Conclusions The characterical changes in ERP and brain topographic maps in tinnitus patients maybe related with the electrophysiological mechanism of tinnitus induction and development. It can be used as an objective biomarker for the evaluation of auditory central in subjective tinnitus patients. These findings support the notion that rTMS treatment in tinnitus patients may exert a beneficial effect.

Surgical treatment of monostotic fibrous dysplasia of the temporal bone: a retrospective analysis.

OBJECTIVE The aim of this study was to analyze the therapeutic effect of external auditory canal stenosis caused by monostotic fibrous dysplasia of the temporal bone by operation. METHODS Seven patients who were finally diagnosed as having monostotic fibrous dysplasia of the temporal bone by temporal bone high-resolution computed tomography (CT) and pathological diagnosis after operation underwent surgical reconstruction of the external auditory canal. The follow-up lasted 2 to 6 years, and it included pure-tone audiometry otoendoscopy, and high-resolution CT of the temporal bone. The hearing recovery and formed external auditory meatus results were retrospectively analyzed. The data were obtained from the Department of Otolaryngology in Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, from April 2003 to September 2008. RESULTS We found 4 ears with combined external auditory canal cholesteatoma intraoperative. The mean pure-tone audiometries (0.5, 1, 2 kHz) and the air-bone gaps for all patients improved after 6 months postoperation. The result was statistically significant. The average air-bone gap was improved, and the external auditory canal restenosis appeared in 1 patient after 4 years. Reconstruction of the external auditory canal was performed in this patient, and no restenosis was found in subsequent 2-year follow-up. All cases were reviewed with CT and otoendoscopy to observe the results and lesion extent, and we found that the lesion was basically stable without significant progress to the periphery major structure. CONCLUSION The monostotic fibrous dysplasia of the temporal bone and its causative external auditory meatus stenosis must be treated as early as possible to recover its patency of external auditory canal to prevent complicated cholesteatoma. Satisfaction results can be obtained from surgical reconstruction of the external auditory canal. We can excise the pathological change of the external auditory canal simply to restore auditory function and eliminate clinical symptoms such as earache, ear muffled sense, and so on. Because the development of lesions was slow during the follow-up, the complete resection of all lesions was not necessary, the external auditory canal restenosis may be operated again, and the prognosis was optimistic.

Intact Canal Wall Mastoidectomy Combined with Balloon Dilation Eustachian Tuboplasty in the Treatment of Middle Ear Cholesterol Granuloma

To the Editor: Cholesterol granuloma (CG) refers to granulation tissue containing cholesterol crystals and giant cells and is a foreign body response elicited by local tissues. The pathogenesis of middle ear CG can be explained using the classic obstruction‐vacuum theory caused by negative middle ear pressure.[1] The Eustachian tube (ET) plays a decisive role in influencing the gas exchange and maintaining the ventilation and pressure of the middle ear. The traditional treatment is mastoidectomy, routinely combined with middle ear ventilation tube insertion or tube insertion during re‐examination after operation.[2] Eustachian tuboplasty by balloon dilation can improve the pathological state of ET via specific mechanisms to achieve functional recovery and satisfactory clinical efficacy.[3,4]

Visually Evoked Visual-Auditory Changes Associated with Auditory Performance in Children with Cochlear Implants

Activation of the auditory cortex by visual stimuli has been reported in deaf children. In cochlear implant (CI) patients, a residual, more intense cortical activation in the frontotemporal areas in response to photo stimuli was found to be positively associated with poor auditory performance. Our study aimed to investigate the mechanism by which visual processing in CI users activates the auditory-associated cortex during the period after cochlear implantation as well as its relation to CI outcomes. Twenty prelingually deaf children with CI were recruited. Ten children were good CI performers (GCP) and ten were poor (PCP). Ten age- and sex- matched normal-hearing children were recruited as controls, and visual evoked potentials (VEPs) were recorded. The characteristics of the right frontotemporal N1 component were analyzed. In the prelingually deaf children, higher N1 amplitude was observed compared to normal controls. While the GCP group showed significant decreases in N1 amplitude, and source analysis showed the most significant decrease in brain activity was observed in the primary visual cortex (PVC), with a downward trend in the primary auditory cortex (PAC) activity, but these did not occur in the PCP group. Meanwhile, higher PVC activation (comparing to controls) before CI use (0M) and a significant decrease in source energy after CI use were found to be related to good CI outcomes. In the GCP group, source energy decreased in the visual-auditory cortex with CI use. However, no significant cerebral hemispheric dominance was found. We supposed that intra- or cross-modal reorganization and higher PVC activation in prelingually deaf children may reflect a stronger potential ability of cortical plasticity. Brain activity evolution appears to be related to CI auditory outcomes.

Logistic Regression Analysis of Factors Influencing the Effectiveness of Intensive Sound Masking Therapy in Patients with Tinnitus

Objectives To investigate factors influencing the effectiveness of intensive sound masking therapy on tinnitus using logistic regression analysis. Design The study used a retrospective cross-section analysis. Participants 102 patients with tinnitus were recruited at the Sun Yat-sen Memorial Hospital of Sun Yat-sen University, China. Intervention Intensive sound masking therapy was used as an intervention approach for patients with tinnitus. Primary and secondary outcome measures Participants underwent audiological investigations and tinnitus pitch and loudness matching measurements, followed by intensive sound masking therapy. The Tinnitus Handicap Inventory (THI) was used as the outcome measure pre and post treatment. Multivariate logistic regression was performed to investigate the association of demographic and audiological factors with effective therapy. Results According to the THI score changes pre and post sound masking intervention, 51 participants were categorised into an effective group, the remaining 51 participants were placed in a non-effective group. Those in the effective group were significantly younger than those in the non-effective group (P=0.012). Significantly more participants had flat audiogram configurations in the effective group (P=0.04). Multivariable logistic regression analysis showed that age (OR=0.96, 95% CI 0.93 to 0.99, P=0.007), audiometric configuration (P=0.027) and THI score pre treatment (OR=1.04, 95% CI 1.02 to 1.07, P<0.001) were significantly associated with therapeutic effectiveness. Further analysis showed that patients with flat audiometric configurations were 5.45 times more likely to respond to intervention than those with high-frequency steeply sloping audiograms (OR=5.45, 95% CI 1.67 to 17.86, P=0.005). Conclusion Audiometric configuration, age and THI scores appear to be predictive of the effectiveness of sound masking treatment. Gender, tinnitus characteristics and hearing threshold measures do not seem to be related to treatment effectiveness. A further randomised control study is needed to provide evidence of the effectiveness of prognostic factors in tinnitus interventions.

The effect of symmetrical and asymmetrical hearing impairment on music quality perception.

The purpose of this study was to investigate the effect of symmetrical, asymmetrical and unilateral hearing impairment on music quality perception. Six validated music pieces in the categories of classical music, folk music and pop music were used to assess music quality in terms of its ‘pleasantness’, ‘naturalness’, ‘fullness’, ‘roughness’ and ‘sharpness’. 58 participants with sensorineural hearing loss [20 with unilateral hearing loss (UHL), 20 with bilateral symmetrical hearing loss (BSHL) and 18 with bilateral asymmetrical hearing loss (BAHL)] and 29 normal hearing (NH) subjects participated in the present study. Hearing impaired (HI) participants had greater difficulty in overall music quality perception than NH participants. Participants with BSHL rated music pleasantness and naturalness to be higher than participants with BAHL. Moreover, the hearing thresholds of the better ears from BSHL and BAHL participants as well as the hearing thresholds of the worse ears from BSHL participants were negatively correlated to the pleasantness and naturalness perception. HI participants rated the familiar music pieces higher than unfamiliar music pieces in the three music categories. Music quality perception in participants with hearing impairment appeared to be affected by symmetry of hearing loss, degree of hearing loss and music familiarity when they were assessed using the music quality rating test (MQRT). This indicates that binaural symmetrical hearing is important to achieve a high level of music quality perception in HI listeners. This emphasizes the importance of provision of bilateral hearing assistive devices for people with asymmetrical hearing impairment.