Temporal Effects on Monaural Amplitude-Modulation Sensitivity in Ipsilateral, Contralateral and Bilateral Noise

Abstract

The amplitude modulations (AMs) in speech signals are useful cues for speech recognition. Several adaptation mechanisms may make the detection of AM in noisy backgrounds easier when the AM carrier is presented later rather than earlier in the noise. The aim of the present study was to characterize temporal adaptation to noise in AM detection. AM detection thresholds were measured for monaural (50 ms, 1.5 kHz) pure-tone carriers presented at the onset (‘early’ condition) and 300 ms after the onset (‘late’ condition) of ipsilateral, contralateral, and bilateral (diotic) broadband noise, as well as in quiet. Thresholds were 2–4 dB better in the late than in the early condition for the three noise lateralities. The temporal effect held for carriers at equal sensation levels, confirming that it was not due to overshoot on carrier audibility. The temporal effect was larger for broadband than for low-band contralateral noises. Many aspects in the results were consistent with the noise activating the medial olivocochlear reflex (MOCR) and enhancing AM depth in the peripheral auditory response. Other aspects, however, indicate that central masking and adaptation unrelated to the MOCR also affect both carrier-tone and AM detection and are involved in the temporal effects.

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Large Facial Nerve Schwannoma With Extensive Temporal Bone Destruction

No abstract available

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The Antioxidant Effect of Rosmarinic Acid by Different Delivery Routes in the Animal Model of Noise-Induced Hearing Loss

Hypothesis: Trans-tympanic Rosmarinic Acid (RA), as compared with the systemic administration, protects against noise-induced auditory hair cell and hearing losses in rats in vivo. Background: ROS production, lipoperoxidative damage, and an imbalance of antioxidant defences play a significant role in noise-induced hearing loss. Several molecules with antioxidant properties have been tested to restore redox homeostasis; however, drug delivery system represents a challenge for their effectiveness. In our model, acute and intense noise exposure induces hearing loss, hair cell death, and oxidative stress, with an increase in superoxide production and over-expression of lipid peroxidation in cochlear structures. Methods: RA was administrated in male Wistar rats by trans-tympanic (20 μl) and systemic (10 mg/kg) modality. In systemic administration, RA was injected 1 hour before noise exposure and once daily for the following 3 days. ABRs were measured before and at days 1, 3, 7, and 30 after noise exposure. Rhodamine-phalloidin staining, dihydroethidium and 8-isoprostane immunostainings were performed to assess and quantify outer hair cells loss, superoxide production, and lipid peroxidation in the different experimental groups. Results: Systemic RA administration significantly decreased noise-induced hearing loss and the improvement of auditory function was paralleled by a significant reduction in cochlear oxidative stress. The trans-tympanic modality of drug administration showed a similar degree of protection both at the functional and morphological levels. Conclusion: The effectiveness of RA given via trans-tympanic injection could be interesting for the future application of this minimally-invasive procedure in the treatment of ROS-induced hearing loss.

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Systematic Review of Hearing Preservation After Radiotherapy for Vestibular Schwannoma

Objective: To determine the long-term hearing preservation rate for spontaneous vestibular schwannoma treated by primary radiotherapy. Data Sources: The MEDLINE/PubMed, Web of Science, Cochrane Reviews, and EMBASE databases were searched using a comprehensive Boolean keyword search developed in conjunction with a scientific librarian. English language papers published from 2000 to 2016 were evaluated. Study Selection: Inclusion criteria: full articles, pretreatment and posttreatment audiograms or audiogram based scoring system, vestibular schwannoma only tumor type, reported time to follow-up, published after 1999, use of either Gamma Knife or linear accelerator radiotherapy. Exclusion criteria: case report or series with fewer than five cases, inadequate audiometric data, inadequate time to follow-up, neurofibromatosis type 2 exceeding 10% of study population, previous treatment exceeding 10% of study population, repeat datasets, use of proton beam therapy, and non-English language. Data Extraction: Two reviewers independently analyzed papers for inclusion. Class A/B, 1/2 hearing was defined as either pure tone average less than or equal to 50 db with speech discrimination score more than or equal to 50%, American Academy of Otolaryngology–Head & Neck Surgery (AAO-HNS) Hearing Class A or B, or Gardner–Robertson Grade I or II. Aggregate data were used when individual data were not specified. Data Synthesis: Means were compared with student t test. Conclusions: Forty seven articles containing a total of 2,195 patients with preserved Class A/B, 1/2 hearing were identified for analysis. The aggregate crude hearing preservation rate was 58% at an average reporting time of 46.6 months after radiotherapy treatment. Analysis of time-based reporting shows a clear trend of decreased hearing preservation extending to 10-year follow-up. This data encourages a future long-term controlled trial.

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Direction-fixed and Direction-changing Positional Nystagmus in Ramsay Hunt Syndrome

Objectives: To investigate the incidence of positional nystagmus (PN) using a head-roll test in patients with Ramsay Hunt syndrome with vertigo (RHS_V) and discuss possible mechanisms. Study Design: Retrospective study. Setting: Tertiary referral academic medical center. Patients: Twenty-eight patients with RHS_V were enrolled. Main Outcome Measure: Eye movements were recorded at positions of head roll to the right or left, and PN was classified as direction-fixed or direction-changing. Vestibular function tests including caloric test were performed. Results: Direction-fixed nystagmus beating away from the affected side was the most common type of PN (61%), followed by direction-changing geotropic type (18%), direction-fixed nystagmus beating toward the affected side (14%), and direction-changing apogeotropic type (7%). The duration of nystagmus was longer than 60 seconds in all patients exhibiting direction-changing PN. Postcontrast T1-weighted internal auditory canal (IAC) magnetic resonance imaging showed enhancement of not only the facial and vestibulocochlear nerves, but also the inner ear structures or dura along the IAC, suggesting inflammatory changes within the labyrinthine membrane or IAC dura. Conclusion: Although direction-fixed PN was more commonly observed (75%), direction-changing PN was also observed in some RHS_V patients (25%). The mechanism of direction-changing PN may be, at least in part, explained by the alteration of specific gravity of the lateral semicircular canal cupula or endolymph due to inflammation in the inner ear membrane.

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Long-term Administration of Salicylate-induced Changes in BDNF Expression and CREB Phosphorylation in the Auditory Cortex of Rats

Hypothesis: We investigated whether salicylate induces tinnitus through alteration of the expression levels of brain-derived neurotrophic factor (BDNF), proBDNF, tyrosine kinase receptor B (TrkB), cAMP-responsive element-binding protein (CREB), and phosphorylated CREB (p-CREB) in the auditory cortex (AC). Background: Salicylate medication is frequently used for long-term treatment in clinical settings, but it may cause reversible tinnitus. Salicylate-induced tinnitus is associated with changes related to central auditory neuroplasticity. Our previous studies revealed enhanced neural activity and ultrastructural synaptic changes in the central auditory system after long-term salicylate administration. However, the underlying mechanisms remained unclear. Methods: Salicylate-induced tinnitus-like behavior in rats was confirmed using gap prepulse inhibition of acoustic startle and prepulse inhibition testing, followed by comparison of the expression levels of BDNF, proBDNF, TrkB, CREB, and p-CREB. Synaptic ultrastructure was observed under a transmission electron microscope. Results: BDNF and p-CREB were upregulated along with ultrastructural changes at the synapses in the AC of rats treated chronically with salicylate (p  0.05). Conclusion: Long-term administration of salicylate increased BDNF expression and CREB activation, upregulated synaptic efficacy, and changed synaptic ultrastructure in the AC. There may be a relationship between these factors and the mechanism of tinnitus.

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Response to Letter to the Editor: “Long-Term Complications and Surgical Failures After Ossiculoplasty”

No abstract available

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