1,720,970 research outputs found
Sudden bilateral hearing loss: Case report of an audiological emergency
No full textHypertensive encephalopathy (HE) is characterized by headache, confusion, seizures and visual disturbance and may progress to coma and death. It is an acute neurological picture caused by sudden increases of arterial pressure. Bilateral deafness is a possible symptom of HE. We describe the first case of a patient affected by a hypertensive attack associated with sudden headache and bilateral hearing loss, refractory to medical treatment, whose condition evolved into coma and rapid expiry. Sudden bilateral deafness can be a warning sign of hypertensive encephalopathy. Prompt and intensive management for HE is needed for patients with sudden bilateral deafness
Cochlear implant and inflammation reaction: Safety study of a new steroid-eluting electrode
No full textDexamethasone is a common anti-inflammatory agent added to cochlear implants to reduce hearing loss due to electrode insertion trauma. We evaluated the safety of eluting silicone rods containing 10% dexamethasone in a Guinea pig model. Animals were implanted with a dexamethasone eluting silicone electrode (DER) or with a non-eluting electrode (NER). The control group only underwent a cochleostomy (CS). Prior to implantation and during the two weeks following implantation, the hearing status of the animals was assessed by means of Compound Action Potentials (CAPs) with an electrode placed near the round window. Two weeks after implantation, the mean click threshold shifts were 1 dB ± 10 dB in the DER group, 10 dB ± 10 dB in the NER group and -4 dB ± 10 dB in the control group. After two weeks the bullae of each animal were extracted to verify the presence of macrophages, the percent of tissue growth in the scala tympani and the tissue sealing around cochleostomy. Silicone electrodes samples were also explanted and examined for bacterial infection. Neither bacterial infection nor enhanced number of macrophages were observed. A limited, but not significant, tissue growth was found in the scala tympani between the experimental and the control group. The data suggest that, in the Guinea pig model, the use of DER is apparently safe as an anti-inflammatory slow-release additive to the cochlear implant
Threshold estimation in adult normal- and impaired-hearing subjects using auditory steady-state responses
No full textBACKGROUND: The aim of the study was to compare the estimation of hearing threshold values by behavioral and electrophysiological (ASSR) methods in subjects with normal hearing and those with sensorineural hearing impairment.
MATERIAL/METHODS: Thirty-two subjects (17 male and 15 female) were tested, with a total of 61 ears. Of these, 11 (22 ears) presented normal hearing threshold values (0-19 dBHL) and 21 (39 ears) sensorineural deficits.
RESULTS: The data showed that for the normal-hearing subjects the mean +/-SD ASSR threshold was approximately 20+/-11 dB for frequencies of 0.25-1.0 kHz. For higher frequencies the ASSR threshold increased to 40+/-12.5 dB at 8.0 kHz. Regression analysis confirmed that the difference between the ASSR-estimated and behavioral threshold values decreased significantly with the amount of hearing loss. The data showed that for a 10-dB increment of the behavioral threshold, the ASSR threshold increased by 7 dB. The difference of about 27 dB between the two methods observed in normal subjects tends to cancel in hearing loss greater than 95-100 dBHL.
CONCLUSIONS: The results of these analyses indicate that the threshold estimates are rather discordant with the behavioral thresholds. in particular it seems that the correction factor applied here does not rely on factors adequately modeled (in terms of instrumentation) to compensate for the effects of hearing loss on ASSR thresholds. The threshold estimation is adequately modeled for high levels of hearing loss, particularly for patients requiring a cochlear implant
Dilatazione dell'acquedotto vestibolare, del dotto e del sacco endolinfatico, aspetti neuroradiologici
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Coupling the Vibrant Soundbridge to cochlea round window: auditory results in patients with mixed hearing loss.
No full textOBJECTIVE: To assess the functional results of the Vibrant Soundbridge (VBS) placed on the round window (RW) in patients with mixed hearing loss. STUDY DESIGN: Retrospective evaluation of functional hearing, with measurements performed 7 to 9 months postoperatively. SETTINGS: Two tertiary referral hospital centers. SUBJECTS: Twelve individuals with mixed severe hearing loss associated with chronic suppurative otitis media and otosclerosis. INTERVENTION: Surgical placement of the VBS mechanical effector in close contact with the RW membrane to directly drive the inner ear fluids. MAIN OUTCOME MEASUREMENT: Functional hearing gain as analyzed via pure-tone audiometry and speech audiometry with VBS off and on in quiet and in noise. RESULTS: We observed a mean gain of 37.5 dB (0.5-4 kHz) with wide individual differences. The overall gain is mainly due to the air-bone gap recovery, whereas a further 12-dB mean improvement of air-conducted threshold is evident at 2 kHz. The speech reception threshold in quiet shows a mean gain of 24 dB, whereas in noise, it requires a signal-to-noise ratio 7 to 13 dB greater than normal-hearing controls. All patients are daily users of their VBS device. CONCLUSION: A middle ear implant capable of directly driving the cochlear fluids seems to be a promising alternative for individuals with a severe to profound mixed hearing loss. However, variability in hearing recovery is great, likely reflecting variability in responsiveness of the cochlea associated with chronic pathologic findings and, possibly, variability in how the VBS effector interfaces with the RW. Modifying the shape of the VBS effector can improve the mechanical coupling to the RW to better exploit the device's amplification power
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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