Audiology & neuro-otology
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Audiology & neuro-otology · Jan 2008
Prevalence and clinical significance of anticardiolipin, anti-beta2-glycoprotein-1, and anti-heat shock protein-70 autoantibodies in sudden sensorineural hearing loss.
Sudden sensorineural hearing loss (SSNHL) is frequently classified as 'idiopathic' since the causative factor responsible for its onset is not identified in most cases. In the present study, we determined whether SSNHL is clinically associated with serum anti-heat shock protein-70 (anti-HSP70) and antiphospholipids (anti-PLs) autoantibodies and whether these autoantibodies have an impact on the prognosis of SSNHL. Sera from 63 patients with SSNHL were screened prospectively for the presence of anti-HSP70 and anti-PLs autoantibodies by an enzyme-linked immunosorbent assay test. ⋯ The detection of autoantibodies to HSP70 and PLs offers a pliable explanation for the immune-mediated mechanism of SSNHL. The present study confirms and supports previous studies regarding the association between anti-HSP70 and anti-PLs antibodies with SSNHL, and is the first to identify a positive association between anti-HSP70 antibodies and a positive outcome of SSNHL. Further studies are necessary in order to identify and further clarify the immunologic role of the presence of autoantibodies and their impact on the prognosis of SSNHL.
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Audiology & neuro-otology · Jan 2008
Augmented ototoxic effect of cisplatin in heterozygotes of the German waltzing guinea pig.
It has previously been demonstrated that the carriers of the German waltzing guinea pig are less susceptible to noise trauma. To explore whether this represents a general resistance to inner ear trauma, carriers of the German waltzing guinea pig were exposed to the ototoxic agent cisplatin. Two doses of cisplatin were injected intravenously into anesthetized carriers and weight-matched control animals. ⋯ The cochleae were harvested to estimate hair cell loss and to analyze total platinum content. The carriers of the German waltzing guinea pig strain suffered from a more pronounced cisplatin-induced hearing loss compared to the control animals. The results suggest that mechanisms responsible for the protection against acoustic stress do not provide any protection against cisplatin in carriers of the German waltzing guinea pig.
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Audiology & neuro-otology · Jan 2008
Electrically evoked auditory steady-state responses in a guinea pig model: latency estimates and effects of stimulus parameters.
Cochlear implant speech processors typically extract envelope information of speech signals for presentation to the auditory nerve as modulated trains of electric pulses. Recent studies showed the feasibility of recording, at the scalp, the electrically evoked auditory steady-state response using amplitude-modulated electric stimuli. ⋯ Two distinct sites, one cortical and another more peripheral, were indicated by latency estimates of 22 and 2 ms, respectively, with the former evoked by lower (13-49 Hz) and the latter by higher (55-320 Hz) modulation frequencies. Furthermore, response amplitudes declined with increasing carrier frequency, exhibited a compressive growth with increasing modulation depths, and were sensitive to modulation depths to as low as 5%.
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Audiology & neuro-otology · Jan 2007
Audiological outcome of infants with congenital cytomegalovirus infection in a prospective study.
The aim of this study was to evaluate the audiological outcome of long-term follow-up of infants with asymptomatic congenital cytomegalovirus (CMV) infection as defined by the presence of CMV DNA in neonatal urine. 12599 pregnant women underwent screening for CMV IgG and IgM antibodies between 1996 and 2003. Eighteen infants with congenital CMV infection were identified. These infants underwent the newborn hearing screening test or auditory brainstem response test. ⋯ Two infants who passed the newborn hearing screening had a delayed-onset SNHL in follow-up examinations up to 4 years of age. Two had progressive hearing loss and 2 had improvement of hearing loss. Screening of pregnant women for CMV infection and repeated audiological examinations of infants are necessary because there are infants with delayed-onset SNHL or improved SNHL caused by asymptomatic congenital CMV infection.
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Audiology & neuro-otology · Jan 2006
Measuring the refractoriness of the electrically stimulated auditory nerve.
Intracochlear recordings in cochlear implant recipients provide access to the electrically evoked compound action potential (ECAP). ECAP thresholds are potential predictors of speech processor map's threshold and comfortable loudness levels. The auditory nerve's refractory properties can influence these levels due to high-rate stimulation with interpulse intervals within the relative refractory period. ⋯ Hence, the auditory nerve is usually in relative refractory state when standard neural response telemetry forward masking is selected because of its default MPI of 500 micro s. This can bias the measurement of ECAP thresholds. Additionally, the shape of standard forward masking recovery functions was explained by the influence of latency shift of the neural response.