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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. Anti-PLs antibodies in this study consisted of anticardiolipin, and anti-β2-glycoprotein-1 antibodies. Serum was assayed for anti-HSP70 IgG antibodies using recombinant human HSP70. Demographic, clinical, and audiometric variables were analyzed to find the possible role of serum autoantibodies in SSNHL patients. Sixteen patients (25.4%) had demonstrable anti-HSP70 antibodies in serum. Twenty-one patients (33.3%) showed a positive result for at least one isotype (IgM or IgG) of anti-PLs. In 19% of the patients, anti-HSP70 and anti-PLs antibodies were positive in two combinations. A statistically significant association was found between anti-HSP70 antibodies and the Siegel recovery grade subgroup. SSNHL patients who were positive for anti-HSP70 antibodies showed a significantly higher rate of complete recovery and incomplete but partial recovery than SSNHL patients without anti-HSP70 antibodies (p = 0.0496). Statistically significant association was found between total anticardiolipin, total anti-β2-glycoprotein-1, total anti-PLs, and anti-PLs in combination with anti-HSP70 antibodies and age (p = 0.0229). 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. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Tympanometry is well established as a means of assessing the presence of fluid in the middle ear. The type B tympanogram is usually considered a unique entity. However, its shape may vary from a rounded type B with a "pseudopeak" to a completely flat response. The aim of this study was to compare the characteristics of the B curve (maximum admittance, tympanometric peak pressure, and area under the curve) to the viscosity of the middle ear fluid and to the air-bone gap (ABG). In 67 children (93 ears) who underwent ventilation tube insertion, no correlation was found between the viscosity of the middle ear fluid and the characteristics of the B curve. However, these characteristics were able to differentiate between a low ABG (0 to 20 dB) and a high ABG (>20 dB). A statistical difference was also found for the three parameters (maximum admittance, p < .0025; pressure, p < .025; and area under the curve, p < .0005). Tympanometry may be used as an objective measure to estimate the extent of conductive hearing loss, especially in young children. [ABSTRACT FROM AUTHOR]

Studies the anatomical details of the ear of the fat sand rat, Psammomys obesus. Bulla comprising the temporal bone; Auditory ossicles; Length of the manubrium in relation to ear size; Accessibility of most parts of the inner ear bulge; Suitability of the fat sand rat as an experimental animal for the investigation of middle and inner ear physiology.

Short latency vestibular evoked potentials (VsEPs) to linear acceleration impulses (L-VsEPs) are initiated in the otolith organs (saccule and utricle). Some of the saccule afferents have been reported to respond not only to linear acceleration, but also to high intensity acoustic stimuli. If so, the L-VsEP recorded from the saccule (elicited with the stimulus orientated relative to the head so as to optimally activate the saccule, i.e. stimulus in the vertical plane, Z-VsEP) should be reduced during high intensity broad band noise (BBN) “masking”. Conversely, the utricular afferents have been reported to be less auditory-sensitive. Therefore, an L-VsEP which is mainly utricular in origin (stimulus in the horizontal plane, X-VsEP) should be less affected by this noise “masking”. This was investigated in rats by recording X-VsEPs and Z-VsEPs and angular VsEPs (A-VsEPs), originating in the lateral semi-circular canals, before, during and after exposure to short duration, high intensity (113 dB SPL) BBN. This intensity completely masked auditory nerve evoked responses. The Z-VsEP did appear to be slightly more affected by the noise “masking” than the X-VsEP, implying the presence of more auditory-sensitive elements in the saccule. The A-VsEP was also affected by the BBN. The overall effect was relatively small (on average, 10-25% depression of the first wave of the different VsEPs). The responses showed recovery 5 min later. [ABSTRACT FROM AUTHOR]

Action potentials of the second-order vestibular neurons of ten cats were recorded, both in rest and responding to sinusoidal and intense impulse acceleration stimuli. The data were compared with the far-field recorded vestibular-evoked response induced by the same impulse stimuli. It was found that the irregular (kinetic) neurons, which had a phase lead relative to head velocity, were capable of responding to these impulses with a latency as short as 3.5 msec after the start of head acceleration. It is assumed, therefore, that these neurons are the generators of the second wave of the vestibular-evoked response, having a similar latency. A high correlation was found between the latency of the first peak in the poststimulus time histogram in response to acceleration impulses and the phase of the response to sinusoidal rotations. The regular (tonic) vestibular neurons did not respond to acceleration impulses and probably did not contribute to the vestibular-evoked response. [ABSTRACT FROM AUTHOR]

The short-latency vestibular-evoked response (VsER) and the auditory brain stem response (ABR) were recorded with scalp electrodes in four cats before, during, and after systemic administration of gentamicin. The VsER was altered and later disappeared in three cats, and in one cat it became asymmetric, typical of a unilateral vestibular lesion. In all cats the ABR was unaffected and remained normal through the end of the experiment 4 months later. Histopathological examination of the temporal bones of three cats showed severe damage to the vestibular end-organ, particularly in the summit of the cristae, but in lesser amounts in the hair cells on the slopes of the cristae and in the maculae. In one cat, the pathological condition was greater in one ear, corresponding to the asymmetry in the VsER records. This new method of inducing and recording the VsER has been demonstrated by the present study to be an effective tool for experimentally assessing vestibular end-organ and nerve function in animal models. Furthermore, these results indicate that the VsER is generated in the vestibular labyrinth, most probably by the cristae of the semicircular canals. [ABSTRACT FROM AUTHOR]