The aim of the study was to investigate the validity of the avian middle ear model for researching the tympanoplasty mechanics. We studied the morphological details, acoustic transmission and quasi-static behavior of the ostrich tympano-ossicular system. The stained specimens of the ostrich middle ear were examined under a light microscope. The sound transfer function and quasi-static performance of the ostrich middle ear were evaluated using laser Doppler vibrometry. The application of pressure to the tip of the extracolumella causes a buckling movement of the ossicle between the cartilaginous and bony parts. Histologically, the intracolumellar connection can be identified as a junction zone between bone and hyaline cartilage. Sound conduction through the human middle ear is less effective than it is through the ostrich middle ear. The greatest difference (35 dB) was observed in the low-frequency region. Because the extracolumella bends, the medial displacements of the eardrum were not fully transmitted to the footplate. The amplitude of the ostrich columella footplate quasi-static medial displacements significantly exceeded that of the human footplate in both intact and reconstructed middle ears. The ostrich middle ear is a suitable model for designing total ossicular replacement implants. The main protective mechanism in the ostrich middle ear under quasi-static stress is a buckling movement of the extracolumella. The total ossicular prostheses of the new generation should contain an elastic element that allows an adaptation to greater quasi-static eardrum movements.
The titanium prostheses with a resilient joint that were investigated in this study had good sound transfer characteristics under optimal conditions as well as in a compressed state. As a result of joint bending, the implants compensate for the small changes in length of the ossicular chain that occur under varying middle ear pressure. The implants require a stable support at the stapes footplate to function properly.
Tumors originating from ceruminous glands are rare lesions of the external auditory canal. The lack of specific clinical and radiological signs makes their diagnosis challenging. We report the case of an exceptionally rare benign tumor, a syringocystadenoma papilliferum (SCAP), in an atypical location in the bony segment of the external auditory canal with uncommon clinical signs. The special traits of the case included the following: the most lateral component of the tumor was macroscopically cystic and a granular myringitis with an obstructing keratin mass plug was observed behind the mass. The clinical, audiological, radiological, and histological characteristics of the neoplasm are consequently presented. Intraoperative diagnosis of the epidermal cyst was proposed. The final diagnosis of SCAP was determined only by histological analysis after the surgical excision. The educational aspects of the case are critically discussed.
Objective. Derivation dependence, inter-and intrasubject/intertest variability, bilateral differences of the eardrum vibration characteristics have been investigated using laser Doppler vibrometry (LDV).Material and methods. A total of 31 normally hearing adults were examined. In each subject, both ears were consecutively stimulated by the chirp acoustic stimulus that covered 500-3700-Hz frequencies. The laser beam was directed to and the reflection was consecutively picked up from the tympanic membrane surface.Results. LDV curves derived from different eardrum loci possessed dissimilar characteristics. The derivation area dependence was particularly apparent for the stimulus frequency constituents above 1500 Hz. The intersubject variability of LDV parameters exceeded the intrasubject/ intertest one. The intersubject divergences looked selectively distinct for the frequencies over 2000 Hz. Under repeated recordings, LDV parameters remained stable. The intertest differences, if appeared, concerned predominantly the magnitudes of separate frequency bands. LDV waveforms registered by experienced and beginner investigators were alike. Bilaterally derived LDV curves regularly differed from each other. In individual cases, the bilateral divergences approximated the intersubject deviation.Conclusions. The derivation area on the eardrum should be taken into account when estimating the actual LDV recording. Over repeated recordings in separate individuals, LDV waveforms are stable while the experience of investigator has slight if any influence on the principal LDV characteristics. Due to bilateral differences in the middle ear transfer function, in LDV testing of the ear suspected to the pathology, LDV recording from the opposite healthy ear could hardly be taken as an appropriate reference sample.
The results suggest that the Lithuanian version of THI maintains its original validity and may serve as reliable and valid measure of general tinnitus related distress that can be used in a clinical setting to quantify the impact of tinnitus on daily living.
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