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Authors relate the history of acoustic hearing aids, from antiquity to our days, for air and bone conductions. It shows an evolution, more due to physical progress than medical progress, composed with deaf's psychology. The accession of electric amplification will make more than half-century to be imperative.
An unique ear refers to those cases of individuals with an air and/or bone conduction allowing a serviceable hearing in one ear, being the other one totally lost, owing to any disease. So it is relatively frequent patients presenting only one ear normal, being the other one deaf. The puzzle rises when the sole running good ear must be operated, for whichever pathology. It may be that these various circumstances were: double cholesteatoma, cholesteatoma with extreme loss of hearing, otosclerosis with total deafness and even patients with chronic middle ear otitis and progressive impairment of bilateral hearing. Before to take the final decision on behalf of surgery we must consider: the ear condition, the age and physical state, the job and the social activity and finally the desire and resolution of the patient himself as well. The paper explain our experience in dealing with 10 solitary ears seen in the last 6 years.
Audiometry of 100 locomotive drivers of different age and duration of the service showed that only 32 subjects had elevated thresholds both in conventional audiogram and wide range audiogram in bone conduction. Out of the other 68 examinees 41 had hearing defects only in wide frequency range. Thus, it is possible to reveal hearing disorders early, before appearance of occupational hypoacusis and to prevent it early.
Marihuana has been said to improve hearing. Two earlier studies have supported this contention. In this investigation, marihuana or placebo cigarettes were randomly smoked by 30 subjects, 15 in each group. Before and after smoking, batteries of standard audiological tests were carried out; pure tone threshold (air and bone conduction), speech reception threshold, speech discrimination at most comfortable level, and relative acoustic impedance measurements including middle ear pressure, stapedial reflexes, compliance, tympanic mobility, and Eustachian tube function. A comparison of pre and post smoking auditory test scores did not demonstrate any significant change in auditory function in the marihuana or placebo group. However, as all subjects had normal hearing and maximum speech discrimination scores pre-smoking, it can only be concluded that smoking marihuana did not worsen the hearing--the experiments were not designed to see whether it would improve hearing.
Many communication systems have been devised to improve the individual's ability to receive speech information in the presence of ambient noise. The purpose of this study was to determine the effectiveness of a speech delivery system which combined a high degree of ambient noise attenuation with the ear's own natural amplification phenomenon--the occlusion effect. It was demonstrated that occlusion of the auditory system at the level of the external auditory meatus, in conjuction with bone-conducted speech stimuli presented at the mastoid, was most effective in providing high speech discrimination ability with significant attenuation of ambient noise.
All cases of malformation of the ear must undergo audiological assessment. Before the age of 6 months, evoked auditory potentials during natural sleep will give information on the threshold for the high frequencies in both ears, and will confirm that the inner ear is functioning. After the age of 6 to 7 months, subjective tests are used to demonstrate the bone conduction thresholds and sometimes (depending on the degree of cooperation of the child) 1 or 2 air conduction curves. When the malformation is unilateral, and the hearing is normal on the opposite side, regular follow-up is required. When the malformation is bilateral, or unilateral in conjunction with a sensorineural hearing loss in the opposite ear, the child must be treated as a deaf child, and provided with a hearing aid.
The case notes of 33 patients with labyrinthine fistulae have been studied; they have been found in 10% of cholesteatomas. The usual site is the lateral semicircular canal. Only 17 patients experienced vertigo, 2 had total deafness, and 14 others had a mixed deafness. Scanning with fine cuts in both the axial and coronal planes demonstrates the lesion definitively in 70% of cases, but the fistula may be discovered only at operation, either in the lateral semicircular canal, or especially at the level of the oval window (5 cases). The authors usually use the closed technique (26 cases), and always seek to remove the matrix in its entirety, followed by the use of bone powder to close the fistula. In 2 patients there was a loss of hearing on bone conduction at 4 and 8 KHz, and only one had total loss of hearing. No patients had vertigo persisting after 6 months. The indications and results are compared with those found in the literature. It now seems unusual to experience postoperative sensory-neural hearing loss provided that the presence of a fistula is recognised early on, and that the covering of squamous epithelium is removed completely atraumatically at the last part of the operation.
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Fluorine content in bone samples taken from the middle ears of otosclerotic patients was determined. Otosclerotic stapes footplate was found to have a significantly higher content of fluorine than skeletal bone from the meatus. Fluorine contents in footplate and meatal wall samples of otosclerotic patients drinking fluoridated water were slightly higher than those of patients drinking low-fluoride water. In the clinical part of the study, hearing levels of 280 patients with otosclerosis living in an area with low-fluoride water were assessed. In 344 operated ears, the preoperative and long-term postoperative air conduction and bone conduction thresholds of patients drinking fluoridated water did not differ significantly from those of patients drinking low-fluoride water. After a mean follow-up period of 9.6 years, air conduction thresholds of non-operated ears in patients drinking fluoride-poor water were found to be significantly worse than those of patients drinking fluoridated tap water, likewise there were significant differences in bone conduction thresholds at 2 and 4 kHz. Thus, fluoridation of drinking water has a beneficial effect on non-operated otosclerotic ears but has no significant effect on hearing levels of operated ears.
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Osteoclastic bone resorption requires a number of complex steps that are under the control of local regulatory molecules. Osteopontin is expressed in osteoclasts and is also present in bone matrix; however, its biological function has not been fully understood. To elucidate the role of osteopontin in the process of osteoclastic bone resorption, we conducted ectopic bone implantation experiments using wild-type and osteopontin knockout mouse. In the wild-type group, bone discs from calvariae implanted ectopically in muscle were resorbed, and their mass was reduced by 25% within 4 weeks. In contrast, the mass of the bone discs from calvariae of osteopontin knockout mice was reduced by only 5% when implanted in osteopontin knockout mice. Histological analyses indicated that the number of osteoclasts associated with the implanted bones was reduced in the osteopontin knockout mice. As osteopontin deficiency does not suppress osteoclastogenesis per se, we further examined vascularization immunohistologically and found that the number of vessels containing CD31-positive endothelial cells around the bone discs implanted in muscle was reduced in the osteopontin knockout mice. Furthermore, sc implantation assays indicated that the length and branching points of the newly formed vasculatures associated with the bone discs were also reduced in the absence of osteopontin. In this assay, tartrate-resistant acid phosphatase-positive area of the bone discs was also reduced in the osteopontin knockout mice, indicating further the link between the osteopontin-dependent vascularization and osteoclast accumulation. The bone resorption defect could be rescued by topical administration of recombinant osteopontin to the bones implanted in muscle. These observations indicate that osteopontin is required for efficient vascularization by the hemangiogenic endothelial cells and subsequent osteoclastic resorption of bones.
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