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At least 1,441 records · Page 80Linked to original sources
PubMed1998

Long-term results with the titanium bone-anchored hearing aid: the U.S. experience.

OBJECTIVE: The purpose of this study is to evaluate the long-term safety and efficacy of the titanium bone-anchored hearing aid (BAHA). STUDY DESIGN: A retrospective review of 24 patients implanted with the BAHA between 1984 and 1987 in a multiinstitutional study designed to evaluate the device in the United States was performed, including detailed clinical and audiologic evaluations of the 10 patients implanted at the Columbia-Presbyterian Medical Center in New York. The data were collected from patients' charts, questionnaires, and the Nobel Biocare patient contact and repair records. PATIENTS: Candidates for the BAHA are unable to use a conventional air conduction hearing aid because of congenital aural atresia, draining mastoid cavities, or recurrent otitis externa. The audiologic indications are a conductive or a mixed hearing loss with a bone conduction average of 45 db or better and a speech discrimination score of 60% or better. INTERVENTION: A BAHA was implanted in a two-stage procedure under local anesthesia on an outpatient basis. MAIN OUTCOME MEASURES: Patients' satisfaction with the device, hearing improvement, and complication rates were reviewed. RESULTS: The majority of the patients analyzed (78%) are still using the device an average of 15.6 hours/day 10 to 13 years after implantation. The overall satisfaction score was 4.5 (1, worst; 5, best). In sound field testing, the mean speech reception threshold improved from 52 db to 27 db (p < 0.05). There were no major complications. CONCLUSION: The BAHA is a safe and effective bone conduction hearing aid with wide applications for patients with bone conduction hearing levels of 45 db and discrimination scores of 60% or better.

Bone Conduction↗
PubMed1985

Verification of the air-bone gap using cancellation and evoked responses.

Using the cancellation method as well as evoked responses, we investigated their application in the estimation of the air-bone gap in patients undergoing operation on middle ear structures. The cancellation method had a closer relationship with pure-tone audiometry than evoked responses in predicting the air-bone gap. This was caused by recruitment, by which the cancellation method was not affected. The results of brainstem-evoked responses to bone and air conduction signals showed therefore an underestimation in the prediction of the air-bone gap. Combining the cancellation method with evoked responses elicited to air conduction signals permitted the estimation of the cochlear reserve without the need of threshold measurement by bone conduction.

Adult↗
PubMed1986

Effect of middle ear modification on umbo vibration. Human temporal bone experiments with a new vibration measuring system.

The effects of aditus blockage, decrease of tympanic cavity volume, and resection of the tensor tympani muscle on umbo displacement were studied in human temporal bones using a new non-contacting video measuring system. This system, combined with stroboscopic illumination, allowed measurement of umbo vibration down to 0.3 micron in the 0.1- to 4.5-kHz frequency range for a constant 124-dB sound pressure level at the tympanic membrane. Aditus blockage caused a mean increase of 5.4 dB with a peak at 2.8 kHz and a mean decrease of 3.4 dB below 1.6 kHz. Decrease of the tympanic cavity volume by 30% to 42% showed an improvement of 2.2 dB in the 1.4- to 3-kHz range and a similar loss below 1 kHz. Resection of the tensor tympani muscle produced a slight improvement of 1.7 dB at 1.8 kHz.

Bone Conduction↗
PubMed2005

Spectrum of middle and inner ear abnormalities in infants with congenital heart defects.

OBJECTIVE: To evaluate temporal bone histopathology in infants with congenital heart defects (CHD). STUDY DESIGN AND SETTING: A retrospective review of our temporal bone collection was conducted to identify temporal bones acquired from infants with CHD. Subjects were divided into nonsyndromic and syndromic CHD groups. The presence of temporal bone abnormalities and the incidence of abnormalities that may result in hearing impairment were determined. RESULTS: Thirty-eight temporal bones obtained from 16 infants with nonsyndromic CHD and 4 with syndromic CHD were evaluated. Nonsyndromic CHD cases had abnormalities such as a mesenchymal remnant, malformed stapes, persistent stapedial artery, shallow round window, dehiscent facial nerve canal, short cochlea, strial basophilic deposits, deformity of the spiral ligament, bulging Reissner's membrane, hypoplastic lateral semicircular canal, and cupular deposits. Syndromic CHD cases had abnormalities including narrow round window niche, facial canal dehiscence, strial basophilic deposits and cysts, and outer hair cell loss. Middle and inner ear abnormalities that may impair hearing were observed in 6 subjects with nonsyndromic CHD and in 1 subject with syndromic CHD. CONCLUSIONS: A wide variety of temporal bone defects were documented in infants with CHD. Congenital middle and inner ear abnormalities should be anticipated in the hearing assessment and otologic surgery of infants with CHD.

Abnormalities, Multiple↗
PubMed1999

Three-dimensional bone structure around hydroxyapatite and titanium implants in rabbits.

Long-term support of dental implants requires adequate bone thickness in the area surrounding the implant. A three-dimensional examination, including calculations of percent bone-implant contact and percent bone volume, was conducted to clarify the bone structure around pure titanium (Ti) and dense hydroxyapatite (HA) implants. The implants were installed in the tibiae of rabbits, and the bone structure was examined after 2, 4, 6 and 8 weeks. The bone formation following implantation differed in the cortical bone and cancellous bone areas. In the cortical bone area, the percent bone-implant contact and percent bone volume were comparatively consistent for both Ti and HA implants during the observation period. In the cancellous bone area, both findings were influenced by the implantation period, and the chronological bone structure in the cancellous bone area also differed between Ti and HA implants. The percent bone-implant contact and percent bone volume in the Ti implant increased over 8 weeks, whereas the dense HA implant increased for the first 4 weeks and then decreased. The implant materials, Ti and HA, affected the bone remodeling in the cancellous bone area.

Analysis of Variance↗
PubMed2006

Key features of the human middle ear.

The human middle ear was investigated using a generalised circuit model which can simulate the spatial vibrations of the ossicular chain. The behaviour was observed for acoustic excitation via the normal air conduction path and for mechanic excitation due to shaking the complete temporal bone. More insight into the functionality of the middle ear was obtained by also considering abnormal conditions such as stiffenings. It turned out that the mammalian middle ear is superior to a columella ear due to its particular design. The placement of comparably heavy bones (malleus head and incus body) outside the main transmission path between the manubrium and the stapes footplate in combination with a very flexible ossicular chain creates several favourable properties.

Acoustic Stimulation↗
PubMed1990

[Mechanical impedance of the human mastoid and forehead--a critique of the mechanical coupler of the IEC373].

Mechanical impedances of human mastoids and foreheads were measured on frequencies from 250 to 6300 Hz for 80 young adults by means of B&K impedance head (#8000) and shaker (#4810) as main parts of the measuring setup. The measurements revealed the following problems in the IEC373 (1971/1981) which had defined the mechanical impedance characteristics of the mechanical coupler for calibration of bone vibrators in audiometric use. The average impedance levels of the mastoids differ significantly from those of the foreheads in middle and high frequencies. The impedance levels of the IEC373 mechanical coupler are higher than those of the present measurements of the mastoids and the foreheads. The differences exceeded the tolerance limits of IEC373 (1981) in every frequency. These findings strongly suggest that the coupler is neither the artificial mastoid nor the artificial forehead but a coupler having a specified impedance, therefore, disregard for effect of the type of bone vibrator on the Reference Equivalent Threshold Force Level, as seen in ISO7566, should be revised and that the RETFL should be determined for an each type of bone vibrator.

Adult↗
PubMedDate not supplied

Use of a new malleable implant as a bone substitute in maxillofacial surgery.

Biocompatible osteoconductive polymer (BOP) has been used since 1979 as a substitute for bone in orthopedic surgery and neurosurgery. To date, in maxillofacial surgery, loss of bone volume as a result of either trauma or osteoporosis has been compensated for by autologous bone onlay graft or subperiosteal apposition grafts of synthetic materials. Neither of these solutions is entirely satisfactory. Autologous bone is subject to reabsorption, requiring initial overcorrection and multiple reoperations to achieve an acceptable result. Preshaped implants of Proplast, Vicryl, Gore-Tex, or silicone do not offer much flexibility, and coral granules and hydroxyapatite are difficult to handle. Finally, all foreign materials can elicit problems with tolerability. In its SP (solution/powder) form, BOP is a paste that can be molded precisely to the required shape, making it ideal for maxillofacial surgery. This study examined the long-term tolerability and facial alterations after implants of BOP in 11 patients who underwent post-trauma and cosmetic surgery.

Adult↗
PubMed1976

[Methods for oscillography on the temporal bone preparation (author's transl)].

Oscillography of the middle ear structure on the temporal bone preparation are of essential importance for the expansion of our knowledge concerning physiological process and thus also for the further development of operation techniques that improve hearing. With the increased technical possibilities we are now able to make processes in the range of only few A measurable and visible. Accordingly, the methods employed for this purpose are complicated and manifold. The goal of this paper is to summarize these techniques as far as possible, to describe them in an understandable way, and to briefly point out their pros and cons. Optical methods, nearly all of which are in use today, as well as new methods such as laser interferometry and the Moessbauer technique, which can be performed only in few laboratories, are discussed.

Bone Conduction↗
PubMed1982

Depletion of reserve in the hemopoietic system. II. Decline in CFU-S self-renewal capacity following prolonged cell cycling.

The prolonged induction of pluripotent hemopoietic stem cells into the cell cycle was accomplished by injecting phenylhydrazine hydrochloride which induced a hemolytic anemia. Phenylhydrazine hydrochloride was intraperitoneally administered 3 days/week for 6 weeks (or every 2 days for 17 weeks) during which time the hematocrit fell to a mean of 32% while the reticulocyte count increased from 0.8 to 83%. The number of CFU-S in S-phase at any time increased from a baseline of 7 up to 64%. After prolonged CFU-S cell cycling, serial bone marrow transplantations were conducted. Control serial bone marrow transplantations could be accomplished 5 times, while if prolonged cycling had occurred, only one transplantation could be successfully accomplished, and even then, reversion to host karyotype occurred within 30 days. These data may be interpreted as supporting a CFU-S generation-age hypothesis with an inherent 'Hayflick limit'.

Animals↗