Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Bone Conduction”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,351 records · Page 75Linked to original sources
PubMed2004

Semicircular canal fenestration - improvement of bone- but not air-conducted auditory thresholds.

Auditory stimulation can, under certain circumstances, activate the vestibular end organs and this is facilitated by fenestration of a semicircular canal (SCC). Several fenestrated profoundly deaf patients reported improvements in their bone- (BC) but not air-conducted (AC) thresholds. Bone conduction auditory thresholds have been reported to be better than normal in several patients with thinning or absence of bone over a SCC (dehiscence). This phenomenon was carefully studied in the fat sand rat (Psammomys obesus) by recording auditory brainstem evoked responses to BC and AC auditory stimulation, before and after SCC fenestration. Fenestration would be expected to decrease the pressure difference across the cochlear partition, causing a reduction in the amplitude of the classical base to apex input traveling wave, and should therefore lead to an elevation in AC and BC thresholds. Instead, BC thresholds decreased (i.e. improved) following fenestration (by 7.0+/-4.2 dB; P<0.005), while AC thresholds did not change. Thus the cochlea becomes more sensitive to BC, but not AC, stimulation in the presence of a SCC fenestration. This may be due to the removal by the fenestration of a factor impeding BC cochlear responses, or by the addition of a facilitating factor. The result that the SCC fenestration did not affect AC threshold provides support for the concept that at low intensities the outer hair cells are directly activated by components of the fluid pressures surrounding them, which alternate at audio-frequencies. These cochlear fluid audio-frequency pressures are induced by stapes footplate movement and not by a base to apex input traveling wave. The audio-frequency pressures would not be affected by SCC fenestration. The outer hair cell motility thus induced somehow excites the inner hair cells and the auditory nerve fibers. At low intensities the outer hair cell motility causes localized displacement at the appropriate position on the basilar membrane.

Acoustic Stimulation↗
PubMed2001

[Early detection of a sensorineural aspect of hypoacusis in patients with chronic purulent otitis media].

To detect initial signs of internal ear dysfunction in 87 patients with otitis media purulenta chronica (OMPC), wide-rage frequency audiometry (WRFA) in bone and air conduction according to B.M. Sagalovich was used. Most of the patients with normal bone conduction in frequencies up to 8 kHz had higher bone thresholds in wide-range frequencies. In mixed hypoacusis these thresholds rose to the highest degree. A correlation was found between a rise of auditory thresholds wide range of frequencies in bone conduction and the disease duration.

Adolescent↗
PubMed2006

[Cochlear protection and surgical precision in stapedotomy with Er:YAG laser].

BACKGROUND: Using laser in stapedotomy has attracted a lot of attention since the nineties. It aims at minimizing complications due to hand-operated equipment, especially inner ear lesions, and achieving higher precision. We analyzed the clinical effect of Er:YAG laser with the question whether the postulated cochlea protection and foot plate perforation, optimized for better sound conduction, are achieved, compared to conventional stapedotomy. PATIENTS AND METHODS: We evaluated retrospectively audiometrical data including pre- and postoperative bone and air conduction thresholds of 114 consecutive patients, on whom we had performed stapedotomy and had inserted platinum-teflon prostheses. The intervention was done conventionally in 72 cases and in 42 cases with Er:YAG laser. RESULTS: In the lower and middle frequencies, laser technique resulted in a more pronounced improvement of bone conduction thresholds compared to conventional stapedotomy. The improvement of air conduction was more distinct in ears after laser surgery; also, the difference between air and bone conduction was reduced at a higher degree. CONCLUSION: Er:YAG laser in stapedotomy is coupled with cochlea protection, as demonstrated under clinical conditions, and allows higher hearing benefit of air conduction compared to conventional stapedotomy. Our results emphasize the impact of innovative laser technique on stapedotomy.

Adult↗
PubMed1990

[Effects of hollow shaft endoprosthesis on stress distribution in cortical bone].

Generally, conduction of the forces from the distal end of the prosthesis stem into the surrounding cortical bone effects a local load increase in the bone. Where bone and stem are in close contact "stress protection" is hardly avoidable, and this, together with the load increase, results in the formation of a "plug of bone" beneath the tip of the prosthesis. Since the prosthesis stem rests on this bone "plug", additional "stress protection" of the femur results, which may possibly lead to total failure of the femur and/or the prosthesis. A 3-dimensional FEM-analysis shows that the hollow-stem prosthesis helps to decrease the stress peak beneath the tip of the prosthesis, while at the same time the stress in the proximal cortical bone increases. The increase in the loading of the bone inevitably causes a reduction in bone breakdown through "stress shielding" in this region.

Biomechanical Phenomena↗
PubMed2006

Effective bone hemostasis and healing using radiofrequency and conductive fluid.

Hemostasis in bone is difficult to achieve because of the mineral content. Current techniques often are ineffective, can have systemic effects, or leave residual material in the wound. Our hypotheses were that a wand device coupling radiofrequency energy with a cooling conductive saline solution, applied topically to bone, could produce superior hemostasis compared with conventional electrocautery or no treatment, and not impede bone healing. Immediate hemostasis and subsequent bone healing for 6 and 12 weeks were evaluated in an iliac crest ostectomy (cancellous bone) and a drilled tibia defect (cortical bone) sheep model. Outcome variables were amount and intensity of bleeding, serial radiography, quantitative computed tomography, histology and mechanical testing. Control of bleeding was nearly complete (93%) and greater with the radiofrequency/saline treatment compared with electrocautery (56%) or no treatment (0%) in cancellous bone and cortical bone. Electrocautery induced surface char (black carbon debris) that could be seen at 6 and 12 weeks. There were no differences in bone healing between the radiofrequency and electrocautery device applications or untreated bone. At 12 weeks, all healing tibiae defects were as strong as undrilled tibiae. This may be an effective method to produce rapid hemostasis in bone without char or healing complications.

Animals↗
PubMed1976

[Recording and evaluation of audiometric data before and after operations in the middle ear a proposal for standardization (author's transl)].

For audiological analysis of the results of operations in the middle ear raising of audiometric values in 10 dB ranges is sufficient, differentiated for bone and air conduction, pre- and postoperatively for frequencies of 0.5/1/2/4/8 kHz. Mean values of frequencies of 0.5/1/2 kHz for air and bone conduction as well as for sound conduction component raised for each patient are used for statistical analysis exclusively. Two hypotheses are under trial, i.e. bone conduction does not change after operation and that postoperative sound conduction component remains possibly small. An audiogramm-like presentation of the results is preferred to frequency distribution curves. Data processing programmes, suited for several computer systems are available.

Audiometry↗
PubMed1988

The effects of methotrexate (MTX) on bone. A densitometric study conducted on 59 patients with MTX administered at different doses.

The bone density of two groups of patients with osteosarcoma treated with high and low doses of MTX is compared with that of a group of healthy subjects of the same age. Bone density was measured in the radius at the mid point and at the trabecular distal point. In the patients treated with low doses there were differences in bone density as compared with the controls. In those treated with high doses the bone mineral content values were significantly lower than those for the controls (p greater than 0.01) at the trabecular distal point but not at the mid point. The significant reduction in BMC in patients treated with high doses indicated that the osteopaenic effect is dose-dependent. The decrease in density only at the site at which trabecular bone is prevalent shows that MTX acts mainly at the level of this type of bone in accordance with the proven greater sensitivity of trabecular bone to the action of other osteopaenic agents.

Adolescent↗
PubMed2000

Decline in osteocyte lacunar density in human cortical bone is associated with accumulation of microcracks with age.

Despite osteocytes' ideal position to sense the local environment and thereby influence bone remodeling, the function of osteocytes in bone remains controversial. In this study, histomorphometric examination of male and female femoral middiaphyseal cortical bone was conducted to determine if bone's remodeling response, indicated by tissue porosity and accumulation of damage, is associated with osteocyte lacunar density (number of osteocyte lacunae per bone area). The results support the sensory role of the osteocyte network as the decline in osteocyte lacunar density in human cortical bone is associated with the accumulation of microcracks and increase in porosity with age. Porosity and microcrack density increased exponentially with a decline in osteocyte lacunar density indicating that a certain minimum number of osteocytes is essential for an "operational" network. No gender-related differences were found in the relationship of osteocyte lacunar density to age, porosity, or microcrack density. The coefficient of variation of osteocyte lacunar density increased linearly with age, indicating that aging bone tissue is characterized by increased heterogeneity in the spatial organization of osteocytes. Osteocyte lacunar density, porosity, and microcrack density exhibited the same exponential probability density distribution in the donor population, indicating their regulation by similar biological phenomena.

Adolescent↗
PubMed1993

Use of demineralized bone as an osteoinductive orbital enucleation implant in the rabbit.

Implanted allogeneic demineralized bone particles (DBP) may be transformed into endochondral bone by inductive or conductive new bone formation. Using a rabbit model, enucleation or evisceration was performed, and DBP was implanted into the socket. Histology confirmed endochondral bone formation in both groups. A morphologic difference existed between enucleation and evisceration: compact bone was produced following evisceration, and cancellous bony spheres were formed following enucleation. Serial quantitative computed tomography (qCT) was performed to monitor mineral density and proved to be an ideal technique to monitor bone mineralization noninvasively in the postoperative orbit. Bone mineral density (BMD, mg/ml) increased approximately 300% in DBP implanted orbits when compared to controls at 6 weeks. The ideal mass/volume ratio of DBP to socket volume was 400 mg/ml. The rapidly formed bone is well vascularized and creates a stable integrated orbital implant, following enucleation and evisceration surgery. DBP implantation into the central orbit results in inductive bone formation with interesting potential in socket and orbit reconstruction.

Animals↗