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PubMed1986

Electrical conduction in bone in frequency range 0.4-1.3 GHz.

Dielectric permittivity and conductivity of bone in different physiological conditions and collagen, a major component of bone are measured in the frequency range 400-1300 MHz using a Network analyzer. The dielectric dispersion observed in each cases are explained in terms of the relaxation of 'bound water' in this frequency range. The relaxation frequency as well as distribution parameter are computed in each case, under certain simplifying conditions, hydration as well as static dielectric permittivity of bound water attached with bone in different physiological conditions and collagen are also calculated. The effect of ultraviolet light irradiation on the dielectric properties of bone in this frequency range is also examined. The change in dielectric properties due to radiation is attributed to the breakage of hydrogen bonds in the ring structure. A consistent physical model in line with other data is presented.

Animals↗
PubMed1990

[Bone-anchored hearing aids. Preliminary results].

The bone conduction hearing aid is employed for patients who cannot tolerate treatment with air conduction hearing aids and for whom operation cannot offer permanent improvement of hearing. Conventional bone conduction hearing aids are, however, uncomfortable to wear, amplification is frequently less effective and sounds are often distorted. A new type of bone conduction hearing aid, the bone-anchored hearing aid (BAHA) is presented. In this, sound is transferred directly to the cranium via a percutaneous titanium implant. The results of treatment of the first six Danish patients are presented after a therapeutic period of 8-24 months. The subjective effect of treatment was satisfactory in all of the patients. They all employed their BAHA all day and found that the effect was better than the effect of air conduction hearing aids and conventional bone conduction hearing aids on practically all points. Speech discrimination investigations in quiet and noisy surroundings confirmed the subjective assessment although the differences between BAHA and the two other types of hearing aids were not as great as the patients subjective impressions. The bone-anchored hearing aid, BAHA, should, in our opinion, become the bone conduction hearing aid of the future for patients who have a permanent need for this. It represents considerable progress in treatment of a group of patients for whom treatment has hitherto been difficult and unsatisfactory.

Aged↗
PubMed1980

Interaural attenuation in the cat, measured with single fibre data.

Acoustic crosstalk was measured in the pentobarbital anesthetized cat using the responses of single units in the auditory nerve to ipsilateral and contralateral sound stimuli. The mean interaural attenuation (IATT) was found to be 76 dB between 350 and 18,000 Hz. No systematic variation of IATT with frequency was found although a large variation between different units with similar characteristic frequencies could be seen. We suggest that this scatter is due to the complex fine structure of the bone conduction pathways (Tonndorf (1966) Bone conduction. Acta Otolaryngol. Suppl. 213, 1-132). There are large discrepancies between these data and values obtained using cochlear microphonic potentials as an indicator. We suggest that cochlear microphonic crosstalk data in the literature should be treated with caution as it is extremely difficult to exclude the effect or direct electrical crosstalk on these analog signals.

Acoustic Stimulation↗
PubMed2001

Ultrasound activates the auditory cortex of profoundly deaf subjects.

Using three-dimensional PET, the cortical areas activated by bone-conducted ultrasound were measured from five profoundly deaf subjects and compared with the cortical areas of normal-hearing subjects activated by stimuli through bone-conducted ultrasonic, air-conducted, bone-conducted, and vibro-tactile hearing aids. All of the hearing aids, including the ultrasonic hearing aid, consistently activated the medial portion of the primary auditory cortex of the normal volunteers. The same cortical area was also significantly activated in the profoundly deaf subjects although the percentage increase in regional cerebral blood flow (rCBF) was smaller than in normal subjects. These results suggest that extra-cochlear routes convey information to the primary auditory cortex and can therefore produce detectable sound sensation even in the profoundly deaf subjects, who reported a sensation themselves.

Adult↗
PubMed1977

Automatic audiometry in stapes motility evaluation.

An automatic Grason-Stadler-Békésy 1701 audiometer with continuous frequency progression (1 octave/min) and increase (or attenuation)of intensity of 2.5 dB/sec, has been employed to perfect an investigation technique for obtaining, by the mean difference in dB between absolute bone conduction (ABC) and relative bone conduction(RBC), a quantity evaluation of stapes motility and monitor alterations brought on by various disease processes. A preliminary study performed on subjects with normal hearing was used to establish the influence of age on motility. It was thus possible to establish an index (stapes motility index, SMI) to represent the degree of normal stapes motility as a function of the subject's age and thus, through variations in this index, identify alterations to the motility of the tympano-ossicular system caused by ongoing disease processes and by surgery.

Adult↗
PubMed1989

Hearing in chronic suppurative otitis media.

In individuals with chronic otitis media, mixed hearing impairments are common but it is unclear whether the raised bone conduction thresholds are a reflection of the pathologic process affecting the inner ear or a combination of the high prevalence of sensorineural hearing impairments in the population along with the artificial elevation of bone conduction thresholds associated with a conductive defect. A total of 395 ears with chronic otitis media but without cholesteatoma were studied. In them, once the artificial elevation (Carhart effect) of the bone conduction thresholds, which occurs whenever there is an abnormality of the sound conduction mechanism, had been taken into account, there was no difference in the bone conduction thresholds compared with those in 920 control ears. In addition, in 100 instances, the contralateral ear was normal and there was no difference in the bone conduction thresholds between the diseased and the normal ears. Raised bone conduction thresholds in chronic otitis media are considerably likely to reflect both the Carhart effect and the high prevalence of sensorineural impairments, rather than disease damage to the inner ear.

Auditory Threshold↗
PubMed2002

[Change in otosclerosis presentation over two decades].

Presentation of otosclerosis in eighties and nineties was compared on the basis of analysis of patients' documentation. A group I of 80 patients treated in 1980-1990 and a group II of 148 patients treated in 1991-2000 were compared with regard to sex, age, incidence of oval window obliteration and bilateral disease. Bone conduction and air conduction threshold and air-bone gap were also compared. There was no difference between two groups regarding sex, age and bone conduction threshold. Oval window obliteration was found in 8 (10%) patients of group I and in 7 (4.7%) patients of group II and the difference was not significant. Bilateral otosclerosis was diagnosed in 77 (96.3%) patients of group I and in 121 (81.8%) patients of group II and the difference was significant (p < 0.01). Air conduction threshold and air-bone gap in patients treated in nineties were significantly smaller than in eighties (p < 0.001). In the last decade patients with otosclerosis presented with smaller hearing loss, smaller air-bone gap and had bilateral disease less frequently than patients in eighties.

Adult↗
PubMedDate not supplied

Labyrinthine otosclerosis studied with a new computed tomography technique.

Forty-two patients (84 ears) with surgically confirmed otosclerosis were examined with a computerized tomographic scanner (Philips Tomoscan 310) equipped with a table swivel mechanism. All ears were scanned in the horizontal and a new semilongitudinal plane. In patients with an unimpaired bone conduction threshold, a normal labyrinthine capsule was found in all ears except two. Normal bone conduction does not exclude extensive labyrinthine otospongiosis. In cases with bone conduction impairment, the bony labyrinth appeared normal in about half the ears. In the other half, areas of bone resorption were present and a positive correlation was found between the degree of bone loss and the amount of bone conduction threshold loss.

Adolescent↗
PubMed2003

Ultrasonic masker clarifies ultrasonic perception in man.

Bone conduction enables ultrasound to be heard. Although several hypotheses about ultrasonic perception have been presented, the perception mechanism of bone-conducted ultrasound has not yet been established. In this study, to investigate ultrasonic perception, the amount of masking produced by 27-, 30- and 33-kHz bone-conducted ultrasonic maskers for air-conducted high-frequency sounds was measured in the frequency range of 8-18 kHz at 1-kHz intervals. The results showed that the air-conducted signals in the frequency range of 10-14 kHz were strongly masked by the ultrasonic maskers. When the masker intensity increased from 5 to 10 dB SL, the growth of masking was more than 10 dB in the frequency range of 9-15 kHz, and the masking spread strongly to lower frequencies. Furthermore, the dynamic range for bone-conducted ultrasound was clearly narrower than that for air-conducted high-frequency sounds. These results suggest that perception of bone-conducted ultrasound depends on inner hair cell activity induced by ultrasound, even without modulation being present, and does not depend on enhancement by the outer hair cells in the basal turn of the cochlea.

Adult↗
PubMed1994

Effect of atmospheric pressure on hearing in normal subjects.

Hearing is assumed to be altered during or immediately after a change in atmospheric pressure, although this has not been tested experimentally. We used a soundproof pressure chamber to examine the effect of alterations in atmospheric pressure on hearing in 26 normal healthy subjects. The subjects were placed in the soundproof pressure chamber in a supine position and instructed to actively equilibrate middle ear pressure or to abstain from doing so. When the pressure was changed to +/- 500 mmH2O at 33 mmH2O/s the results were as follows: When subjects did not equilibrate middle ear pressure, air conduction at low frequency tones increased more than bone conduction. The degree of deterioration in hearing was greater when the chamber pressure was increased (descent) than where pressure was decreased (ascent). When the subjects equilibrated middle ear pressure, little change in the levels of air or bone conduction was observed. Most of the deterioration in bone conduction was considered to reflect functional loss due to increased stiffness and damping of the sound transmission mechanism.

Adult↗
PubMed2005

Prospective clinical study on cochlear function after erbium:yttrium-aluminum-garnet laser stapedotomy.

OBJECTIVE: To assess whether the application of the emitting erbium:yttrium-aluminum-garnet (Er:YAG) laser in stapedotomy has negative effects on vestibular and cochlear functions. DESIGN: Prospective, with 12 to 14 months follow-up. SETTING: Academic tertiary referral center. PATIENTS: Twenty-four patients undergoing stapedotomy (primary surgery) in otosclerosis. INTERVENTION: All patients underwent Er:YAG laser-assisted stapedotomy for otosclerosis between January 2000 and June 2002. MAIN OUTCOME MEASURES: Early (1-3 days after surgery) and late (12-14 months after surgery) postoperative bone-conduction thresholds and the presence of post-operative tinnitus and vertigo were analyzed. In addition, the relation between applied laser energy and postoperative bone-conduction thresholds was calculated. RESULTS: In 22 patients, unchanged preoperative minus early postoperative pure-tone bone-conduction averages at 1, 2, and 4 kHz were observed. In one patient, a slight early deterioration between 10 and 20 dB was seen. In 18 patients, unchanged preoperative minus late postoperative pure-tone bone-conduction averages at 1, 2, and 4 kHz were observed. In two patients, a slight late deterioration between 10 and 20 dB was seen. In two patients, a new postoperative tinnitus was observed. No patient suffered from vertigo at the time of second evaluation. No correlation between applied laser energy and both postoperative bone-conduction thresholds was found. CONCLUSIONS: The Er:YAG laser stapedotomy in otosclerosis is a safe technique. Vestibular and cochlear function is not significantly disturbed after Er:YAG laser stapedotomy.

Adult↗
PubMed2002

[Long-term results after stapes surgery for otosclerosis].

In a retrospective study, hearing results before and after stapedectomy were compared with those of individuals not undergoing surgery. Subjects were 51 patients who were surgically diagnosed as having otosclerosis and who could be followed up for more than 5 years. Of these, 31 contralateral ears surgically diagnosed as otosclerotic did not undergo surgery (nonsurgery group). Nineteen ears underwent stapedectomy using a wire loop prosthesis (TS group). Thirty-eight ears underwent stapedotomy using a wire piston prosthesis (SFS group). In the nonsurgery ear group, the last air conduction threshold deteriorated equally at all frequencies. Deterioration of the high frequency air conduction threshold seemed to cause deterioration of the bone conduction threshold. Deterioration of the last air conduction threshold in the SFS group was somewhat less than that in the TS group, although not significantly. In patients up to 50 years old, the air conduction loss/year in the SFS group was significantly less than that in the nonsurgery ear group at 0.25 kHz and 0.5 kHz. The bone conduction loss/year in the SFS group was less than that in both the TS group and nonsurgery ear group at 1 kHz. No significant differences was seen in either air or bone conduction loss/year among the 3 groups in patients 51 years or older. We concluded that stapedotomy and wire piston prosthesis are the surgical techniques of choice in the treatment of otosclerosis.

Adult↗
PubMed1975

[Noise-induced hearing loss with chronic otitis media (author's transl)].

Two different otological noxes add up in their effect. In some cases, however, the first one may cause a reduction of the noxious effect of the second one. Opinions are divided as to whether the susceptibility to noise of an ear with chronic otitis media is increased or decreased. From 14,300 audiograms we selected those 131 cases with unilateral chronic otitis media and, at the same time, with a typical noise-induced recruitment-positive c5-dip on the other side. There were 86 cases with larger bone conduction hearing loss on the ear with chronic otitis media. In these cases, the bone conduction hearing loss, by all differential diagnostic criteria, could be judged to be caused by the chronic otitis media. On the other hand, in all those 45 cases which, on the side with chronic otitis media, had a bone conduction loss in form of a c5-dip, this was in each single case less pronounced than on the other ear. Regarding the susceptibility to noise, the reduction of sound intensity by the conductive deafness seems to be more important than noxious effects of the chronic otitis. Generally a substantial bone conduction hearing loss with chronic otitis media and noise exposure should be attributed to effects of the otitis.

Adult↗
PubMed2001

Bone-anchored hearing aids: current status in adults and children.

The BAHA is the only cochlea stimulator in clinical use using bone conduction as the mode of stimulation. Sound transmitted through bone conduction is a natural way of hearing and the fundamentals of bone conduction are presented. The simple but important procedure has been refined and is presented in some detail. As the BAHA is approved by the Food and Drug Administration for children, aspects relevant for this age group will be addressed. The future includes semi-implantable BAHA, percutaneous electrical coupling, and a BAHA for tinnitus suppression.

Adult↗
PubMed1994

Long-term hearing results following stapedotomy.

Stapedotomy, or small fenestra stapes surgery, offers several advantages over total stapedectomy, including less postoperative vertigo and better closure of the air-bone gap at higher frequencies. Although early postoperative results are encouraging for the small fenestra technique, few data are available for longer follow-up periods. In this retrospective study, the hearing results of 35 stapedotomy patients, representing 37 operated ears, were analyzed. Each patient had a follow-up period ranging from 5 to 11 years, with audiograms obtained preoperatively, postoperatively, and at the longterm follow-up intervals. Data obtained included air conduction, bone conduction, and speech discrimination for both ears. The long-term hearing results of the small fenestra technique compared favorably to those reported for total stapedectomy, although a statistical analysis is difficult because of the differing methods used to report the data. Results showed a linear deterioration of air conduction thresholds over time, which corresponded to a decrease of bone conduction thresholds in the operated ear. The rate of deterioration of bone conduction appeared to be the same as that associated with presbycusis alone. After good initial closure of the air-bone gap at all measured frequencies, there was no significant increase in conductive hearing loss with time. In the nonoperated ear, the bone conduction for the speech frequencies deteriorated at a rate significantly higher than that for the operated ear and was probably related to Carhart's effect.

Adult↗
PubMed1981

ABG, dips and notches evaluation of cochlear reserve in otosclerosis.

This study of a possible relationship between the ABG and the remodeling of the niche in otosclerosis in a significant number of patients operated on by stapedectomy allows the authors to define six types of ABG shape, corresponding to various types of stapedial fixation and remodeling of the niche. But the difficulties in finding the real bone conduction threshold levels, which ABG shapes depend on, lead us first to explain the mechanism of the various dips and notches altering bone conduction curves; and second, to try to find a safe and sure method for precise evaluation of the real cochlear reserve in otospongiosis/otosclerosis. We conclude that the best method is the bone conduction speech audiometry, mainly the bone conduction speech Weber tes, which automatically shows the true cochlear reserve of the ear to be operated on.

Audiometry, Speech↗
PubMedDate not supplied

Sensorineural hearing loss in stapedial otosclerosis.

Controversy exists as to whether individuals with stapedial otosclerosis have elevated bone conduction thresholds due to cochlear involvement by the focus. A comparison was made between the Carhart-corrected bone conduction thresholds in 45 unoperated, non-noise-exposed individuals with stapedial otosclerosis and the thresholds in a matched random sample of the population with no conductive hearing loss. No consistent, significant difference was discerned. It is considered that individuals with stapedial otosclerosis do not in general have elevated bone conduction thresholds compared with control subjects. However, there was a suggestion that there may be a small, progressive elevation of bone conduction thresholds in older patients.

Adult↗
PubMed1983

[Functional results of tympanum drainage in chronic seromuco-tympanum--Clinical course up to 2 years following the operation].

The hearing capacity of 95 children with chronic seromuco-tympanum (SMT) treated with middle-ear ventilation tubes was studied preoperatively and for a period of up to two years after the operation. A total of 510 audiograms with the threshold of air conduction and bone conduction were evaluated. The pre-surgery audiogram shows on the average an air-bone gap of 30 dB. In the first post-surgery audiogram the air-bone gap was improved on the average by 15-20 dB. The observation carried out over a period of two years shows that in general this improvement of the hearing capacity is preserved. The treatment of SMT by middle-ear ventilation tubes and the resulting improvement of the hearing capacity prevents the negative effects on children's acquisition of speech and on their intellectual development.

Adolescent↗