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PubMed1996

Fetal hearing: characterization of the stimulus and response.

Before sounds originating outside the abdomen of pregnant women can reach the inner ear of the fetus, they must first pass through the tissues and fluids surrounding the fetal head. Low-frequency sound energy easily penetrates to the fetal head, less than 5 dB attenuation for frequencies below 500 Hz, whereas higher frequencies are attenuated by up to 20 to 30 dB. The sound energy in amniotic fluid stimulates fetal hearing through a bone conduction route rather than through the external and middle ear systems. During passage through the bones of the skull, sound energy is slightly diminished for frequencies less than 250 Hz (10 to 20 dB), yet significantly reduced for frequencies from 500 to 2,000 Hz (40 to 50 dB). Thus, the fetus in utero can easily detect low-frequency sound energy (< 500 Hz) produced at levels that are comfortably loud for its mother, but probably cannot detect acoustic energy at frequencies higher than 500 Hz.

Bone and Bones↗

PubMed2006

Effectiveness of instillation of triamcinolone acetonide into the middle ear for eosinophilic otitis media associated with bronchial asthma.

BACKGROUND: Eosinophilic otitis media (EOM) is a newly recognized middle ear disease found in asthmatic patients. EOM is characterized by a highly viscous middle ear effusion that contains many eosinophils and is extremely unresponsive to conventional treatments for common otitis media. To our knowledge, no systemic study regarding the efficacy of treatments for EOM has been performed. OBJECTIVE: To determine the effectiveness of instillation of triamcinolone acetonide, which is a suspension of steroids, into the mesotympanum and eustachian tube as a treatment for patients with EOM. METHODS: We studied the efficacy of the instillation of triamcinolone acetonide in 43 ears of 24 patients with EOM. Efficacy was evaluated according to the length of the period without middle ear effusion or otorrhea. We also determined the otomicroscopic findings and the hearing levels before and after therapy. For controls, 27 ears of 14 patients treated by topical administration of betamethasone were similarly evaluated. RESULTS: The middle ear effusion or otorrhea was controlled for more than 3 weeks after 1 instillation of triamcinolone acetonide in 35 ears, and the efficacy rate (81%) was significantly higher than that in the controls (7 ears, 26%). In the triamcinolone acetonide group, the average air conduction hearing level at the speech frequency range was significantly improved, and deterioration of the bone conduction hearing threshold was rarely found during therapy. CONCLUSION: The instillation of triamcinolone acetonide into the mesotympanum and eustachian tube is an effective treatment for patients with EOM.

Adult↗

PubMed2006

Choice of probe tone and classification of trace patterns in tympanometry undertaken in early infancy.

Tympanometry using 226 Hz, 678 Hz, and 1000 Hz probe tones was undertaken on two groups of babies, age 2 to 21 weeks. A group of 104 babies with normal ABR thresholds or TEOAEs were compared with a second group of 107 babies who had evidence of temporary conductive hearing loss based on the findings of a test battery, which included air and bone conduction ABR. The tympanograms were classified by Method 1, a simple visual classification system, and Method 2, adapted from a system described by Marchant et al (1986). The majority of tympanograms recorded in both groups using the 226 Hz probe tone were 'normal' Type A, with no significant difference in middle ear pressure or static admittance. However, both classification methods demonstrated significant differences between the two groups using the higher frequency probe tones, with Method 2 being the preferred system of classification. Tympanometry using 226 Hz is invalid below 21 weeks and 1000 Hz is the frequency of choice.

Acoustic Impedance Tests↗

PubMed2001

The relationship between localised SAR in the arm and wrist current.

Calculations are presented of the specific energy absorption rate, SAR, in the lower arm of the NRPB anatomically realistic voxel model. NORMAN, for induced currents from 100 kHz to 80 MHz. The wrist region has a narrow cross section and contains little high conductivity muscle, comprising mainly low conductivity bone, tendon and fat. Consequently there is a channelling of the current through the high conductivity muscle, which produces high, localised values of the SAR. Values averaged over 10 g and 100 g of tissue are calculated as a function of the current flowing through the wrist.

Absorption↗

PubMed2006

Bone augmentation in rabbit calvariae: comparative study between Bio-Oss and a novel beta-TCP/DCPD granulate.

AIM: In the present in vivo study, we compare the bone regeneration capacity of a novel brushite cement synthesized in our laboratory (DTG) with Bio-Oss using rabbits as an animal model. METHODS: The study was performed in a group of 14 adult New Zealand rabbits using the bone conduction model. Two titanium cylinders were fixed into perforated slits made on the parietal cortical bone of each rabbit. One cylinder was left empty (negative control) and the other was filled with either Bio-Oss or brushite set-cement granules (test cylinder). Four weeks after the intervention, the animals were sacrificed and biopsies were taken. The following parameters were analysed: bone tissue augmentation, bone mineral density and biomaterial resorption. The comparison of data between the different groups was performed using the Mann-Whitney test with a significance level of p<0.05. RESULTS: The mean bone mineral density and augmented mineral tissue inside the test cylinders were similar but higher than those of negative controls. Material resorption and bone tissue augmentation were significantly higher in the defects treated with the brushite-based set cement (p<0.05). CONCLUSIONS: Brushite cement granules were more resorbable and generated more bone tissue than Bio-Oss inside the titanium cylinders placed in the rabbit calvaria.

Absorbable Implants↗

PubMed2002

[Channel fixation of a fascial graft to the manubrium mallei in tympanoplasty].

Long-term results of tympanoplasty with channel fixation of the fascial graft to the manubrium mallei (MM) is described. For better contact of the fascia with the malleus, a blind channel in the graft is created and the graft is put on the MM. The above operation was performed in 86 patients. The results were compared to those of 51 tympanoplasties when the MM was passed through the hole created in the graft. Better late results were obtained in tympanoplasty with channel fixation. The tympanic membrane healing rate was 92%, no lateralization occurred. The average pure air conduction threshold at frequencies 0.5-2 kHz has become 22.1 +/- 1.64 dB (before operation 37.7 +/- 1.60 dB; p < 0.001), average bone conduction threshold 11.8 +/- 1.21 dB (before operation 13.7 +/- 1.25 dB; p > 0.05) and air-bone gap was 10.4 +/- 0.9 dB.

Fascia↗

PubMed1995

Tapping the head activates the vestibular system: a new use for the clinical reflex hammer.

We investigated the use of skull taps with a modified clinical reflex hammer as a method of vestibular activation. Using recently described EMG techniques to measure vestibulocollic reflexes in response to clicks, we were able to show analogous short-latency potentials to taps. The earliest responses were invariably absent on the side of a previous vestibular nerve section but were preserved in profound sensorineural or conductive hearing loss. We propose that the taps activated the vestibular apparatus directly by a bone-conducted vibration wave.

Acoustic Stimulation↗

PubMed2004

Avoiding electromagnetic artifacts when recording auditory steady-state responses.

Electromagnetic artifacts can occur when recording multiple auditory steady-state responses evoked by sinusoidally amplitude modulated (SAM) stimuli. High-intensity air-conducted stimuli evoked responses even when hearing was prevented by masking. Additionally, high-intensity bone-conducted stimuli evoked responses that were completely different from those evoked by air-conducted stimuli of similar sensory level. These artifacts were caused by aliasing since they did not occur when recordings used high analog-digital (AD) conversion rates or when high frequencies in the electroencephalographic (EEG) signal were attenuated by steep-slope low-pass filtering. Two possible techniques can displace aliased energy away from the response frequencies: (1) using an AD rate that is not an integer submultiple of the carrier frequencies and (2) using stimuli with frequency spectra that do not alias back to the response frequencies, such as beats or "alternating SAM" tones. Alternating SAM tones evoke responses similar to conventional SAM tones, whereas beats produce significantly smaller responses.

Acoustic Stimulation↗

PubMed1998

Impaction of cancellous bone grafts impairs osteoconduction in titanium chambers.

The method of using morselized compacted cancellous allografts for hip arthroplasty revision shows results that seem to differ dramatically from other kinds of allografting. In structural cancellous allografts, bone ingrowth usually is limited to 2 to 3 mm, whereas morselized compacted grafts seem to be remodeled totally in several cases, as judged by radiography. In the current study, impacted cancellous allografts were compared with unimpacted allografts. Seventeen rats had a bone conduction chamber implanted in the tibias bilaterally. On one side the chambers contained an impacted graft (bone volume fraction 65%) and on the contralateral side an unimpacted graft (bone volume fraction 35%). Impaction of the grafts was done preoperatively with a pressure of either 25 or 2500 MPa. Ingrowing bone could enter the cylindrical interior of the chamber only at one end. After 6 weeks the mean distance the ingrown bone had reached into the graft was measured on histologic slides. With both impaction pressures, the bone ingrowth distance was decreased to 30% of the unimpacted controls. It appears that impaction alone does not have a favorable effect on the osteoconductive properties of a bone graft. On the contrary, impaction seems to disfavor osteoconduction. However, in the clinical situation this is not necessarily a disadvantage.

Animals↗

PubMed2002

Sympathetic cochleolabyrinthitis in revision stapedectomy surgery.

OBJECTIVE: The purpose of this study was to determine whether revision stapedectomy could precipitate sensorineural hearing loss in the contralateral ear. METHODS: We conducted a retrospective review of 148 patients undergoing primary or revision stapedectomy at an academic, tertiary care facility. RESULTS: Stapedectomy resulted in significant improvements in mean air conduction thresholds in the ipsilateral ear. Overall, there were no significant changes in either the air or bone conduction values of the contralateral ear. Two patients demonstrated a >20-dB decline in speech reception threshold and/or >20% decrease word recognition in the contralateral ear. Both of these patients demonstrated the decline only after revision surgery. CONCLUSION: Revision stapedectomy is on rare occasions associated with hearing loss in the contralateral ear. Contralateral hearing loss after revision stapedectomy may be due to sympathetic cochleolabyrinthitis.

Adolescent↗

PubMed1998

Mutagenicity of ethyl carbamate to lacZ- transgenic mice.

The mutagenicity of the rodent carcinogen ethyl carbamate (EC, urethane) has been assessed using the lacZ- transgenic mouse mutation assay (Muta Mouse). In two separate experiments a single i.p. dose of 900 mg/kg urethane followed by a 14-16 day expression period yielded statistically significant (approximately 2-fold) increases in mutation frequency (MF) in the lung and liver of the mice. In the second experiment MF in the spleen and bone marrow was also assessed and statistically significant increases in MF were observed in each case. Concomitantly conducted bone marrow micronucleus assays gave 15.8- and 8-fold increases respectively in the incidence of micronucleated polychromatic erythrocytes in the two studies.

Animals↗

PubMed2004

Canal wall down tympanoplasty surgery with or without ossiculoplasty in cholesteatoma: hearing results.

Aim of the study was to evaluate the functional results, in two homogeneous groups, for severity of the disease, submitted to canal-wall-down tympanoplasty (TPL CWD), with and without ossiculoplasty. A total of 60 patients who underwent canal-wall-down tympanoplasty for cholesteatoma were evaluated: 31 underwent ossiculoplasty (group A) and 29 classic Wullstein type III and IV operation (group B). Hearing results were evaluated 2 years after surgery according to the AAO-HHS guidelines. Pre-operative audiometrics revealed an air conduction PTA (AC-PTA) of 45.12 dB in group A, and 56.25 dB in group B. Bone conduction PTA (BC-PTA) was 16.86 dB in group A and 26.06 in group B. Two years after surgery, AC-PTA was 42.98 dB in group A and 58.65 dB in group B; BCPTA was 18.79 dB in group A and 25.13 dB in group B. The mean pre-operative ABG was 28.44 dB in group A and 30.14 dB in group B. Two years after surgery, group A showed a mean ABG of 24.06 and group B of 35.54 dB, the difference between the two groups was significant (p = 0.03). In conclusion, the functional results observed in the present study support the need to reconstruct the ossicular chain in canal-wall-down tympanoplasty, in fact, ossiculoplasty is associated with a better hearing gain than the classic Wullstein operations.

Adult↗

PubMed2005

Audiometric predictions using stimulus-frequency otoacoustic emissions and middle ear measurements.

OBJECTIVE: The goals of the study are to determine how well stimulus-frequency otoacoustic emissions (SFOAEs) identify hearing loss, classify hearing loss as mild or moderate-severe, and correlate with pure-tone thresholds in a population of adults with normal middle ear function. Other goals are to determine if middle ear function as assessed by wideband acoustic transfer function (ATF) measurements in the ear canal account for the variability in normal thresholds, and if the inclusion of ATFs improves the ability of SFOAEs to identify hearing loss and predict pure-tone thresholds. DESIGN: The total suppressed SFOAE signal and its corresponding noise were recorded in 85 ears (22 normal ears and 63 ears with sensorineural hearing loss) at octave frequencies from 0.5 to 8 kHz, using a nonlinear residual method. SFOAEs were recorded a second time in three impaired ears to assess repeatability. Ambient-pressure ATFs were obtained in all but one of these 85 ears and were also obtained from an additional 31 normal-hearing subjects in whom SFOAE data were not obtained. Pure-tone air and bone conduction thresholds and 226-Hz tympanograms were obtained on all subjects. Normal tympanometry and the absence of air-bone gaps were used to screen subjects for normal middle ear function. Clinical decision theory was used to assess the performance of SFOAE and ATF predictors in classifying ears as normal or impaired, and linear regression analysis was used to test the ability of SFOAE and ATF variables to predict the air conduction audiogram. RESULTS: The ability of SFOAEs to classify ears as normal or hearing impaired was significant at all test frequencies. The ability of SFOAEs to classify impaired ears as either mild or moderate-severe was significant at test frequencies from 0.5 to 4 kHz. SFOAEs were present in cases of severe hearing loss. SFOAEs were also significantly correlated with air conduction thresholds from 0.5 to 8 kHz. The best performance occurred with the use of the SFOAE signal-to-noise ratio as the predictor, and the overall best performance was at 2 kHz. The SFOAE signal-to-noise measures were repeatable to within 3.5 dB in impaired ears. The ATF measures explained up to 25% of the variance in the normal audiogram; however, ATF measures did not improve SFOAEs predictors of hearing loss except at 4 kHz. CONCLUSIONS: In common with other OAE types, SFOAEs are capable of identifying the presence of hearing loss. In particular, SFOAEs performed better than distortion-product and click-evoked OAEs in predicting auditory status at 0.5 kHz; SFOAE performance was similar to that of other OAE types at higher frequencies except for a slight performance reduction at 4 kHz. Because SFOAEs were detected in ears with mild to severe cases of hearing loss, they may also provide an estimate of the classification of hearing loss. Although SFOAEs were significantly correlated with hearing threshold, they do not appear to have clinical utility in predicting a specific behavioral threshold. Information on middle ear status as assessed by ATF measures offered minimal improvement in SFOAE predictions of auditory status in a population of normal and impaired ears with normal middle ear function. However, ATF variables did explain a significant fraction of the variability in the audiograms of normal ears, suggesting that audiometric thresholds in normal ears are partially constrained by middle ear function as assessed by ATF tests.

Acoustic Impedance Tests↗

PubMed2004

Bone formation induced by a novel form of mechanical loading on joint tissue.

Because of insufficient mechanical loading, exposure to weightlessness in space flight reduces bone mass. In order to maintain bone mass in a weightless condition, we investigated a novel form of mechanical loading--joint loading. Since some part of gravity-induced loading to our skeletal system is absorbed by viscoelastic deformation of joint tissues, we hypothesized that deformation of joint tissues would generate fluid flow in bone and stimulate bone formation in diaphyseal cortical bone. In order to test the hypothesis, we applied directly oscillatory loading to an elbow joint of mice and conducted bone histomorphometry on the diaphysis of ulnae. Using murine femurs ex vivo, streaming potentials were measured to evaluate a fluid flow induced by joint loading. Bone histomorphometry revealed that compared to no loading control, elbow loading increased mineralizing surface, mineral apposition rate, and bone formation rate 3.2-fold, 3.0-fold, and 7.9-fold, respectively. We demonstrated that joint loading generated a streaming potential in a medullar cavity of femurs. The results support a novel mechanism, in which joint loading stimulates effectively bone formation possibly by generating fluid flow, and suggest that a supportive attachment to joints, driven passively or actively, would be useful to maintain bone mass of astronauts during an exposure to weightlessness.

Animals↗

PubMed2005

Fistula of the cochlear labyrinth in noncholesteatomatous chronic otitis media.

OBJECTIVE: To discuss the clinical aspects and management of promontory fistula of the cochlear labyrinth. STUDY DESIGN: Case report and review of the literature. SETTING: University hospital, tertiary referral center. PATIENT, INTERVENTION, AND RESULTS: The authors describe an unusual case of cochlear fistula localized to the promontory discovered during tympanoplasty for noncholesteatomatous chronic otitis media in a 59-year-old woman. Bone conduction was slightly impaired after operation and hearing improved after a revision myringoplasty performed for reperforation. CONCLUSION: Erosion of the bone of the labyrinth can also be observed in noncholesteatomatous otitis media. The presence of a fistula is not always associated with profound hearing loss. Overlying pathologic tissue can be removed without damaging the membranous labyrinth.

Audiometry, Pure-Tone↗

PubMed2004

Hearing thresholds in patients affected by rheumatoid arthritis.

The aim of the study was to evaluate hearing thresholds in 38 patients with rheumatoid arthritis, divided according to disease activity into active (group A, n = 20) and non-active (group B, n = 18) patients. Pure tone audiometry, tympanometry and complete rheumatological assessment were performed. All patients presented poorer auditory thresholds compared with controls. Patients of group A had both air and bone conduction thresholds poorer than group B (although not statistically significant), and most patients of both groups presented an air-bone (a-b) gap. No significant difference in middle ear pressure was noticed between patients and controls. No correlation between hearing impairment and duration of the disease or patients' age was found. The high prevalence of hearing loss in autoimmune diseases supports the importance of audiometric evaluation in such patients. The auditory recovery through middle ear surgery before cranial nerve involvement could be considered in selected patients. Further investigations are needed for a better knowledge of the middle and inner ear involvement in patients with rheumatoid arthritis.

Acoustic Impedance Tests↗

PubMed1994

[Effects of pollution with fluoride on bone dynamics of periosteum in iliac of domestic pigs].

Studies on bone dynamic parameters of iliac periosteum and endosteum in domestic pigs with fluorosis caused by coal-burning contamination were conducted. Bone dynamics of 12 pigs with experimental fluorosis and nine controls both labelled with double tetracycline was investigated. Results showed the distance between two labels on iliac periosteum of domestic pigs with fluorosis shortened and, rates of mineralization and bone matrix formation slowed. It suggested fluorosis played significantly inhibitory roles in bone formation on the periosteal membrane of pig iliac.

Air Pollution↗

PubMed1998

Association of NIDDM and hearing loss.

OBJECTIVE: To evaluate the association of NIDDM with hearing loss in a large population-based study. RESEARCH DESIGN AND METHODS: Data from population-based longitudinal studies of aging conducted in Beaver Dam, Wisconsin, were used in these analyses. Hearing thresholds were determined by pure-tone air- and bone-conduction audiometry performed by trained technicians following American Speech-Language-Hearing Association specifications. Hearing loss was defined as the pure-tone average of the frequencies 500, 1,000, 2,000, and 4,000 Hz greater than 25 decibels hearing level in the worse ear. Diabetes status was determined by self-report of physician-diagnosed diabetes or by elevated glucose or glycated hemoglobin levels at examination. RESULTS: Of 3,571 study participants, 344 were classified as having NIDDM. Subjects with NIDDM were more likely to have a hearing loss than were subjects without diabetes (59 vs. 44%). After results were adjusted for age, this difference was not statistically significant. After individuals with hearing loss patterns inconsistent with presbycusis were excluded, there was an association between NIDDM and hearing loss when controlling for potential confounders (odds ratio [OR] 1.41, 95% CI 1.05-1.88). There was no association between duration of diabetes or glycemic control and hearing loss. Individuals with NIDDM and nephropathy were more likely to have a hearing loss than were those with NIDDM but no nephropathy (OR 2.28, 95% CI 1.04-5.00). CONCLUSIONS: These data are suggestive of a weak association between NIDDM and hearing loss.

Adult↗