Unusual audiological findings in cranial metaphyseal dysplasia.
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Audiometry↗
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Surgery and histopathology of the stapes in osteogenesis imperfecta tarda.
Fourteen stapedectomies were performed on ten patients with osteogenesis imperfecta tarda. Clinically, the footplates were softer and more tenuously fixed than in otosclerosis and floating footplates seemed more common. Stapes and stapes fragments from all 14 operations were examined microscopically. The histopathology of osteogenesis imperfecta was contrasted to that of otosclerosis. We believe that the greater degree of structural disorganization and greater area occupied by resorption spaces clearly distinguish the new bone formed in osteogenesis imperfecta from otosclerosis.
Adolescent↗
Cochlear reserve in otosclerosis. A long-term follow-up study of fenestration cases.
In this long-term follow-up study of fenestration cases, a remarkable stability in sensorineural hearing levels is demonstrated. Since the focus of otosclerosis was not removed at the time of fenestration surgery, this bone conduction stability is an indication that the ear can withstand the presence of an otosclerotic lesion that produces stapes fixation for long periods of time without sensorineural deterioration. It would seem that the otosclerotic lesion in ears suitable for fenestration surgery has had little tendency to invade deeply into the cochlear capsule.
Adult↗
Cochlear blood flow. Effect of noise.
Cochlear blood flow as investigated in anesthetized gerbils exposed to high-frequency (10 to 40 kHz), high-intensity (113 dB sound pressure level noise for 13 minutes. Blood flow was measured using a newly developed technique, which combines the surface preparation dissecting of the cochlea with the microsphere method. Our experiments indicate that short-lasting, high-intensity noise exposure causes a highly significant elevation of the blood flow in noise-exposed inner-ear areas. On the exposed side, blood flow increase was observed in the first turn of the stria vascularis-supralis ossea. On the opposite side, which was exposed only through bone conduction, blood flow was significantly elevated only in the basilar membrane.
Animals↗
Preservation of hearing after removal of the membranous canal with a cholesteatoma.
Normal cochlear function was preserved in a patient after excision of the membranous canal from a huge fistula at revision surgery eight years after the primary procedure. A recurrent cholesteatoma had eroded the entire prominence of the horizontal canal and surrounded its membranous portion. The cholesteatoma, including the membranous canal, was removed in a one-stage procedure. The open ends of the bony canal were sealed with a fascia soaked in fibrin glue. After initial dizziness and severely reduced hearing, the patient quickly recovered, with normal bone conduction and a stable 30-dB hearing level by air conduction. The lumen of the membranous canal was patent, and only the ampullar end was atretic. Presumably, the fistula became separated from fluid spaces by formation of perilymphatic partitions and by collapse of the membranous labyrinth adjacent to the fistula.
Adult↗
'Tripod' ossiculoplasty in incudal lesions.
A method of ossiculoplasty, in cases where the long process of the incus is eroded, is described. The defect created by the erosion of the incus is bridged by an autogenic or allogenic bone graft that leans on the stapes, the remaining part of the incus, and the side of the malleus. These three contact points allow for stability of the bony graft and account for the name tripod. The method was applied in 30 ears and was successful in all but three cases. All the rest (ie, 27 ears) achieved an average gain of 24.8 dB, leaving an average air-bone gap of 11.1 dB. The postoperative air-bone gap was 20 dB or less in all 27 ears that were successfully operated on; and in 21 of them (77.8%), it was no more than 10 dB. The average period of follow-up was 23.8 months. Operative success depended on both the technique chosen and the favorable selection of cases.
Bone Conduction↗
Early bone formation around calcium-ion-implanted titanium inserted into rat tibia.
Rat tibia tissue into which calcium ion (Ca2+)-implanted titanium was surgically placed was histologically analyzed to investigate the performance of the Ca(2+)-implanted titanium as a biomaterial. Calcium ions were implanted into only one side of titanium plates at 10(17) ions/cm2 and the Ca(2+)-treated titanium was surgically implanted into rat tibia for 2, 8, and 18 days. Tetracycline and calcein were used as hard-tissue labels. After excision of the tibia, the tissues were fixed, stained, embedded in polymethyl methacrylate, and sliced. The specimens were observed using a fluorescence microscope. A larger amount of new bone was formed on the Ca(2+)-treated side than on the untreated side, even at 2 days after surgery. In addition, part of the bone made contact with the Ca2(+)-treated surface. On the other hand, bone formation on the untreated side was delayed and the bone did not make contact with the surface. Mature bone with bone marrow formed in 8 days. Neither macrophage nor inflammatory cell infiltration was observed. The results indicated that Ca(2+)-implanted titanium is superior to titanium alone for bone conduction.
Animals↗
Bone-bonding behavior of alumina bead composite.
Previously we developed an alumina bead composite (ABC) consisting of alumina bead powder (AL-P) and bisphenol-alpha-glycidyl methacrylate (Bis-GMA)-based resin and reported its excellent osteoconductivity in rat tibiae. In the present study, are evaluated histologically and mechanically the effect of alumina crystallinity on the osteoconductivity and bone-bonding strength of the composite. AL-P was manufactured by fusing crushed alpha-alumina powder and quenching it. The AL-P was composed mainly of amorphous and delta-crystal phases of alumina. Its average particle size was 3.5 microm, and it took a spherical form. Another composite (alpha ALC), filled with pure alpha-alumina powder (alpha AL-P), was used as a referential material. The proportion of powder added to each composite was 70% w/w. Mechanical testing of ABC and alpha ALC indicated that they would be strong enough for use under weight-bearing conditions. The affinity indices for ABC, determined using male Wistar rat tibiae, were significantly higher than those for alpha ALC (p < 0.0001) up to 8 weeks. Composite plates (15 x 10 x 2 mm) that had an uncured surface layer on one side were made in situ in a rectangular mold. One of the plates was implanted into the proximal metaphysis of the tibia of a male Japanese white rabbit, and the failure load was measured by a detaching test 10 weeks after implantation. The failure loads for ABC on its uncured surface [1.91+/-1.23 kgf (n = 8)] were significantly higher than those for alpha ALC on its uncured surface [0.35+/-0.33 kgf (n = 8); (p < 0.0001)], and they also were significantly higher than those for ABC on the other (cured surface) side (p < 0.0001). Histological examinations using rabbit tibiae revealed bone ingrowth into the composite only on the uncured surface of ABC. This study revealed that the amorphous phase of alumina and formation of an uncured surface layer are needed for the osteoconductive and bone-bonding ability of ABC. ABC shows promise as a basis for the development of a highly osteoconductive and mechanically strong biomaterial.
Aluminum Oxide↗
The biocompatibility and osteoconductive activity of a novel hydroxyapatite/collagen composite biomaterial, and its function as a carrier of rhBMP-2.
A hydroxyapatite/type I collagen (HAp/Col) composite, in which the hydroxyapatite nanocrystals align along the collagen molecules, has been prepared. The biocompatibility, osteoconductive activity, and efficacy as a carrier of recombinant human bone morphogenetic proteins (rhBMPs) of this novel biomaterial were examined. The composite material was implanted in the backs of Wistar rats, and specimens were collected for histological observations until week 24. In a second experiment, other samples of the composite material (5 x 5 x 10 mm3) were drilled and immersed in a solution of rhBMP-2 (0, 200, 400 microg/mL), and subsequently grafted in radii and ulnae in beagle dogs. As a control, three unfilled holes were left in one radius and ulna. X-ray images were prepared, and specimens collected for histological observation at weeks 8 and 12. Histological findings of the composites grafted in rats showed that the surface of the material was eroded as a result of macrophage infiltration. X-ray images and histological findings for the composites implanted in dogs support the idea that HAp/ Col has a high osteoconductive activity and is able to induce bone-remodeling units. In cases where the implants are grafted at weight bearing sites, treatment with rhBMP-2 at a dose of 400 microg/mL may be useful to shorten the time needed until bone union has occurred.
Animals↗
Auditory response to pulsed radiofrequency energy.
The human auditory response to pulses of radiofrequency (RF) energy, commonly called RF hearing, is a well established phenomenon. RF induced sounds can be characterized as low intensity sounds because, in general, a quiet environment is required for the auditory response. The sound is similar to other common sounds such as a click, buzz, hiss, knock, or chirp. Effective radiofrequencies range from 2.4 to 10000 MHz, but an individual's ability to hear RF induced sounds is dependent upon high frequency acoustic hearing in the kHz range above about 5 kHz. The site of conversion of RF energy to acoustic energy is within or peripheral to the cochlea, and once the cochlea is stimulated, the detection of RF induced sounds in humans and RF induced auditory responses in animals is similar to acoustic sound detection. The fundamental frequency of RF induced sounds is independent of the frequency of the radiowaves but dependent upon head dimensions. The auditory response has been shown to be dependent upon the energy in a single pulse and not on average power density. The weight of evidence of the results of human, animal, and modeling studies supports the thermoelastic expansion theory as the explanation for the RF hearing phenomenon. RF induced sounds involve the perception via bone conduction of thermally generated sound transients, that is, audible sounds are produced by rapid thermal expansion resulting from a calculated temperature rise of only 5 x 10(-6) degrees C in tissue at the threshold level due to absorption of the energy in the RF pulse. The hearing of RF induced sounds at exposure levels many orders of magnitude greater than the hearing threshold is considered to be a biological effect without an accompanying health effect. This conclusion is supported by a comparison of pressure induced in the body by RF pulses to pressure associated with hazardous acoustic energy and clinical ultrasound procedures.
Animals↗
Statistical methods for multivariate interval-censored recurrent events.
Multi-type recurrent event data arise when two or more different kinds of events may occur repeatedly over a period of observation. The scientific objectives in such settings are often to describe features of the marginal processes and to study the association between the different types of events. Interval-censored multi-type recurrent event data arise when the precise event times are unobserved, but intervals are available during which the events are known to have occurred. This type of data is common in studies of patients with advanced cancer, for example, where the events may represent the development of different types of metastatic lesions which are only detectable by conducting bone scans of the entire skeleton. In this setting it is of interest to characterize the incidence of the various types of bone lesions, to estimate the impact of treatment and other covariate effects on the development of new lesions, and to understand the relationship between the processes generating the bone lesions. We develop joint models for multi-type interval-censored recurrent events which accommodate dependencies between different types of events and enable one to examine the covariate effects via regression. However, since the marginal likelihood resulting from the multivariate random effect model is intractable, we describe a Gibbs sampling algorithm to facilitate model fitting and inference. We use generalized estimating equations for estimation and inference based on marginal models. The finite sample properties of the marginal approach are studied via simulation. The estimates of both the regression coefficients and the variance-covariance parameters are shown to have negligible bias and 95 per cent confidence intervals based on the asymptotic variance formula are shown to have excellent empirical coverage probabilities in all of the settings considered. The application of these methods to data from a trial of women with advanced breast cancer provides insight into the clinical course of bone metastases in this population.
Bayes Theorem↗
Sound and vibration sensitivity of VIIIth nerve fibers in the grassfrog, Rana temporaria.
We have studied the sound and vibration sensitivity of 164 amphibian papilla fibers in the VIIIth nerve of the grassfrog, Rana temporaria. The VIIIth nerve was exposed using a dorsal approach. The frogs were placed in a natural sitting posture and stimulated by free-field sound. Furthermore, the animals were stimulated with dorso-ventral vibrations, and the sound-induced vertical vibrations in the setup could be canceled by emitting vibrations in antiphase from the vibration exciter. All low-frequency fibers responded to both sound and vibration with sound thresholds from 23 dB SPL and vibration thresholds from 0.02 cm/s2. The sound and vibration sensitivity was compared for each fiber using the offset between the rate-level curves for sound and vibration stimulation as a measure of relative vibration sensitivity. When measured in this way relative vibration sensitivity decreases with frequency from 42 dB at 100 Hz to 25 dB at 400 Hz. Since sound thresholds decrease from 72 dB SPL at 100 Hz to 50 dB SPL at 400 Hz the decrease in relative vibration sensitivity reflects an increase in sound sensitivity with frequency, probably due to enhanced tympanic sensitivity at higher frequencies. In contrast, absolute vibration sensitivity is constant in most of the frequency range studied. Only small effects result from the cancellation of sound-induced vibrations. The reason for this probably is that the maximal induced vibrations in the present setup are 6-10 dB below the fibers' vibration threshold at the threshold for sound. However, these results are only valid for the present physical configuration of the setup and the high vibration-sensitivities of the fibers warrant caution whenever the auditory fibers are stimulated with free-field sound. Thus, the experiments suggest that the low-frequency sound sensitivity is not caused by sound-induced vertical vibrations. Instead, the low-frequency sound sensitivity is either tympanic or mediated through bone conduction or sound-induced pulsations of the lungs.
Acoustic Stimulation↗
Sound and vibration sensitivity of VIIIth nerve fibers in the frogs Leptodactylus albilabris and Rana pipiens pipiens.
1. Responses of 73 fibers to dorso-ventral vibration were recorded in the saccular and utricular branchlets of Rana pipiens pipiens using a ventral approach. The saccular branchlet contained nearly exclusively vibration-sensitive fibers (33 out of 36) with best frequencies (BFs) between 10 and 70 Hz, whereas none of the 37 fibers encountered in the utricular branchlet responded to dorso-ventral vibrations. 2. Using a dorsal approach we recorded from the VIIIth nerve near its entry in the brainstem and analyzed responses to both sound and vibration stimuli for 65 fibers in R. pipiens pipiens and 25 fibers in Leptodactylus albilabris. The fibers were classified as amphibian papilla (AP), basilar papilla (BP), saccular or vestibular fibers based on their location in the nerve. Only AP and saccular fibers responded to vibrations. The AP-fibers responded to vibrations from 0.01 cm/s2 and to sound from 40 dB SPL by increasing their spike rate. Best frequencies (BFs) ranged from 60 to 900 Hz, and only fibers with BFs below 500 Hz responded to vibrations. The fibers had identical BF's for sound and vibration. The saccular fibers had BFs ranging from 10 to 80 Hz with 22 fibers having BFs at 40-50 Hz. The fibers responded to sound from 70 dB SPL and to vibrations from 0.01 cm/s2. 3. No differences in sensitivity, tuning or phase-locking were found between the two species, except that most BP-fibers in R. pipiens pipiens had BFs from 1.2 to 1.4 kHz, whereas those in L. albilabris had BFs from 2.0 to 2.2 kHz (matching the energy peak of L. albilabris' mating call). 4. The finding that the low-frequency amphibian papilla fibers are extremely sensitive to vibrations raises questions regarding their function in the behaving animal. They may be substrate vibration receptors, respond to sound-induced vibrations or bone-conducted sound.
Animals↗
Permanent electric polarization and pyroelectric behaviour of the vertebrate skeleton. IV. The cranial bones of man.
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Adolescent↗
Hearing thresholds in an auto assembly plant: prospects for hearing conservation in an Nigerian factory.
The hearing of 165 auto assembly workers exposed to noise levels of between 94 and 108 dB was assessed by means of air and bone conductance audiograms obtained during peak and low production periods to determine acute shifts in hearing. Compared to non-industrially exposed and non-production subgroups, the exposed subjects had significantly (P less than 0.001) elevated thresholds at both peak and low production periods. There was an acute and significant (P less than 0.001) drop in the hearing thresholds of the exposed subjects during low production period. This was especially true of cross-sections of the exposed subjects and of a cohort specifically sampled at both high and low production periods. Hearing thresholds for the exposed subjects increased with both age and duration of employment and were significantly correlated with duration of employment (P less than 0.05). Of all the confounders (age, duration of employment, residential density) assessed by stepwise multiple regression analysis, duration of employment was the only significant contributor to the threshold shift. There was no conductive deafness among the study subjects. There was no consistent association between blood pressure and either hearing threshold or noise level. The results indicate good prospects for hearing conservation for Nigeria workers if hearing protection and noise abatement programs, currently not mandated by statutes, can be instituted.
Adult↗
On the influence of the middle ear muscles upon changes in sound transmission.
The influence of artificially induced impedance changes on the frequency response of the middle ear has been investigated in three experienced listeners. The tensor-reflex has been simulated by application of positive and negative air-pressure to the outer ear canal. In this test-situation, the thresholdshift ("l) obtained is greatest in the surrounding of the first resonance of the middle ear ("l = 8 dB at 500 Hz). For bone-conduction, the effect is weaker by about 2 dB than for air-conduction. The change in sound transmission is constant for all SPL's and is mainly due to the impedance change of the middle ear. In contrast the influence of the stapedial reflex is strongly dependent on SPL. In the range between hearing-threshold and 70 dB (HL) the attenuation is only 2 dB below l kHz. At higher levels the attenuation may amount to 30 dB. Thus excitation of the cochlea remains nearly constant. We suppose that the intensity-dependent influence of the stapedius reflex on sound transmission is due to a change of the stapes motion. The regulating device works without considerable distortion but with an attack-time of about 100 ms. The phenomenon of conductive recruitment in otosclerosis is probably due to the lack of this regulating effect by the fixed stapes. One function of the stapedial reflex could be the protection of the ear from high amplitudes during phonation and shouting. Furthermore, because frequencies above l kHz are also attenuated, a protective function of the stapedial reflex in industrial noise exposure can be assumed.
Acoustic Impedance Tests↗
Some minerals' content of Egyptian feedstuffs.
Determination of five minerals for the more common Egyptian feedstuffs was conducted. Bone and fish meals contained the highest amounts of calcium, 33.43 and 0.25%, while wheat and corn grains contained the lowest amounts, 0.04 and 0.02%, respectively. Bone and meat meals contained the highest amounts of phosphorus, 12.31 and 5.06%, while corn grains and wheat straw contained the lowest amounts, 0.26 and 0.23%, respectively. Meat and fish meals contained the highest amounts of sulfur, 0.89 and 0.68%, while wheat straw and bone meal contained the amounts of sulfur, 0.89 and 0.68%, while wheat straw and bone meal contained the lowest amounts, 0.20 and 0.18%, respectively. Rice and wheat brans contained the highest amounts of manganese, 395.3 and 99.8 mg/kg, while corn grains and dried skim milk contained the lowest amounts, 7.2 and 3.1 mg/kg. Bone and meat meals contained the highest amounts of iron, 0.127 and 0.084%, while barley and dried skim milk contained the lowest amounts, 0.004 for each feed material, respectively.
Animal Feed↗
[Bilateral auditory canal squamous cell carcinoma].
Only a small number of cases of bilateral carcinomas of the external ear canal have been described in the literature. We present the first case of a 72 year old male patient with a bilateral squamous cell carcinoma of the external ear canal at a very early stage. A computed tomography of the temporal bone revealed a well-pneumatized mastoid on both sides. Both external ear canals were filled with soft tissue without radiological signs of destruction of the adjacent bone. The carcinomas of the external ear canal were surgically removed using a canal-wall down technique and a selective neck dissection of regions II-IV. Histology confirmed a well differentiated squamous cell carcinoma of the external ear canal without lymph node metastasis on both sides (TNM classification: pT1 G2 N0 M0 R0). Bilateral radiation therapy with 59.4 Gy resulted in stenosis of both ear canals. Hearing rehabilitation was achieved with bone conductive hearing glasses. Diagnosis und therapy of bilateral external ear carcinomas are presented and discussed.
Aged↗