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At least 19 recordsLinked to original sources
PubMed2005

Responses of ventral cochlear nucleus neurons to contralateral sound after conductive hearing loss.

Conductive hearing loss (CHL) is an attenuation of signals stimulating the cochlea, without damage to the auditory end organ. It can cause central auditory processing deficits that outlast the CHL itself. Measures of oxidative metabolism show a decrease in activity of nuclei receiving input originating at the affected ear but, surprisingly, an increase in the activity of second-order neurons of the opposite ear. In normal hearing animals, contralateral sound produces an inhibitory response to broadband noise in approximately one third of ventral cochlear nucleus (VCN) neurons. Excitatory responses also occur but are very rare. We looked for changes in the binaural properties of neurons in the VCN of guinea pigs at intervals immediately, 1 day, 1 wk, and 2 wk after the induction of a unilateral CHL by ossicular disruption. CHL was always induced in the ear ipsilateral to the VCN from which recordings were made. The main observations were as follows: 1) ipsilateral excitatory thresholds were raised by at least 40 dB; 2) contralateral inhibitory responses showed a small but statistically significant immediate decrease followed by an increase, returning to normal by 14 days; and 3) there was a large increase in the proportion of units with excitatory responses to contralateral BBN. The increase was immediate and lasting. The latencies of the excitatory responses were at least 6 ms, consistent with activation by a path involving several synapses and inconsistent with cross talk. The latencies and rate-level functions of contralateral excitation were similar to those seen occasionally in normal hearing animals, suggesting an upregulation of an existing pathway. In conclusion, contralateral excitatory inputs to the VCN exist, which are not normally effective, and can compensate rapidly for large changes in afferent input.

Acoustic Stimulation↗
PubMed2004

When is a conductive hearing loss not a conductive hearing loss? Causes of a mismatch in air-bone threshold measurements or a "pseudoconductive" hearing loss.

The otolaryngologist is sometimes faced with a patient with an apparent conductive hearing loss on audiometric testing who appears to have normal and mobile middle ear structures on ear exploration. Some causes of these "pseudoconductive" hearing losses can be diagnosed without resorting to surgery. This article reviews several possible mechanisms for this condition with diagnostic procedures to distinguish etiologic diseases. Conditions discussed include poor audiometry, functional hearing losses, "third window" causes, obliterated round window, abnormal inner ear connection with the cerebrospinal fluid space, inner ear mechanical conductive hearing loss, and apparent inner ear loss owing to missed middle ear pathology.

Audiometry↗
PubMed2002

Congenital conductive hearing loss.

Congenital conductive hearing loss due to ossicular deformities can be treated by either rehabilitation with a hearing aid or surgical reconstruction. We present the results of exploratory tympanotomy performed in a large paediatric otolaryngology centre in 67 patients with non-serous congenital conductive hearing loss. Forty-two children had malformation of one or more ossicles without fixation of the stapes, and 19 had fixed stapes. In 26 cases, the surgeon decided not to perform surgical correction. Seven operated patients were lost to follow-up. As a group, 47 per cent of the patients who underwent reconstruction showed no significant benefit from surgery, with post-operative air-bone gaps (ABG) greater than 30 dB. Assessment of the results by pathology showed that 64 per cent of the patients with mobile stapes had an air-bone gap within 30 dB compared to only 33 per cent of the patients with fixed stapes. One patient sustained severe sensorineural loss after the procedure. Considering that exploratory tympanotomy is a relatively minimal, benign procedure but that findings during exploration may exclude the option of reconstruction (in 39 per cent of our patients), we suggest exploring the ear, but in a more realistic, informed way.

Adolescent↗
PubMed1992

Maturation of binaural interaction components in auditory brainstem responses of young guinea pigs with monaural or binaural conductive hearing loss.

Reversible conductive hearing loss created during the first 4 weeks post partum caused marked alterations in the maturation of binaural interaction components in the auditory brainstem responses of guinea pigs. In untreated control animals all three components investigated demonstrated postnatal development in terms of latency shortening that was completed during the first 3 weeks of life. Plugging of both external ear canals caused a significant delay in the maturation of the late component DN2, where latency values of the controls were reached only 2 weeks after the end of the treatment, i.e. after 6 weeks of life. Monaural deprivation likewise led to a retarded development of peak latencies during the phase of imbalanced sensory input. After the end of the one-sided conductive hearing loss the maturation process was markedly enhanced, even resulting in latency values for DN2 and DP1 that were significantly shorter than those of the controls. This phenomenon persisted until the end of the study period and was the case for both plugged and untreated ears in this group of animals. The time course of latencies in two other groups of experimental animals which were deprived in the same way as adults suggests that the effects observed are due to a sensitive period in the maturation process of the auditory pathway.

Age Factors↗
PubMedDate not supplied

Densitometry of the cochlear capsule and correlation between bone density loss and bone conduction hearing loss in otosclerosis.

Radiodensity of the bony cochlear capsule was investigated by CT-scanning in 134 ears with otosclerosis and 35 normal control ears. A technique of densitometry of the cochlea was developed comprising the measurement of maximum and minimum density together with mapping of the cochlea and measurement of the density at six predefined points in the cochlear capsule. Bone density in the normal cochlea showed very little interindividual variation. In the otosclerosis patients, minimum density was decreased in 58% of the ears, indicating the presence of a focus. At visual examination, foci were only detectable when density loss exceeded 200 Hounsfield. A positive correlation was found between bone density loss and bone conduction hearing loss with a maximum at 2,000 Hz and the medioventral point of the cochlear wall. The method appears to be useful for the follow-up during fluoride treatment, as is demonstrated by a case report.

Cochlea↗
PubMed1993

Maturation of auditory evoked potentials in young guinea pigs with binaural conductive hearing loss.

A reversible conductive hearing loss produced during the first 4 weeks post partum caused marked alterations in the development of click-evoked auditory brainstem (ABR) and middle latency (MLR) responses in guinea pigs. The early component PI in the ABR in controls showed adult-like latencies at the time of birth, while the later ABR components PIII and PV and all components investigated in the MLR showed postnatal development characterized by a shortened latency that persisted for the whole period of investigation. The course of the ABR latencies showed the sharpest decrease during the first 2-3 weeks of life, while that for the MLR took place during the first 5 weeks. In addition to the increased ABR thresholds and lengthened ABR latencies due to the conductive hearing loss, development of the ABR inter-peak latencies (IPL) and MLR latencies was retarded. The IPL reached control values 1 week after the end of the deprivation phase, while the delay in MLR started later (4th week) and lasted longer than did that in the ABR. These findings showed that a long-lasting postnatal conductive hearing loss does not generate sustained impairment at the level of the brainstem but can evoke longer-lasting deficiencies at higher stations of the auditory pathway.

Aging↗
PubMed2003

Congenital conductive hearing loss in dyschondrosteosis.

Conductive hearing loss was detected in a boy with a previous diagnosis of dyschondrosteosis. Dyschondrosteosis is a rare inherited condition characterized by mesomelic dwarfism and Madelung's deformity. The syndrome can be caused by mutations in the SHOX gene, and in that case, the pattern of inheritance is pseudoautosomal dominant. Indeed, SHOX mutation analysis in our patient revealed a deletion. The combination of dyschondrosteosis and conductive hearing loss has been reported in 2 previous cases. In our patient, exploratory tympanotomy revealed ankylosis of the stapes and a malformed incus. A substantial gain in hearing threshold was obtained by a stapedectomy in combination with a malleovestibulopexy.

Abnormalities, Multiple↗
PubMed1994

Aided free-field thresholds in children with conductive hearing loss fitted with air- or bone-conduction hearing aids.

Although conductive hearing loss is often found in children, few reports have appeared on the fitting of hearing aids in these children. In the present study, aided thresholds were determined in 40 children and 30 adults with pure conductive hearing loss (bone-conduction thresholds of 20 dB HL or less) who were successfully fitted with hearing aids. The patient group was split into subgroups according to the type of hearing aid used (bone-conduction hearing aid, binaural or monaural air-conduction hearing aids). Within each subgroup, the aided thresholds proved to be comparable between the adults and children and were nonconsistently related to the degree of (air-conduction) hearing loss. In the patients with a bone-conduction hearing aid, the aided free-field thresholds at the most important frequencies for speech perception (1, 2 and 4 kHz) were found to be between 20 and 30 dB HL, while in the patients with an air-conduction hearing aid, irrespective of whether it was applied monaurally or binaurally, these thresholds were between 15 and 20 dB HL. It is suggested that these values should be considered as target thresholds when fitting hearing aids in children with conductive hearing loss.

Adolescent↗
PubMed1998

A cross-sectional study of speech- and language-abilities of children with normal hearing, mild fluctuating conductive hearing loss, or moderate to profound sensoneurinal hearing loss.

A total of 1528 pre-school children (mean age 4 years and 9 months), being identified as speech or language delayed, were evaluated with respect to micro-otoscopy, nose and throat pathology, hearing function, and speech-language abilities. Subjects were classified into groups of (I) constant normal hearing, (II) fluctuating conductive hearing loss and (III) bilateral moderate to profound sensorineural hearing loss requiring hearing aids. In groups II and III, severe speech and language pathologies were found more frequently than in group I. Additionally, auditory perception skills were less in group II, even if peripheral hearing function was normalized. Group III was affected more than group II, but not significantly. The results indicate that in children having speech or language delay for severals reasons, mild fluctuating hearing loss can additionally alter language acquisition, but less than in cases of moderate or profound sensoneurinal hearing loss. The need of early detection of sensoneurinal hearing loss appears widely accepted; this study demonstrates also the necessity of early diagnosis of mild fluctuating hearing loss, especially in children with speech-language delay.

Acoustic Impedance Tests↗
PubMed1983

Noise-induced hearing loss in shipyard workers with unilateral conductive hearing loss.

In a study of 6500 workers in the shipbuilding industry, 8 subjects were found to have unilateral conductive hearing impairment established before the noise exposure period and without recurrent attacks of acute or chronic infection or clinical diagnosis of otosclerosis. All subjects demonstrated a more pronounced sensorineural hearing loss at 4.0 kHz in the ear with normal middle ear function. The results show the value of even a small permanent conductive hearing loss for protection against noise-induced hearing loss. The observations are discussed in relation to the role of individual variations in sound transmission, the value of the acoustic reflex in noise-induced hearing loss and the efficiency of continuous use of hearing protectors.

Auditory Threshold↗
PubMed1998

Tympanoscopy to increase the accuracy of diagnosis in conductive hearing loss.

The diagnosis of conductive hearing loss is usually based on audiological methods and radiology. The aim of our study was to show that there is a useful additive method to clarify the findings of diseases with conductive hearing loss. Patients (151 ears) with conductive hearing loss were examined using several methods: otomicroscopy, air- and bone-conduction threshold,pure tone average, speech threshold, speech discrimination, tympanometry and stapedial reflex and tympanoscopy. The management of the patients changed in 17 per cent of cases due to tympanoscopy. In a group with normal tympanic membrane the movement of the stapes during endoscopy was compared to stapedial reflex. Stiff stapes were found more often than an abnormal stapedial reflex. Middle ear endoscopy can increase the accuracy of diagnosis of conductive hearing loss thus enhancing decision making in the case of the patient.

Adolescent↗
PubMed1999

Conductive hearing loss produces a reversible binaural hearing impairment.

Conductive hearing loss, produced by otitis media with effusion, is widespread in young children. However, little is known about its short- or long-term effects on hearing or the brain. To study the consequences of a conductive loss for the perception and processing of sounds, we plugged the left ear canal of ferrets for 7-15 months during either infancy or adulthood. Before or during plugging, the ferrets were trained to perform a binaural task requiring the detection of a 500 Hz tone, positioned 90 degrees to the right, that was masked by two sources of broad-band noise. In one condition ("control"), both noise sources were 90 degrees right and, in the second condition ("bilateral"), one noise source was moved to 90 degrees left. Normal ferrets showed binaural unmasking: tone detection thresholds were lower (mean 10.1 dB) for the bilateral condition than for the control condition. Both groups of ear-plugged ferrets had reduced unmasking; the mean residual unmasking was 2.3 dB for the infant and 0.7 dB for the adult ear-plugged animals. After unplugging, unmasking increased in both groups (infant, 7.1 dB; adult, 6.9 dB) but not to normal levels. Repeated testing during the 22 months after unplugging revealed a gradual return to normal levels of unmasking. These results show that a unilateral conductive hearing loss, in either infancy or adulthood, impairs binaural hearing both during and after the hearing loss. They show scant evidence for adaptation to the plug and demonstrate a recovery from the impairment that occurs over a period of several months after restoration of normal peripheral function.

Acoustic Stimulation↗
PubMed1995

Auditory brainstem responses of CBA/J mice with neonatal conductive hearing losses and treatment with GM1 ganglioside.

Exogenous administration of GM1 ganglioside to CBA/J mice with a neonatal conductive hearing loss ameliorates the atrophy of spiral ganglion neurons, ventral cochlear nucleus neurons, and ventral cochlear nucleus volume. The present investigation demonstrates the extent of a conductive loss caused by atresia and tests the hypothesis that GM1 ganglioside treatment will ameliorate the conductive hearing loss. Auditory brainstem responses were recorded from four groups of seven mice each: two groups received daily subcutaneous injections of saline (one group had normal hearing; the other had a conductive hearing loss); the other two groups received daily subcutaneous injections of GM1 ganglioside (one group had normal hearing; the other had a conductive hearing loss). In mice with a conductive loss, decreases in hearing sensitivity were greatest at high frequencies. The decreases were determined by comparing mean ABR thresholds of the conductive loss mice with those of normal hearing mice. The conductive hearing loss induced in the mice in this study was similar to that seen in humans with congenital aural atresias. GM1 ganglioside treatment had no significant effect on ABR wave I thresholds or latencies in either group.

Acoustic Stimulation↗
PubMed1997

[Active electronic cochlear implants for middle and inner ear hearing loss--a new era in ear surgery. I: Basic principles and recommendations on nomenclature].

Hearing aids have fundamental disadvantages: (1) stigmatization of the patient; (2) the sound is often found to be unsatisfactory due to the limited frequency range and undesired distortion; (3) in many patients, the ear canal fitting device generally necessary leads to an occlusion effect; (4) acoustic feedback when amplification is high. Conventional hearing aids transmit sound into the ear canal via a small microphone. Sound has the disadvantage of requiring high output sound pressure levels for its transmission. This along with the necessary miniaturization of the loudspeaker as well as the resonances and reflections in the closed ear canal contribute to the disadvantages mentioned. In contrast, implantable hearing aids do not make sound signals but micromechanical vibrations. An implantable hearing aid has an electromechanical transducer instead of the loudspeaker of a conventional hearing aid. The hearing signal does not leave the transducer as sound but as a mechanical vibration which is directly coupled to the auditory system bypassing the air. This implantable hearing aid is either coupled to the tympanic membrane, the ossicular chain, the perilymph of the inner ear, or the skull. An implantable hearing aid is expected to have: 1 Better sound fidelity than a hearing aid 2 No ear canal fitting device, free ear canal 3 No feedback 4 Invisibility Requirements on electronic hearing implants designed for patients with conductive hearing loss differ from those on implants for sensorineural hearing loss. Conductive hearing loss requires the implant to replace the impedance transformation, thus being an impedance transformation implant (ITI). In various respects, the demands on an ITI are lower than the demands on an electronic hearing aid for patients with sensorineural hearing loss. The latter are mostly patients with a failure of the cochlea amplifier (CA). A damage to the CA is clinically discernible by a positive recruitment and loss of otoacoustic emissions (OAE). Since these patients form the majority of cases with sensorineural hearing loss, an active hearing implant for such patients should partially replace the function of the CA. Therefore, the suggestion is to refer to a CAI (cochlea amplifier implant). The implant expressions ITI (for patients with conductive hearing loss) and CAI (for patients with sensorineural hearing loss) used in this context allow nomenclatural association with the CI (cochlear implant) for complete inner ear failure as well as with the BSI (brainstem implant) in the case of hearing nerve failure.

Cochlear Implants↗
PubMed1997

[Early diagnosis of neurosensory component in various forms of conductive hearing loss].

Audiological examination including routine methods, tonal threshold audiometry (10000-20000 Hz frequency range), noise resistance of the acoustic analyzer in contralateral masking with noises of different intensity has been made to identify early subclinical neurosensory hypoacusis in 96 patients with acute and chronic inflammation of the middle ear aged 17-75 years. 140 subjects with normal hearing served control. The findings show the ability of such tests to assess noise resistance of the acoustic analyzer and tonal threshold audiometry in wide range of frequencies to detect latent neurosensory hypoacusis which is correctable if discovered early.

Adolescent↗
PubMed1996

Conductive hearing loss following retrolabyrinthine surgery.

BACKGROUND: Conductive hearing loss can occur following neuro-otological procedures due to bony ossicular fixation resulting from viable bone dust remains. OBJECTIVE: To highlight the frequency and features of the complication of conductive hearing loss following retrolabyrinthine surgery. DESIGN: In a review of 77 retrolabyrinthine neuro-otological procedures, 3 cases (3.9%) of postoperative conductive hearing loss were encountered. RESULTS: Bone dust can cause a postoperative conductive hearing deficit that becomes apparent 6 months following surgery, and progressive deterioration can occur up to 18 months. The anatomical areas of ossicular fixation are the incudomalleal joint in the attic and around the stapes in the oval window niche. Excision of these bony accumulation particles does not revert the conductive hearing loss. CONCLUSIONS: We advocate the use of occlusive material in the aditus during temporal bone surgery to prevent bone dust accumulation in the attic and middle ear. In the event of such a complication, an incus transposition ossiculoplasty is recommended.

Adult↗
PubMedDate not supplied

Effect of conductive hearing loss and middle ear surgery on binaural hearing.

This study investigated whether conductive hearing loss reduces normal binaural hearing advantages and whether binaural hearing advantages are normal in patients who have had hearing thresholds improved by middle ear surgery. Binaural hearing was assessed at a test frequency of 500 Hz using the masking level difference and interaural time discrimination thresholds. Results indicated that binaural hearing is often poor in conductive lesion patients and that the reduction in binaural hearing is not always consistent with a simple attenuation of the acoustic signal. Poor binaural hearing sometimes occurs even when middle ear surgery has resulted in bilaterally normal hearing thresholds. Our preliminary results are consistent with the interpretation that auditory deprivation due to conductive hearing loss may result in poor binaural auditory processing.

Adolescent↗