An implantable hearing aid for inner ear hearing loss. Short-term implantation of microphone and transducer

A microphone constructed for implantation in the posterior wall of the auditory canal and a piezoelectric transducer serving as the main components of an implantable hearing aid were temporally implanted in five patients during middle ear surgery under local anesthesia. The microphone was positioned beneath the skin of the auditory canal such that it completely covered the microphone membrane. The vibratory element of the transducer was coupled to the malleus in four patients with normal ossicular chains and directly to the stapes in one patient with missing incus. The microphone and transducer were electrically connected with an external battery-driven signal amplifier. Speech material and music were presented in the operation room at a sound level of 65 dB SPL under free-field conditions. The patients had to estimate the quality of speech, music, and their own voice as well as the effects of bone-conducting noises. All patients were able to hear with the system. An intraoperative talk without vision contact was possible without any problems, as was understanding of numerals ("Freiburger Zahlentest"). Perception of music was judged as "clear and undistorted with all broadband component." The estimation was also valid for one patient with a sensorineural hearing loss. One patient declared the music to be "a little of unnatural." Bone-conducted sound was estimated as normal in two patients, better than without an implant in one patient with sensorineural hearing loss, and "somewhat metallic" in another patient. Hearing the own voice was considered "normal" in two cases "monotonous" in one case, and "a little bit roaring" in another case. An amplification factor that can be technically realized in an implantable hearing aid was necessary for one of the patients with sensorineural hearing loss to perceive music at a pleasant volume. On the basis of this study, essential requirements for the construction of a fully implantable hearing aid are fulfilled.     

The action of perchlorate on malignant-hyperthermia-susceptible muscle

We developed two types of implantable hearing aids, a totally implantable hearing aid (TIHA) and a partially implantable hearing aid (PIHA) in 1983. In both types a piezoelectric ceramic bimorph was used as an ossicular vibrator which was coupled to the stapes to transmit sound signals to the inner ear efficiently. Due to technological immaturities, clinical application of the TIHA has not yet been realized. But the PIHA is available for clinical use at present. In the PIHA only the ossicular vibrator is implanted with inner link coil. The rest of components such as microphone, amplifier, battery, and outer link coil remain in their usual location behind the auricle. Since 1984, we have applied the PIHA to 37 patients with mixed deafness. Careful follow-up studies have been conducted on all of them to assess clinical and audiological results. We have confirmed that the device could function safely for more than 10 years affording natural quality of hearing without howling and wearing discomforts. Our studies suggest that the PIHA can be a choice of rehabilitation for mixed deafness due to middle ear diseases which cannot be rehabilitated satisfactorily by either surgical means or a conventional hearing aid. Functional principle of device, indications and surgical methods of implantation were described. Failures and delayed problems we experienced were also presented together with the preventive measures. We believe that an implantable hearing aid of this type will be an otologic breakthrough if substantial technological difficulties are cleared.     

A comparison of various methods of soft tissue management following the immediate placement of implants into extraction sockets

This study included 10 subjects with sensorineural hearing loss. They had not previously used hearing aids. The hearing aid fitting with "behind-the-ear' aids was based on the NAL method. Judging the sounds in their ordinary home environment, three sound situations (programmes) were selected, permitting the subjects to listen to one programme with speech, another with music and a third with "background noise'. For the group as a whole, significant differences were found between the sound quality judgements with and without the hearing aid. When the judgements of the programmes with background noise were excluded in the analysis, there were significant differences over time in the group as a whole on the scales for clarity and total impression.     

Hearing loss

Hearing loss may be caused by either a conductive problem, such that the sound waves do not reach the tympanic membrane, ossicles or inner ear, or a sensorineural problem, in which the cochlea and/or auditory nerve are somehow damaged. A combination of the above may also occur. The various causes of hearing loss and the options in treatment will be presented.     

Sudden sensorineural hearing loss associated with anticardiolipin antibody

We experienced three female patients with sudden sensorineural hearing loss. All the patients showed elevation of anticardiolipin antibody in the serum. Immunoglobulin (Ig) M anticardiolipin antibody was present in case 1 (a 34-year old woman). IgG anticardiolipin antibodies were present in cases 2 (a 50-year-old woman) and 3 (a 9 year old girl). The patient in case 1 showed hearing disturbance of low tone in the left ear and normal vestibular function in both ears. The case 2 patient had an average hearing level of 81.7dB at 0.5. 1, and 2kHz and severe canal paresis in the right ear. In case 3 the patient showed an average hearing level of 53.3dB in the right ear and normal vestibular function in both ears. It was suggested that thrombosis which might have been induced by anticardiolipin antibody could have caused the sudden sensorineural hearing loss in these patients. Steroid therapy cured the hearing disturbance completely in case 1. Steroid and prostaglandin E1 therapy did not improve the hearing disturbance in case 2. Steroid, prostaglandin E1, and ticlopidine hydrochloride therapy improved the hearing disturbance in case 3. It appears that not only steroids but also prostaglandin E1 and ticlopidine hydrochloride therapy may be effective in patients with sensorineural hearing loss associated with anticardiolipin antibody.     

Surgical management of the congenital atresia of the ear

This study presents a 15 year experience of surgical treatment in 47 patients with congenital atresia of the ear. Emphasizing on the importance of pre-surgical evaluation of the patients for a better prognostic indicator. The ages of 40 patients were between 5-15 years. 24 patients (61%) had complete atresia and 23 (49%) incomplete. 27 patients (57%) with bilateral disease and 20 (43%) unilateral. Auditory test before surgery showed a conductive hearing loss of approximately 60 decibels (dB) and one case with total sensorineural hearing loss. There was an auditory average gain of 28.3 dB. 3 patients (6.4%) had associated cholesteatoma. Complications presented: Closure of the external auditory canal in 6 patients (12.7%), and facial nerve paralysis in 2 patients with recovery. The different surgical technics are described. In conclusion, for this type of surgery, combination between the otologist and plastic surgeon should be done for better results.     

An implantable piezoelectric hearing aid transducer for inner ear deafness. II: Clinical implant]

A miniature, hermetically sealed implant was development and manufactured in several clinical and technical iteration steps based on the prototype of an implantable piezo-electric hearing-aid transducer described in Part 1 of the work presented here. The transducer is made of pure titanium (medical grade 2, ASTM F67) and designed to be implanted into the mastoid cavity. Transfer of mechanical oscillations to an ossicle in the middle ear is effected by a fixed directly coupling rod of pure titanium or via suitable coupling elements. The transducer is highly tuned with a resonance frequency in the range of 7-10 kHz, depending on the dynamic mass load. Below this resonance and down to low frequencies, the frequency response of elongation is smooth with a very small ripple of less than +/- 1 dB. Unlike the prototype, an increase in vibration amplitude of around 10 dB was achieved for a comparable power consumption. Vibration amplitude at low and middle frequencies is about 60 nm with a transducer voltage of 1 V, corresponding to an equivalent sound-pressure level of around 100 dB SPL at up to 1 kHz. At higher frequencies of up to 10 kHz, the output level increases to beyond 130 dB SPL. Nonlinear distortions at maximum volume (1 V) are extremely small (THD < 0.1%) throughout the whole transfer range. Due to an extremely short attack time (50 microseconds) and short release time (approximately 2 ms), the dynamic properties of the transducer allow good transmission of audio signals with fast changes in the time domain, i.e., plosives in speech signals. Electric power consumption at full volume and broadband signals is in the region of 1 microW. Unlike electromagnetic transducers described in the literature, the low power consumption of this piezoelectric transducer allows the realization of fully implantable hearing aids for rehabilitation of moderate to severe sensorineural hearing loss.     

Stapedectomy in profound cochlear loss

Stapedectomy can be used in certain patients with profound sensorineural hearing loss and stapes fixation to improve hearing to a level at which a hearing aid may be effective. This study reviews the outcomes of 11 patients with profound cochlear loss secondary to otosclerosis who underwent stapes surgery performed by the senior author (M.E.G.) over a 25-year period. Postoperative hearing aid usage was effective in 9 of 11 patients. Preoperatively, these patients derived no benefits from hearing aids. Stapedectomy may be of immense value in patients with the proper history and profound cochlear loss.     

Bone conduction implants for amplification: comparison of results

We compared the results from the North American patient database on the Xomed Audiant Bone Conductor to those reported on the NobleBiocare (previously Noblepharma) HC200 bone-anchored hearing aid (BAHA) implant, using the literature and specific results provided by one of the authors. It has been proposed that the percutaneous coupling of the NobleBiocare implant transduces energy more powerfully than the Audiant transcutaneous coupling. If true, percutaneous coupling could provide greater amplification, helping patients experiencing both conductive and sensorineural hearing loss. Aided sound-field thresholds corresponding to bone-conduction thresholds were compared retrospectively through the speech frequencies. Both the BAHA and the Audiant devices amplified in the sound field to approximate preoperative bone-conduction thresholds. No statistically significant differences existed between the amplification of warble tones through the speech frequencies for either device. We conclude that amplification with the Audiant device offers as much gain as the HC200 device through the speech frequencies. While both devices can supply effective amplification for select patients suffering from conductive hearing loss, neither provides gain superior to preoperative bone-conduction thresholds to address the needs of select patients with a substantial sensorineural component.     

Drill-generated noise levels in ear surgery

The noise levels in the cochlea when a drill is used in the mastoid process have been calculated from vibration measurements on intact skulls of human cadavers and temporal bones. The results lend support to the conclusion that, in ear surgery the ipsilateral cochlea is exposed to noise levels of about 100 dB and the contralateral cochlea to levels 5-10 dB lower every time the drill is used. This noise trauma may account for some of the high-tone sensorineural hearing losses after tympanoplasty described by other authors.     

Effect of a hearing aid on progressive hearing loss

A group of 72 children with hearing aids followed in 4 different clinical settings presented progressive increase in sensorineural hearing loss. The mean hearing loss over time, the duration of hearing aid use and the gain were studied to test the hypothesis that continued progression in hearing loss was due to overly powerful amplification. No correlation was found between the progressive increased gain levels were associated with less progression in hearing loss than at lower gain levels. Therefore, the use of hearing aids was not directly and significantly related to the increase in hearing loss in the population studied. However according to the above criteria a few cases (4%) of progressive hearing loss did seem to be associated with hearing aid use.     

Free-field binaural unmasking in ferrets.

Free-field detection by normal and monaural ferrets (N?=?4) of a 500-Hz tone presented over 1 laterally placed loudspeaker and partially masked by narrowband noise from 2 sources was studied at 2 angular separations of the noise sources (0° and 180°). Monaural listening was achieved either by plugging 1 ear canal or removing 1 cochlea. Normal ferrets showed an improvement in detectability of the tone when there was a 180° separation between the noise sources. This unmasking of the tone was abolished in both groups of monaural ferrets, suggesting that the unmasking was due to binaural processing. The development of an animal model demonstrating free-field binaural unmasking, in a species other than humans, will allow investigation into the functional consequences of experimental hearing loss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hearing and Sj?gren's syndrome

Immune sensorineural hearing loss is manifested in several systemic immune diseases. Although hearing loss has been previously documented in patients with Sj?gren's syndrome (SS), the effect of SS on hearing is unclear. This prospective study was designed to assess the presence of hearing loss in 14 patients with SS and, if sensorineural hearing loss was present, to determine if the hearing loss was immune-mediated. Patients were evaluated with basic audiologic tests as well as for cellular immune inner ear reactivity as measured by the lymphocyte transformation test (LTT). Three patients had evidence of sensorineural hearing loss. Two patients had a positive LTT without evidence of sensorineural hearing loss. This preliminary study suggests that SS may not directly cause sensorineural hearing loss, immuno-mediated or otherwise.     

Toynbee Memorial Lecture 1997. Middle ear mechanics in normal, diseased and reconstructed ears

A review of the structure-function relationships in normal, diseased and reconstructed middle ears is presented. Variables used to describe the system are sound pressure, volume velocity and acoustic impedance. We discuss the following: (1) Sound can be transmitted from the ear canal to the cochlea via two mechanisms: the tympanoossicular system (ossicular coupling) and direct acoustic stimulation of the oval and round windows (acoustic coupling). In the normal ear, middle-ear pressure gain, which is the result of ossicular coupling, is frequency-dependent and smaller than generally believed. Acoustic coupling is negligibly small in normal ears, but can play a significant role in some diseased and reconstructed ears. (2) The severity of conductive hearing loss due to middle-ear disease or after tympanoplasty surgery can be predicted by the degree to which ossicular coupling, acoustic coupling, and stapes-cochlear input impedance are compromised. Such analyses are used to explain the air-bone gaps associated with lesions such as ossicular interruption, ossicular fixation and tympanic membrane perforation. (3) With type IV and V tympanoplasty, hearing is determined solely by acoustic coupling. A quantitative analysis of structure-function relationships can both explain the wide range of observed post-operative hearing results and suggest surgical guidelines in order to optimize the post-operative results. (4) In tympanoplasty types I, II and III, the hearing result depends on the efficacy of the reconstructed tympanic membrane, the efficacy of the reconstructed ossicular chain and adequacy of middle-ear aeration. Currently, our knowledge of the mechanics of these three factors is incomplete. The mechanics of mastoidectomy and stapedectomy are also discussed.     

Comparison of two digital hearing aids

OBJECTIVE: The objective of this investigation was to compare real and perceived benefit for two currently marketed digital hearing aids, the Oticon DigiFocus and the Widex Senso. The hearing aids have different philosophies of design and fitting strategies; as a result, it was hypothesized that there would be performance differences. DESIGN: Twenty subjects with documented sensorineural hearing losses were fit with each of the two digital hearing aids. After 4 wk of use with each hearing aid, a battery of objective and subjective tests was completed to assess hearing aid benefit. RESULTS: No significant differences were found between the hearing aids as revealed by the objective testing of speech recognition and self-report inventories of hearing aid benefit. The DigiFocus was shown by real ear measurements to provide more high-frequency gain than the Senso. The Widex Senso was preferred by 13 of the 20 subjects (seven of 10 of the new hearing aid users). This may be explained, in part, by the increased high-frequency gain provided by the Oticon DigiFocus, which was perceived as having greater "harshness." CONCLUSIONS: Based on the results of this investigation, neither hearing aid processor was shown to be superior to the other. In addition, the least amount of objective benefit was shown in the presence of background noise.     

Computerized tomography in children and adolescents with suspected petrous bone abnormality

PURPOSE: To demonstrate HRCT findings and their therapeutic relevance in suspected congenital hearing disorders. MATERIAL AND METHODS: It was checked in 96 young patients if HRCT findings of the temporal bone could explain functional findings. Furthermore, the therapeutic consequences were noted. RESULTS: Normal CT and normal functional findings were obtained in 49 temporal bones (TB). In conductive hearing loss (41 TB), dysplasias of the conducting apparatus (37 TB) and inflammatory changes (3 TB) were found. Combined hearing loss (18 TB) was clarified completely or partially in half the cases. There were 22 dysplasias of the inner ear, 3 dysplasias of the middle ear, 1 abandoned examination (2 TB), and 55 normal CT findings in senorineural hearing disorders (82 TB). 1 retardate had a malformation of the inner ear and, contralaterally, inflammatory middle ear. In cases of vestibular disorders (24 TB), 14 malformations of the inner ear were detected. An indication for an operation was given in 23 TB. In 22 TB, it was contraindicated. The CT was one preliminary examination to a cochlea implant in 19 patients. The therapy was carried on with hearing devices in the other patients. CONCLUSION: HRCT is an important method in diagnosis and therapeutic planning of suspected malformations of the temporal bone.     

Immune-mediated inner ear disease: report of clinical cases

Many clinical and experimental studies have obtained evidence of immune-mediated inner ear disease. Discrepancies between theories of the mechanisms of injury to the inner ear and the laboratory tests that identify it mean that the diagnosis is based on clinical symptoms and a positive response to treatment. We report four cases of immune-mediated inner ear disease characterized by endolymphatic hydrops, fluctuating hearing loss, sudden deafness (first symptom of primary Sj?gren's syndrome), and rapidly progressive sensorineural hearing loss.     

Perceived sound quality of three bone-anchored hearing aid models

Eighteen patients judged the sound quality of the new Classic 300 and the existing HC 100 or HC 200 on 4 five-stage sound quality scales. Two of the scales relate to the perceptual dimensions softness and clarity, one relates to interference or noise and one relates to the overall impression. The evaluations were made, based on a questionnaire, in the patients' own homes and comprised the listening situations: TV news, music, conversation with two to three people in a noisy environment and one optional choice. The patients also stated which hearing aid was best in each situation and made a confidence rating for their selection. The patients were accustomed to wearing the HC 100 or HC 200. In these comparisons of the different bone-anchored hearing aid models, the Classic 300 received the best ratings overall. Seventeen patients changed their previously fitted hearing aid to a Classic 300 and satisfactory sound quality was undoubtedly one of the principal reasons. When it came to the confidence rating for their selections, some two-thirds of the patients stated that it was without hesitation or with little hesitation. Our overall conclusion is that the sound quality of bone-anchored hearing aids is satisfactory when it comes to clarity and overall impression. However, it may be expected that these patients with conductive losses get a better sound quality than other patients with sensorineural losses if the same type of aid is used.     

A prearranged mentorship program: can it work long distance?

The results of a series of scanning electron microscopical studies were used to construct a model for the vascular pathways in the inner ear. Corrosion cast preparations of the vessels of the inner ear of the adult rat were used in this study. The inner ear is, like a hand, an end organ containing four sense organs (cochlea, saccule, utricle and the cristae ampullaris). All these specific inner ear structures have their own vascular supply. We have developed a blood flow diagram of the inner ear. This model was used for a classification of different types of ischemia in the inner ear and forms a concept for some forms of sensorineural hearing loss and vertigo. Four types of inner ear ischemia are proposed. In type I (a or b) of inner ear ischemia only the vessels of the cochlea are involved resulting in two types of hearing loss without vertigo. Type II is characterized by ischemia of a part of the cochlea and a part of the vestibular system. In type III (a or b) only the vestibular system is involved, while in type IV no blood circulation will be present in the inner ear resulting in total deafness and severe vertigo. Inner ear partition at ultramicroscopical level of these structures may be possible in the future and new imaging techniques will probably support the vascular schematic model presented in this study.