J. V. D. Hough

Method and apparatus for implanting hearing device

A bone conduction hearing device in the form of a magnetic disk is implanted and fastened to the temporal bone by a screw thread connection. Apparatus includes instruments for accurately drilling and tapping a hole in the temporal bone, and a wrench for tightening the magnetic disk hearing device against the bone.

A middle ear implantable hearing device for controlled amplification of sound in the human: A preliminary report

Millions of people in the United States suffer from hearing impairment that is not benefited or poorly benefited by surgery or conventional hearing aids. Recently, we introduced an implantable Temporal Bone Stimulator (TBS) designed for those patients having a hearing loss due to external canal conditions; such as, external canal atresia or disease, inoperable ossicular problems, atelectasis or eustachian tube malfunction, and chronic open‐cavity mastoid disease. This device requires relatively good cochlear function. However, the electromagnetic application of this device has led to the development of a new device we call the Implantable Hearing Device (IHD). This device stimulates, by an electromagnetic field, an independent electromagnetic sensitive prosthesis attached to the ossicular chain. This direct energy transfer to the ossicular chain provides a high degree of sound amplification and fidelity, thus providing benefit for those with various degrees of sensorineural hearing impairment.

Middle Ear Implantable Hearing Device: Ongoing Animal and Human Evaluation

The first five patients have been permanently implanted with an electromagnetic middle ear implantable hearing device. Hearing tests were performed at the time of operation and at 8 weeks postoperatively with a coil held at the isthmus of the ear canal. All patients reported clear, high fidelity sound, as proven by speech discrimination scores. Improvements were seen in all frequencies, including 4,000 Hz. Improvement in pure tones as tested with an audiometer monitoring sounds amplified by a 3-V sound processor was as high as 50 dB sound pressure level. That which remains to be done is the final design of a compact, wearable sound processor with filtering and signal-processing capabilities to meet the needs of the sensorineural hearing-impaired population.

Semi-implantable electromagnetic middle ear hearing device for moderate to severe sensorineural hearing loss.

Despite the many improvements in hearing aid technology, conventional hearing aids continue to have significant limitations, which has led to increased interest in implantable hearing devices. The SOUNDTEC Direct Drive Hearing System for moderate to moderately severe sensorineural hearing loss is one such device. In this article the authors present results on five individuals enrolled in a Food And Drug Administration Phase I feasibility study.

The use of rare‐earth magnet couplers in cochlear implants

The cochlear implant is an electronic auditory prosthesis gaining widespread acceptance as a means of restoring partial hearing to the totally deaf. A number of engineering and biological hurdles remain toward the improvement of existing implantable systems and development of multichannel systems. One hurdle concerns reliable transcutaneous coupling of the external electrical signal to the implanted device. To date this has been accomplished by inductive means through coils which were mechanically held in place. The incorporation of small, permanent, rare‐earth (SmCo5) magnets with the coil assemblies has eliminated the unreliable mechanical supporting devices. Magnetic attachment was simulated in dogs to examine for biological compatibility. Electron micrographs indicated normal subcellular structures in tissue exposed for 10 weeks. Five patients were implanted with magnet‐modified coil assemblies and tested for the proper alignment and support of the external coil assembly, as well as efficiency of inductive coupling. Electromagnetic coupling was not interferred with and mechanical support was adequate. We conclude that rare‐earth magnets provide an effective means for supporting and positioning in place medical devices, such as the cochlear implant.

Biomechanical influences of magnetic resonance imaging on the SOUNDTEC Direct System implant

OBJECTIVE: The purpose of this study was to measure the forces experienced by the SOUNDTEC Direct System magnetic implant during 0.3-T MRI. STUDY DESIGN: Torsional and linear forces imposed on 8 implants were measured by using calibrated neurologic Von Frey hairs and were compared with finite-element analysis predictions and the forces required to separate the incudostapedial joints of unpreserved temporal bones. An implanted embalmed autopsy specimen was also examined before and after 1.5-T MRI. RESULTS: Peak linear force at the orifice of the MRI core measured 0.51 g ±0.2 SD). Maximum torque occurred at the MRI core center and measured 11.4g-cm (±1.2 SD). The mean torque required to separate the incudostapedial joints of 12 unpreserved temporal bones was 33.8g-cm (±20.4 SD). The autopsy specimen sustained a 1.5-T MRI scan without disruption of the ossicular chain or explantation. CONCLUSIONS: Physical and mechanical testing of the SOUNDTEC implant indicates that the structural integrity of the ossicles will be maintained during 0.3-T MRI of the human head.

The cochlear implant — oklahoma group experience to date

The establishment of a cochlear implant team and the implementation of the Oklahoma City project was for the purpose of monitoring techniques and results reported by other investigators as well as perhaps contributing to the improvement of this method of restoring sound to profoundly deafened individuals. Years of planning and 3 years of actual experience with over 25 patients who have been implanted will be documented. Technical advances in prosthetic attachments and new transformer circuitry as well as better methods of evaluating results will be presented. Our assessment of the value of the cochlear implant and its future will be discussed.

Implantable hearing devices: contemporary options

The search for improved hearing rehabilitation options for patients with sensorineural hearing loss has led to the investigation of implantable hearing devices. Theoretically, the present need for such devices includes more powerful amplification for more useable or functional gain; reduction of feedback, occlusion effect, and distortion; and perhaps better cosmesis. Cost-effectiveness and benefit-to-risk ratio are also very important considerations for any surgically implantable device. To date, two semi-implantable devices have obtained US Food and Drug Administration approval, and at least three other implantable devices are under investigation. Totally implantable devices are awaiting regulatory trials and approval. This review summarizes the recent literature surrounding these devices and other investigations that may affect the field of implantable hearing devices.

15: The Floating Mass Transducer: Theory, Development, and Initial Human Use

goal of this study was to examine the impact of anemia on the critical primary ischemic time in free flaps. Methods: Thirty-eight Sprague-Dawley rats were divided into two groups. The experimental group consisted of 18 rats with an average weight of 364 gm. These were divided into 3 groups of 5 and one group of 3. Using the left femoral artery, 31% _+ 3% of the total blood volume was removed and replaced with an equal volume of normal saline. Standard fasciocutaneous abdominal flaps, based on the right epigastric vessels, were elevated. Groups A, B, C, and D received 4, 6, 8, or 10 hours of ischemia time, respectively, by clamping of the pedicle. Clamps were removed, and the flaps were resutured to the abdominal wall. Flap viability was assessed at 7 days. The control groups consisted of 20 normocythemic rats exposed to 4, 6, 8, or 10 hours of ischemia. Results: In the experimental group the hematocrit was 44 _+ 2 preoperatively and 29 • 3 postoperatively. All flaps in the anemic and control groups survived after 4 hours of ischemia. With a 6-hour ischemic time, four of five anemic flaps survived compared with three of five control flaps. At 8 hours three of five anemic flaps survived, compared with none in the control group (p < 0.05). At 10 hours none of the flaps survived, the critical ischemic time was 8.2 hours in the anemic group compared with 6.2 hours in the control group (p < 0.05). Conclusions: lsovolemic anemia is not detrimental to free flap survival. Fasciocutaneous free flaps in anemic animals are more resistant to ischemic than those in normocythemic animals. Decreased blood viscosity and dilution of coagulation factors are probably responsible for this effect.

Tympanoplasty—Part 2: Ossicular Chain Reconstruction

Educational objectives: To have a more complete understanding of the advantages of homograft ossiculoplasty and to solve the technical problems that may be encountered during ossiculoplasty more readily.