The cochlear implant--Oklahoma group experience to date.
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Adolescent↗
Biomedical subjects
J Hough
Publications and source records attributed to J Hough.
Evaluation of kangaroo aortic valved conduits in a juvenile sheep model: preliminary findings.
BACKGROUND: Biological heart valve substitutes, manufactured from either porcine or bovine tissue, have been in use for more than 30 years. Despite low thrombogenicity and excellent performance, bioprosthetic heart valves tend to degenerate and calcify early in young patients because of patient and valve related factors. The aim of this study was to examine the calcification behavior of glutaraldehyde-preserved kangaroo heart valves in a juvenile sheep model. METHODS: Porcine (n = 10) and kangaroo (n = 10) valved conduits were implanted in the descending aortic position of juvenile sheep and retrieved after 6, 8, and 12 months. Retrieved valved conduits were examined for morphological changes and calcification of the valve tissue, using Von Kossa's stain technique and atomic absorption spectrophotometry. RESULTS: Structural valve deterioration, characterized by increased stiffness and severe calcification, occurred in 100% of the porcine conduits within 4 months. Kangaroo valve leaflets were significantly (p < 0.001) less calcified at 6 months (3.39+/-1.80 microg/mg), 8 months (5.86+/-4.57 microg/mg), and at 12 months (14.38+/-6.72 microg/mg), compared to porcine valves at 3 months (176.45+/-42.88 microg/mg ) and at 4 months (154.67+/-52.67 microg/mg ). Porcine aortic wall tissue was more calcified (118.24+/-42.86 microg/mg) than kangaroo aortic wall tissue (79.55+/-26.40 microg/mg). CONCLUSIONS: Kangaroo heart valves calcify less than porcine heart valves. These findings suggest that a different donor valve tissue has a lower calcification potential probably due to a difference in the morphological ultrastructure. This could result in improved long-term durability of kangaroo heart valves.
Animals↗
Experiences with implantable hearing devices and a presentation of a new device.
Following animal experiments, anatomic examinations, and histologic studies, an implantable hearing device was developed. This device, the temporal bone stimulator (TBS), uses an inductive coil without percutaneous connection that transmits bone-conducted vibrations to the inner ear. Ten patients have been implanted and followed by the Central Ear Research Institute. The TBS is effective and may have wide application in producing amplification in good sound fidelity when used in patients who have external canal, middle ear, or eustachian tube disease that is poorly corrected by surgery or conventional hearing aids. The utilization of similar principles of electromagnetic transfer of energy directly to the ossicles appears reasonable and is potentially highly rewarding for those who have sensorineural hearing impairments with thresholds greater than 40 dB. The enormous potential benefits derived from the application of these implantable hearing devices is worthy of the greatest effort in future otologic investigation.
Animals↗
Histologic findings in two very small intracanalicular solitary schwannomas of the eighth nerve.
Two very small intracanalicular tumors, resected en bloc with the complete eighth nerve, were serially sectioned in order to study the relationship between the tumors and the nerves of origin. Both cases met the size criteria for hearing conservation surgery; however, the patient with the smaller tumor and the better hearing had no recognizable cochlear nerve fibers passing the tumor. The cochlear nerve in the patient with poorer hearing was completely free of tumor. The tumor with the infiltrated cochlear nerve seemed to originate from the inferior vestibular nerve. The other tumor seemed to arise from the superior vestibular nerve. Proximally, the tumors occupied a more central location in the involved nerves, but they abruptly became eccentric and exophytic as they proceeded laterally. Nerve fibers remaining about the tumors were displaced to the periphery. These nerve fiber aggregates became quite thin and attenuated, frequently separating into smaller aggregates which, ultimately, were incorporated into the tumors. As fibers came closer to the tumors, they tended to change from their longitudinal direction toward a more circumferential orientation about the surface of the tumors. The tumor-nerve fiber interfaces were quite variable throughout the course of the tumor, ranging from large aggregates of nerve fibers distinctly separate from the tumors to aggregates separate but tightly applied to the tumors without a tissue plane between, to aggregates partially incorporated within the periphery of the tumors, to aggregates completely incorporated into the periphery of the tumors.(ABSTRACT TRUNCATED AT 250 WORDS)
Cochlear Nerve↗
Implantable bone conduction hearing device: Audiant bone conductor. Update on our experiences.
An implantable hearing device has been developed and has undergone testing by animal experimentation and clinical trials in humans. Recently, the Food and Drug Administration has approved the use of this device in adults who are within the criteria of its utilization, mainly patients with conductive hearing impairments who have good inner ear reception and who are unable to benefit from surgical correction. This update describes observations and experiences we have had during the device's development and defines its limitations as well as its unique thrust into the future relief of hearing impairment. Clinical trials during the investigational period and engineering problems as well as progress are thoroughly discussed.
Adolescent↗
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.
Animals↗