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Biomedical subjects

W F House

Publications and source records attributed to W F House.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

Degenerative changes in the distal stump of the severed human facial nerve.

Specimens of distal segments of the human facial nerve obtained at reinnervation surgery (hypoglossal-facial anastomosis) were studied by light and electron microscopy. Severance of the facial nerve led to the Wallerian degeneration in the distal segment. When the lesion was made at the intracranial level of the nerve, the sensory bundle remained intact. In a specimen 17 days after section, motor fibers either had disappeared or had loss of axons and advanced stage of myelin breakdown. Sensory fibers appeared intact. In two specimens three months after severance, many Schwann cells of degenerated fibers still possessed degraded myelin; most Schwann cells had ingested myelin and formed endoneurial tubes (bands of Büngner). Endoneurium showed proliferation of fibroblasts and increased collagen deposition. A specimen obtained seven months after section showed fibrosis only. The fifth specimen obtained 30 months after severance of the tympanic segment showed only mild collagenization and well formed, not appreciably shrunken Schwann tubes. The distal stump of human facial nerve appears to undergo less denervation atrophy than demonstrated in the peripheral nerves of experimental animals. The collagenization process appears to be essentially completed already after three months denervation with little change after that. The distal stump of the human facial nerve appears to provide a good structural basis for reinnervation even after prolonged denervation.

Adult↗
PubMedDate not supplied

Morphology of Human cochlear nerve after labyrinthectomy.

Five temporal bones and three surgical cochlear nerve specimens from patients who previously underwent labyrinthectomy were studied by light and electron microscopy. All cochleas had nearly total loss of sensory cells, extensive or total loss of both cochlear nerve fibers in the osseous spiral lamina, and spiral ganglion cells. In spite of this severe distal degeneration of the cochlear nerve, it processes within the internal auditory canal appeared normal in four of the five temporal bones, and the majority of the myelinated nerve fibers had survived in all three surgical specimens. Most of the central processes of the primary neurons of the cochlear nerve appear to have resisted retrograde degeneration when it was induced by a lesion primarily causing degeneration of the organ of Corti. This peculiar situation of a few nerve cell bodies and disproportionately large numbers of central axons is discussed.

Adult↗
PubMedDate not supplied

Vestibular nerve findings in 150 neurectomized patients.

Vestibular nerve specimens obtained at neurectomy were studied by light and electron microscopy in 150 patients with various neuro-otological disorders. The vestibular nerve was considered morphologically normal in only 20% of the cases but the changes observed in most cases were interpreted as artifacts or physiological changes of aging. In nearly half of the cases there was excessive fibrosis of the perineurium or endoneurium of the vestibular nerve, or occurrence of glial tissue within or near Scarpa's ganglion. When these changes are of moderate or severe degree, they may be of pathological significance. Severe nerve cell destruction with subsequent fibrosis, indicating primary neuropathy, was found in four cases.

Adult↗
PubMedDate not supplied

The cochlear implant in preschool-aged children.

Long-term experience with the single-electrode cochlear implant has shown this device to provide significant benefit with minimal risk to the deaf adult. Based on these findings, the decision was made to begin implanting children. As of September 1, 1982, 27 profoundly deaf children (ranging in age from 2.7 to 17.5 years) have received the cochlear implant. Tests results are consistent with those found in adults, and the children have adapted well to using the device. Of particular interest are the results observed in the preschool-aged children, eight of whom have been implanted. Two of these children have now had the implant for a year. Findings to date indicate that progress with the implant is initially slower for the preschool-aged child than for older children and adults. In time, however, similar results are attained. Ultimately the younger children adapt even better to the device. These preliminary results are encouraging, but only long-term experience with a large number of subjects will better determine the benefits of the cochlear implant for the preschool-aged child.

Adult↗
PubMedDate not supplied

Labyrinthine ossification secondary to childhood bacterial meningitis: implications for cochlear implant surgery.

Of 20 children who underwent cochlear implantation for profound sensorineural hearing loss secondary to bacterial meningitis, 14 had round-window and cochlear ossification at surgery. Preoperative polytomography demonstrated ossification in 11 of these. The incidence of ossification was highest after meningitis secondary to pneumococcal pneumonia. In only one of four children with severe ossification of the labyrinth was implant surgery unsuccessful. Preliminary results indicate that mild labyrinthine ossification is not a contraindication to cochlear implantation.

Bacterial Infections↗
PubMedDate not supplied

Comparison of promontory and cochlear implants within a single subject.

Audiometric pure tone, speech, and psychoacoustic data were obtained from a patient who had worn a promontory electrode for two years. Subsequently the promontory implant was replaced by a scala tympani electrode (cochlear implant) and testing was repeated. Warbled tone thresholds ranged from 52-68 dB SPL for the octave frequencies 250-8000 Hz with the cochlear implant (CI), and from 65-74 dB SPL with the promontory electrode (PE). Speech discrimination scores were better with the CI than with the PE, although performance on an environmental sounds test was slightly better with the PE. Smaller intensity difference limens (DLs) were obtained with the CI (1 dB) than with the PE (about 4 dB). Frequency discrimination was poor with both electrode systems. The CI provided better frequency DLs at 250, 500, and 1000 Hz; the PE produced better DLs at 2000 Hz. When the CI was combined with a hearing aid worn on the better implanted ear, performance improved over that with either prosthesis alone.

Aged↗
PubMedDate not supplied

A multiple-electrode cochlear implant.

A multiple-electrode cochlear implant comprised of three intracochlear and four extracochlear electrodes is described. A percutaneous plug allowed for direct electrical measurements and presentation of stimuli to selected electrode combinations. Electrical impedance measurements revealed functions that decreased as frequency increase to about 20 kHz. Absolute impedance magnitude varied across electrodes. Equal loudness contours were similar in shape for all three cochlear electrodes, although dynamic range was significantly reduced for the most apical electrode. Periodicity and place pitch were demonstrated; effects were most salient for low frequency stimuli. A 3-channel sound processor was built and multiple-channel stimulation was compared to single-channel stimulation. Significant performance differences were not found between single-channel and multiple-channel systems for environmental or speech sounds. However, the patient subjectively reported superior quality with the multiple-channel system.

Auditory Fatigue↗
PubMedDate not supplied

The cochlear implant program: an overview.

The single-electrode cochlear implant used at the House Ear Institute is undergoing clinical trials under Food and Drug Administration regulations governing medical devices. The program involves selection and evaluation of suitable subjects, surgery, basic guidance or training in implant use, and regular follow-up. As of November 1, 1981, 199 deaf subjects have had cochlear implant surgery. They range in age from 3.5 to 75 years old. Subjects with a wide variety of etiologies have been successfully implanted. The vast majority use their device on a daily basis, and subjects as a group have received more than 800,000 hours of electrical stimulation. Fifteen other otologists in the United States have implanted one or more subjects as coinvestigators in this clinical trials program. The otologists and their implant teams are trained by the House Ear Institute. Results indicate that the implant program can be performed adequately in a variety of clinical settings.

Adolescent↗
PubMedDate not supplied

Effects of the single-electrode cochlear implant on the vestibular system of the profoundly deaf adult.

Twenty-two profoundly deafened adults, implanted with the single-electrode cochlear implant, were involved in a study to observe the effects of cochlear electrical stimulation on the vestibular system. Previous investigators had found evidence that the implant might disrupt postural stability. As there had been no general complaints of dizziness or dysequilibrium by the implant subjects, a study was undertaken to replicate the earlier study and to compare the results to more standardized procedures. A Sono-postural Test was devised from the Ataxia Test Battery for the testing of balance with and without an auditory prosthesis. Electronystagmography was also performed on the subjects before and after surgery as a means of monitoring vestibular status over time. Results from the these tests indicate that the single-electrode implant does not disrupt the balance system to any significant degree. In fact, evidence indicates that postural stability may actually improve with the cochlear implant activated.

Adult↗
PubMedDate not supplied

Initial experience with the cochlear implant in children.

The decision to implant cochlear prostheses in children came after positive findings with deaf adults and the belief that the benefits of receiving sound far outweigh the potential risks involved. As of December 1981, 12 profoundly deaf children have received the single-electrode cochlear implant. Their ages range from 3.5 to 17 years. Test results are consistent with those of adults. Mean thresholds across the frequency range fall between 59-64 dB SPL. With the implant, these children can perform specific timing and intensity differentiations which could not be done with hearing aids. Their voices are quieter and more modulated, and the children are not quite as noisy with objects in the environment (eg, do not slam doors any more). This preliminary data demonstrates that implanting subjects under the age of 18 years is feasible.

Acoustic Stimulation↗