Faculty Bibliography

The objective of this study was to explore the hypothesis that developing labyrinthine sensory receptors attract ingrowing neurites by chemotaxis. Cocultured otic explants which shared a single statoacoustic nerve (VIIIn) ganglion were explanted from 11-, 12.5-, and 14-day-old mouse embryos. Heterotypic ganglion explants consisted of 12-day-old otic explants which had their VIIIn replaced by a 10.5-day-old trigeminal nerve (Vn) ganglion. All cultures were grown to the equivalent of 20 days of gestation. Neurites of the (+) VIIIn explants grew into the sensory areas of both the (+) and (-) VIIIn cocultured explants. Neurites of the 14-day-old cocultured otic explants were only found in association with sensory areas within the (+) VIIIn explant. Neurites of nerve V of the heterotypic ganglion explants were found in association with the sensory areas of these otic explants. These results support the hypothesis that a limited period of chemotaxis (nonspecific in nature) is a possible mechanism for the establishment of the pattern of neurite ingrowth to the areas of the inner ear sensory receptors.

Breakdown of the normal protective function of the larynx, either through primary laryngologic or neurologic causes, leads to chronic aspiration, recurrent pneumonitis and possibly death. In this paper we discuss the existing surgical treatments for chronic aspiration. Tracheal separation and trecheoesophageal diversion are discussed, as are the difficulties of using these procedures in patients with pre-existing tracheostomies. A modification of tracheoesophageal diversion is presented whereby this procedure can now be utilized in those patients with pre-existing tracheostomies. The modified tracheoesophageal diversion is performed in five patients successfully. Since most patients have already had tracheotomies in an attempt to control aspiration, we feel that our technique of modified tracheoesophageal diversion enables this group of patients to benefit from this procedure as well.

After a varied history over the past 15 years, basic acoustic immittance measures now include certain physical measures and certain physiological measures. This article reviews current concepts in the terminology and the instrumentation used for these basic measures. It is designed to provide an understanding of standard acoustic immittance measures and a framework for interpreting the results of special acoustic immittance procedures discussed in this issue.

The observation that interferon (IFN) therapy causes regression of lesions in some patients with recurrent respiratory papillomatosis (RRP) raises the possibilities that these patients may have abnormalities in endogenous IFN production or in antitumor immune responses stimulated by IFN. We have measured IFN production and natural cytotoxicity (NK activity) in nine patients with RRP, three of whom were receiving exogenous IFN at the time of testing. Production of IFN-gamma induced by the T cell mitogen Staphylococcus enterotoxin A was normal in all patients. Production of IFN-alpha induced by two viruses (Sendai and Newcastle disease viruses) was normal in the six untreated patients, but significantly lower in the patients on IFN therapy. Natural cytotoxicity against K562 target cells, both spontaneous and IFN-stimulated, was normal in all RRP patients tested. Thus, we have shown that the NK-IFN system was intact in untreated patients with RRP. IFN-alpha production in the RRP patients on IFN therapy was low. The significance of these findings is discussed.

Audiologic findings in a child who received a single-channel cochlear implant are presented. The measures used were threshold sensitivity to frequency-specific stimuli and results on various subtests from the Test of Auditory Comprehension (Trammel, 1976), the Monosyllable, Trochee, Spondee Test (Erber & Alencewicz, 1976), and the Minimal Auditory Capabilities Battery (Owens, Kessler, Telleen, & Schubert, 1981). The results for the implanted ear indicated uneven change in performance across measures compared to results with conventional amplification prior to receiving the implant. Performance of the implanted ear did not approach performance of the better contralateral ear. Observations by teachers and guardians indicated that there was no apparent change in auditory performance even after the cochlear implant had been worn for 6 months. Overall there was no evidence that the cochlear implant worn for 6 months provided any practical benefit to this child.

We have used a modification of the Blom-Singer technique in our last 24 tracheoesophageal punctures, performed on 20 patients. At the time of puncture a surgical stent with an indwelling Dacron polyester suture is placed to form the fistula. Forty-eight to 72 hours later the stent is backed out of the puncture site but the suture is allowed to remain. The Blom-Singer duckbill prosthesis is fitted and taped in the routine fashion. The suture is left to traverse the tracheoesophageal tract until the time of discharge, when it is removed. At discharge the patient is given a Silastic dilator, to be used if the puncture site becomes too small to allow for insertion of the duckbill prosthesis. Seventeen of the 20 patients in this group obtained good voice. Six operations would have been failures because of the loss of the patient's prosthesis in the immediate postoperative period if the modified technique had not been used

Abnormal mineral deposits from the membranous labyrinths of deaf Dalmatian puppies were examined microscopically. Most such deposits were located on the saccular otoconial membrane and were associated with collapse of the saccule and of Reissner's membrane. In both ears of one pup, crystals resembling otoconia were found on the surface of the stria vascularis. In two others, grossly abnormal crystals were seen on the utricular otoconial membrane, and in one of these crystals were also attached to the cupula of the left horizontal canal. In four animals the tectorial membrane was calcified. Most deposits consisted of apatite spherulites, but large multiple crystals (probably of calcite) were occasionally present. Some of the abnormal mineral deposits in the Dalmatian closely resemble those found in man, and they may originate in the same way.

Four variations and degrees of severity of the Mondini malformation were found in the temporal bones from two neonates, one with congenital heart disease and the other with trisomy D, and from one teenager with leukemia: 1) short cochlea and normal vestibular organs; 2) short cochlea and persistent horizontal canal anlage; 3) markedly shortened cochlea with no modiolus, wide internal auditory meatus, and persistent horizontal canal anlage; 4) same as variation 3, but with persistent anlagen in all semicircular canals. Variations 3 and 4 were from the case of trisomy D, in which the left cochlea had a normal hair cell population but few nerve fibers, and the intraganglionic spiral bundle was displaced from Rosenthal's canal to the osseous spiral lamina. The right ear had no cochlear nerve fibers; the organ of Corti was present, but hair cells were unusually small. In the case of trisomy D, both ears showed subtotal loss of vestibular nerve fibers. Although the rudimentary cristae of the right ear had numerous hair cells, the macular hair cells were fewer and malformed. No hydrops was present.