Biomedical subjects
L Z Meiteles
Publications and source records attributed to L Z Meiteles.
Cochlear implant device failure: diagnosis and management.
Complete, irreversible failure of the implanted receiver-stimulator of the Cochlear Corporation multichannel implant are relatively rare. However, as the implanted patient population grows, malfunctions may be expected. From the over 200 patients implanted at the University of Michigan Medical Center, 6 patients with a complete and irreversible cochlear implant receiver-stimulator failure have been identified and treated. This represents a 3% failure rate. The amount of time between initial implantation and device failure ranged from 6 months to 3.5 years. Determination of device failure was made using psychophysical, electrophysiologic, and averaged electrode voltage measurements. The measurement of the average electrode voltages proved to be useful in determining the condition of the implant. Physiologic changes causing reduced electrical excitability were ruled out using psychophysical or electrophysiologic promontory testing. All patients were successfully explanted and reimplanted.
Scar formation in the vestibular sensory epithelium after aminoglycoside toxicity.
Hair cell degeneration and the repair process due to differing types of trauma have been studied extensively in the organ of Corti. It has been determined that, during scar formation, after differing types of trauma to the auditory sensory system, the reticular lamina is maintained with adherens junctions and tight junctions. We investigated the repair process within the vestibular epithelium. Hair cell degeneration was induced by the unilateral application of streptomycin to the inner ears of guinea pigs. Whole mount preparations of all five vestibular organs were processed and examined by fluorescence, light and electron microscopy. Scar formation was seen as early as 4 days post-treatment with streptomycin and was noted to coincide with hair cell degeneration. Neighboring supporting cells swelled and filled the space beneath the degenerating hair cell. Between three and five supporting cells participate in the reparative process. The distribution of cytokeratin is also altered during scar formation. The area once occupied by the hair cell becomes filled with cytokeratin-rich processes of supporting cells. It appears that differing numbers of supporting cells are involved in the reparative process within the vestibular sensory epithelium as compared to the auditory system. The reticular lamina remains intact at all times. This may possibly prevent mixing of fluids between different compartments in the inner ear and dysfunction of the vestibular sensory organs.
Distribution of cytokeratins in the vestibular epithelium of the guinea pig.
Cytokeratin expression in the vestibular labyrinth of the guinea pig was investigated with immunofluorescence and immunoperoxidase staining on surface preparations of the vestibular epithelium. Phalloidin, an F-actin-specific probe, was used to distinguish between hair cells and supporting cells. Cytokeratin expression was not found in the cytoplasmic domain of hair cells of the crista ampullaris, utricle, or saccule. Cytokeratin expression was abundant in supporting cells of the vestibular sensory epithelium. Electron microscopy revealed the presence of desmosomes, which are associated with cytokeratins, within type 2 hair cells of the vestibular epithelium. It appears that cytokeratins are absent within the cytoplasmic domain of hair cells, but are present in association with intercellular junctions. The functional significance of this unique pattern of cytokeratin expression within the vestibular epithelium is discussed.
Facial nerve monitoring in surgery for congenital auricular atresia.
Surgery for congenital auricular atresia places the facial nerve at risk because of its potential aberrancy; iatrogenic facial paralysis is a well-known potential risk. Five cases of congenital auricular atresia are presented. All patients had intraoperative monitoring of the facial nerve. The facial nerve was found to be abnormally displaced, usually due to hypoplasia of the tympanic ring. Preoperative and postoperative facial nerve function was unchanged by surgery. Facial nerve monitoring is an important adjunct in congenital ear surgery because it allows for early and precise identification of the nerve in the absence of normal surgical landmarks and provides for continuous monitoring of the nerve.
Squamous cell carcinoma of the temporal bone arising 43 years after fenestration procedure.
Squamous cell carcinoma originating in the middle ear cleft is a rare tumor that tends to be diagnosed late in its course. The presenting symptoms mimic inflammatory disease of the middle ear space, and hence biopsy is often delayed. Herein we present a case of squamous cell carcinoma of the temporal bone arising 43 years after fenestration procedure. Operative findings were significant for complete dissolution of the tegmen tympani, tegmen mastoideum, and posterior fossa dura plate with dural exposure and sigmoid sinus exposure. Tumor was noted to invade the labyrinth at the horizontal semicircular canal. This case report highlights the aggressiveness of this particular tumor in a previously exenterated mastoid cavity and its proclivity to penetrate the otic capsule via pre-formed pathways. The treatment of choice is aggressive surgical resection followed by radiotherapy.
Modified epiglottoplasty for prevention of aspiration.
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Foreign body of the skull base due to transorbital penetrating trauma.
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An anatomic study of the external laryngeal framework with surgical implications.
Precise knowledge of the level of the vocal fold as projected on the external thyroid cartilage is of critical importance for the performance of thyroplasty type I and supraglottic laryngectomy. Measurements of the external laryngeal framework were made on the larynges of 18 human cadavers in order to identify landmarks that will aid the surgeon in determining endolaryngeal anatomy. On the basis of our results, the following guidelines are recommended: (1) Thyroid cartilage incision for supraglottic laryngectomy should be made on a line joining the juncture of the upper one third and lower two thirds of the midline length and the juncture of the upper one third and lower two thirds of the oblique line. This will ensure a position above the level of the anterior commissure and the true vocal cord; (2) In thyroplasty type I, the superior border of the thyroid cartilage window should be made at a line joining the midpoint of the midline length and the juncture of the upper two thirds and lower one third of the oblique line. Formation of the cartilage window according to this guideline will ensure its placement lateral to the vocalis muscle.
Sinus and nasal manifestations of the acquired immunodeficiency syndrome.
The AIDS epidemic has made previously uncommon infectious diseases and tumors commonplace in HIV-infected individuals. In this article we discuss specific cases of various infections and tumors of the sinonasal tract. Several of these diseases may be the presenting signs of HIV-seropositivity and AIDS. As a result, the clinician first to see such patients must be aware of the diagnosis of these diseases and tumors so that proper testing and treatment may ensue.
Bronchoesophageal manifestations of acquired immunodeficiency syndrome.
Among the more common manifestations of acquired immunodeficiency syndrome (AIDS) are tumors and infections that occur in regions treated by the bronchoesophagologist. In reviewing our institutional experience in the diagnosis and treatment of 396 patients with AIDS in 1987, we have noted that 226 (57%) had some form of pneumonia and 133 (34%) had candidiasis. In this communication we discuss the various types of bronchopulmonary, oropharyngeal, and esophageal infections that have been reported among AIDS patients. We also review the universal precautions and specific guidelines recommended for safeguarding the bronchoesophagologist and other health care workers who treat these patients.