Faculty Bibliography

This paper deals with the Nucleus C124R (CS) (Contour) cochlear Implant: its characteristics, differences compared with the previous generation of devices, the perimodiolar electrode, and the surgical technique used for safe insertion. We also discuss the rationale behind perimodiolar electrodes in general, as well as the results of laboratory studies validating the design and safety of this particular electrode array. The differences in surgical technique between this device and prior Nucleus cochlear implants are as follows: the incision and the size of the well, or recess, for the electronics are smaller; the cochleostomy is larger; the posterior portion is placed in a subpericranial pocket, not tied down, before electrode insertion; and the insertion process itself is quite different, due to the nature of the electrode, its size, shape, and stylet. The technique described is that used by one experienced cochlear implant center, and reflect the authors' practice. Clearly, there are other possible variations on this theme, which may be equally satisfactory in other hands. Most surgeons find this device to be easier to place than previous generations: complications to date have been uncommon

OBJECTIVE: To examine the relationship between histopathology, immunohistochemistry, and clinical behavior in atypical and low-grade malignant vestibular schwannomas. STUDY DESIGN: The study design was a retrospective case review in conjunction with a histopathologic and immunohistochemical proliferation marker study of archival specimens. DATA SOURCES: A tertiary referral center's anatomic pathology and vestibular schwannoma computerized databases. METHODS: The diagnosis of atypical or low-grade malignant vestibular schwannoma was based on the number of mitotic figures present per tumor slide. MIB1 labeling indices were used to compare the proliferative activity of the atypical and low-grade malignant groups with that in an age-matched and size-matched control group. RESULTS: Eight cases of atypical and six cases of low-grade malignant vestibular schwannoma were diagnosed from 1990 to 1998. In the atypical and low-grade malignant groups, respectively, the average patient age was 54.3 years (range, 38-74 yr) and 50 years (range, 38-72 yr), and the average total tumor size was 1.53 cm (range, 0.7-3.5 cm) and 1.55 cm (range, 1.5-2 cm). Two recurrences were identified from the low-grade malignant group, and there was one postoperative House-Brackmann Grade III facial weakness. There were no recurrences or facial palsies in the atypical group. No distant metastasis or aggressive local invasion was observed in either group. MIB1 labeling indices were significantly (p < or = 0.001) higher in the atypical (4.69%) and low-grade malignant (5.23%) groups than in the control group (1.99%). CONCLUSIONS: These findings suggest a tendency for recurrence in proliferative tumors; however, the designation of malignancy should be reconsidered

The insertion of an intrascalar electrode array during cochlear implantation causes immediate damage to the inner ear and may result in delayed onset of additional damage that may interfere with neuronal stimulation. To date, there have been reports on fewer than 50 temporal bone specimens from patients who had undergone implantation during life. The majority of these were single-channel implants, whereas the majority of implants inserted today are multichannel systems. This report presents the histopathologic findings in temporal bones from 8 individuals who in life had undergone multichannel cochlear implantation, with particular attention to the type and location of trauma and to long-term changes within the cochlea. The effect of these changes on spiral ganglion cell counts and the correlation between speech comprehension and spiral ganglion cell counts were calculated. In 4 of the 8 cases, the opposite, unimplanted ear was available for comparison. In 3 of the 4 cases, there was no significant difference between the spiral ganglion cell counts on the implanted and unimplanted sides. In addition, in this series of 8 cases, there was an apparent negative correlation between residual spiral ganglion cell count and hearing performance during life as measured by single-syllable word recognition. This finding suggests that abnormalities in the central auditory pathways are at least as important as spiral ganglion cell loss in limiting the performance of implant users

OBJECTIVES/HYPOTHESIS: The most common indication for cochlear reimplantation is device failure. Other, less frequent indications consist of 'upgrades' (e.g., single to multichannel), infection, and flap breakdown. Although the percentage of failures has decreased over time, an occasional patient requires reimplantation because of device malfunction. The varying designs of internal receiver/stimulators and electrode arrays mandate an examination of the nature and effects of reimplantation for the individual designs. The purpose of the current study was to investigate the reimplantation of several implant designs and to determine whether differences in surgical technique, anatomical findings, and postoperative performance exist. STUDY DESIGN: Retrospective chart review. METHODS: The subjects were 33 of 618 severely to profoundly deaf adults and children who had implantation at the New York University Medical Center (New York, NY) between February 1984 and December 2000. The subjects had previously had implantation with either a single-channel 3M/House (House Ear Institute, Los Angeles, CA) or 3M/Vienna (Technical University of Vienna, Vienna, Austria) device or with one of the multichannel Clarion (Advanced Bionics, Sylmar, CA), Ineraid (Smith & Nephew Richards, TN), or Nucleus (including the Contour) devices (Cochlear Corp., Englewood, CO) before reimplantation. RESULTS: Length of use before reimplantation ranged from 1 month to 13 years and included traumatic and atraumatic (electronic) failures, as well as device extrusion or infection. Results indicated that postoperative performance was either equal to or better than scores before failure. None of the devices explanted caused damage that precluded the implantation of the same or an upgraded device. These findings support the efficacy and safety of internal implant designs as related to the maintenance of a functional cochlea for the purpose of reimplantation. CONCLUSIONS: Cochlear reimplantation can be performed safely and without decrement to performance. The number of implanted electrodes at reinsertion were either the same or greater in all cases

Organelle transport by myosin-V is down-regulated during mitosis, presumably by myosin-V phosphorylation. We used mass spectrometry phosphopeptide mapping to show that the tail of myosin-V was phosphorylated in mitotic Xenopus egg extract on a single serine residue localized in the carboxyl-terminal organelle-binding domain. Phosphorylation resulted in the release of the motor from the organelle. The phosphorylation site matched the consensus sequence of calcium/calmodulin-dependent protein kinase II (CaMKII), and inhibitors of CaMKII prevented myosin-V release. The modulation of cargo binding by phosphorylation is likely to represent a general mechanism regulating organelle transport by myosin-V

The use of traditional electrocautery is prohibited in revision or replacement cochlear implant surgery because of the concern for end organ tissue damage. Additionally, electrical current spread to the malfunctioning device could interfere with an accurate cause-of-failure analysis. Clinical reports have confirmed the utility of the Shaw scalpel for dermatologic, ophthalmic, and head and neck surgery. The Shaw scalpel is a thermally activated cutting blade that provides a bloodless field through immediate capillary and small vessel hemostasis. Avoidance of wound and flap complications is of primary concern in cochlear implant surgery. The long-term wound healing compared favorably to that of other surgical cutting instruments in several experimental reports. We have routinely used the Shaw scalpel in revision cochlear implant surgery and in primary surgery whenever electrocautery was contraindicated. We have retrospectively evaluated 22 cases in which the Shaw scalpel was used for cochlear implant revision and primary surgery. The chart review included patient demographics, the indication for surgery, the contraindication for electrocautery, intraoperative surgical notes, the wound healing evaluation, the evaluation for alopecia, and postoperative speech understanding. No significant complications occurred intraoperatively, and the long-term wound healing results were no different from those obtained with conventional surgical techniques. The explanted devices were undamaged, and valuable diagnostic information could be obtained. All patients performed at or better than their preoperative levels on speech recognition testing. Our results indicate that the Shaw scalpel is a relatively safe, easy-to-use, and effective instrument

The known etiologies of acquired sensorineural hearing loss include acoustic trauma, physical trauma, ototoxicity, genetic predisposition, infections, Meniere's disease, aging, and autoimmune disease. Treatments are directed at eliminating or managing the underlying disease process and aiding hearing with amplification. Rarely is it possible to improve unaided hearing after sensorineural loss except when the severe to profound level of loss is reached and cochlear implantation becomes an option. Autoimmune inner ear disease, however, is a treatable cause of sensorineural hearing loss and it is important for physicians and hearing health professionals to recognize that proper early diagnosis and management strategies may result in stabilization and possibly improvement in hearing

HYPOTHESIS: This study was conducted to evaluate the electrode to modiolus proximity of two commonly used electrodes (Nucleus and Clarion) and a new prototype electrode. BACKGROUND: Theoretical advantages of modiolus-hugging cochlear implant electrodes include reduced stimulus energy requirements, more efficient power management and longer battery life, more discreet ganglion cell population stimulation, and reduced facial nerve stimulation. METHODS: Fluoroscopic analysis and histologic surface preparation analysis of electrode position and trauma. RESULTS: The Nucleus straight electrode occupied an outer wall position in the scala tympani. The Clarion electrode occupied a more intermediate position. The actively coiling prototype electrode was modiolus hugging but caused more trauma than the other two electrodes tested. CONCLUSIONS: The optimal modiolus-hugging atraumatic intracochlear electrode does not currently exist

OBJECTIVE: This study was conducted to evaluate the insertion properties and intracochlear trajectories of three perimodiolar electrode array designs and to compare these designs with the standard Cochlear/Melbourne array. BACKGROUND: Advantages to be expected of a perimodiolar electrode array include both a reduction in stimulus thresholds and an increase in dynamic range, resulting in a more localized stimulation pattern of the spiral ganglion cells, reduced power consumption, and, therefore, longer speech processor battery life. METHODS: The test arrays were implanted into human temporal bones. Image analysis was performed on a radiograph taken after the insertion. The cochleas were then histologically processed with the electrode array in situ, and the resulting sections were subsequently assessed for position of the electrode array as well as insertion-related intracochlear damage. RESULTS: All perimodiolar electrode arrays were inserted deeper and showed trajectories that were generally closer to the modiolus compared with the standard electrode array. However, although the precurved array designs did not show significant insertion trauma, the method of insertion needed improvement. After insertion of the straight electrode array with positioner, signs of severe insertion trauma in the majority of implanted cochleas were found. CONCLUSIONS: Although it was possible to position the electrode arrays close to the modiolus, none of the three perimodiolar designs investigated fulfilled satisfactorily all three criteria of being easy, safe, and atraumatic to implant