Surgical Implantation and Biocompatibility of Central Nervous System Auditory Prostheses

1989 ◽  
Vol 98 (12) ◽  
pp. 965-970 ◽  
Author(s):  
John K. Niparko ◽  
Richard A. Altschuler ◽  
James A. Wiler ◽  
Xiaolin Xue ◽  
David J. Anderson
Keyword(s):  
Cochlear Nucleus ◽  
Neuronal Loss ◽  
Tissue Reaction ◽  
Auditory Prosthesis ◽  
Future Studies ◽  
Potential Problems ◽  
Iridium Wire ◽  
Surgical Implantation ◽  
Glial Cell Proliferation ◽  
Suboccipital Approach

As part of a program to determine the feasibility of a CNS auditory prosthesis, the tissue reaction to electrodes chronically implanted in the cochlear nucleus (CN) of the guinea pig was examined. Varied open operative approaches and microelectrode designs were utilized. Silicon substrate thin film and platinum-iridium wire electrodes, tethered and untethered, were placed successfully in different divisions of the CN. Implantation through a posterior suboccipital approach was most successful. Histologic examinations demonstrated a glial cell proliferation confined to the area of the electrode track that never exceeded 15 μm in width. No neuronal loss or significant effect on cell morphology was seen, and reactive cells were absent. Electrode migration was apparent in a minority of animal preparations. Although potential problems were identified, our findings lend support to the feasibility of implanting a neuroprosthesis in the CN and have helped to establish methods for future studies of chronic intranuclear stimulation.

scholarly journals Single-neuron recordings from unanesthetized mouse dorsal cochlear nucleus

2012 ◽  
Vol 107 (3) ◽  
pp. 824-835 ◽  
Author(s):  
Wei-Li Diana Ma ◽  
Stephan D. Brenowitz
Keyword(s):  
Cochlear Nucleus ◽  
Single Neuron ◽  
Dorsal Cochlear Nucleus ◽  
Future Studies ◽  
Auditory Neuroscience ◽  
Neuronal Mechanisms ◽  
Auditory Physiology ◽  
Complex Spikes

Because of the availability of disease and genetic models, the mouse has become a valuable species for auditory neuroscience that will facilitate long-term goals of understanding neuronal mechanisms underlying the perception and processing of sounds. The goal of this study was to define the basic sound-evoked response properties of single neurons in the mouse dorsal cochlear nucleus (DCN). Neurons producing complex spikes were distinguished as cartwheel cells (CWCs), and other neurons were classified according to the response map scheme previously developed in DCN. Similar to observations in other rodent species, neurons of the mouse DCN exhibit relatively little sound-driven inhibition. As a result, type III was the most commonly observed response. Our findings are generally consistent with the model of DCN function that has been developed in the cat and the gerbil, suggesting that this in vivo mouse preparation will be a useful tool for future studies of auditory physiology.

Auditory Brainstem Prosthesis: Biocompatability of Stimulation

1989 ◽  
Vol 101 (3) ◽  
pp. 344-352 ◽  
Author(s):  
John K. Niparko ◽  
Richard A. Altschuler ◽  
David A. Evans ◽  
Xiaolin Xue ◽  
Jamille Farraye ◽  
...  
Keyword(s):  
Cochlear Nucleus ◽  
Neuronal Damage ◽  
Cell Loss ◽  
Auditory Brainstem ◽  
Tissue Reaction ◽  
Tissue Response ◽  
Adverse Tissue Reaction ◽  
Middle Latency ◽  
Different Levels ◽  
Stimulation Of

As part of a program to develop a central auditory system prosthesis, we have examined the reaction of tissue to different levels of stimulation from electrodes chronically implanted in the cochlear nucleus of the guinea pig. Tolerance and histologic reaction to 20 hours of periodic electrical stimulation of the cochlear nucleus were analyzed. Intraoperative and postoperative electrically evoked middle latency responses were monitored during stimulus trials. The threshold necessary to generate the middle latency responses was frequently below 50 μA. In the animals that received 50 and 100 μA of blphasic charge-balanced stimulation (corresponding to approximately 200 and 400 μC/cm2 phase), adverse tissue reaction was minimal, and glial proliferation along the electrode tract never exceeded 25 μm in width. Stimulation intensities of 150 and 200 μA (approximately 600 and 800 μC/cm2 phase) produced significant tissue response at the site of the electrode terminus, with necrosis, cell loss, and reactive cells present. Therefore neuronal damage was observed to occur at an intensity far greater than that required for eliciting an electrophysiologic response.

Multiple-Channel Stimulation of the Cochlear Nucleus

1989 ◽  
Vol 101 (6) ◽  
pp. 651-657 ◽  
Author(s):  
David E. Evans ◽  
John K. Niparko ◽  
Josef M. Miller ◽  
Robert W. Jyung ◽  
David J. Anderson
Keyword(s):  
Electric Fields ◽  
Cochlear Nucleus ◽  
Growth Function ◽  
Auditory Brainstem ◽  
Auditory Prosthesis ◽  
Electrode Arrays ◽  
Multiple Channel ◽  
Middle Latency Response ◽  
Latency Response ◽  
Middle Latency

To further test the feasibility of a central nervous system auditory prosthesis, the characteristics of the electrically evoked middle latency response were studied in a series of acutely anesthetized pigmented guinea pigs, with multi-channel penetrating cochlear nucleus electrodes placed into the cochlear nucleus under direct visualization. These stimulating electrodes consisted of a silicone substrate, with five stimulating pads each, sputtered with Iridium. Monopolar and bipolar stimulation were used. Threshold, latency, and input-output functions of the electrically evoked middle latency response were studied. Systematic differences were observed, depending on the site and parameters of stimulation. Principally, higher currents were required to produce waves of equal amplitude when the electrodes were closely spaced. For near electrode pairs, the maximum wave amplitudes obtainable within the limits of tissue safety were much lower than for distant electrode pairs. The slope of the growth function curve was steeper for widely spaced electrodes than for adjacent sites. Monopolar stimulation demonstrated maximum wave amplitudes with the lowst current Intensity, implying current spread to the entire cochlear nucleus with this stimulation montage. In some cases, threshold differences were observed, higher thresholds being associated with closely spaced elecrodes. These findings are consistent with simple models of the electric fields expected to be generated by these electrode arrays. The results support the hypothesis that activtalon of subpopulations of auditory brainstem neurons with multi-channel penetrating microelectrodes is possible.

Anatomical Results with Titanium Implants in the Mastoid Region

1997 ◽  
Vol 76 (4) ◽  
pp. 231-236 ◽  
Author(s):  
D. Portmann ◽  
P. Boudard ◽  
D. Herman
Keyword(s):  
Soft Tissue ◽  
Pure Titanium ◽  
Tissue Reaction ◽  
Titanium Implants ◽  
Skin Reactions ◽  
Aural Rehabilitation ◽  
Bone Anchored Hearing Aid ◽  
Surgical Implantation ◽  
Mastoid Region

We report our experience with titanium implants for extra-aural rehabilitation in the mastoid region with a bone-anchored hearing aid (BAHA) and auricular prosthesis. The purpose of this study was to evaluate the clnical status of the soft tissue adjacent to 63 skin-penetrating devices in 43 patients and to compare our findings with those of other reports. Forty-four fixtures have been implanted in 36 patients for the BAHA and 19 in seven patients for the auricular prostheses. The evaluation concerns osseointegration, pain in the mastoid area, skin reaction around the abutment and removal of the abutment. Three implants extruded; one due to trauma and two with no explanation. Follow-up ranged from 3 to 60 months after surgical implantation. The first outpatient check-up was performed at three months after implantation and then every six months. The soft tissue reaction around the percutaneous unit was classified at each control according to the classification proposed by Holgers et al.1 There was no irritation (type 0) in 87.5% of the controls for the BAHA group and in 87.2% for the group of auricular prostheses. No adverse skin reactions were noted in 61.36% of the BAHA group and in 66.66% of the auricular prosthesis group. Results of this study confirm the skin's ability to tolerate a skin-penetrating unit made of pure titanium. The importance of reducing the thickness of the skin around the implant and of local hygienic conditions is emphasized.

Carcinomatous Encephalomyelitis with Auditory and Vestibular Manifestations

1976 ◽  
Vol 85 (1) ◽  
pp. 120-126 ◽  
Author(s):  
Trevor McGill
Keyword(s):  
Cochlear Nucleus ◽  
Stria Vascularis ◽  
Neuronal Loss ◽  
Organ Of Corti ◽  
Sensory Neuropathy ◽  
Pathological Study ◽  
Striking Change ◽  
Oat Cell Carcinoma ◽  
Cochlear Neurons ◽  
Microglial Response

A clinical and pathological study of carcinomatous encephalomyelitis is presented. Attention is drawn to the various types of nonmetastatic paraneoplastic syndromes and their particular association with oat cell carcinoma of the lung. The feature of special interest in this study is the onset with otologic symptoms, sudden deafness in the left ear and vertigo, at a time when the neoplastic basis for the disease was not clinically evident. The most striking change in the left temporal bone is the almost total loss of cochlear neurons in Rosenthal's canal and degeneration of both divisions of the vestibular nerve. The organ of Corti and stria vascularis are normal throughout the cochlear duct. The vestibular sense organs are normal. The left cochlear nucleus is devoid of neurons, this neuronal loss is accompanied by a well developed astrocytic and microglial response similar to that in the medulla and spinal cord. This represents a carcinomatous sensory neuropathy involving the left VIII nerve with simultaneous involvement of the left cochlear nucleus. The pathogenesis of this condition still defies explanation, but there are some insights in the autoimmune sector.

Microbulldozing and Microchiseling

1969 ◽  
Vol 27 ◽  
pp. 134-135
Author(s):  
J.N. Ramsey ◽  
D.P. Cameron ◽  
F.W. Schneider
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Material Handling ◽  
Microprobe Analysis ◽  
Foreign Matter ◽  
Specific Location ◽  
Potential Problems ◽  
Knoop Indenter ◽  
Scanning Electron ◽  
Microhardness Tester

As computer components become smaller the analytical methods used to examine them and the material handling techniques must become more sensitive, and more sophisticated. We have used microbulldozing and microchiseling in conjunction with scanning electron microscopy, replica electron microscopy, and microprobe analysis for studying actual and potential problems with developmental and pilot line devices. Foreign matter, corrosion, etc, in specific locations are mechanically loosened from their substrates and removed by “extraction replication,” and examined in the appropriate instrument. The mechanical loosening is done in a controlled manner by using a microhardness tester—we use the attachment designed for our Reichert metallograph. The working tool is a pyramid shaped diamond (a Knoop indenter) which can be pushed into the specimen with a controlled pressure and in a specific location.

Techniques For The Preparation of Tissue Samples Containing Injectable Polymer Microcapsules

1985 ◽  
Vol 43 ◽  
pp. 710-711
Author(s):  
G.E. Visscher ◽  
R. L. Robison ◽  
G. J. Argentieri
Keyword(s):  
Drug Delivery ◽  
Drug Delivery Systems ◽  
Gastrocnemius Muscle ◽  
Degradation Process ◽  
Delivery Systems ◽  
Tissue Reaction ◽  
Electron Microscopic ◽  
Tissue Samples ◽  
Injectable Polymer ◽  
Microscopic Techniques

The use of various bioerodable polymers as drug delivery systems has gained considerable interest in recent years. Among some of the shapes used as delivery systems are films, rods and microcapsules. The work presented here will deal with the techniques we have utilized for the analysis of the tissue reaction to and actual biodegradation of injectable microcapsules. This work has utilized light microscopic (LM), transmission (TEM) and scanning (SEM) electron microscopic techniques. The design of our studies has utilized methodology that would; 1. best characterize the actual degradation process without artifacts introduced by fixation procedures and 2. allow for reproducible results.In our studies, the gastrocnemius muscle of the rat was chosen as the injection site. Prior to the injection of microcapsules the skin above the sites was shaved and tattooed for later recognition and recovery. 1.0 cc syringes were loaded with the desired quantity of microcapsules and the vehicle (0.5% hydroxypropylmethycellulose) drawn up. The syringes were agitated to suspend the microcapsules in the injection vehicle.

An Early Developmental Marker for Radial Glia in Rat Spinal Cord

1996 ◽  
Vol 54 ◽  
pp. 36-37
Author(s):  
V. Kriho ◽  
H.-Y. Yang ◽  
C.-M. Lue ◽  
N. Lieska ◽  
G. D. Pappas
Keyword(s):  
Spinal Cord ◽  
Intermediate Filament ◽  
Radial Glia ◽  
Rat Spinal Cord ◽  
Future Studies ◽  
Spinal Cord Development ◽  
Median Septum ◽  
Differentiation Marker ◽  
Early Developmental ◽  
Developing Rat

Radial glia have been classically defined as those early glial cells that radially span their thin processes from the ventricular to the pial surfaces in the developing central nervous system. These radial glia constitute a transient cell population, disappearing, for the most part, by the end of the period of neuronal migration. Traditionally, it has been difficult to definitively identify these cells because the principal criteria available were morphologic only.Using immunofluorescence microscopy, we have previously defined a phenotype for radial glia in rat spinal cord based upon the sequential expression of vimentin, glial fibrillary acidic protein and an intermediate filament-associated protein, IFAP-70/280kD. We report here the application of another intermediate filament-associated protein, IFAP-300kD, originally identified in BHK-21 cells, to the immunofluorescence study of radial glia in the developing rat spinal cord.Results showed that IFAP-300kD appeared very early in rat spinal cord development. In fact by embryonic day 13, IFAP-300kD immunoreactivity was already at its peak and was observed in most of the radial glia which span the spinal cord from the ventricular to the subpial surfaces (Fig. 1). Interestingly, from this time, IFAP-300kD immunoreactivity diminished rapidly in a dorsal to ventral manner, so that by embryonic day 16 it was detectable only in the maturing macroglial cells in the marginal zone of the spinal cord and the dorsal median septum (Fig. 2). By birth, the spinal cord was essentially immuno-negative for this IFAP. Thus, IFAP-300kD appears to be another differentiation marker available for future studies of gliogenesis, especially for the early stages of radial glia differentiation.

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