Graeme Clark Collection
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ItemCochlear implants in children: the value of cochleostomy seals in the prevention of labyrinthitis following pneumococcal otitis media( 1995)Cochlea implantation at an early age is important in rehabilitating profoundly hearing impaired children. Given the incidence of pneumococcal otitis media in young children, there has been concern that cochlear implantation could increase the possibility of otitis media, leading to labyrinthitis in this age group. Clinical experience has not indicated an increase in the frequency of otitis media and labyrinthitis in implanted adults or children over two years. However, labyrinthitis has occurred in implanted animals with otitis media. In order to assess the impact of cochlear implants on the occurrence of labyrinthitis, pneumococcal otitis media was induced in 21 kittens. Thirty-two kitten cochleas were implanted, of which 9 had a fascial graft and 9 a Gelfoam® graft. Nine control cochleas were unimplanted. Labyrinthitis occurred in 44% of unimplanted controls. 50% of implanted ungrafted cochleas, and 6% of implanted grafted cochleas. There was no statistically significant difference between the incidence of labyrinthitis in the implanted cochleas and the unimplanted controls. However there was a statistically significant difference between the ungrafted and grafted cochleas, but not between the two types of graft.
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ItemCochlear implantation in young children: histological studies on head growth, leadwire design, and electrode fixation in the monkey model( 1994)For safe cochlear implantation in children under 2 years of age, the implant assembly must not adversely affect adjacent tissues or compromise head growth. Furthermore, growth changes and tissue responses should not impair the function of the device. Dummy receiver-stimulators, interconnect plugs, and leadwire-lengthening systems were implanted for periods of 36 months in the young monkey to effectively model the implantation of the young child. The results show that implanting a receiver-stimulator package has no adverse effects on skull growth or the underlying central nervous system. The system for fixing the electrode at the fossa incudis proved effective. There was marked osteoneogenesis in the mastoid cavity, resulting in the fixation of the leadwire outside the cochlea. This study provides evidence for the safety of cochlear implantation in young subjects.
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ItemCochlear implantation in children: labyrinthitis following pneumococcal otitis media in unimplanted and implanted cat cochleas( 1994)Pneumococcal otitis media is frequent in young children and could lead to labyrinthitis post-implantation. To assess the risk and methods of minimizing it by a graft to the round window around the electrode entry point, we have used a cat animal model of pneumococcal otitis media. Twenty-one kittens were used in the study. Thirty-two cochleas were implanted when the kittens were 2 months of age. Fourteen cochleas were implanted without using a graft (12 were available for study); 9 had a fascial graft, and 9 a Gelfoam® graft (7 were available for study). The implanted kittens had their bullae inoculated with Streptococcus pneumoniae 2 months after implantation and were sacrificed 1 week later. There were also 9 unimplanted control ears which were inoculated when the animals were 4 months of age. Labyrinthitis occurred in 44% of unimplanted control, 50% of implanted ungrafted, and 6% of implanted grafted (fascia and Gelfoam®) cochleas. There was no statistically significant difference between the unimplanted control and the implanted cochleas (p < 0.05). There was, however, a difference between the implanted-ungrafted and implanted grafted cochleas, but not between the use of fascia and Gelfoam® to graft the round window entry point. As a result, the data indicates that cochlear implantation does not increase the risk of labyrinthitis following pneumococcal otitis media, but it is desirable to use fascia as a graft to the round window around the electrode entry point.
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ItemAnimal models of human disease: otitis media( 1991)Otitis media is an inflammation of the middle ear, which may or may not be of microbial origin. Genetic, immunologic, allergic conditions, antecedent viral respiratory infections, and mastoid size are contributing factors for middle ear disease. Dysfunction of the eustachian tube predisposes to acute otitis media. Collection of fluid within the middle ear cavity is part of the disease process and is equally observed in infectious and noninfectious middle ear disease. Streptococcus pneumonia, Haemophilus influenza, Streptococcus pyogenes, and Streptococcus aureus are the most common organisms that cause acute infectious otitis media.