Graeme Clark Collection
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ItemSurgical implications of perimodiolar cochlear implant electrode design: avoiding intracochlear damage and scala vestibuli insertion.(Informa UK Limited, 2001-09)OBJECTIVE: To review the mechanisms and nature of intracochlear damage associated with cochlear implant electrode array insertion, in particular, the various perimodiolar electrode designs. Make recommendations regarding surgical techniques for the Nucleus Contour electrode to ensure correct position and minimal insertion trauma. BACKGROUND: The potential advantages of increased modiolar proximity of intracochlear multichannel electrode arrays are a reduction in stimulation thresholds, an increase in dynamic range and more localized neural excitation. This may improve speech perception and reduce power consumption. These advantages may be negated if increased intracochlear damage results from the method used to position the electrodes close to the modiolus. METHOD: A review of the University of Melbourne Department of Otolaryngology experience with temporal bone safety studies using the Nucleus standard straight electrode array and a variety of perimodiolar electrode array designs; comparison with temporal bone insertion studies from other centres and postmortem histopathology studies reported in the literature. Review of our initial clinical experience using the Nucleus Contour electrode array. RESULTS: The nature of intracochlear damage resulting from electrode insertion trauma ranges from minor, localized, spiral ligament tear to diffuse organ of Corti disruption and osseous spiral lamina fracture. The type of damage depends on the mechanical characteristics of the electrode array, the stiffness, curvature and size of the electrode in relation to the scala, and the surgical technique. The narrow, flexible, straight arrays are the least traumatic. Pre-curved or stiffer arrays are associated with an incidence of basilar membrane perforation. The cochleostomy must be correctly sited in relation to the round window to ensure scala tympani insertion. A cochleostomy anterior to the round window rather than inferior may lead to scala media or scala vestibuli insertion. CONCLUSION: Proximity of electrodes to the modiolus can be achieved without intracochlear damage provided the electrode array is a free fit within the scala, of appropriate size and shape, and accurate scala tympani insertion is performed.
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ItemSurgery(Singular Publishing, 1997)Cochlear implant surgery should be undertaken only after the cochlear implant team has established that the child is not achieving useful communication with a hearing aid. This can be difficult because of poor language development in deaf children in this age group or because the child is at a preverbal stage and too young for the use of formal assessment tests. The child's unaided and aided thresholds, however, are important for assessment, as are his or her communication skills. These need to be evaluated by an experienced paediatric audiologist.
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ItemPreoperative medical evaluation(Singular Publishing, 1997)The aim of the medical assessment of infants and children is to determine the cause, severity and duration of any hearing loss as well as the presence of any medical conditions that may influence their management with a cochlear implant. There should also be an initial assessment of the child's communication skills and the parental expectations for his or her education.
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ItemSurgical considerations for the placement of the new Cochlear Pty Limited micro-multiple-channel cochlear implant for research studies( 1995)A new micro-receiver-stimulator for research studies on very young children as well as adults has been developed by Cochlear Pty Limited. The dimensions of the device are length 58 mm and width at front 18 mm. The width starts to increase 19 mm from the front, and the back section, which has the receiver coil and magnet, has a maximum diameter of 33 mm. The depth or thickness of the front portion of the electronic package is 5.7mm, and the remainder of the package 4.0 mm. The antenna section is 3.5 mm thick. The other dimensions of the front section of the electronic package are length 9.5 mm and width 13.7 mm. There is an angle of 160° between the titanium electronic package and the receiver coil. The dimensions of the receiver-stimulator were arrived at after anatomic studies on the temporal bones of children ranging in age from 2 to 11 months.
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ItemSurgical complications with the cochlear multiple-channel intracochlear implant: experience at Hannover and Melbourne( 1991)The surgical complications for the first 153 multi-channel cochlear implant operations carried out at the Medizinische Hochschule in Hannover and the first 100 operations at The University of Melbourne Clinic, The Royal Victorian Eye and Ear Hospital, are presented. In the Hannover experience the major complications were wound breakdown, wound infection, electrode tie erosion through the external auditory canal, electrode slippage, a persistent increase in tinnitus, and facial nerve stimulation. The incidence of wound breakdown requiring removal of the package was 0.6% in Hannover and 1.0% in Melbourne. The complications for the operation at both clinics were at acceptable levels. It was considered that wound breakdown requiring implant removal could be kept to a minimum by making a generous incision and suturing the flap without tension.
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ItemSurgery for the safe insertion and reinsertion of the banded electrode array( 1987)Adhering to the surgical technique outlined in the protocol for the Nucleus implant has resulted in over 100 patients worldwide obtaining significant benefit from multichannel stimulation. A detailed analysis of the results in 40 patients shows that it improves their awareness of environmental sounds and their abilities in understanding running speech when combined with lipreading. In addition, one third to one half of the patients also understand significant amounts of running speech without lipreading and some can have interactive conversations over the telephone. It is clear that any insertion trauma is not significant, which is confirmed by the excellent clinical results.