Consensus Panel on a Cochlear Coordinate System Applicable in Histologic, Physiologic, and Radiologic Studies of the Human Cochlea (original) (raw)
2010, Otology & Neurotology
Hypothesis-An objective cochlear framework, for evaluation of the cochlear anatomy and description of the position of an implanted cochlear implant electrode, would allow the direct comparison of measures performed within the various sub-disciplines involved in cochlear implant research. Background-Research on the human cochlear anatomy in relation to tonotopy and cochlear implantation is conducted by specialists from numerous disciplines such as histologists, surgeons, physicists, engineers, audiologists and radiologists. To allow accurate comparisons between and combinations of previous and forthcoming scientific and clinical studies, cochlear structures and electrode positions must be specified in a consistent manner. Methods-Researchers with backgrounds in the various fields of inner ear research as well as representatives of the different manufacturers of cochlear implants (Advanced Bionics Corp, Med-El, Cochlear Corp) were involved in consensus meetings held in Dallas, March 2005 and Asilomar, August 2005. Existing coordinate systems were evaluated and requisites for an objective cochlear framework were discussed. Results-The consensus panel agreed upon a 3-dimensional, cylindrical coordinate system of the cochlea using the "Cochlear View" as a basis and choosing a z-axis through the modiolus. The zero
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The Size of the Cochlea and Predictions of Insertion Depth Angles for Cochlear Implant Electrodes
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Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology, 2010
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The influence of cochlear morphology on the final electrode array position
European Archives of Oto-rhino-laryngology, 2017
Objective Preoperative information about cochlear morphology and size increasingly seems to be a defining factor of electrode choice in cochlear implant surgery. Different types of electrodes differ in length and diameter to accommodate individual cochlear anatomy. Smaller cochlear size results in increased insertion depth with a higher risk to dislocate and causes cochlear trauma with reduced postoperative outcome. The objective of the current study is to describe the three-dimensional size of the cochlea, to compare interindividual differences, to determine the relationship between cochlear size and insertion angle, and to define risk factors for dislocation during insertion. Design Four hundred and three patients implanted between 2003 and 2010 inserted via cochleostomy with a perimodiolar electrode array (Cochlear™ Contour Advance ® electrode array) have been compared. CBCT (Cone beam computed tomography) was used to determine electrode array position (scala tympani versus scala vestibuli insertion, intracochlear dislocation, and insertion angle) and cochlear size (diameters and height). The trajectory of the electrode array and the lateral wall have been measured, and the position of the electrode array has been estimated. Results The mean value of the largest diameter was 9.95 mm and that of the perpendicular distance was 6.54 mm. There was a statistically significant correlation between those values. Mean height was 3.85 mm. The intracochlear relation of the electrode array and the modiolus showed a statistically significant relationship with the cochlear expanse. The electrode array was more likely to dislocate in cochleae with a smaller diameter and a lower height. Cochleae with insertions into scala vestibuli exhibited a smaller height compared to scala tympani insertions with statistical significance. Conclusion Cochlear size and shape is variable, and the measured data of this study confirm the finding of other researchers. This study established two heights by two different planes to achieve a three-dimensional understanding of the cochlea. The electrode array was more likely to dislocate in cochleae with smaller diameter and smaller height. It can be assumed that the height established in this study seems to be a new preoperative parameter to underline the risk of scalar dislocation and not favored scala vestibuli insertion if using a cochleostomy approach. In conclusion, cochlear size, especially the height, is influencing the final position of the electrode array. Using preoperative scans of the cochlear diameters and cochlear height, a next step to custom-sized arrays is available.
Human cochlea: anatomical characteristics and their relevance for cochlear implantation
Anatomical record (Hoboken, N.J. : 2007), 2012
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Surgical Anatomy of the Basal Turn of the Human Cochlea as Pertaining to Cochlear Implantation
Otology & Neurotology, 2015
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Brazilian Journal of Otorhinolaryngology, 2008
2 full professor of otorhinolaryngology-Medical School of the university of São paulo, head of the Department of ophthalmology and otorhinolaryngology of the fMuSp. 3 graduate student in otorhinolaryngology-phD-Medical School-university of São paulo, assistant physician-uSp university hospital. faculdade de Medicina da universidade de São paulo. Send correspondence to: Mariana Bogar-rua da figueiras 720 ap.141 Bairro Jardim Santo andré Sp 09080-300. fapESp. paper submitted to the aBorl-ccf Sgp (Management publications System) on January 6, 2007 and accepted for publication on april 23th, 2007. cod. 3570. cochl ear ossification, mainly secondary to meningitis, prevents the complete conventional cochlear implant insertion. implants with two electrode bundles shorter than the conventional ones were specifically developed for ossified cochleas. however, during surgery there is a high risk of damaging the internal carotid artery (ica). therefore, measuring cochleostomy depth in order to insert the two electrode bundles would greatly increase the procedure's safety. Aims: 1) find the distances between cochleostomies and ica in cadaver temporal bones. 2) Design an instrument that can be used in cochlear implant surgery to introduce an implant with two bundles of electrodes. Study Design: Experimental prospective. Materials and Methods: in 21 temporal bones from cadavers we performed: 1) canal wall down mastoidectomy; 2) cochleostomy in the cochlear basal and middle turns; 3) ica identification; 4) length determination between the cochleostomies and the artery. Results: the average distance ± standard deviation obtained for the upper tunnel was of 8.2 ± 1.1 mm and for the lower tunnel it was of 8.1± 1.3 mm. the shortest distance found was of 6.5 mm for the upper tunnel and 6.0 mm for the lower tunnel. Conclusion: Despite the values calculated, we concluded that the best value to be considered in creating a surgical instrument are the minimum lengths obtained for each one of the cochlear turns, because this is the safest way to avoid damaging the ica, that can be fatal.
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Indian Journal of Otolaryngology and Head & Neck Surgery, 2017
To test whether there are variations in cochlear orientation with respect to age and sex, and its relevance in cochlear implant surgery. Implant otologists rely upon the anatomic landmarks including the facial recess and round window niche and round window membrane for accessibility and placement of electrode array into scala tympani of basal turn of cochlea. Anecdotally, surgeons note variations in cochlear orientation with respect to age. Cochlear orientation studied radiologically by pre-operative CT scan of temporal bone can guide a Surgeon's approach to cochlear implantation. To investigate the changes in cochlear orientation with respect to age and sex; and its relevance in cochlear implantation. A retrospective analytical study was performed on CT scans of temporal bones in patients (of our hospital from July 2013 to January 2015 i.e. for a period of 18 months) with no congenital or radiological abnormalities of cochlea. The basal turn angulations of cochlea varied with age and majority of change occurred during early age. The basal turn angulations of cochlea in difficult situations during cochlear implantation were correlated with the data. There is a significant variation in cochlear orientation as measured radiologically by basal turn angulations relative to midsagittal plane. The more obtuse and acute basal turn angulations have implications like difficulty in cochleostomy and electrode placement during cochlear implantation. Keywords Cochlear orientation Á Basal turn angulations Á Radiological orientation of cochlea Á Cochlear implant surgery Á Cochleostomy and Round window insertion
Impact of electrode design and surgical approach on scalar location and cochlear implant outcomes
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Cochlear implants: Insertion assessment by computed tomography
American journal of otolaryngology, 2018
Imaging exams play a key role in cochlear implants with regard to both planning implantation before surgery and quality control after surgery. The ability to visualize the three-dimensional location of implanted electrodes is useful in clinical routines for assessing patient outcome. The aim of this study was to evaluate linear and angular insertion depth measurements of cochlear implants based on conventional computed tomography. Tools for linear and angular measurements of cochlear implants were used in computed tomography exams. The tools realized the insertion measurements in an image reconstruction of the CIs, based on image processing techniques. We comprehensively characterized two cochlear implant models while obviating possible changes that can be caused by different cochlea sizes by using the same human temporal bones to evaluate the implant models. The tools used herein were able to differentiate the insertion measurements between two cochlear implant models widely used i...
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