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Predicting Basal Cochlear Length for Electric-Acoustic Stimulation
Oliver Adunka, MD;
Marc H. Unkelbach, MD;
Martin G. Mack, MD, PhD;
Andreas Radeloff, MD;
Wolfgang Gstoettner, MD, PhD
Arch Otolaryngol Head Neck Surg. 2005;131:488-492.
Objective To assess the feasibility and accuracy of predicting electrode insertion depth necessary in cochlear implantations for electric-acoustic stimulation by means of preoperative high-resolution computed tomography (HRCT).
Design Human temporal bone study with evaluation of cochlear dimensions.
Setting Tertiary care medical center.
Methods Eight fresh human temporal bones were scanned, and basal cochlear structures were reconstructed and measured. Standard cochlear implantations with a free-fitting array were performed, and the bones then underwent histologic analysis using a technique that allows sectioning of undecalcified bones. After embedding, all bones underwent conventional radiologic analysis with further insertion measurements. Preimplantation HRCT data were compared with radiologic and histologic data.
Results Preimplantation HRCT-based measurements correlated very well with postimplantation radiologic data. A mean failure of 0.3 mm was found. Mean values for the first 360° ranged from 18.8 to 22.0 mm.
Conclusions Preimplantation HRCT-based prediction of cochlear implant insertion depths is both feasible and accurate. It is especially useful when aiming for hearing preservation, where insertion depths of 360° are necessary.
Author Affiliations: Departments of Otorhinolaryngology (Drs Adunka, Unkelbach, Radeloff, and Gstoettner) and Diagnostic and Interventional Radiology (Dr Mack), J.W. Goethe University, Frankfurt am Main, Germany.
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