Scalar localization by computed tomography of cochlear implant electrode carriers designed for deep insertion.
OBJECTIVE
This study aimed to evaluate the possibility of predicting radiologically the scalar localization of a 31.5-mm-long, free-fitting electrode carrier for cochlear implantation, using conventional planar computed tomography.


METHODS
A cross-sectional human temporal bone study was conducted.


METHODS
Twenty human temporal bones were acquired postmortem and implanted with 31.5-mm-long electrode carriers. Ten of these were implanted into the scala tympani using the round window approach, whereas the other 10 electrodes were inserted into the scala vestibuli by cochleostomy. Computed tomography was then performed, and 2 experienced blinded radiologists evaluated the intracochlear position of the array.


METHODS
The estimated position of the electrode carrier was described using a 5-point scale. After sectioning and histologic investigation, the results of the radiologic and histologic investigations were compared.


RESULTS
In 17 of 20 cases, it was possible to estimate the correct position of the electrode carrier within the basal turn of the cochlea by means of computed tomography. As the insertion angles widened beyond 360 degrees, it became increasing difficult for the radiologists to correctly determine the position of the electrode carrier.


CONCLUSIONS
The comparison of our temporal bone experiment results with the computed tomography results revealed the difficulty of assessing the correct position of intracochlear electrodes. Scalar localization of deeply inserted electrode carriers cannot be precisely determined by means of computed tomography.
Department of Otorhinolaryngology, Goethe University, University Clinic, Frankfurt am Main, Germany. silke.helbig@kgu.de
Silke
S
Helbig
Martin
M
Mack
Boris
B
Schell
Hansjürgen
H
Bratzke
Timo
T
Stöver
Matthias
M
Helbig
D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D003430:Cross-Sectional Studies; D006801:Humans; D011859:Radiography; D012533:Scala Tympani / Q000000981:diagnostic imaging / Q000601:surgery*; D054738:Scala Vestibuli / Q000000981:diagnostic imaging / Q000601:surgery*; D013701:Temporal Bone / Q000000981:diagnostic imaging / Q000601:surgery*