The new mid-scala electrode array: a radiologic and histologic study in human temporal bones.
OBJECTIVE
To analyze the quality of insertion of the newly developed midscala (MS) electrode, which targets a midscalar electrode position to reduce the risk of trauma to the lateral wall and the modiolus.


BACKGROUND
Modern cochlear implant surgery aims for a safe intracochlear placement of electrode arrays with an ongoing debate regarding cochleostomy or round window (RW) insertion and the use of lateral wall or perimodiolar electrode placement. Intracochlear trauma after insertion of different electrodes depends on insertion mode and electrode design and may result in trauma to the delicate structures of the cochlear.


METHODS
We performed a temporal bone (TB) trial with insertion of the MS electrode in n = 20 TB's after a mastoidectomy and posterior tympanotomy. Insertion was performed either via the RW or a cochleostomy. Electrode positioning, length of insertion, and angle of insertion were analyzed with rotational tomography (RT). TBs were histologically analyzed. Results of RT and histology were compared.


RESULTS
Scala tympani (ST) insertion could be accomplished reliably by both RW and via a cochleostomy approach. In 20 TBs, 1 scala vestibuli insertion, 1 incomplete (ST), and 1 elevation of basilar membrane were depicted. No trauma was found in 94.7% of all ST insertions. RT allowed determination of the intracochlear electrode position, which was specified by histologic sectioning.


CONCLUSIONS
The new MS electrode seems to fulfill reliable atraumatic intracochlear placement via RW and cochleostomy approaches. RT is available for evaluation of intracochlear electrode position, serving as a potential quality control instrument in human implantation.
*Department of Otorhinolaryngology-Head and Neck Surgery, †Department of Radiology, and ‡Institute of Musicians' Medicine, Freiburg University Medical Center, Freiburg, Germany.
Frederike
F
Hassepass
Stefan
S
Bulla
Wolfgang
W
Maier
Roland
R
Laszig
Susan
S
Arndt
Rainer
R
Beck
Lousia
L
Traser
Antje
A
Aschendorff
D002102:Cadaver; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D006801:Humans; D012405:Round Window, Ear / Q000601:surgery*; D012533:Scala Tympani / Q000601:surgery*; D013701:Temporal Bone / Q000601:surgery*; D014057:Tomography, X-Ray Computed