Impact of electrode insertion depth on intracochlear trauma.
OBJECTIVE
To assess the effect of cochlear implant (CI) insertion depth and surgical technique on intracochlear trauma.


METHODS
Twenty-one fresh human temporal bones were implanted with CI electrodes and underwent histologic processing and evaluation. Specimens were grouped into 3 categories: 1) soft implantation technique and standard electrode; 2) soft implantation technique and flexible prototype array; 3) forceful implantations and standard electrode. Based on the grading system (1 to 4), 2 numeric values were calculated indicating the overall severity of cochlear damage (trauma indices).


RESULTS
Mean trauma index values were 13.8, 36.3, and 59.2 for group 1, 2, and 3, respectively. Differences in cochlear trauma (trauma index) were nonsignificant between specimens in groups 1 and 2 but were significant between groups 1 and 3.


CONCLUSIONS
This study gives evidence that intracochlear trauma increases with deep insertions. Thus, in cases where cochlear integrity might be important, limited insertions should be achieved.
Adunka
Oliver
O
Department of Otolaryngology, Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7070, USA. oadunka@mac.com
Kiefer
Jan
J
D000497:Alloys / Q000737:chemistry; D001489:Basilar Membrane / Q000293:injuries / Q000473:pathology; D002102:Cadaver; D003051:Cochlea / Q000293:injuries*; D003053:Cochlear Duct / Q000293:injuries / Q000473:pathology; D019929:Cochlear Implantation / Q000009:adverse effects / Q000379:methods*; D003054:Cochlear Implants / Q000009:adverse effects; D006801:Humans; D007431:Intraoperative Complications; D007495:Iridium / Q000737:chemistry; D010984:Platinum / Q000737:chemistry; D018583:Pliability; D011474:Prosthesis Design; D012533:Scala Tympani / Q000293:injuries / Q000473:pathology; D012825:Silicon / Q000737:chemistry; D013137:Spiral Lamina / Q000293:injuries / Q000473:pathology; D013314:Stress, Mechanical; D013499:Surface Properties; D013701:Temporal Bone / Q000601:surgery
D000497:Alloys; D007495:Iridium; D010984:Platinum; D012825:Silicon