Optimal cochlear implant insertion vectors.
OBJECTIVE
An optimal insertion trajectory during cochlear implantation may be determined from the anatomic relationship between the facial nerve and round window.


BACKGROUND
Cochlear implantation functional outcomes improve with insertion of the implant into the scala tympani. This depends on creating a cochleostomy in the proper position and inserting the electrode along a trajectory coaxial with the centerline of the scala tympani. The anatomic landmarks for this insertion trajectory have not been described.


METHODS
Clinical computed tomography and micro-computed tomographic analysis of 8 cadaveric temporal bones.


RESULTS
Appropriate insertion vectors pass inferior or anteroinferior to the round window membrane. In many individuals, the facial nerve interrupts all or most of the insertion vectors coaxial to the centerline of the scala tympani.


CONCLUSIONS
A cochleostomy placed inferior or anteroinferior to the round window membrane may facilitate atraumatic insertion of a cochlear implant along the centerline of the scala tympani. The lateral and anterior wall of the fallopian canal must be adequately thinned to achieve an optimal insertion trajectory. This is particularly true when inserting through cochleostomies placed away from the round window along the basal turn of the cochlea.
Meshik
Xenia
X
Department of Otolaryngology-Head and Neck Surgery, Washington University in St. Louis, St. Louis, Missouri, USA.
Holden
Timothy A
TA
Chole
Richard A
RA
Hullar
Timothy E
TE
D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D003638:Deafness / Q000601:surgery; D005154:Facial Nerve / Q000033:anatomy & histology* / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008953:Models, Anatomic; D012405:Round Window, Ear / Q000033:anatomy & histology* / Q000601:surgery
Otol Neurotol. 2005 Mar;26(2):188-95
15793403
Scand Audiol Suppl. 1979 Mar;11:157-70
299183
Cochlear Implants Int. 2007 Mar;8(1):1-11
17479968
Laryngorhinootologie. 2004 Dec;83(12):840-4
15611904
Otol Neurotol. 2007 Aug;28(5):641-8
17667773
Hear Res. 2005 May;203(1-2):68-79
15855031
Ann Otol Rhinol Laryngol. 1993 Dec;102(12):909-16
8285510
Laryngoscope. 2005 May;115(5):796-802
15867642
Laryngoscope. 2001 Oct;111(10):1828-33
11801953
Otol Neurotol. 2008 Oct;29(7):920-8
18667935
HNO. 1993 Jul;41(7):356-9
8376183
Otolaryngol Head Neck Surg. 2006 Sep;135(3):374-82
16949967
Laryngoscope. 2007 Dec;117(12):2187-94
17921902
Acta Otolaryngol. 2005 Aug;125(8):870-6
16158535
Am J Otol. 1988 Jan;9(1):8-13
3364540
Laryngoscope. 2007 Dec;117(12):2195-200
17909447
J Speech Lang Hear Res. 2005 Aug;48(4):853-67
16378478
Ann Otol Rhinol Laryngol. 1991 Sep;100(9 Pt 1):695-9
1952658
Adv Otorhinolaryngol. 2000;57:127-30
11892125
Ear Hear. 2007 Apr;28(2 Suppl):75S-79S
17496653
J Digit Imaging. 2008 Sep;21(3):323-8
17574499
Arch Otolaryngol Head Neck Surg. 2005 Dec;131(12):1049-54
16365217
Hear Res. 2005 May;203(1-2):54-67
15855030
Otolaryngol Head Neck Surg. 2008 Jan;138(1):8-12
18164986
Acta Otolaryngol. 2007 Jan;127(1):41-8
17364328
Audiol Neurootol. 2006;11 Suppl 1:42-8
17063010
Acta Otolaryngol. 2004 May;124(4):348-52
15224851
Audiol Neurootol. 2006;11 Suppl 1:34-41
17063009
ORL J Otorhinolaryngol Relat Spec. 2004;66(6):306-12
15668529
Ear Hear. 2002 Jun;23(3):207-23
12072613
J Speech Lang Hear Res. 2007 Aug;50(4):1048-62
17675604
Laryngoscope. 2007 Aug;117(8):1397-402
17585282
J Laryngol Otol. 2008 Mar;122(3):246-52
17666134