Cochlear anatomy study used to design surgical instruments for cochlear implants with two bundles of electrodes in ossified cochleas.
Cochlear ossification, mainly secondary to meningitis, prevents the complete conventional cochlear implant insertion. Implants with two electrode bundles shorter than the conventional ones were specifically developed for ossified cochleas. However, during surgery there is a high risk of damaging the internal carotid artery (ICA). Therefore, measuring cochleostomy depth in order to insert the two electrode bundles would greatly increase the procedure's safety.


OBJECTIVE
1) Find the distances between cochleostomies and ICA in cadaver temporal bones. 2) Design an instrument that can be used in cochlear implant surgery to introduce an implant with two bundles of electrodes.


METHODS
Experimental prospective.


METHODS
In 21 temporal bones from cadavers we performed: 1) canal wall down mastoidectomy; 2) cochleostomy in the cochlear basal and middle turns; 3) ICA identification; 4) Length determination between the cochleostomies and the artery.


RESULTS
the average distance +/- standard deviation obtained for the upper tunnel was of 8.2 +/- 1.1 mm and for the lower tunnel it was of 8.1+/- 1.3 mm. The shortest distance found was of 6.5 mm for the upper tunnel and 6.0 mm for the lower tunnel.


CONCLUSIONS
Despite the values calculated, we concluded that the best value to be considered in creating a surgical instrument are the minimum lengths obtained for each one of the cochlear turns, because this is the safest way to avoid damaging the ICA, that can be fatal.
Mariana
M
Bogar
Ricardo Ferreira
RF
Bento
Robinson Koji
RK
Tsuji
D002102:Cadaver; D020212:Carotid Artery Injuries / Q000517:prevention & control*; D002343:Carotid Artery, Internal / Q000033:anatomy & histology*; D003051:Cochlea / Q000033:anatomy & histology / Q000601:surgery; D015834:Cochlear Diseases / Q000473:pathology* / Q000601:surgery; D003054:Cochlear Implants; D004566:Electrodes; D006801:Humans; D009999:Ossification, Heterotopic / Q000473:pathology* / Q000601:surgery; D011446:Prospective Studies; D011474:Prosthesis Design; D013701:Temporal Bone / Q000601:surgery