[Navigation-controlled cochleostomy. Is an improvement in the quality of results for cochlear implant surgery possible?].

BACKGROUND

The correct positioning of the electrode, which is the limiting factor for the functional integrity of cochlear implants, is decisively influenced by the cochleostomy. Localisation and form of the drilling canal have been solely defined by the surgeon during the operation and an enlargement of the drilling canal is often necessary. Thanks to the improved resolution of new slice imaging techniques, computed tomography allows an exactly defined optimal point for cochleostomy.

MATERIAL AND METHODS

In a cadaver study, we examined whether the target defined with computed tomography can be reached in a reproducible way with the help of navigated computer assisted surgery. We chose titanium screw markers as the gold standard for referencing.

RESULTS

There was a real deviation of 1.6 mm in the target field. Thus, in a cochleostomy with a diameter of 0.5 mm the goal was not reached in a reproducible way. With this deviation a target of 2.56 mm(2) is defined.

CONCLUSIONS

A target assessed by navigation is better than one reached without navigation in view of reproducibility and accuracy. With further technical progress navigated cochleostomy will be possible.