Minimizing Intracochlear Pressure: Influence of the Insertion Sheath.

OBJECTIVE: Atraumatic cochlear implantation (CI) and insertion of the electrode in particular are major goals of recent CI surgery. Perimodiolar electrode arrays need a stylet or exosheath for insertion. The sheath can influence the intracochlear pressure changes during insertion of the electrode. The aim of this study was to modify the insertion sheath to optimize intracochlear pressure changes. METHODS: In an artifical cochlear model, 7 different modified insertion sheaths were used. The intracochlear pressure was measured with a micro-optical sensor in the apical part of the model cochlea. RESULTS: Significant lower intracochlear pressure changes were observed when the apical part of the insertion sheath was either shortened or tapered. Modification of the stopper does influence the intracochlear pressure significantly. CONCLUSION: Modification of the insertion sheath leads to lower intracochlear pressure gain. The differences and impact on intracochlear pressure changes found in this study underline the importance of even subtle modifications of the electrode insertion technique.