Incidence for Tip Foldover During Cochlear Implantation.

Objective: Incidence and clinical presentation of tip foldover during cochlear implantation (CI).

Study Design: Retrospective case review.

Setting: Tertiary referral university hospital.

Patients: One thousand three hundred twenty CI recipients who underwent postoperative Stenvers view, digital computed tomography (CT), or digital volume tomography (DVT).

Main Outcome Measure: Tip foldover rates were evaluated with regard to perimodiolar (PM), lateral wall (LW), and mid-scalar (MS) electrode carriers; the electrode insertion angle was estimated and postoperative complications and the necessity for revisions were described.

Results: One thousand three hundred twenty CI recipients (1,722 ears) had detailed surgery reports and postoperative imaging available for review. Tip foldover occurred in 15 ears (0.87%) with the highest rate (1.67%) for PM electrodes. In three patients tip foldover was accompanied by costimulation of the facial nerve and one patient reported vertigo. Eleven patients underwent revision surgery. In two of them revision was performed in the same surgical intervention due to abnormality in spread of excitation measurement. In four patients no revision was conducted due to uncompromised aided speech perception.

Conclusion: In a large academic center with experienced surgeons, tip foldover verified by CT/DVT arose at a rate of 0.87%. PM electrode carriers inherited the highest risk for this electrode malposition. Revision surgery was feasible in these cases.