Cochlear orientation: pre-operative evaluation and intra-operative significance

The study primarily aimed to calculate the orientation of the cochlea pre-operatively, using high-resolution computed tomography of the temporal bone, and predict the ease of electrode insertion.

Pre-operatively, high-resolution computed tomography scans were conducted on children scheduled for cochlear implantation, and two angles, α and β, were calculated. The values of α and β were then correlated with intra-operative difficulty in insertion of the electrode array.

Ninety-six children were included in the study. Of the seven patients who had an α angle of less than 50 degrees, the surgeon experienced difficulties in electrode insertion. However, there were four patients with an α angle of more than 50 degrees for whom the surgeon also experienced difficulties in electrode insertion. In all these patients, the β angle was more than 20 degrees.

Calculation of cochlear orientation and its angle with the surgical axis (α and β) can aid the planning of surgery, particularly with regard to the cochleostomy site and preservation of residual hearing.