Difficult round window access during cochlear implantation: a simple prediction method utilising pre-operative CT...

Difficulty visualising the round window is occasionally encountered during cochlear implant surgery. This paper presents a novel method for predicting difficult round window accessibility using pre-operative computed tomography (CT) imaging.

This is a retrospective multicentre study of all cochlear implantation surgical procedures conducted in two Singaporean tertiary hospitals between 2018 and 2021. Pre-operative CT temporal bone scans were reviewed and two lines were drawn on a single axial cut. Where both lines intersect medially, difficult round window visualisation is predicted. Computed tomography predictions were compared with intra-operative findings, and statistical analysis was performed.

In 9 of 89 cases (10.1 per cent) difficult round window access was noted intra-operatively and 8 cases (88.9 per cent) were correctly predicted by the novel method (p < 0.001; sensitivity, 89 per cent; specificity, 100 per cent).

This study describes a simple, effective method to predict difficult round window access on axial CT temporal bone images, without reconstructed images or complex calculations.