Significance of High Resolution CT Scan in Otosclerosis

Objectives: Computed tomographic (CT) scanning with slices of more than 1mm has not been sufficient to demonstrate otosclerotic foci in most cases to date. Methods: We investigated the validity of CT scans with a 0.75-1mm cubical scan technique, with and without planar reconstruction, and correlated these findings with audiologicai data and to determine its usefulness to predict hearing deterioration and surgical difficulties. Fifty one CT scans from 29 patients with conductive or mixed hearing loss were evaluated. Results: Otosclerotic foci were visualized in 68.9% of the cases. Whereas in fenestral otosclerosis a correlation was found between the size of the focus and the airbone gap, no correlation was seen between the size of the focus and bone conduction thresholds with cochlear involvement. Among 31 operative ears, 19 were classified as positive for otosclerosis and this was confirmed during surgery, 7 were classified as negative for otosclerosis and during surgery, 3 of them (42.8%) proved to be cases of otosclerosis and they were could infra-radiologic cases. The remaining 5 cases were doubtful according to preoperative CT scans. Four of them (80%) were found to have otosclerotic foci during surgery. Conclusions: High-resolution CT scans are a valid tool that can be used to confirm, localize, and determine the size of clinically suspected otosclerotic foci. Doubtful and negative preoperative cases should alert surgeons to the possibility of intraoperative complications and possibility of postoperative sensorineural hearing loss.