A comparative study of special petrous views and tomography in the diagnosis of acoustic neuromas

A review is presented of the value of special petrous views and tomography in 56 patients with acoustic neuromas. Ninety-two per cent of these patients showed abnormality of the petrous bones. Tomography was found to be only slightly more productive than special plain film views of the petrous pyramids in terms of positive diagnosis, and it gave rise to an increased incidence of false positives. For this reason, and to reduce unnecessary exposure, it is recommended that tomography of the internal auditory canals should be considered only after a careful study of adequate plain radiographs, which may themselves be diagnostic. In 73 per cent of the patients in this series the diagnosis could be made with a single slit perorbital projection.