Early diagnosis of small acoustic tumors.

This paper is reported about the otoneurological findings and the neuroradiological results containing air or metrizamide CT cisternograpy in the six patients with acoustic tumors less than 1.5cm in size located within the internal auditory canal (intracanal type) or projecting into the cerebellopontine cisterna (cisternal type).1. The six patients had asymmetric neurosensory type hearing impairment and more recruitment phenomena than signs of retrocochlear lesions on the basis of false negative results in this research. Therefore, the ABR test should be used only a screening test.2. The three patients were tested by electronystagmography and their response to the bilateral caloric test was normal.3. Petrous tomograms revealed an enlargement of the internal auditory canal in only three of these patients. Conventional CT scans gave false negative results in five patients. A new radiological technique, air or metrizamide CT cisternography, revealed small acoustic tumors in all six patients. These were confirmed at surgery.