Ct air-contrast scanning of the internal auditory canal.

Two hundred and four patients with audiometric and vestibular findings suggestive of a retrocochlear lesion were studied prospectively by computed tomographic scan with air contrast of the internal auditory canal. With this technique tumor limits are clearly defined. In the absence of disease the internal auditory canal has been completely air-filled in over 97% of cases. Soft tissue masses occluding the internal auditory canal were demonstrated in 11 patients. Four studies were inconclusive and there was one false positive. Headaches have been the only side effect and there have been no complications. In reporting their results the authors examined the indications, accuracy and limitations of this technique. This study demonstrates that computed tomographic scan with air contrast of the internal auditory canal should be considered as the radiologic procedure of choice for the evaluation of small acoustic tumors.