Diagnostic procedure for acoustic neuroma

The authors' diagnostic procedure for unilateral acoustic neuroma and the reasoning behind it are explained. The actual methods involved will change with advances in methodology. At the present time, however, pure tone audiometry and simple radiographic imaging of the internal auditory canal (transorbital and Stenvers View) are first carried out. Then, if the hearing level (average hearing at 4 kHz and 8 kHz) is 70 dB or lower, auditory brain stem response audiometry is carried out. If it is 71 dB or higher, the patient is examined by MRI or CT. Contrast-enhanced CT is carried out when MRI is not available. Air CT is not necessary if MRI is available, but, in cases where hearing preservation is indicated, it may provide valuable information for identifying the tumor site within the internal auditory canal.