Presentation and diagnosis of small acoustic tumors.

With the recent advent of magnetic resonance imaging and auditory brain stem response, it is now possible to diagnose acoustic tumors while they are still quite small. As a result, it is becoming obvious that the clinical presentation of these smaller lesions can be somewhat variant to what is considered typical for an acoustic neuroma. Likewise, although the sensitivity of auditory brain stem response for larger tumors is believed to be quite good, the sensitivity for smaller tumors has recently been questioned, particularly when the patient is first seen early in the course of the disease with only mild otologic complications. To assess auditory brain stem response results as well as clinical and audiologic presentations, we conducted a retrospective study of patients treated for small acoustic tumors (less than 1 cm). Of the 70 patients included in the study, auditory brain stem response was abnormal in 65 (93%), on the basis of wave V latency prolongation and interaural latency differences. This would indicate that auditory brain stem response is a valid screening test for acoustic tumors, even in early stages of development. The clinical presentation of patients with small acoustic tumors was similar to that reported for acoustic tumors in general, but with vertigo occurring more frequently in patients with smaller tumors. Several atypical patterns of hearing loss were also noted.