CLINICAL PRESENTATION AND DIAGNOSIS OF SMALL ACOUSTIC NEUROMAS

With the invention of magnetic resonance imaging (MRI) and the auditory evoked brain stem responses (AEBR), it has become possible to diagnose acoustic tumours while they are still small. As a result, it has become obvious that the clinical presentation of smaller lesions can be somewhat different from what is considered typical of an acoustic neuroma. Likewise, whereas the sensitivity of auditory brain stem responses for larger tumours is good, the sensitivity for smaller tumours has recently been in doubt, particularly if the patient presents early in the course of the disease with only mild otologic complaints. A retrospective study of patients treated for small acoustic neuromas, defined as less than 1 cm extension into the cerebellopontine angle, was conducted to assess ABR results as well as the clinical and audiological presentation in these patients. Of the 70 patients included in the study, auditory brain stem responses were abnormal in 65 (93 %), based on wave V latency prolongation and intra-aural latency differences. These would indicate that auditory brain stem responses are a valid screening test for acoustic neuromas, even in the early stages of development. The clinical presentation of patients with small acoustic tumours was similar to the presentation reported for acoustic neuromas in general, but with vertigo occurring more often in patients with smaller tumours. Several atypical patterns of hearing loss were seen in this population.