Modern diagnostic strategy for acoustic neuromas.

Abstract

We have reviewed the most recent 120 cases of acoustic neuromas operated upon in Bordeaux, France. In so doing, we have defined the strategy required to reach an accurate diagnosis as essentially comprising three stages. The first of these is to understand that the presenting symptom complex may be typical with progressive unilateral hearing loss, tinnitus, etc., or atypical with sudden hearing loss (10%), recovering facial paralysis (3.3%) or a Menière's syndrome (3.3%). Included in the first stage of diagnosis are audiovestibular investigations. An absent stapedial reflex was noted in 41% of our cases and an abnormality in vestibular testing in 95% of cases tested. These findings would be clear indicators to proceed to the second stage of the diagnostic strategy. This second stage comprises electric response audiometry consisting of auditory brainstem response (ABR) testing and electrocochleography (ECochG) employed as a filter for determining which patients should proceed to the third stage of testing. A combination of ABR and ECochG provides the clinician with results of high sensitivity and specificity. The false-negative rate for combined results in our experience has been less than 1%. The final diagnostic stage is radiological imaging, in particular using magnetic resonance imaging (MRI) with gadolinium contrast as the modality of choice. MRI is superior to CAT scanning, especially in the diagnosis of stage I intracanalicular tumors.