| Popis: |
The diagnostic value of routine clinical tests for predicting the presence of an acoustic neuroma (AN) was assessed retrospectively in a group of 391 patients having magnetic resonance imaging (MRI) scans because of a suspected retrolabyrinthine lesion. An AN was found by MRI only in 9% of these patients. The positive predictive value of unilateral sensorineural hearing loss in a pure-tone audiogram (PTA) and unilaterally impaired caloric response was 9% and 12%, respectively. In contrast, AN was found in 36% of patients with pathological brainstem evoked response audiometry (BE-RA). A normal PTA or normal caloric response did not exclude the presence of AN (specificity 90% and 71%, respectively). A normal BERA was found in less than 5% of the patients with AN. According to these results, the following guidelines should be followed for the diagnosis of AN: (1) patients with a high suspicion for AN from history, PTA and caloric responses should be sent directly for MRI; (2) patients with low suspicion for AN from screening tests should have BERA performed to exclude a retrolabyrinthine lesion. |
