A modified screening protocol for the diagnosis of acoustic neuromas.

In many centres the diagnosis of acoustic neuromas relies on a preliminary screening protocol. The current method is a combination of caloric tests, tomography of the internal auditory meati and brain stem evoked response audiometry (BSERA) with 2 positive results indicating the need for further investigation. This protocol, although sensitive lacks specificity and results in a high incidence of normal CT air meatograms. As this procedure is associated with a significant morbidity, we have devised a 'weighted' system of scoring to avoid subjecting large numbers of normal patients to CT air meatography. The proposed system has been derived from screening 61 patients with unilateral sensorineural hearing loss, 24 of whom had an acoustic neuroma. This method reduced the false positive rate of CT air meatography from 68%, using the 2 out of 3 criteria, to 18%, whilst the false negative incidence remained at 8%.