Diagnostic strategies in search for acoustic neuromas. Findings in 300 acoustic neuroma patients.

The diagnostic findings in 300 patients with acoustic neuromas are reported. Because of a centralized treatment of acoustic neuromas, we have a uniform work-up of all the patients, which enables us to make a non-selected comparison of the diagnostic efficiency of the various tests. Diagnostic dilemmas in patients with normal hearing, anakusis, normal auditory brainstem recordings, normal vestibular function and normal tomography of the internal acoustic meatus are discussed. In patients with hearing better than 80 dB, a normal ABR, the presence of recruitment and a normal caloric reaction can exclude the presence of a tumour, making tomography superfluous. In patients with poor hearing, the need for tomography is imperative. We perform CT if two procedures among the following produce tumour-positive results: ABR, recruitment tests, caloric test, and tomography. Those who have only one tumour-positive finding at the screening are re-examined after one year. If, even with contrast enhancement, CT proves negative, we continue to perform air CT. Only then do we know for sure whether the patient has a tumour or not. An advantage with using many tests for the same physiological function is that they complement each other, though, on the other hand this often adds to the confusion. With fewer tests, the confusion is reduced, but the requirements regarding technical quality must be very stringent. ABR, the Metz recruitment test and tomography are purely objective, while the caloric test is subjective on the part of the investigator. The Hallpike procedure, however, has stood the test of time in separating pathologic from normal.