CPA tumors with normal routine audiometry and positive reflex and BSER tests.

Recently, in a ten-day-period, three patients whose hearing was within normal limits with good speech discrimination were found to have large cerebellopontine angle tumors. There were neurologic symptoms in only one patient. In these three cases, stapedius reflexes were absent with the affected ear stimulated. Brain stem evoked responses (BSER) were clearly abnormal in the three cases. Postoperative brain stem testing showed essentially no change in the nonoperated ear owing to brain stem manipulation. In two cases hearing was preserved. In one patient, the brain stem recordings returned to near-normal after surgery. In another, brain stem responses remained the same and the stapedius reflexes returned to normal. It appears that stapedius reflex testing and the BSER are highly useful tools that can be used to diagnose an acoustic neuroma before it grossly affects hearing.