This is a review of our experience using far-field auditory brainstem
monitoring during acoustic neuroma removal. The observations are based
on 144 consecutive cases beginning in 1986. The factors of importance
are tumor size, preoperative auditory function, and the preoperative
presence of a wave V on the auditory brainstem response. Our experienc
e suggests that preservation of hearing in tumors >2.5 cm is rare. It
was observed that preserving wave V does not guarantee preservation of
hearing. Conversely, loss of wave V does not preclude preservation of
hearing. It has also been noted that the presence of only wave I preo
peratively does offer some hope that hearing can be preserved postoper
atively. Finally, postoperative hearing function is usually equal to o
r worse than the preoperative function. Only rarely does the postopera
tive function improve.