FAR-FIELD AUDITORY BRAIN-STEM RESPONSE IN NEUROTOLOGIC SURGERY

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.