Far-field auditory brainstem 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 experience 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 preoperatively does offer some hope that hearing can be preserved postoperatively. Finally, postoperative hearing function is usually equal to or worse than the preoperative function. Only rarely does the postoperative function improve.