Auditory-nerve integrity after middle-fossa acoustic-tumor removal

We sought to investigate the functional integrity of the auditory nerve in patients with postoperative hearing loss after middle cranial fossa acousti c-tumor removal in a case-series descriptive study. The study setting was a tertiary referral center, a private otologic practice. The study populatio n comprised seven patients who underwent a middle-cranial-fossa approach fo r unilateral acoustic-tumor resection and sustained postoperative anacusis with an anatomically intact auditory nerve. Four were men and three women; they ranged in age from 30 to 60 years; all underwent surgery between 1990 and 1994 and agreed to return to the center to participate in the study dur ing 1995, Diagnostic electrical promontory stimulation was used to determin e the functional integrity of the auditory nerve, Our main outcome measures were the presence or absence of discrete tone perception, electrical thres hold, maximum acceptable level and dynamic range, gap detection and tempora l difference limen during electrical promontory stimulation, Three of the s even patients demonstrated positive responses to electrical promontory test ing (e.g., discrete tone perception). All three were able to perform the ga p-detection and temporal difference limen tests. None of the preoperative c haracteristics was related to performance on promontory stimulation testing , We conclude that the middle cranial fossa approach permits anatomic-and, in some cases, functional auditory-nerve preservation. These data suggest t hat auditory rehabilitation in some patients who sustain anacusis after the middle cranial fossa approach to acoustic tumors, as in neurofibromatosis 2, may be provided with cochlear implantation.