This study was performed to investigate the capability of preoperative evaluations in predicting the precise anatomic origin of intracanalicular tumors. We conducted a retrospective case review of 11 patients (8 male, 3 female; 26-70 yr of age) with intracanalicular tumors that were treated surgically. Data included preoperative pure tone audiogram, auditory brainstem response, caloric test, electroneurographies and temporal MRIs.
Postoperatively, facial nerve schwannomas were diagnosed pathologically in two of 11 patients (18%). There were no clues suggesting facial nerve schwannoma in preoperative evaluations: A facial nerve schwannoma may be misdiagnosed as a vestibular schwannoma, especially when the tumor is confined to the internal auditory canal. There are no useful preoperative evaluation tools to predict the precise nerve origins of intracanalicular tumors. These emphasize the need to fully inform the patient preoperatively.