Recurrence after incompletely resected acousticus neurinomas.

It is known that the recurrence rate is high when an acoustic neurinoma is incompletely excised, but the details of the process of recurrence are still unclear. We reviewed the recurrence of acoustic neurinomas, as evaluated by computed tomography (CT) or magnetic resonance imaging (MRI), in 51 consecutive patients over the past 10 years who underwent tumor resection and had postoperative follow-up by CT or MRI. The factors promoting recurrence related to incomplete excision of tumor were analyzed. Total resection of the tumor was performed in 22 patients (43%), nearly total resection in 17 patients (33%) and subtotal resection in 12 patients (24%). The recurrence rates were 29% (5 of 17 patients) and 25% (2 of 8 patients) for nearly total and subtotal resection, respectively, whereas no recurrence occurred following total resection. Of the patients having nearly total resection, all recurrences arose from residual tumor in the internal auditory meatus (5 of 12 patients). In contrast, there were no recurrences from residual tumor at the site of the brain stem (none of 4 patients). Acoustic neurinomas should be totally removed through neurosurgical and neuro-otological approaches whenever possible. If a small fragment of tumor is left in the internal auditory meatus due to fear of damaging the facial or cochlear nerves, it should be strictly followed up by CT or MRI.