Surgical Resection of Acoustic Neuromas: Comparison of Hearing and Facial Nerve Outcomes between Primary and Redo Operations

Introduction: The outcomes of patients with acoustic neuromas who underwent a first-time surgical or radiosurgery procedure are well documented in the existing literature. It is currently not well known how the outcomes of these patients compare with those who have microsurgical resection of these tumors after a primary failed first debulking or fractionated or nonfractionated stereotactic radiosurgery. The objective of this study is to show this comparison of outcomes, focusing on differences in functional hearing, and facial nerve preservation rates.

Methods: The demographic, surgical, and outcomes data for a retrospective consecutive series of 139 patients with acoustic neuromas who underwent a microsurgical procedure between 2000 and 2014 were reviewed. A total of 120 patients underwent a first-time surgical resection or debulking of the tumor; 19 patients had previously had surgery or radiosurgery and presented with regrowth of the tumor.

Results: Of the 19 patients who had redo surgeries, 9 were males and 10 were females, the average age was 54 years (range, 29.1–79.0 years), and 4 of the 19 (21.1%) had neurofibromatosis type II. There were a total of 29 prior surgeries: 11 were stereotactic radiosurgeries and 12 were open surgeries. Overall, 7 operations were via retrosigmoid approach, 10 via translabyrinthine, and 2 through a combined retrosigmoid and translabyrinthine approach. Overall, 6 patients had KOOS grade 1 or grade 2 tumors (31.6%) and 13 had KOOS grade 3 or grade 4 tumors (68.4%).

Of the 120 patients undergoing first-time surgery, 45 were males and 75 were females. The average age was 49 years (range, 9.5–80.3 years), and 7 patients (5.8%) had neurofibromatosis type II. Overall, 18 patients underwent a middle fossa approach, 40 retrosigmoid, 59 translabyrinthine, and 3 patients had a combined approach. KOOS grade 1 or grade 2 tumors were present in 57 of 120 patients (47.5%) and grade 3 or grade 4 tumors in 63 of 120 patients (52.5%).

In the redo cohort, 14 of 19 patients (73.7%) had House-Brackmann scores of 1, 2, or 3 preoperatively compared with 16 of 19 (84.2%) postoperatively. Nine patients (47.4%) had a preoperative Gardner-Robertson score of 1 or 2 compared with 4 of 19 (21.1%) postoperatively. In the first-time surgery cohort, 112/ of 120 patients (93.3%) had a House-Brackmann score of 1, 2, or 3 preoperatively compared with 101 of 120 (84.2%) postoperatively, and 61 of 120 (50.8%) had a Gardner-Robertson score or 1 or 2 preoperatively compared with 51 of 120 (42.5%) postoperatively.

Of the 15 patients, 2 (13.3%) patients in the redo cohort experienced resolution of imbalance postoperatively, 5 of 5 (100%) experienced resolution of dizziness, and 7 of 8 (87.5%) experienced resolution of tinnitus. In the first-time surgery cohort, 25 of 87 (28.7%) experienced resolution of imbalance, 29 of 57 (50.9%) resolution of dizziness, and 57 of 80 (71.3%) resolution of tinnitus. The average length of follow-up was 17.4 months.

Conclusion: Comparisons of objective measurements of hearing and facial nerve function and the resolution of key symptoms of imbalance, dizziness, and tinnitus show that in our cohorts, redo operations following failed radiosurgery or open surgery resulted in fewer instances of improvement. Further research with a larger population is needed to clarify what types of expectations are realistic for improvement in reoperations for acoustic neuromas.