Large or Giant Vestibular Schwannomas: Analysis of Factors Affecting Postoperative Facial Function

Objective: Surgical removal is the principle to treat vestibular schwannoma more than 3 cm in diameter. Personal series were retrospectively analyzed to define affecting factors.

Methods: There were 67 cases of large or giant tumor (more than 3 cm in the CP angle cistern) in the personal consecutive 174 cases with unilateral vestibular schwannoma operated as an initial treatment. The retrosigmoid approach was used and microsurgical complete tumor removal was intended while trying to preserve nerve function. Microsurgical total removal could be achieved in 57 cases. In 10 cases, the removal was nearly total and was subtotal in 4 cases in order to preserve nerve function.

Results: Good facial function (H-B 1 or 2) was obtained in 85.1% at the follow-up period. There was significant difference in the result between tumors smaller than 4 cm and larger than 4 cm, 94.6% and 73.3%, respectively. We introduced an advanced facial nerve monitoring system (NIM) in 2000. After the introduction of NIM, the number of Grade 1 cases increased significantly. There was no significant difference between the total removal group and the nearly total removal group. One patient of the nearly total group showed radiological tumor recurrence in 7 years and one patient of the subtotal group should be reoperated in 10 years due to regrowth of the tumor.

Conclusion: Size of a tumor, accumulation of surgical experience, and progress of monitoring were large factors for postoperative facial nerve function preservation. Surgeons should try to do their best to remove tumor completely with functional preservation.