Surgical Management of Patients with a Vestibular Schwannoma

Introduction: The aim of this study was to review some of the results of the microsurgical management of patients with a vestibular schwannoma. Material and Methods: Data were, partly retrospectively and partly prospectively, collected from all patients operated upon within the period 1982 to 2003; 328 tumors in 317 patients were included. There were 180 female and 137 male patients. Mean age was 49 years (range: 10–86 years). One hundred seventy-nine tumors were right sided and 149 were left sided. There were 12 tumors in 10 NF 2 patients. Tumor sizes were as follows: 93 (28%) small, 137 (42%) medium, and 98 (30%) large. The retrosigmoid approach was used in all but 3 tumors (translabyrinthine). Tumor removal was total in 209 (64%), near-total in 45 (14%), subtotal in 30 (9%), and partial in 44 (13%) patients. MRI follow-up, including a postoperative scan after 3 months, was available in 188 patients. The follow-up regarding facial nerve outcome was at least 1 year. The House-Brackmann classification (1985) was used. Hearing preservation was attempted only in patients with small tumors and class A or B hearing (AAO-HNS classification, 1995). Results: The proportions of small, medium, and large tumors did not change much over the years in spite of the introduction of MRI in the early years and a policy of more observation and radiosurgery in later years. Overall facial nerve outcome (N = 298) was grade I 75%, grade II 6%, grade III 9%, grade IV 2%, grade V 1%, and grade VI 7%. When two periods were compared, 1986 to 1994 and 1995 to 2002, grade I or grade II outcome improved from 72% to 89%. This could be attributed to the policy of more near-total and subtotal tumor removals in the second period. Hearing preservation (class A or B) was achieved in 50% of 36 small tumors. However, after a mean follow-up period of 5 years and 9 months (range: 6 months – 15 years) hearing preservation was only 36%. The three-month postoperative MRI of 63 total removals showed no nodular enhancement in 46 and small nodular or point-like enhancement in 17 patients. In 27 near-total removals the postop MRI showed no nodular enhancement in 13 and small nodular enhancement in 14 patients. The MRI in 22 subtotal removals showed a nodular enhancement in 20 and no enhancement in 2 patients. The MRI scans of 116 total removals after a mean follow-up of 6 years and 9 months showed a recurrence in 4 (4%) patients and stable nodular enhancement in 14 (12%) patients. The MRI follow-up of 34 near-total removals after a mean of 5 years and 6 months showed a regrowth in 3 (9%), a stable remnant in 11, no nodular enhancement in 16, and regression in 4 patients. The MRI of 20 subtotal removals showed at a mean follow-up of 4 years and 5 months regrowth in 2 (10%), a stable remnant in 16, no nodular enhancement in 1, and regression in 1 patient(s). Of 18 partial removals the remnant tumor had grown in 6, remained stable in 11, and regressed in 1 patient(s). This makes up a total of 15 (8%) MRI-documented true and false recurrences in 188 patients. Patients with remnant or recurrent tumors were treated by observation, microsurgery, or radiosurgery. In general, the MRI findings included: cerebellar atrophy, arachnoid cysts; linear, triangular and nodular enhancement; loss of signal in the inner ear structures; enhancement of inner ear structures; and occlusion of the sigmoid sinus (3). Conclusions: We conclude that the preservation of facial nerve function should have a higher priority than radical tumor removal. Many remnants after near-total or subtotal removal do not grow within a long follow-up period. If they do, they can be treated by radiosurgery. In the management of patients with a small- or medium-sized vestibular schwannoma our policy has gradually changed toward observation and stereotactic radiotherapy or radiosurgery.