Conservative Management of Vestibular Schwannoma: Results and Suggestions after 20 Years of Experience

Introduction: There was a time when almost every vestibular schwannoma (VS) was surgically treated. Approximately 20 years ago, we started to adopt a conservative management in some cases of small intracanalicular tumors affecting elderly people. In this period, the development of neuroradiological techniques, combined with a greater awareness of its usefulness among physicians, caused an increase in the clinical incidence of VS. Small and medium tumors are today more frequently detected. The collective experience and reports from the literature seem to support the concept that conservative management of VS may sometimes be preferred to surgery or radiotherapy, even considering the increasing importance attributed to the quality of life of patients. We report an update of our experience with the conservative management of patients with VS.

Methods: Among 514 consecutive patients affected by unilateral VS, 147 (28.6%) were primarily observed. The study group consisted of 142 subjects (1 elderly patient presenting with non-NF2 bilateral VS).Patients with cystic tumors and patients without second scans were excluded). Reasons for observation included tumor size, age, general condition, symptoms, hearing function, and the preference of the patient. Each patient was examined by means of gadolinium-enhanced MRI scans, and tumor size was defined as the maximum diameter in the 3 axes of projection. The second scan was performed 6 months after the first one, and further scans were scheduled at 1-year intervals in case no significant (<2 mm) growth was recorded. The average size of VS was 10.8 mm (range, 2–28 mm) and the mean follow-up period was 5.1 years (range, 6–207 months). Hearing function was also evaluated during the observation period.

Results: During the entire follow-up period, no evidence of growth was recorded in 89 of 143 cases (62.2%), whereas 54 of 143 tumors (37.8%) grew. The incidence of tumor shrinkage was 4.2%(6 of 143 cases). Within the group of growing tumors, 19 out of 54 subjects were surgically treated and all of them had no complications and normal facial nerve function. Sixty-six (46.4%) out of 142 patients had useful hearing (classes A and B of the AAO-HNS classification) at diagnosis, and only 18 of them (27.2%) lost it during the observation period. These data were not influenced by the growth pattern of the tumors, and the results are better than those generally reported in surgical series aiming at the preservation of hearing.

Discussion: The results of our 20 years of experience of conservative management of VS indicate that the “wait and scan” policy is a safe and effective strategy. In fact, most of the tumors do not grow; in case of tumor growth, surgical outcomes are not negatively influenced by delaying the procedure. Moreover, the results regarding useful hearing preservation are far better than with primary surgery. Regular and periodic neuroradiological examinations are needed because of the irregular and unforeseeable behavior of the tumor.