Update on Conservative Management of Vestibular Schwannoma—The Manchester Experience

Purpose: Gadolinium MRI has made it possible to detect vestibular schwannoma (VS) as small as 2 mm. Such early detection has led to wait and rescan as one of the treatment options. Radiological surveillance hinges on the assumption that the majority of the VS do not grow. This study aims to ascertain the natural history of VS managed conservatively by means of serial imaging.

Methods: Between 1977 and 2006, 492 VS were managed conservatively at the Department of Otolaryngology of The University of Manchester in UK. The outcome of these patients was analyzed using a prospective database and additional information obtained retrospectively by case notes review, to determine the growth rate and success of conservative management. Maximum tumor size was used to measure tumor size. The tumor growth rate was derived by noting the difference in tumor size between the initial scan and the latest follow-up scan and dividing the difference by the duration between the scans. The relationship between age, initial tumor size, and growth rate were analyzed using the Pearman correlation. The Mann-Whittney test was used to compare the growth rate in non-neurofibromatosis type 2 (non-NF2) and NF2 groups.

Results: One third of the tumors were part of NF2. Mean follow-up was 3.6 years (range, 1 to 14 yrs). Thirty percent of the tumors showed radiological evidence of growth. Twenty-three percent of the tumors required microsurgery, of which the majority was due to increasing growth and the remainder due to increasing symptoms and patient preference. Two tumors regressed in size and a further 2 resolved completely on subsequent imaging. Eighteen opted for radiotherapy, 8 died due to unrelated causes, 17 were discharged, and 68% showed no change in size. There was a statistically significant correlation between initial tumor size and growth rate in patients without NF2; however, the correlation was insignificant in the group with NF2. The mean growth rate and tumor size at referral was significantly higher in the NF2 group compared with the non-NF2 patients. About three quarters of the tumors selected for conservative treatment required no further intervention.

Conclusion: Conservative management is a desirable alternative in a selected group of patients. VS in patients with NF2 requiring surgery behave more aggressively than the non-NF2 patients.