Epidemiological and evolutionary study of vestibular schwannomas after different types of treatment

Resumo

Over the last couple of decades, the increased availability of magnetic resonance imaging dramatically influenced to the therapeutic approach of vestibular schwannomas (VSs). However, there are few reports about the course of VS patients following conservative management (CM) compared with gamma knife radiosurgery (GKR). In the current study, we present data of 106 unilateral and one bilateral (due to NF2) VS patient controlled CM (67), GKRS (27) and conventional neurosurgery (13). Objectives The main aim of our study was to compare CM and/or the natural course of VS growth with the effects following GKR along with additional treatment and symptom development during the follow-up. We also aimed to evaluate the utility of diagnostic tests and efficiency of CM in case of small VSs. Methods We performed a retrospective follow-up study based on medical records, clinical and instrumental test data of VS. Statistics of collected data were performed by using Pearson and Spearman correlation coefficient, Kaplan-Meier plot and repeated measures linear regression models. In order to avoid noncompliance and missing outcomes we also used intention-to-treat analysis where possible. Results Mean follow-up time was 56.52 ±10.79 (range 25.02-71.74) months. The hearing loss (68 (64.1%)) and tinnitus (24 (22, 1%)) was the most common primary symptoms of VS. We found significant relationship between localization and initial symptoms of VS p=0.01(Spearman). 21 (31,34%) patients changed their (CM or GKR) treatment options. The statistical difference in tumor size between the initial and last time points in CM group was not significant (p=0,52), while in GKR group was baseline significant (p=0.05) (A Repeated Measures ANOVA). The hearing loss was significant in both groups, but GKR group showed more pronounced and significant hearing loss (p= 0.000) than CM (p<0.001) group (A Repeated Measures ANOVA). The GKR group showed dramatic changes in audiometric configuration towards lower frequencies over the follow-up years p<0.0001(t-test). Symptom development did not differ significantly between the groups. Conclusions The GKR reduces the tumor growth rate, but it makes the hearing deterioration more prominent. In patients with small VS, the CM is a correct therapeutic approach which does not worsen the medium-term prognosis. We consider the conservative approach as a ¿screening tool¿ for VS in the early stages of VS management.