SRS for Vestibular Schwannomas – Current Status

Abstract

Stereotactic radiosurgery (SRS) is an established modality of treatment for vestibular schwannomas (VS). We aim to summarize the evidence-based use of SRS in VSs and address the specific considerations pertaining to the same, along with our own clinical experiences. A thorough review of the literature was done to gather evidence regarding the safety and efficacy of SRS in VSs. Additionally, we have reviewed the senior author's experience in treating VSs (N = 294) between 2009 and 2021 and our experiences with microsurgery in post-SRS patients. Available scientific evidence upholds the role of SRS in VSs, in small-to-medium-sized tumors (5-year local tumor control >95%). The risk of adverse radiation effects remains minimal, while the hearing preservation rates are variable. Our center's post-GammaKnife VS follow-up cohort (sporadic – 157, neurofibromatosis-2 – 14) showed excellent tumor control rates at the last follow-up of 95.5% (sporadic) and 93.8% (neurofibromatosis-2), with a median margin dose of 13 Gy and mean follow-up periods of 3.6 (sporadic) and 5.2 (neurofibromatosis-2) years. Microsurgery in post-SRS VSs poses a formidable challenge due to the resulting thickened arachnoid and adhesions to critical neurovascular structures. Near-total excision is the key to better functional outcomes in such cases. SRS is here to stay as a trusted alternative in the management of VSs. Further studies are required to propose means of accurate prediction of hearing preservation rates and also to compare the relative efficacies of various SRS modalities.