The efficacy of stereotactic radiosurgery in the management of Vestibular Schwannomas – a retrospective analysis

Abstract

Vestibular Schwannomas (VS) are benign tumours arising from the neural sheath of the vestibular nerve, located near the auditory canal and cerebello-pontine angle adjacent to the brainstem making tumours "malignant by position". With high complication rates following surgery for tumour resection it is essential that alternative yet comparable management options such as Stereotactic Radiosurgery (SRS) be more fully evaluated in order to attain its efficacy and provide patients with alternative treatment modalities.The aim of this study was to critically evaluate the treatment outcomes of patients treated with SRS for Vestibular Schwannomas at the Cromwell Hospital's Gamma Knife Centre between 1998 and 2002. To facilitate this, information regarding patient's clinical history and SRS treatment parameters was collated and analysed via departmental on-line systems.In total the study provided a representative sample size of 74 patients with follow up data ranging from 6 months to 4 years post SRS (with a median of 12 months).At the maximum point of follow up attained by each patient 43% had an overall smaller tumour volume than at the time of treatment whilst 18% demonstrated a volume increase and 39% remained unchanged. In total 67% demonstrated evidence of decreased central tumour contrast enhancement (necrosis). 27% of patients suffered some form of immediate complication post SRS, all of which had resolved within 6 months. No correlation was found between the severity of the complication, prescription dose and tumour volume.Results are comparable with those from other published series highlighting a positive response from the tumour (decrease in volume) with few immediate complications, largely unchanged severity of symptoms post SRS and no negative impact on the patients quality of life. Although a number of significant papers have been published regarding the role of SRS in the management of VS there remains no definitive answer as to the best management option. Tumour control rates are comparable in both options and whilst both have their limitations, complication rates are generally much lower in the SRS group. Even so it is yet to be widely accepted as the treatment of choice in suitable cases. Nonetheless broadening the knowledge base with more research and education regarding the benefits of SRS will allow it to be promoted as a primary, contemporary treatment option in the management of VS.

<tocheading>Forum for Applied Education and Training</tocheading>

“…Side effects are very rare as little or no normal tissue is treated. However of those possible, all are transient, most resolving within a few days post treatment and even the more severe effects having resolved within 6 months of treatment (Gordon & Eddy, 2006).…”