Gamma Knife surgery for large vestibular schwannomas: a single-center retrospective case-matched comparison assessing the effect of lesion size

Abstract

Object. Gamma Knife surgery (GKS) is a safe and effective treatment for patients with small to moderately sized vestibular schwannomas (VSs). Reports of stereotactic radiosurgery for large VSs have demonstrated worse tumor control and preservation of neurological function. The authors endeavored to assess the effect of size of VSs treated using GKS.Methods. This study was a retrospective comparison of 24 patients with large VSs (> 3 cm in maximum diameter) treated with GKS compared with 49 small VSs (≤ 3 cm) matched for age, sex, radiosurgical margin and maximal doses, length of follow-up, and indication.Results. Actuarial tumor progression-free survival (PFS) for the large VS cohort was 95.2% and 81.8% at 3 and 5 years, respectively, compared with 97% and 90% for small VSs (p = 0.009). Overall clinical outcome was better in small VSs compared with large VSs (p < 0.001). Patients with small VSs presenting with House-Brackmann Grade I (good facial function) had better neurological outcomes compared with patients with large VSs (p = 0.003). Treatment failure occurred in 6 patients with large VSs; 3 each were treated with resection or repeat GKS. Treatment failure did not occur in the small VS group. Two patients in the large VS group required ventriculoperitoneal shunt placement. Univariate analysis did not identify any predictors of treatment failure among the large VS cohort.Conclusions. Patients with large VSs treated using GKS had shorter PFS and worse clinical outcomes compared with age-, sex-, and indication-matched patients with small VSs. Nevertheless, GKS has efficacy for some patients with large VSs and represents a reasonable treatment option for selected patients.

Keyhole retrosigmoid approach for large vestibular schwannomas: strategies to improve outcomes

“…Although radiosurgery has been reported to produce similar facial nerve outcomes for Koos grade 3 tumors (mean volume 9 cm 3 ), its role in the context of large vestibular schwannomas remains controversial and it may be indicated only in patients with minimal symptoms of brainstem compression, surgical contraindications, or significant residual tumor mass despite attempted debulking. 4,15,25,41,43,44,47,50 A proposal to stage large vestibular schwannomas between 2 surgeries has been shown to improve facial nerve outcome and morbidity. 30 Staging the tumor resection was decided intraoperatively if there was cerebellar or The extent of resection is another important factor, with several studies demonstrating significantly lower rates of recurrence with complete or near-complete resections compared with subtotal or partial debulking.…”

Hearing subclassification may predict long-term auditory outcomes after radiosurgery for vestibular schwannoma patients with good hearing

“…4,12,16,19,27 Despite variations in technologies, fractionation, delivery techniques, dose delivered, conformality of 3D dose delivery, and selectivity (fall off outside the tumor volume), focused radiation has become an important management option across the world. Previous studies demonstrated that despite variations in methods and technologies, sustained tumor growth control was obtained in 90%-98% of patients.…”

The Outcome of Hypofractionated Stereotactic Radiosurgery for Large Vestibular Schwannomas

“…37 Compilation of the relevant literatures on the outcome of VS of at least Koos Grade III treated by radiosurgery, the overall progression free survival rates range from 82-100% at long-term follow-up (Table 4). 12,29,30,33,[37][38][39][40][41] The available evidence suggested that large VSs are potentially amenable to primary SRS therapy, but there may still be poor tumor control in the largest of tumors. We confirmed this relationship when further stratifying our cohort by volume, with tumors < 15 cm 3 associating with better control rates.…”

“…Prior work has similarly indicated that cystic pathology is not predictive of tumor progression, collectively suggesting that SRS treatment for large cystic lesions focus on postoperative complication management. 33,38 While prior work has shown that preoperative hydrocephalus is more common for cystic VS of all sizes, few articles have specifically characterized the full relationships across large, cystic VS, and their need for postoperative shunting. 43,44 Williams et al reported that there was a tendency for large tumors to present with cystic lesions (25% vs 0%), hydrocephalus (8% vs 0%) and require a postoperative shunt (8% vs 0%) relative to smaller VSs, but did not specify their interaction.…”

“…28 Despite a growing literature supporting the role of SRS in the care of large VSs, most is limited to that of Gamma Knife radiosurgery and the definition of large VS is highly variable in the radiosurgery literatures. 12,[29][30][31][32][33] Furthermore no studies have expressly compared the role of CyberKnife (CK) radiosurgery for the treatment of large solid or cystic VS, which might have a different biological response to radiosurgery.…”