Predictors of response to Gamma Knife radiosurgery for intracranial meningiomas

Seyed Alireza Mansouri, Soroush Larjani, George Klironomos, Normand Laperriere, Michael Cusimano, Fred Gentili, Michael Schwartz, Gelareh Zadeh

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


OBJECT: In this paper, the authors' aim was to determine short-term volumetric and diametric tumor growth and identify clinical, radiological, and dosimetric predictors of adverse radiation events (AREs) following stereotactic radiosurgery (SRS) for intracranial WHO Grade I meningiomas. METHODS: This is a retrospective review of all WHO Grade I meningiomas that were treated with SRS (primary or adjuvant) between December 2005 and June 2012 at the University Health Network. Seventy-five patients had at least 24 months of both clinical and radiological follow-up and were, therefore, included in this study. Tumor growth was defined as any volumetric or diametric change greater than 10% per year. Any variation less than +10% was considered growth stability. Volumetric measurements were made using T1-weighted gadolinium-enhanced 3-T MRI scans and ITK-SNAP software. Tumor growth rates were calculated using the specific growth rate (SGR). Univariate statistics were used to identify predictors of post-SRS AREs. All statistical analyses were performed using IBM SPSS. RESULTS: Women accounted for 69.3% of patients, and the mean treatment age was 58.6 years. Median follow-up was 36.2 months. Twenty-one (28%) patients had undergone prior resection. Two (3%) patients required salvage surgical intervention following SRS. The majority of the lesions (56%) were skull base tumors. Median tumor volume and diameter were 5.2 cm3 and 27.5 mm, respectively. The absence of tumor growth was observed in 39 cases (52%) based on the volumetric measurements, while the absence of tumor growth was observed in 69 cases (92%) based on the diametric measurements. Twenty-six patients (34.6%) experienced new-onset AREs, including headache (17.3%), cranial neuropathy (10.6%), speech impairment (2.7%), tremors (2.7%), and ataxia (1.3%). Fourteen patients (18.7%) experienced new-onset edema, and 4 of these patients were symptomatic. A lower conformity index (1.24 vs 1.4) was significantly associated with the development of edema (p < 0.001 power > 0.8). Patients with meningiomas that had growth rates of more than 10% per year were more likely to experience long-term headaches after SRS (p = 0.022). CONCLUSIONS: Volume-based reporting of SRS outcomes for meningiomas may be a more accurate method given the complex morphology of some lesions. The conformity index was identified as a predictor of edema following radiosurgery.

Original languageEnglish (US)
Pages (from-to)1294-1300
Number of pages7
JournalJournal of neurosurgery
Issue number5
StatePublished - Nov 2015

All Science Journal Classification (ASJC) codes

  • Surgery
  • Clinical Neurology


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