J Neurol Surg B Skull Base 2014; 75 - A122
DOI: 10.1055/s-0034-1370528

Predictors of Meningioma Response to Stereotactic Radiosurgery and Post-Operative Complications

Soroush Larjani 1, Alireza Mansouri 1, Alexandra Kilian 1, George Kilronomos 1, Fred Gentili 1, Gelareh Zadeh 1
  • 1Toronto, Canada

Purpose: To identify clinical, radiological, and dosimetric predictors of meningioma response to stereotactic radiosurgery (SRS), and post-SRS adverse radiation events.

Methodology: We retrospectively reviewed a prospectively maintained database of all meningioma patients treated with SRS between September 2005 and June 2013 at the University Health Network using Leksell Model 4C Gamma Knife Unit (Elekta, Atlanta). Of all patients treated with SRS, seventy-five had at least 24 months of both clinical and radiological follow-up, and were therefore included in this study. All treatment plans were reviewed and radiation characteristics were collected. All clinical complications that arose post-operatively and that were associated with SRS were recorded. Tumor control was defined as any volumetric change less than 10%. Volumetric measurements were made using T1-Gadolinium enhanced MRI scans using ITK-SNAP 2.2. Tumor growth rates were calculated using the Specific Growth Rate. All statistical analyses were performed using IBM SPSS v20.0.

Results: Forty-eight (64.0%) patients experienced some form of new-onset complication after SRS; the complications experienced were pain (42.7%), fatigue (18.7%), vomiting (2.7%), nausea (9.3%), headache (22.7%), dizziness (13.3%), ataxia (2.7%), tremor (2.7%), memory impairment (5.3%), speech impairment (2.7%), cognitive disturbance (2.7%), and edema (18.7%). Thirty-nine (52.0%) patients achieved tumor control with an average growth rate of -10.7%/annum. The thirty-six (48.0%) meningiomas that continued to grow after SRS had an average growth rate of +42.7%/annum. Lower Conformity index (1.24 versus 1.4), and higher treatment-volume ratio (TVR) (0.80 versus 0.72) were significantly associated with development of edema after SRS (p values equal to 0.000001 and 0.000004, respectively). Patients with meningiomas that had a growth rates of more than 10%/year were more likely to have long-term headache after SRS (p = 0.022).

Conclusion: SRS was effective in achieving tumor control in approximately half of meningiomas. Conformity index and TVR were identified as predictors of edema following radiosurgery.