title: Edema following Gamma Knife radiosurgery for parasagittal and parafalcine meningiomas.
abstract: OBJECTIVE
  Stereotactic radiosurgery (SRS) has been shown to offer a high probability of tumor control for Grade I meningiomas. However, SRS can sometimes incite edema or exacerbate preexisting edema around the targeted meningioma. The current study evaluates the incidence, timing, and degree of edema around parasagittal or parafalcine meningiomas following SRS.
  
  
  METHODS
  A retrospective review was undertaken of a prospectively maintained database of patients treated with Gamma Knife radiosurgery at the University of Virginia Health System. All patients with WHO Grade I parafalcine or parasagittal meningiomas with at least 6 months of clinical follow-up were identified, resulting in 61 patients included in the study. The median radiographic follow-up was 28 months (range 6-158 months). Rates of new or worsening edema were quantitatively assessed using volumetric analysis; edema indices were computed as a function of time following radiosurgery. Statistical methods were used to identify favorable and unfavorable prognostic factors for new or worsening edema.
  
  
  RESULTS
  Progression-free survival at 2 and 5 years was 98% and 90%, respectively, according to Kaplan-Meier analysis. After SRS, new peritumoral edema occurred or preexisting edema worsened in 40% of treated meningiomas. The median time to onset of peak edema was 36 months post-SRS. Persistent and progressive edema was associated with 11 tumors, and resection was undertaken for these lesions. However, 20 patients showed initial edema progression followed by regression at a median of 18 months after radiosurgery (range 6-24 months). Initial tumor volume greater than 10 cm3, absence of prior resection, and higher margin dose were significantly (p<0.05) associated with increased risk of new or progressive edema after SRS.
  
  
  CONCLUSIONS
  Stereotactic radiosurgery offers a high rate of tumor control in patients with parasagittal or parafalcine meningiomas. However, it can lead to worsening peritumoral edema in a minority of patients. Following radiosurgery, transient edema occurs earlier than persistent and progressive edema. Longitudinal follow-up of meningioma patients after SRS is required to detect and appropriately treat transient as well as progressive edema.
authors.affiliation: Departments of 1 Neurological Surgery and.|Radiation Oncology, University of Virginia Health System, Charlottesville, Virginia.
authors.forename: Jason P
authors.initials: JP
authors.lastname: Sheehan
authors.affiliation: Departments of 1 Neurological Surgery and.
authors.forename: Cheng-Chia
authors.initials: CC
authors.lastname: Lee
authors.affiliation: Departments of 1 Neurological Surgery and.
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Xu
authors.affiliation: Departments of 1 Neurological Surgery and.
authors.forename: Colin J
authors.initials: CJ
authors.lastname: Przybylowski
authors.affiliation: Departments of 1 Neurological Surgery and.
authors.forename: Patrick D
authors.initials: PD
authors.lastname: Melmer
authors.affiliation: Departments of 1 Neurological Surgery and.|Radiation Oncology, University of Virginia Health System, Charlottesville, Virginia.
authors.forename: David
authors.initials: D
authors.lastname: Schlesinger
mesh_terms: D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D001929:Brain Edema / Q000188:drug therapy / Q000209:etiology* / Q000628:therapy*; D016208:Databases, Factual; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008579:Meningioma / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D011183:Postoperative Complications / Q000188:drug therapy / Q000628:therapy*; D011379:Prognosis; D016634:Radiosurgery / Q000009:adverse effects*; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D000305:Adrenal Cortex Hormones; D000893:Anti-Inflammatory Agents
keywords: GKRS = Gamma Knife radiosurgery; Gamma Knife; SRS = stereotactic radiosurgery; VEGF = vascular endothelial growth factor; edema; meningioma; stereotactic radiosurgery