Volume-staged Gamma Knife radiosurgery for orbital venous malformations.

OBJECTIVEThis article is a preliminary evaluation of the efficacy of volume-staged Gamma Knife radiosurgery (GKRS) in the treatment of patients with orbital venous malformations (OVMs).METHODSTwenty patients with moderate to large OVMs were treated with volume-staged GKRS between March 2005 and October 2015. The series included 8 male and 12 female patients with an average age of 22.5 years (range 9-45 years). The diagnoses were confirmed intraoperatively and at pathological examination in 14 cases and presumed in accordance with clinical and imaging findings in 6 cases. The median OVM volume was 12.2 cm3 (range 7.1-34.6 cm3). The median interval between stages was 10 months (range 6-12 months). The tumor margin dose for each stage ranged from 11.0 to 13.5 Gy. The median duration of follow-up was 45.5 months (range 18-98 months).RESULTSPeriodically scheduled MRI studies demonstrated evidence of a significant reduction of the original OVM volume in all cases. Visual acuity (VA) was preserved in 18 cases (90%). Five patients (25%) experienced vision improvement of varying degrees, and 13 (65%) experienced long-term preservation of VA at their pre-GKRS level. Deterioration in VA was observed in only 2 cases (10%). MRI demonstrated OVM regression after treatment in all cases, and all patients were found to have reduction of exophthalmos after volume-staged GKRS. Follow-up MRI revealed recurrence in only 1 case (5%). Three patients (15%) developed transient conjunctival edema.CONCLUSIONSThis retrospective investigation indicates that volume-staged GKRS provides an effective management option in selected patients with OVMs, providing excellent visual outcomes. The study adds substantial support for volume-staged GKRS as a major treatment for OVMs.