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.

Hypofractionated stereotactic radiosurgery: a new treatment strategy for giant cavernous sinus hemangiomas.

OBJECTIVE Cavernous sinus hemangiomas (CSHs) are rare benign vascular tumors that arise from the dural venous sinuses lateral to the sella. Stereotactic radiosurgery (SRS) has emerged as a principal alternative to microresection for small- and medium-sized CSHs. Resection is a reasonable option for large (3-4 cm in diameter) and giant (> 4 cm in diameter) CSHs. However, management of giant CSHs remains a challenge for neurosurgeons because of the high rates of morbidity and even death that stem from uncontrollable and massive hemorrhage during surgery. The authors report here the results of their study on the use of hypofractionated SRS (H-SRS) to treat giant CSH. METHODS Between January 2008 and April 2014, 31 patients with a giant CSH (tumor volume > 40 cm3, > 4 cm in diameter) treated using CyberKnife radiosurgery were enrolled in a cohort study. Clinical status and targeted reduction of tumor volume were evaluated by means of serial MRI. The diagnosis for 27 patients was determined on the basis of typical imaging features. In 4 patients, the diagnosis of CSH was confirmed histopathologically. The median CSH volume was 64.4 cm3 (range 40.9-145.3 cm3). Three or 4 sessions of CyberKnife radiosurgery were used with a prescription dose based on the intent to cover the entire tumor with a higher dose while ensuring dose limitation to the visual pathways and brainstem. The median marginal dose to the tumor was 21 Gy (range 19.5-21 Gy) in 3 fractions for 11 patients and 22 Gy (range 18-22 Gy) in 4 fractions for 20 patients. RESULTS The median duration of follow-up was 30 months (range 6-78 months) for all patients. Follow-up MRI scans revealed a median tumor volume reduction of 88.1% (62.3%-99.4%) at last examination compared with the pretreatment volume. Ten patients developed new or aggravated temporary headache and 5 experienced vomiting during the treatment; these acute symptoms were relieved completely after steroid administration. Among the 30 patients with symptoms observed before treatment, 19 achieved complete symptomatic remission, and 11 had partial remission. One patient reported seizures, which were controlled after antiepileptic drug administration. No radiation-induced neurological deficits or delayed complications were reported during the follow-up period. CONCLUSIONS Hypofractionated SRS was an effective and safe modality for treating giant CSH. Considering the risks involved with microsurgery, it is possible that H-SRS might be able to serve as a definitive primary treatment option for giant CSH.

Biological implications of whole-brain radiotherapy versus stereotactic radiosurgery of multiple brain metastases.

OBJECT: The efficacy and safety of treatment with whole-brain radiotherapy (WBRT) or with stereotactic radiosurgery (SRS) for multiple brain metastases (> 10) are topics of ongoing debate. This study presents detailed dosimetric and biological information to investigate the possible clinical outcomes of these 2 modalities. METHODS: Five patients with multiple brain metastases (n = 11-23) underwent SRS. Whole-brain radiotherapy plans were retrospectively designed with the same MR image set and the same structure set for each patient, using the standard opposing lateral beams and fractionation (3 Gy × 10). Physical radiation doses and biologically effective doses (BEDs) in WBRT and SRS were calculated for each lesion target and for the normal brain tissues for comparison of the 2 modalities in the context of clinical efficacy and published toxicities. RESULTS: The BEDs targeted to the tumor were higher in SRS than in WBRT by factors ranging from 2.4- to 3.0- fold for the mean dose and from 3.2- to 5.3-fold for the maximum dose. In the 5 patients, mean BEDs in SRS (calculated as percentages of BEDs in WBRT) were 1.3%-34.3% for normal brain tissue, 0.7%-31.6% for the brainstem, 0.5%-5.7% for the chiasm, 0.2%-5.7% for optic nerves, and 0.6%-18.1% for the hippocampus. CONCLUSIONS: The dose-volume metrics presented in this study were essential to understanding the safety and efficacy of WBRT and SRS for multiple brain metastases. Whole-brain radiotherapy results in a higher incidence of radiation-related toxicities than SRS. Even in patients with > 10 brain metastases, the normal CNS tissues receive significantly lower doses in SRS. The mean normal brain dose in SRS correlated with the total volume of the lesions rather than with the number of lesions treated.