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. 2017 Feb 1;80(2):210-216.
doi: 10.1227/NEU.0000000000001227.

Emerging Indications for Fractionated Gamma Knife Radiosurgery

Emory McTyre  1 , Corbin A Helis  1 , Michael Farris  1 , Lisa Wilkins  1 , Darrell Sloan  1 , William H Hinson  1 , J Daniel Bourland  1 , William A Dezarn  1 , Michael T Munley  1 , Kounosuke Watabe  2 , Fei Xing  2 , Adrian W Laxton  3 , Stephen B Tatter  3 , Michael D Chan  1
Affiliations

Emerging Indications for Fractionated Gamma Knife Radiosurgery

Emory McTyre et al. Neurosurgery. .

Abstract

Background: Gamma Knife radiosurgery (GKRS) allows for the treatment of intracranial tumors with a high degree of dose conformality and precision. There are, however, certain situations wherein the dose conformality of GKRS is desired, but single session treatment is contraindicated. In these situations, a traditional pin-based GKRS head frame cannot be used, as it precludes fractionated treatment.

Objective: To report our experience in treating patients with fractionated GKRS using a relocatable, noninvasive immobilization system.

Methods: Patients were considered candidates for fractionated GKRS if they had one or more of the following indications: a benign tumor >10 cc in volume or abutting the optic pathway, a vestibular schwannoma with the intent of hearing preservation, or a tumor previously irradiated with single fraction GKRS. The immobilization device used for all patients was the Extend system (Leksell Gamma Knife Perfexion, Elekta, Kungstensgatan, Stockholm).

Results: We identified 34 patients treated with fractionated GKRS between August 2013 and February 2015. There were a total of 37 tumors treated including 15 meningiomas, 11 pituitary adenomas, 6 brain metastases, 4 vestibular schwannomas, and 1 hemangioma. At last follow-up, all 21 patients treated for perioptic tumors had stable or improved vision and all 4 patients treated for vestibular schwannoma maintained serviceable hearing. No severe adverse events were reported.

Conclusion: Fractionated GKRS was well-tolerated in the treatment of large meningiomas, perioptic tumors, vestibular schwannomas with intent of hearing preservation, and in reirradiation of previously treated tumors.

Keywords: Gamma Knife radiosurgery; Meningioma; Pituitary adenoma; Radiosurgery; Vestibular schwannoma.

PubMed Disclaimer

Conflict of interest statement

The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.

Figures

FIGURE 1.
FIGURE 1.
Composite dose-volume histogram for all patients with perioptic tumors. Solid lines represent the mean dose to the given volume, while dashed lines represent the minimum and maximum doses to these volumes.
FIGURE 2.
FIGURE 2.
Magnetic resonance imaging (MRI) of a pituitary adenoma before treatment A and 6 months posttreatment B, and an MRI of a large meningioma before treatment C and 6 months posttreatment D. Both patients were treated to a total dose of 20 Gy/4 fractions. Color version available online only.
FIGURE 3.
FIGURE 3.
Tumor response to fractionated gamma knife radiosurgery as assessed by relative change in volume between pretreatment and follow-up magnetic resonance imaging (MRI) (performed 6 months posttreatment for benign tumors and 1-2 months posttreatment for malignant tumors). Color version available online only.
See this image and copyright information in PMC

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