Post-stereotactic radiosurgery brain metastases: a review.

Stereotactic radiosurgery (SR) is a standard therapy for brain metastases. Radiation necrosis (RN) of the brain is a syndrome of brain coagulative and fibrinoid necrosis and cortical irritation that occurs following radiotherapy. RN following SR peaks in a delayed fashion at 9-12 months postprocedure. Vasogenic cerebral edema secondary to necrosis occurs and can affect surrounding brain function. No definitive non-invasive diagnostic study exists to differentiate post-SR RN from recurrent metastatic tumor. Magnetic resonance (MR) imaging, MR spectroscopy, positron emission tomography, and perfusion-weighted MR imaging have been used to evaluate RN and are discussed. Treatment options for post-SR brain metastases include observation, corticosteroids, pentoxifylline and vitamin E, bevacizumab, radiotherapy, laser-interstitial thermal therapy, and surgical resection.