(AVM) can be managed by microsurgery, endovascular embolization, or Radiosurgery. Microsurgery is regarded as the standard first-line treatment, but SRS is offered to patients who have residual AVM after microsurgery or those who are deemed not to be good candidates for microsurgery. AVMs are regarded as category 1 targets for radiosurgery.
Target delineation is done using a combination of angiography and stereotactic MR or CT imaging.
Trigeminal neuralgia is defined by the International Association for the Study of Pain (IASP) as sudden, usually unilateral, severe, brief, stabbing or lancinating, recurrent episodes of pain in the distribution of one or more branches of the trigeminal nerve.
Treatment options include medications, surgical procedures including microvascular decompression, radiofrequency rhizotomy, glycerol rhizolysis and balloon compression, and SRS (Gamma Knife– or linear accelerator–based radiosurgery).
Meningiomas constitute approximately 20% of all primary intracranial tumors, and tumor grade bears clear prognostic importance. Complete surgical resection, if feasible, is the standard of care. However, meningioma may recur after surgery, and safe curative resection is often not possible, especially for skull base tumors.
Radiosurgery can deliver a single, high dose of radiation to a localized area in the brain for the treatment of meningiomas that are unresectable, recurrent, or residual after surgery.
Acoustic neuroma is also known as acoustic schwannoma, acoustic neurinoma, vestibular schwannoma, and vestibular neurilemoma. It is a Schwann cell–derived tumor arising from the vestibular portion of the eighth cranial nerve. Treatment options include observation, microsurgery, SRS, and stereotactic radiotherapy.
Radiosurgery is a viable treatment option for selected patients with smaller tumors (< 3cm) or for enlarging tumors in patients who are not candidates for surgery. Acoustic neuromas are category 2 targets and therefore they are ideal targets for Radiosurgery.
Pituitary adenomas are histologically benign tumors, but the potential neurological and physiological complications can be devastating. In patients with acromegaly, excessive growth hormone production can lead to life-threatening cardiovascular and respiratory complications, diabetes mellitus, and, possibly, an increased risk of colon cancer
Radiosurgery has been used in the treatment of endocrine-inactive as well as secretory pituitary adenomas. Radiosurgery is suitable for patients with a gap of at least 2-5 mm between the pituitary adenoma (≤3-4 cm in diameter in general) and the optic pathway.
Brain metastases tend to be spherical and have a sharp demarcation from normal brain parenchyma.
These characteristics are ideal for Radiosurgery because spherical dose distributions can readily be generated by the radiosurgical systems and the use of tight margins is feasible.
Brain metastases are regarded as category 4 targets where the radiologically defined targets contain only tumor cells, which are an early-responding tissue. Compared with surgical resection, Radiosurgery has the advantage of being able to treat surgically inaccessible lesions and multiple lesions.
Malignant glioma is highly lethal. Despite best treatment, nearly all patients eventually succumb to their disease. Two randomized studies showed a radiation dose response for survival. Because the majority of recurrences occur within 2 cm of the enhancing edge of the original tumor, the possibility of dose escalation to improve tumor response and potentially survival has been explored. Multiple strategies, including Radiosurgery, have been used to execute dose escalation.
Malignant gliomas are category 4 targets, where there is no normal brain parenchyma within the radiologically defined targets, and are suitable for Radiosurgery.
The standard treatment for low-grade astrocytoma is surgery and / or conventional radiosurgery.
Radiosurgery has been used to treat low-grade astrocytoma in the recurrent, boost, and primary setting.
For low-grade astrocytoma, Radiosurgery most likely has the strongest indication in the recurrent setting, especially when there are no other local therapy options, as in previously irradiated patients within operable recurrent disease, and more study is needed to define its role in other settings.
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