• IRSA. Stereotactic radiosurgery for patients with intracranial arteriovenous malformations (AVM). Harrisburg (PA): IRSA; 2003 Sep. 10 p. (Radiosurgery Practice Guideline Report; no. 2-03). [46 references]

This is the current release of the guideline.

Stereotactic radiosurgery is defined as a relatively high dose of focused radiation delivered precisely to the arteriovenous malformations (AVM), under the direct supervision of a medical team (neurosurgeon, radiation oncologist, registered nurse, and medical physicist), in one surgical session.

Patient Selection

• Patients with intracranial AVM defined by modern neurodiagnostic imaging, including computed tomography (CT), magnetic resonance imaging (MRI) scan, and cerebral angiography, should be considered for radiosurgery. Such patients typically present with brain hemorrhage (especially when located in deep anatomic locations of the brain), persistent seizures, vascular headache syndrome, or progressive neurological deficits.
• The selection of patients suitable for radiosurgery is dependent on the prior bleeding history, the age of the patient, existing co-morbidities, anatomic location, and clinical history.

Treatment/Management

• Arteriovenous malformations are considered suitable for four management strategies alone or in combination: observation only, surgical excision, endovascular embolization (designed to reduce either a selected volume or flow through the AVM), and stereotactic radiosurgery.
• Stereotactic radiosurgery is typically employed alone but also may be employed in combination with prior surgery or embolization in particular circumstances. Size ranges of average diameter are usually less than 3 cm (0.1 – 10 cm³). Prospective stereotactic radiosurgery volumetric staging is frequently performed for those symptomatic patients with AVM volumes >15 cm³ in the absence of other acceptable risk management strategies and can be considered for AVMs between 10 to 15 cm³.
• The optimal dose range for volumetric conformal stereotactic AVM radiosurgery has been largely established based on location and volume of the AVM. Doses at the margin of the AVM typically range from 16 to 25 Gy in a single fraction, wherein the volume of the AVM is defined by stereotactic guidance during the procedure itself. Stereotactic volumetric axial plane imaging (MRI or CT) supplemented by conventional or digital subtraction angiography is usually necessary for complete conformal dose planning.
• Dose selection depends on location, volume, estimated adverse radiation risks, pre-existing neurological conditions, and prior bleeding history. Depending upon the technology used, the margin of the AVM dose is usually 50 to 70% of the central target dose within the AVM. Sharp fall-off of the radiation dose outside of the target volume is required. Current radiation delivery technologies for volumetric stereotactic conformal single fraction radiosurgery include Gamma Knife®, proton beam using Bragg peak effect, and specially modified linear accelerators.
• Patients usually receive a single dose (40 mg) of methylprednisolone at the conclusion of the radiosurgery procedure. They can continue to take their other medications (e.g., antiepileptics, analgesics) during and after the procedure as recommended by their physicians.
• Some AVM patients will have been previously treated by embolization for volumetric reduction or flow reduction. Some patients may have had prior intracranial surgery for blood clot (hematoma) evacuation or partial AVM resection. The safe interval between surgery and stereotactic radiosurgery is not known, but it is reasonable to perform radiosurgery once the patient has achieved a stable neurological recovery or plateau (generally within two to three months after the intracranial hemorrhage or prior surgery). The optimal time between prior embolization and radiosurgery is not known, but generally waiting for a period of several weeks is considered beneficial in order to reduce the likelihood of vascular ischemic complications or residual cerebral edema sometimes associated with embolization followed by early radiosurgery.
• Postradiosurgical clinical examinations and magnetic resonance (MR) studies are requested by referring physicians at six-month intervals for the first three years to assess the effect of radiosurgery on AVM (gradual obliteration). If MR at the three-year mark suggests complete disappearance of the AVM nidus, an angiogram is obtained to confirm the obliteration. If the MR imaging before three years suggests nidus obliteration, angiography is generally delayed until three full years have elapsed. If angiography after three years demonstrates that the AVM nidus is not obliterated, repeat stereotactic radiosurgery is recommended.
• Patients who have residual arteriovenous malformations identified by neurodiagnostic imaging at three years (after radiosurgery) may be candidates for a second stereotactic radiosurgical procedure. Alternatively, patients with larger volume AVMs (e.g., >10 cm³) may be considered suitable for up-front volumetric staging of AVMs by treating different anatomic components of the AVM at intervals staged between three and six months. The interval for staging of radiosurgery prospectively is not established. Stereotactic radiosurgery should not be considered as the panacea for large volume AVMs unsuitable for surgery or embolization. At selected centers with experience, estimated obliteration rates after two radiosurgical procedures at five years approach 60 to 70%. For smaller volume AVMs (e.g., average diameters <3 cm³), estimated complete obliteration rates at three years after a single procedure vary from 70 to 90%.
• Causes for failure of stereotactic radiosurgery have been identified and include inadequate visualization of the target nidus, lack of intraoperative stereotactic 3-D (volumetric axial plane imaging), insufficient dose to achieve the obliterative response, compression of the AVM nidus by a prior hematoma, or poor nidus visualization secondary to overlying vascular structures. In a few cases, selected radiobiological resistance of undetermined etiology may be the cause of obliteration failure.
• At present, technologies delivered to provide volumetric stereotactic radiosurgery are limited to Gamma Knife®, modified linear accelerators at centers supplemented by significant experience, and proton beam facilities in the United States.

The original guideline contains a clinical algorithm for arteriovenous malformation management.

Type I, II, and III evidence exists in support of stereotactic radiosurgery for arteriovenous malformations (AVMs). Refer to the "Rating Scheme for the Strength of the Evidence" field.

• IRSA. Stereotactic radiosurgery for patients with intracranial arteriovenous malformations (AVM). Harrisburg (PA): IRSA; 2003 Sep. 10 p. (Radiosurgery Practice Guideline Report; no. 2-03). [46 references]

Not applicable: The guideline was not adapted from another source.

2003 Sep

IRSA - Professional Association

IRSA (International RadioSurgery Association) is a non-profit entity dedicated to promoting the development of scientifically relevant practice guidelines for stereotactic radiosurgery. IRSA works to educate and provide support for physicians, hospitals, insurers, and patients.

IRSA (International RadioSurgery Association)

IRSA (International RadioSurgery Association) Physician Advisory Board Guidelines Committee and other professionals who provide radiosurgery

Committee Members: L. Dade Lunsford, MD, Neurosurgeon, (Chair); Douglas Kondziolka, MD, Neurosurgeon; Ajay Niranjan, MBBS, MCh, Neurosurgeon; Christer Lindquist, MD, Neurosurgeon (European Co-Chair); Jay Loeffler, MD, Radiation Oncologist; Michael McDermott, MD, Neurosurgeon; Michael Sisti, MD, Neurosurgeon; John C. Flickinger, MD, Radiation Oncologist; Ann Maitz, MS, Medical Physicist; Michael Horowitz, MD, Neurosurgeon and Interventional Radiologist; Tonya K. Ledbetter, MS, MFS, Editor; Rebecca L. Emerick, MS, MBA, CPA, ex officio

Not stated

This is the current release of the guideline.

None available

This NGC summary was completed by ECRI on March 8, 2004. The information was verified by the guideline developer on April 7, 2004.

This guideline is copyrighted by IRSA (International RadioSurgery Association) and may not be reproduced without the written permission of IRSA. IRSA reserves the right to revoke copyright authorization at any time without reason.