• International RadioSurgery Association (IRSA). Stereotactic radiosurgery for patients with vestibular schwannomas. Harrisburg (PA): International RadioSurgery Association (IRSA); 2006 May. 16 p. (Radiosurgery practice guideline report; no. 4-06). [110 references]

This is the current release of the guideline.

• Patients with vestibular schwannomas defined by modern neurodiagnostic imaging (computed tomography [CT], magnetic resonance imaging [MRI]) constitute the study group. Such patients typically present with symptoms of hearing loss, tinnitus, and/or imbalance. Vestibular schwannomas are considered suitable for various management strategies such as observation with serial imaging, stereotactic radiosurgery, and surgical excision. Stereotactic radiosurgery is typically employed as the first management option in patients with small to medium size tumors (without symptomatic brainstem compression). It is also used to control growth of recurrent or residual tumor after surgical resection. Stereotactic radiosurgery, a minimally invasive, single high-dose, closed skull management strategy, may be especially suitable for patients who desire preservation of neurological function (cochlear, facial nerve) and a high rate of tumor growth control.
• Stereotactic volumetric MR imaging (high resolution) is usually necessary for precisely conformal dose planning. Contrast-enhanced gradient recalled MR images are ideal for radiosurgery dose planning. T2 weighted MR images (3-D volume) are helpful in defining the cranial nerves and the inner ear structures (cochlea and semicircular canals). Sharp fall-off of the radiation dose outside of the target volume is required.
• Current radiation delivery technologies for volumetric conformal stereotactic radiosurgery include Gamma Knife®, proton beam using the Bragg peak effect, and specially modified linear accelerators (LINACs).
• The optimal single session dose range for volumetric conformal stereotactic vestibular schwannoma radiosurgery has been largely established based on tumor anatomy (proximity of brainstem), hearing status, tumor volume, and estimated adverse radiation risks. Minimum doses to the margin of vestibular schwannoma typically range from 12–13 Gy in a single session.
• Depending upon treating physicians' preferences, patients may or may not receive a single stress dose of corticosteroids at the beginning or conclusion of the radiosurgery procedure. Alternatively several doses of steroids at regular intervals (3–4 hourly) can be given on the day of the procedure. Patients can continue to take other medications as recommended by their physicians.
• Post-radiosurgical clinical examinations and MR studies are typically performed at predetermined intervals such as at six months, one year, two years, and four years. For patients with preserved serviceable hearing, audiograms are recommended at intervals coinciding with clinical and neuroimaging re-evaluations. Tumors proven to be stable over 4–5 years can subsequently be reassessed at 2–4 year intervals.
• Patients with large tumors causing symptomatic brainstem compression should be managed with surgical decompression of the tumor. Residual tumor can be treated by radiosurgery.
• Patients with hydrocephalus but without symptoms of brainstem compression can have a shunt inserted prior to radiosurgery, especially if the patient is aged or medically infirm and consequently not a good candidate for resection.
• Causes for failure of stereotactic radiosurgery include inadequate visualization of the tumor, lack of intraoperative stereotactic 3-D (volumetric) imaging, and insufficient dose (due to large tumor volume and proximity to the brainstem) to achieve a growth control response.

Stereotactic Radiosurgery for Vestibular Schwannomas

Stereotactic radiosurgery is defined as a single session, high-dose delivery of focused radiation precisely to the vestibular schwannoma, as identified by stereotactic imaging. In systems requiring head fixation of the stereotactic frame (e.g., Gamma Knife®), radiation delivery occurs under the direct supervision of a medical team consisting of a neurosurgeon, radiation oncologist, registered nurse, and medical physicist, at a minimum. At some centers a neurotologist is also part of the radiosurgery team. The neurosurgeon and/or neurotologist are an integral part of the critical decision making steps and the target planning and dose approval within the brain for both LINAC and proton beam based systems (whether single session or stereotactically hypofractionated radiation therapy) regardless of head fixation system. The radiation delivery of the approved targeting and dosing plan (as designed and approved by the neurosurgeon/neurotologist and radiation oncologist together) may occur on subsequent days for LINAC or proton beam based single session or hypofractionated sessions under the direct supervision of a radiation oncologist without the neurosurgeon or neurotologist present. In this case, the minimum delivery team should consist of a certified radiation therapist and medical physicist. Should the original targeting plan require modification during the radiation delivery of the subsequent sessions, the neurosurgeon and/or neurotologist should review/design and approve the new targeting and dosing plan before the continuation of the radiation delivery by the radiation oncologist.

An algorithm is provided in the original guideline document for Management of Acoustic Tumors.

The type of supporting evidence is not specifically stated for each recommendation.

• International RadioSurgery Association (IRSA). Stereotactic radiosurgery for patients with vestibular schwannomas. Harrisburg (PA): International RadioSurgery Association (IRSA); 2006 May. 16 p. (Radiosurgery practice guideline report; no. 4-06). [110 references]

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

2006 May

IRSA - Professional Association

IRSA (International RadioSurgery Association)

The IRSA Medical Advisory Board Guidelines Committee and physician representatives in the industry.

This radiosurgery guidelines group is comprised of neurosurgeons, neurotologists, and radiation oncologists.

Group Members: L. Dade Lunsford, MD, Neurosurgeon, Chair; Ajay Niranjan, MBBS, MCh, Neurosurgeon; Georg Norén, MD, Neurosurgeon; Jay Loeffler, MD, Radiation Oncologist; Alain de Lotbinière, MD, Neurosurgeon; Jordan Grabel, MD, Neurosurgeon; Douglas Kondziolka, MD, Neurosurgeon; Jean Régis, MD, Neurosurgeon; Pierre-Hughes Roche, MD, Neurosurgeon; Robert Smee, MD, Radiation Oncologist; Burton Speiser, MD, Radiation Oncologist; Mark Alden, MD, Radiation Oncologist; Sandra Vermeulen, MD, Radiation Oncologist; William F. Regine, MD, Radiation Oncologist; Barry Hirsch, MD, Neurotologist; Tonya K. Ledbetter, MS, MFS, Editor; Rebecca L. Emerick, MS, MBA, CPA, ex officio

IRSA makes every effort to avoid any actual or potential conflicts of interest that may arise as a result of a personal, professional, or business interest of a member of the radiosurgery guidelines group.

This is the current release of the guideline.

This NGC summary was completed by ECRI on July 26, 2006. The information was verified by the guideline developer on September 27, 2006.

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.