Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines on the Role of Radiosurgery and Radiation Therapy in the Management of Patients With Vestibular Schwannomas
Authors: Germano Isabelle M , Sheehan Jason , Parish Johnathan , Atkins Tyler , Asher Anthony , Hadjipanayis Constantinos G , Burri Stuart H , Green Sheryl , Olson Jeffrey J 
Published: October 2017

Abstract

RADIOSURGERY VS OBSERVATION

Question
What are the indications for stereotactic radiosurgery (SRS) treatment vs observation for patients with intracanalicular vestibular schwannomas without evidence of radiographic progression?

Recommendation
Level 3: If tinnitus is not observed at presentation, it is recommended that intracanalicular vestibular schwannomas and small tumors (<2 cm) without tinnitus be observed as observation does not have a negative impact on tumor growth or hearing preservation compared to treatment.

RADIOSURGERY TECHNOLOGY

Question
Is there a difference in outcome based on radiosurgery equipment used: Gamma Knife (Elekta, Stockholm, Sweden) vs linear accelerator-based radiosurgery vs proton beam?

Recommendation
There are no studies that compare 2 or all 3 modalities. Thus, recommendations on outcome based on modality cannot be made.

RADIOSURGERY TECHNIQUE

Question
Is there a difference in outcome based on the dose delivered?

Recommendation
Level 3: As there is no difference in radiographic control using different doses, it is recommended that for single fraction SRS doses, <13 Gy be used to facilitate hearing preservation and minimize new onset or worsening of preexisting cranial nerve deficits.

Question
Is there a difference in outcome based on the number of fractions?

Recommendation
As there is no difference in radiographic control and clinical outcome using single or multiple fractions, no recommendations can be given.

RADIOGRAPHIC FOLLOW-UP, RETREATMENT, AND TUMORIGENESIS AFTER RADIOSURGERY

Question
What is the best time sequence for follow-up images after SRS?

Recommendation
Level 3: Follow-up imaging should be obtained at intervals after SRS based on clinical indications, a patient's personal circumstances, or institutional protocols. Long-term follow-up with serial magnetic resonance imagings to evaluate for recurrence is recommended. No recommendations can be given regarding the interval of these studies.

Question
Is there a role for retreatment?

Recommendation
Level 3: When there has been progression of tumor after SRS, SRS can be safely and effectively performed as a retreatment.

Question
What is the risk of radiation-induced malignant transformation of vestibular schwannomas treated with SRS?

Recommendation
Level 3: Patients should be informed that there is minimal risk of malignant transformation of vestibular schwannomas after SRS.

NEUROFIBROMATOSIS TYPE 2

Question
What are the indications for SRS in patients with neurofibromatosis type 2?

Recommendation
Level 3: Radiosurgery is a treatment option for patients with neurofibromatosis type 2 whose vestibular schwannomas are enlarging and/or causing hearing loss.
The full guideline can be found at: https://www.cns.org/guidelines/guidelines-management-patients-vestibular-schwannoma/chapter_7.