Stereotactic Radiotherapy for Trigeminal Schwannomas BACKGROUND: Data on radiotherapy for trigeminal schwannomas (TSs) and com- parison of stereotactic radiosurgery (SRS) with fractionated stereotactic radiotherapy (FSRT) are limited. OBJECTIVE: We present a large retrospective review of our institutional experience treating TSs with SRS and FSRT. We also describe a flare phenomenon experienced by some patients. METHODS: The records of 23 consecutive TSs patients treated with radiotherapy between 1996 and 2011 were reviewed. We investigated radiographic response, tumor control, and toxicity. RESULTS: Ten patients underwent SRS and 13 underwent FSRT, with median clinical follow-up of 32 months (range, 3-120 months). Tumor control at 5 and 10 years was 94% overall. Symptom control at 5 years was achieved in 48% of all patients, with non- significant improvement in more patients in the FSRT group than those in the SRS group (56% vs 40%, P = .37). Acute toxicity was higher in the FSRT group (38.5 vs 0%, P , .01), although lesions treated with FSRT were larger (mean, 9.5 mL vs 4.8 mL, P , .01). A symptomatic flare phenomenon occurred in 2 patients (8.7% overall) during FSRT, involving transient cystic formation and dramatic size increase. One lesion regressed in size and 1 remained stable on follow-up. CONCLUSION: Tumor control rates for TSs are excellent with SRS and FSRT with minimal toxicity. This represents the first documented report of a flare phenomenon after FSRT for TS treatment. Flare risk after FSRT in previously resected large lesions should be discussed with patients before treatment, and prophylactic oral steroids may be considered. KEY WORDS: Flare phenomenon, Fractionated stereotactic radiotherapy, Stereotactic radiosurgery, Stereo- tactic radiotherapy, Trigeminal schwannoma Neurosurgery 71:270–277, 2012 DOI: 10.1227/NEU.0b013e318256bbc5 www.neurosurgery-online.com T rigeminal schwannomas (TSs) are rare, benign, slow-growing lesions, occurring most frequently in middle-aged patients. 1 They are the second most common schwannoma affecting the cranial nerves, representing 1% to 8% of intracranial schwannomas. 2 Patients fre- quently present with trigeminal nerve and surrounding cranial nerve dysfunction manifes- ted as pain, numbness, and masticator muscle weakness, although some patients may remain asymptomatic. 3 TSs had been traditionally trea- ted with microsurgical resection, with reported control rates of 83% to 100%. 4,5 Stereotactic radiation in the form of stereotac- tic radiosurgery (SRS) and fractionated stereotac- tic radiotherapy (FSRT) has more recently become a standard treatment option. Initial literature in patients treated with stereotactic radiotherapy for acoustic schwannomas reported favorable outcomes with decreased treatment toxicity and cranial neuropathy compared with surgical resection. 6,7 Several studies on TSs have reported on tumor control with both SRS and FSRT, revealing control rates of 88% to 100%, comparable to rates of surgical treatment. 8-12 Colin E. Champ, MD* Mark V. Mishra, MD* Wenyin Shi, MD, PhD* Joshua Siglin, MD* Maria Werner-Wasik, MD* David W. Andrews, MD‡ James J. Evans, MD‡ Departments of *Radiation Oncology; ‡Neurological Surgery, Kimmel Cancer Center and Jefferson Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania Correspondence: Colin E. Champ, MD, Thomas Jefferson University, Bodine Cancer Center, 111 South 11th Street, Philadelphia, PA 19107. E-mail: colin.champ@jeffersonhospital.org Received, November 28, 2001. Accepted, March 7, 2012. Published Online, April 2, 2012. Copyright ª 2012 by the Congress of Neurological Surgeons SANS LifeLong Learning and NEUROSURGERY offer CME for subscribers that complete questions about featured articles. Questions are located on the SANS website (http://sans.cns.org/). Please read the featured article and then log into SANS for this educational offering. ABBREVIATIONS: CTCAE, Common Terminology Criteria for Adverse Events; FSRT, fractionated stereotactic radiotherapy; GTV, gross tumor volume; KPS, Karnofsky Performance Status; SRS, stereotactic radiosurgery; TS, trigeminal schwannoma RESEARCH—HUMAN—CLINICAL STUDIES TOPIC RESEARCH—HUMAN—CLINICAL STUDIES 270 | VOLUME 71 | NUMBER 2 | AUGUST 2012 www.neurosurgery-online.com Copyright © Congress of Neurological Surgeons. Unauthorized reproduction of this article is prohibited.