HSC Section 8_April 2017

Reprinted by permission of Laryngoscope. 2016; 126(11):2580-2586.

The Laryngoscope V C 2016 The American Laryngological, Rhinological and Otological Society, Inc.

Surgical Salvage of Recurrent Vestibular Schwannoma Following Prior Stereotactic Radiosurgery

Stephanie C. Wise, MD; Matthew L. Carlson, MD; Øystein Vesterli Tveiten, MD; Colin L. Driscoll, MD; Erling Myrseth, MD, PhD; Morten Lund-Johansen, MD, PhD; Michael J. Link, MD

Objectives/Hypothesis: To evaluate outcomes of salvage surgery for vestibular schwannoma (VS) that failed primary stereotactic radiosurgery (SRS). Methods: Case-control study of 37 patients who underwent surgical resection of sporadic VS following prior SRS at two tertiary academic referral centers between 2003 and 2015. A cohort of nonirradiated control subjects, matched according to tumor size, age, and treatment center, were used as comparison. Results: Thirty-seven patients were included. The median time from radiation to surgical salvage was 36 months (range 9.6–153 months). Following tumor progression after SRS, 18 (49%) patients underwent gross total resection, 10 (27%) underwent near-total resection, and nine (24%) underwent subtotal resection. Postoperative complications following salvage surgery included one (3%) case of stroke, four (11%) cases of cerebrospinal fluid leak, and two (5%) cases of meningitis. Twenty-seven (73%) patients had good postoperative facial nerve outcome (House-Brackmann Score I–II) at long-term fol- low-up. There were no cases of tumor recurrence or regrowth after a median length of 26 months following microsurgical salvage (range 3–114 months). The rate of satisfactory postoperative facial nerve function was not different between study and control subjects (73% vs. 76%; P 5 0.8); however, less-than-complete resection was utilized more frequently among pre- viously radiated patients ( P 5 0.01). Conclusion: Microsurgical salvage of VS following primary radiation therapy is challenging. Less-than-complete resection is required in a greater percentage of patients to preserve facial nerve integrity and prevent neurological complications. Long-term follow-up is needed to determine the risk of delayed progression following incomplete tumor removal. Key Words: Vestibular schwannoma, acoustic neuroma, recurrence, radiosurgery, gamma knife, microsurgery. Level of Evidence: Level 3.

Laryngoscope , 00:000–000, 2016

INTRODUCTION The primary goals of vestibular schwannoma (VS) management include long-term tumor control, preserva- tion of hearing and facial nerve function, and mainte- nance of quality of life. 1 Currently, there are three primary management strategies for small- to medium- sized VSs, including microsurgery, radiation, and obser- vation. 2 Over the past decade, there has been a trend in the United States toward less frequent use of microsur- gery, increasing primary observation, and the use of radiation remaining fairly steady. 3 Options for radiation therapy include stereotactic radiosurgery delivered in one to five fractions (stereotactic radiotherapy [SRS]), fractionated SRS ( > 5 fractions), and proton beam ther- From the Department of Otolaryngology–Head and Neck Surgery ( S . C . W ., M . L . C ., C . L . D ., M . J . L .); the Department of Neurologic Surgery ( M . L . C ., C . L . D ., M . J . L .), Mayo Clinic School of Medicine, Rochester, Minnesota, U.S.A.; the Department of Neurosurgery, Haukeland University Hospital ( Ø . V . T ., E . M ., M . L - J .); and the Department of Clinical Medicine, University of Bergen ( Ø . V . T ., M . L - J .), Bergen, Norway. Editor’s Note: This Manuscript was accepted for publication February 2, 2016. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Michael J. Link, MD, Department of Neu- rologic Surgery, Mayo Clinic, 200 First St SW, Rochester, Minnesota, 55905. E-mail: link.michael@mayo.edu

apy. Currently, single fraction SRS is by far the most common radiation modality used for VS in the United States. 4 Stereotactic radiotherapy carries minimal risk of perioperative morbidity or mortality, and the period of convalesce is negligible, making it an attractive treat- ment choice for many patients. More than 77,000 VSs have been treated with Gamma Knife (Elekta Instruments AB, Stockholm, Swe- den) radiosurgery alone as of 2013. 5 The reported rate of radiation failure, with progressive tumor growth, is less than 10%. 4 Subsequent treatment and outcomes of VS that fail primary radiation therapy are less well docu- mented. With a growing number of patients receiving low-dose radiosurgery, the ability to manage postradia- tion tumor progression will become increasingly rele- vant. Microsurgical resection is a common salvage therapy in this setting because repeat radiation therapy is thought by many to carry increased adverse risk and a higher rate of secondary failure, with limited data available to support this alternate treatment paradigm. Most authors agree that operating on previously radiated VS is more difficult compared to primary treat- ment. 6–9 Recognizing the greater risks of VS surgery after radiation, it was recently emphasized that subtotal resection should be considered in cases for which an unfavorable dissection plane exists between the tumor and facial nerve in order to preserve facial nerve

DOI: 10.1002/lary.25943

Wise et al.: Surgical Salvage for Recurrent VS

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