Gamma Knife Radiosurgery for the Management of Glomus Tumors: A Multicenter Study Jason P. Sheehan, PhD1, Shota Tanaka2, Michael J Link3, Douglas Kondziolka, MSc, MD4, David Mathieu, MD5, Christopher Duma6, A. Byron Young7, Anthony M Kaufmann8, Heyoung McBride9, Zhiyuan Xu10, L. Dade Lunsford111Department of Neurosurgery, University of Virginia 2Massachusetts General Hospital 3Mayo Clinic 4Department of Neurological Surgery, University of Pittsburgh 5Division of Neurosurgery, Université de Sherbrooke, Centre Hospitalier Universitaire de Sherbrooke 6Newport Beach, United States 7University of Kentucky 8University of Manitoba 9Phoenix, United States 10University of Virginia 11University of Pittsburg Keywords: glomus tumor, brain tumor, gamma knife, radiosurgery, skull baseInteractive ManuscriptAsk Questions of this Manuscript: What is the background behind your study?Glomus tumors are rare skull base neoplasms that frequently involve critical cerebrovascular structures and lower cranial nerves. Complete resection is often difficult and may increase cranial nerve deficits. Stereotactic radiosurgery has gained an increasing role in the management of patients with glomus tumors. What is the purpose of your study?This study examines the outcomes after radiosurgery in a large, multicenter patient population. Describe your patient group.One hundred and thirty four patients were included in the study. Prior resection was performed in 51 patients and prior fractionated external beam radiotherapy was performed in six patients. Median age at the time of radiosurgery was 59 years. Forty percent of patients had pulsatile tinnitus at the time of radiosurgery. Patients received a median dose of 15 Gy to the tumor margin. The median follow-up was 50.5 months (range 5 to 220 months). Describe what you did.Under the auspices of the North American Gamma Knife Consortium (NAGKC), eight Gamma Knife radiosurgery (GKRS) centers that treat glomus tumors retrospectively combined their outcome data. Describe your main findings.Overall tumor control was achieved in 93% of patients at last follow up; actuarial tumor control was 88% at 5 years post-radiosurgery. The absence of trigeminal nerve dysfunction at the time of radiosurgery (p=0.001), and higher number of isocenters (p=0.005) were statistically associated with progression free tumor survival. Those demonstrating new or progressive cranial nerve deficits were also likely to demonstrate tumor progression (p=0.002). Pulsatile tinnitus improved in 49% of patients who demonstrated it at presentation. New or progressive cranial nerve deficits were noted in 15% of patients; improvement in pre-existing cranial nerve deficits was observed in 11% of patients. No patient died as a result of tumor progression. Describe the main limitation of this study.This was a retrospective study. Describe your main conclusion.Gamma Knife radiosurgery was a well tolerated management strategy that provided a high rate of long term glomus tumor control. Symptomatic tinnitus improved in almost one half of the patients. Describe the importance of your findings and how they can be used by others.Overall neurological status and cranial nerve function were preserved or improved in the vast majority of patients after radiosurgery. Glomus tumors are rare skull base neoplasms that frequently involve critical cerebrovascular structures and lower cranial nerves. Complete resection is often difficult and may increase cranial nerve deficits. Stereotactic radiosurgery has gained an increasing role in the management of patients with glomus tumors. This study examines the outcomes after radiosurgery in a large, multicenter patient population. One hundred and thirty four patients were included in the study. Prior resection was performed in 51 patients and prior fractionated external beam radiotherapy was performed in six patients. Median age at the time of radiosurgery was 59 years. Forty percent of patients had pulsatile tinnitus at the time of radiosurgery. Patients received a median dose of 15 Gy to the tumor margin. The median follow-up was 50.5 months (range 5 to 220 months). Under the auspices of the North American Gamma Knife Consortium (NAGKC), eight Gamma Knife radiosurgery (GKRS) centers that treat glomus tumors retrospectively combined their outcome data. Overall tumor control was achieved in 93% of patients at last follow up; actuarial tumor control was 88% at 5 years post-radiosurgery. The absence of trigeminal nerve dysfunction at the time of radiosurgery (p=0.001), and higher number of isocenters (p=0.005) were statistically associated with progression free tumor survival. Those demonstrating new or progressive cranial nerve deficits were also likely to demonstrate tumor progression (p=0.002). Pulsatile tinnitus improved in 49% of patients who demonstrated it at presentation. New or progressive cranial nerve deficits were noted in 15% of patients; improvement in pre-existing cranial nerve deficits was observed in 11% of patients. No patient died as a result of tumor progression. This was a retrospective study. Gamma Knife radiosurgery was a well tolerated management strategy that provided a high rate of long term glomus tumor control. Symptomatic tinnitus improved in almost one half of the patients. Overall neurological status and cranial nerve function were preserved or improved in the vast majority of patients after radiosurgery. Project Roles:
J. Sheehan (), S. Tanaka (), M. Link (), D. Kondziolka (), D. Mathieu (), C. Duma (), A. Young (), A. Kaufmann (), H. McBride (), Z. Xu (), L. Lunsford ()
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