Gamma knife radiosurgery in younger patients with vestibular schwannomas.
OBJECTIVE
Management options for patients with vestibular schwannoma include observation, surgical resection, stereotactic radiosurgery (SRS), and stereotactic radiation therapy. In younger patients, resection is often advocated because of concern regarding the long-term effects of radiation. We studied tumor response and clinical outcomes after SRS in such patients.


METHODS
We reviewed long-term outcomes in 55 patients with vestibular schwannomas. Patients were 40 years of age or younger, underwent gamma knife (GK) SRS between 1987 and 2003, and were followed up for a minimum of 4 years. The median patient age was 35 years (range, 13-40 years). Forty-one patients had Gardner-Robertson class 1 to 4 hearing. Thirteen patients (24%) had undergone surgical removal. The median tumor volume was 1.7 mm. The median tumor margin dose was 13.0 Gy (range, 11-20 Gy).


RESULTS
At a median of 5.3 years, (range, 4-20 years), 2 of 55 patients underwent GK SRS for a second time; 1 of these patients had had a recurrence after initial resection. The 5-year rate of freedom from additional management was 96%. Hearing preservation rates (i.e., remaining within the same Gardner-Robertson hearing class) were 93%, 87%, and 87% at 3, 5, and 10 years, respectively. In patients with serviceable hearing before SRS, it was maintained in 100%, 93%, and 93% of patients at 3, 5, and 10 years, respectively. Hearing preservation was related to a margin dose lower than 13 Gy (P = 0.017). At the last assessment, facial and trigeminal nerve function was preserved in 98.2% and 96.4% of patients, respectively; the only facial deficit (House-Brackmann grade III) occurred in a patient who received a tumor dose of 20 Gy early in our experience (1988). None of the patients treated with doses lower than 13 Gy experienced facial or trigeminal neuropathy. All patients continued their previous level of activity or employment after GK SRS. No patient developed a secondary radiation-related tumor.


CONCLUSIONS
Our experience indicates that GK SRS is an effective management strategy for younger patients with vestibular schwannoma, most of whom have no additional cranial nerve dysfunction.
Lobato-Polo
Javier
J
Department of Neurological Surgery and the Center for Image-Guided Neurosurgery, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
Kondziolka
Douglas
D
Zorro
Oscar
O
Kano
Hideyuki
H
Flickinger
John C
JC
Lunsford
L Dade
LD
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D003056:Cochlear Nerve / Q000503:physiopathology / Q000528:radiation effects; D003390:Cranial Nerve Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D005154:Facial Nerve / Q000503:physiopathology / Q000528:radiation effects; D020220:Facial Nerve Injuries / Q000453:epidemiology / Q000517:prevention & control; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000453:epidemiology / Q000517:prevention & control; D006801:Humans; D008297:Male; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology / Q000517:prevention & control / Q000601:surgery; D009464:Neuroma, Acoustic / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D017063:Outcome Assessment, Health Care; D011183:Postoperative Complications / Q000453:epidemiology*; D011829:Radiation Dosage; D011859:Radiography; D016634:Radiosurgery / Q000009:adverse effects / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D016896:Treatment Outcome; D014276:Trigeminal Nerve / Q000503:physiopathology / Q000528:radiation effects; D020433:Trigeminal Nerve Diseases / Q000453:epidemiology / Q000517:prevention & control; D014725:Vestibular Nerve / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D055815:Young Adult