Low-Dose Gamma Knife Radiosurgery for Vestibular Schwannomas: Tumor Control and Cranial Nerve Function Preservation After 11 Gy.
This study aims to report tumor control rates and cranial nerve function after low dose (11.0 Gy) Gamma knife radiosurgery (GKRS) in patients with vestibular schwannomas.



A retrospective chart review was performed on 30 consecutive patients with vestibular schwannomas treated from March 2004 to August 2010 with GKRS at the Robert H. Lurie Comprehensive Cancer Center of Northwestern University. The marginal dose for all patients was 11.0 Gy prescribed to the 50% isodose line. Median follow-up time was 42 months. The median treatment volume was 0.53 cm3. Hearing data were obtained from audiometry reports before and after radiosurgery.



The actuarial progression free survival (PFS) based on freedom from surgery was 100% at 5 years. PFS based on freedom from persistent growth was 91% at 5 years. One patient experienced tumor progression requiring resection at 87 months. Serviceable hearing, defined as Gardner-Robertson score of I-II, was preserved in 50% of patients. On univariate and multivariate analyses, only higher mean and maximum dose to the cochlea significantly decreased the proportion of patients with serviceable hearing.



Vestibular schwannomas can be treated with low doses (11.0 Gy) of GKRS with good tumor control and cranial nerve preservation.
Department of Radiation Oncology, Kaiser Permanente, Los Angeles, California, United States.
Andrew J
AJ
Schumacher
Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States.
Rohan R
RR
Lall
Department of Neurological Surgery, University of Texas Medical Branch, Galveston, Texas, United States.
Rishi R
RR
Lall
Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States.
Allan
A
Nanney
Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States.
Amit
A
Ayer
Department of Radiation Oncology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States.
Samir
S
Sejpal
Department of Radiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States.
Benjamin P
BP
Liu
Department of Radiation Oncology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States.
Maryanne
M
Marymont
Department of Radiation Oncology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States.
Plato
P
Lee
Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States.
Bernard R
BR
Bendok
Department of Radiation Oncology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States.
John A
JA
Kalapurakal
Department of Neurological Surgery, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States.
James P
JP
Chandler
acoustic; neuroma; radiosurgery; vestibular schwannoma