Analysis of risk factors associated with radiosurgery for vestibular schwannoma (original) (raw)
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Evolution in technique for vestibular schwannoma radiosurgery and effect on outcome
International Journal of Radiation Oncology*Biology*Physics, 1996
Purpose: To define changes in treatment technique for vestibular scbwannoma radiosurgery and to relate them wges in outcome, a large single institution experience was reviewed. Methods and Materials: Two hundred seventy-three patients with unilateral vestibulsr scbwaunoasasu~derwent Gamma knife radiosurgery: 118 with computed tomography (CT) treatment planning during 1987-1991, and 155 with magnetic resonance imaging (MR) treatment planning in 1991-1994. Mean treatment fered between tbe CT and MR groups: minimum tumor dose @,,& was 17 vs. 14 Gy, number o 3.4 vs. 5.8, and volume was 3.5 vs. 2.7 cc., respectively. Results: The actuarial 7-year clinical tumor control rate (no requirement for surgical b&ervention) for the entire series was 96.4 t 2.3%, with a radiographic tumor control rate of 91.0 ? 3.4% CT and MR groups. Significantly lower rates of postradiosurgery facial, trige were observed in the MR group compared to the CT group. Multivariate analyses correlations of increasing rates of facial and trigemlnal neuropatby with increasing transverse tusng'r diameter and J-b, as well as with CT treatment planning (compared to MR). Decreased hearing was si~larly correlated with diameter and CT planning but not with D,ti. Conclusions: Changes in radiosurgery technique and the use of lower doses improved the ~tcome afte lar schwanuoma radiosurgery by decreasing cranial neuropatby rates. MR-based treatment plam&?g to have significantly contributed to this improvement. Despite decreases in radiation dose, no change in the high rate of tumor control has yet been observed. 77s 276 I.
Radiosurgery for Vestibular Schwannomas
Journal of the Chinese Medical Association, 2005
Background: Radiosurgery has been established as an important alternative to microsurgery. We report our experience with radiosurgery for tumor control and the complications of unilateral vestibular schwannomas. Methods: We reviewed our early experience regarding clinical presentation, management and outcomes in 45 patients with acoustic schwannomas who underwent gamma knife stereotactic radiosurgery. The median follow-up period was 25 months (range, 6-48 months). Thirteen patients had undergone 1 or more previous resections before radiosurgery; 32 underwent radiosurgery as the first procedure. Median tumor volume was 4.5 mL (range, 0.5-30.0), and median radiotherapy dose was 11.5 Gy (range, 10.5-14.0 Gy). Results: Tumor control was achieved in 43 patients (95.6%). Loss of central contrast enhancement was a characteristic change and was noted in 29 patients (64.4%). Reduction in tumor size was shown in 15 patients (33.3%). Thirteen patients (28.9%) had good or serviceable hearing preoperatively, and in all of these, the preoperative status was retained immediately after radiosurgery. At follow-up, however, 10 patients (76.9%) had preserved hearing and 3 (23.1%) had reduced hearing on the treated side. Hearing in 1 patient that was not serviceable preoperatively later improved to a serviceable level. No patients had delayed facial palsy or lower cranial nerve dysfunction, but one had delayed trigeminal sensory loss. Conclusion: Radiosurgery achieved a high tumor control rate and a relatively low post-radiosurgical complication rate for acoustic neuromas. [
Journal of Neurosurgery, 2016
G amma Knife radiosurgery (GKRS) has become a widely accepted primary treatment modality for small-to medium-size vestibular schwannomas (VSs). Although rates of tumor control after radiosurgery are comparable to those after microsurgery, the advantages of radiosurgery, apart from being a less invasive procedure, include better preservation of cranial nerve (CN) function and of serviceable hearing. 11,20 In the early radiosurgery era, marginal radiation doses as high as 20-70 Gy were applied. 21 This dosage was gradually reduced to 12-13 Gy, after it was shown that lower marginal doses achieved equivalent tumor control but resulted in significantly lower complication rates. 12,18 The first GKRS treatment for VS in the Gamma Knife abbreviatioNs CN = cranial nerve; GKRS = Gamma Knife radiosurgery; VS = vestibular schwannoma.
Journal of Neurological Surgery Part B: Skull Base, 2016
Objectives 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. Methods 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 cm 3. Hearing data were obtained from audiometry reports before and after radiosurgery. Results 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. Conclusion Vestibular schwannomas can be treated with low doses (11.0 Gy) of GKRS with good tumor control and cranial nerve preservation.
Follow-up after gamma knife radiosurgery for vestibular schwannomas
The Laryngoscope, 2011
Objectives/Hypothesis: A prospective long-term follow-up study was conducted to evaluate the results of gamma knife radiosurgery (GKRS) for vestibular schwannoma (VS) patients. Both axial and volumetric measurements are used to determine tumor size during follow-up.