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Radiologic and histopathologic changes after Gamma Knife radiosurgery for acoustic schwannoma
1Department of Neurological Surgery, Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Korea. ykwon@www.amc.seoul.kr
Stereotactic and Functional Neurosurgery
|February 22, 2000
Summary
Gamma knife radiosurgery (GKRS) effectively controls most acoustic schwannomas, with 91% showing stable or reduced volume. However, some larger tumors may develop cysts requiring surgery.
Area of Science:
- Neurosurgery
- Radiation Oncology
- Oncology
Background:
- Acoustic schwannomas are tumors that develop on the nerve connecting the ear to the brain.
- Gamma Knife Radiosurgery (GKRS) is a common treatment for smaller acoustic schwannomas.
Purpose of the Study:
- To evaluate the efficacy and outcomes of Gamma Knife Radiosurgery (GKRS) for acoustic schwannomas.
- To assess tumor volume changes and complications following GKRS treatment.
Main Methods:
- Retrospective analysis of 102 acoustic tumors in 101 patients treated with GKRS between May 1990 and February 1998.
- Follow-up data for 77 patients with over six months of observation (mean 55 months).
- Comparison of pre- and post-GKRS histological findings for four tumors with volume changes.
Main Results:
- 91% (70/77) of tumors remained unchanged or reduced in volume post-GKRS.
- Seven cases showed tumor volume increase; four involved solid tumors, with one requiring surgery for brain stem compression.
- Three cases developed cysts causing brain stem and fourth ventricle compression, necessitating surgery; MRI showed transient contrast enhancement changes.
Conclusions:
- GKRS is an effective treatment for controlling acoustic schwannoma volume in the majority of patients.
- Cyst formation and subsequent compression can occur, particularly after treating larger tumors, potentially requiring surgical intervention.
- Histological analysis did not reveal definitive radiation-induced changes despite observed MRI alterations.