Outcome of large vestibular schwannoma treated with intracapsular decompression or radical resections followed by gamma knife radiosurgery

Hung-Chuan Pan, PhD1, Ming-Hsi Sun2, Dar-Yu Yang3

1Department of Neurosurgery, University of Virginia 2Department of Neurosurgery, Taichung Veterans General Hospital, Taiwan 3Department of Neurosurgery, Chang Bing Show Chwan Memorial Hospital, Taiwan

Keywords: vestibular schwannoma, resection, gamma knife, outcome, facial nerve function

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     Microsurgery was the mainstay in the treatment of large vestibular schwannoma. However, the outcome of microsurgery was counteracted by the hearing loss and facial nerve dysfunction. 
     In this study, we investigate the outcome of intracapsular decompression followed by gamma knife radiosurgery (GK) compared to the attempted microsurgery followed by GK.
     From August 2003 to October 2008, there were 35 patients with large vestibular schwannoma (>3cm in diameter) at least 3 years follow up entering into this study including 18 patients treated with intracapsular decompression followed by GK (group I) and 17 patients treated with radical resection followed by GK (group II). Marginal dose of 12 Gy were delivered to residual tumor.
      All patients received hearing test, electroneuronography (ENoG), SF-36, and MRI periodically. Student’s test and repeated ANOVA were used for statistical analysis.
     The age distribution of group I and II were 50 ± 3 and 49±2.3, respectively. The sex distribution of (F/M) were 8/10 and 7/10, respectively. After operation, 16 patients (89%) in group I and 6 patients (35%) in group II preserved excellent facial function (p<0.01). Eleven of 11 patients (100%) and 0 of11 (0%) had servable hearing post-operatively in group I and II, respectively (p<0.001). In group I, the mean tumor volume was 17.5 ± 1.1ml and post operative volumes were 9.53 ± 1.02 ml. In group II, the mean tumor volume was 16.4±0.95 ml, whereas post operative volume was 1.1±1.04 ml (p<0.001). After GK, the tumor volume was shrunk to 5.12±1.1 and 0.9 ±0.1ml (p<0.001), respectively at the last follow up. All patients did not experience adverse effect after GK. The time of returning to work was 2.4 ± 0.16 and 33.4 ± 4.3 weeks, in group I and II, respectively (p<0.001). There were better quality of life in group I than in group II such as RF (p<0.001), RE (p<0.001), and SF (p<0.001).
     This was a retrospective study.
     Intracaspsular decompression followed by GK seemed better than the attempted microsurgery followed by GK not only in hearing and facial nerve function preservation but also via substantial improvement in quality of life.
     Combined strategies for large tumors may improve outcomes.


Project Roles:

H. Pan (), M. Sun (), D. Yang ()