Imaging of vestibular schwannomas following γ-Knife treatment – a series of 79 cases

Gamma-Knife became an established therapeutic alternative for selected cases of vestibular schwannomas (benign tumors rooting from Scwann cells of vestibular nerve). However, the long term results and effects on the tumor and surrounding brain are still a matter of research. We analyze the imagistic findings in the patients with vestibular scwannomas treated with gamma-knife radiosurgery in the GammaKnife Department, Hygeia Hospital, Athens. We performed radiosurgery on 79 cases of vestibular scwannomas. 23 of them were first operated with incomplete resection and had gamma-knife performed on residual tumor. Of all cases, one patient died 4 years after the treatment, while 4 cases didn’t comply with the follow-up protocol and were excluded from the study. The other cases underwent a follow-up protocol with MRI sudies at 6, 12, 18, and 24 months following the gamma-knife session. We looked at the tumoral volume, and the evolution of the tumor in relationship with the iradiation dise and isodose curve. Our results confirm the landmark results of Karolinska an Pittsburg studies. We show that small gamma-knife doses are suitable for a satisfactory control of tumoral volume. Stereotactic MRI imaging and multiple doses programs are the main factors contributing to these results.