Two-staged gamma knife radiosurgery for the treatment of large petroclival and cavernous sinus meningiomas

Background In this study. we report on the effectiveness and usefulness of two-staged gamma knife radiosurgery (GKS) for large petroclival and cavernous sinus meningiomas that have a high rate of surgical morbidity. Methods We have treated 7 patients suffering from large petroclival and cavernous sinus meningiomas using two-staged radiosurgery since March 1995. The tumors were located in the petroclival region in 4 patients, the cavernous sinus region in 2 patients, and in the petrocavernous region in the remaining patient. Three of the patients had been surgically treated and 4 patients (57%) were only followed with MR imaging. The volume of the tumors ranged between 34.5 to 101 cm(3) (mean 53.5 cm(3)). The treatment volume was between 6.8 to 29.6 cm(3) (mean 18.6 cm(3)). The treatment interval between the first GKS and second GKS was 6 months. The marginal doses for the tumors were 8 to 12 Gy (mean, 9 Gy). Results Six patients demonstrated tumor growth control during the follow-up period after the first radiosurgery (mean 39 months). Tumor regression was observed in 3 patients (43%). Three patients (43%) had improved clinically by the time of the follow-up examinations. No patient suffered from symptomatic radiation injury. Conclusion Although we have treated only 7 patients using two-staged GKS, we believe this treatment may be a very useful option for large petroclival and cavernous sinus meningiomas in selected patients. (C) 2001 by Elsevier Science Inc.