Analysis of treatment outcome after stereotactic radiosurgery for cavernous sinus meningiomas

Object. The long-term outcome of stereotactic radiosurgery for cavernous si nus (CS) meningiomas is not fully understood. The authors retrospectively r eviewed their experience with 40 CS meningiomas treated with gamma knife ra diosurgery. Methods. Follow-up periods for the 40 patients ranged from 12 to 123 months (median 42 months), and the overall tumor control rates were 86.4% at 3 ye ars and 82.3% at 10 years. Factors associated with tumor recurrence in univ ariate analysis were histological malignancy (p < 0.0001). partial treatmen t (p < 0.0001), suprasellar tumor extension (p = 0.0201), or extension in m ore than three directions outside the CS (p = 0.0345). When the tumor was c ompletely covered with a dose to the margin that was higher than 14 Gy (Gro up A, 22 patients), no patient showed recurrence within the median follow-u p period of 37 months. On the other hand, when a part of the tumor was trea ted with 10 to 12 Gy (Group B, 15 patients) or did not receive radiation th erapy (Group C, three patients), the recurrence rates were 20% and 100%, re spectively. Neurological deterioration was seen in nine patients, but all s ymptoms were transient or very mild. Conclusions. The data indicate that stereotactic radiosurgery can control t umor growth if the whole mass can be irradiated by dosages of more than 14 Gy. When optimal radiosurgical planning is not feasible because of a tumor' s large size, irregular shape, or proximity to visual pathways, use of limi ted surgical resection before radiosurgery is the best option and should pr ovide sufficient long-term tumor control with minimal complications.