Principal Risk of Peritumoral Edema After Stereotactic Radiosurgery for Intracranial Meningioma Is Tumor-Brain Contact Interface Area

OBJECTIVE: Stereotactic radiosurgery (SRS) of meningiomas is associated with posttreatment peritumoral edema (PTE). The purpose of this study was to evaluate the prevalence and risk factors of post-SRS PTE for intracranial meningiomas. METHODS: A total of 163 patients with 182 meningiomas treated with SRS were retrospectively reviewed. Tumors were divided into 4 pre-SRS groups according to whether they had undergone previous surgery and whether they had preexisting PTE. Several risk factors were investigated by univariate and multivariate analysis in all tumors, tumors without previous surgery, tumors without preexisting PTE, and preexisting PTE. RESULTS: Of 182 tumors, 45 (24.7%) developed post-SRS PTE. Compared with tumors without preexisting PTE, the odds of developing post-SRS PTE in tumors with preexisting PTE were 6.0 times higher in all tumors, and 6.9 times higher in tumors without previous surgery. A 1-cm(2) increase in tumor-brain contact interface area increased the odds of developing post-SRS PTE by 17% in all tumors, 16% in tumors without previous surgery, and 26% in tumors without preexisting PTE. Of 118 tumors without previous surgery, 13 had preexisting PTE, the existence of which had a significant relationship to both tumor-brain contact interface area and tumor volume. CONCLUSION: Post-SRS PTE is common in patients with meningioma. Tumor-brain contact interface area and preexisting PTE were the most significant risk factors for post-SRS PTE. Tumor volume and tumor-brain contact interface area were significant risk factors for the development of preexisting PTE.