Stereotactic Radiosurgery-Induced Peritumoral Edema in Asymptomatic Convexity, Parasagittal, and Parafalcine...

To evaluate the incidence and identify the risk factors of stereotactic radiosurgery (SRS)-induced peritumoral edema (PTE) in the asymptomatic convexity, parasagittal, and parafalcine meningiomas without pre-existing PTE.

We retrospectively analyzed 52 patients with asymptomatic convexity, parasagittal, or parafalcine meningiomas without pre-existing PTE who underwent single-fraction Gamma Knife radiosurgery between 2019 and 2024. The median tumor volume and the maximum tumor diameter were 3.3 cc (range: 0.31–10.2 cc) and 2.0 cm (range: 0.98–3.1 cm), respectively. The median margin dose was 12 Gy (range: 11 Gy–13 Gy). The median radiological and clinical follow-up durations were 21 months (range: 6–65 months) and 26 months (range: 12–66 months), respectively.

SRS-induced PTE occurred in 5.8% of patients (n=3), exclusively in elderly individuals (≥65 years) with parasagittal or parafalcine meningiomas. No cases were observed in convexity meningiomas (0/24). Multivariable analysis revealed a trend toward statistical significance for the association between age and SRS-induced PTE (p=0.074). In the overall cohort, the incidence of SRS-induced PTE was significantly higher in elderly patients compared to younger patients (< 65 years) (3/14 vs. 0/38, p=0.016), and this difference remained significant within the parasagittal/parafalcine subgroup (3/7 vs. 0/21, p=0.011).

SRS appears to be a safe treatment modality in terms of PTE risk in patients aged below 65 years with asymptomatic convexity, parasagittal, or parafalcine meningiomas without pre-existing PTE. In contrast, elderly patients with parasagittal or parafalcine meningiomas may be more susceptible to SRS-induced PTE, thereby warranting a more cautious approach to SRS in this subgroup. Additional studies involving larger cohorts are warranted to validate these findings.