We used our prospective patient registry to obtain data imaging and clinical outcomes. Additional volumetric measurements were made from imaging data.

279 motor cortex metastases with volumes from 0.01 cm³ to 12.18 cm³ (mean 0.74 cm³) in 208 patients treated with SRS between 2012 and 2021 were analyzed. Margin dose varied from 10 Gy to 20 Gy (mean 16.9 Gy). Control rate after SRS was 97.8%. Perilesional edema was seen in up to 25% of tumors at presentation. After SRS, adverse radiation effects (ARE) were noted in 6% of all tumors, symptomatic in 1.4%. Median time to symptomatic ARE was 8 months. All patients with ARE exhibited edema post treatment. Edema without ARE was seen in an additional 13%. New focal seizures were seen in 5 patients (2%), and new generalized seizures in 1 (0.3%). Thirty-six patients (17%) presented with motor deficits. At final follow up, 85% were improved or unchanged – 13 (41%) had a normal exam, 10 (31%) had mild deficits, and 9 (28%) still had moderate deficits. New brain metastases were found in 31% of patients at a median of 8 months. KPS improved following SRS in 24%. Median survival after radiosurgery was 10 months. Absence of neurological deficit, RPA Class I and II, and margin dose > 18 Gy were each associated with a significant survival advantage on univariate analysis.