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Variable Practice Patterns and Seizure Outcomes In the Radiosurgical
Treatment of Brain Metastases
Won Kim, MD. UCLA Department of Neurosurgery
Co-author: Michelle Shizu Miller MD, Donatello Telesca PhD, Stephen Tenn
PhD, John Hegde MD, Tania Kaprealian MD.
Introduction: Stereotactic radiosurgery (SRS) has become the mainstay of brain
metastases (BM) treatment. Seizures are a common presenting symptom of
BMs, affecting 15-20% of newly diagnosed patients. However, variable practice
patterns in the initiation and tapering of antiepileptic medications (AEDs) makes
it difficult to determine true seizure risk following SRS. We performed a retro-
spective analysis of our BM patients to delineate our post-SRS seizure rate and
practice pattern variability when it comes to the management of these patients.
Methods: We performed a retrospective analysis of patients receiving SRS at
UCLA from 2013-2020 and identified 444 patients. Patients without 90-day fol-
low-up, supratentorial brain metastases, or SRS as part of their treatment plan
were excluded. Our cohort included 288 patients, of which 155 had sufficient
planning target volume (PTV) to perform additional analyses on the relationship
between overall tumor volume and seizure risk.
Results: Of the 288 patients included in our overall cohort, 34 (11.8%) experi-
enced a seizure prior to SRS. Of the 254 patients that did not have seizures
prior to SRS, 26 (10.2%) had seizures within the 90 days post treatment, of
whom 13 (50%) were on prophylactic AEDs. 13/140 (9.3%) seizure / AED naïve
patients experienced seizures within 90 days post-treatment. Of the 228 pa-
tients (89.8%) that did not have seizures in the 90 days following radiosurgery,
28 (12.3%) were maintained on AED treatment without ever experiencing a
seizure. PTV data was available in 155 patients. PTV was a significant inde-
pendent factor on regression analyses for likelihood of seizures (OR 1.619, SE
0.191, p < 0.012) independent of treatment type.
Conclusion: Our radiosurgery experience demonstrates considerable heteroge-
neity in the practice patterns of AED prescription in patients undergoing treat-
ment with brain metastases. PTV was an independent factor of seizures follow-
ing radiosurgery and may guide the use of prophylactic AEDs.

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