Seizures following Proton Beam Therapy for Meningiomas: Case Series and Systematic Review of the Literature

Introduction: Stereotactic radiosurgery (SRS) and proton beam therapy (PBT) are common adjuvant treatments for meningiomas. Compared to SRS, PBT results in a more rapid decrease in radiation beyond the proposed target. Less is known about the side effect profile of PBT for the treatment of meningiomas. We report two cases of new or worsening seizures following PBT and performed a systematic review of the literature to determine the incidence of this adverse event following PBT for meningiomas.

Methods: We reviewed all meningioma patients at our institution who underwent PBT following either surgical resection or a period of observation. Seizures were defined as either witnessed abnormal motor or sensory events without alternative explanation or EEG-confirmed seizure activity. Patients with “worsened” seizure activity were defined as those with breakthrough seizure events despite ongoing therapy or a change in severity of previous seizures. We then performed a systematic review of Medline, Embase, and Google Scholar for English language publications between January 1, 2008, and February 28, 2023. All potential studies were screened by title and abstract for inclusion by 2 independent reviewers. Full text review was performed by the same 2 reviewers and relevant data extracted from the publications where possible. Any disagreements were settled by a third-party reviewer. We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement.

Results: Our institutional review found two patients who developed new or worsening seizures following PBT. These events occurred within 3 months following therapy in both patients. Our systematic review identified 153 potential articles. Fifty were included for full text review, and 16 studies were ultimately included. All studies were case reports, case series, or retrospective cohort studies. We identified 707 total patients across these 16 publications ([Table 1]). A total of 156 (22.1%) patients experienced any complication following PBT. Five (0.7%) patients developed new (2, 0.28%) or worsening (3, 0.42%) seizures ([Table 2]). Including our 2 patients, 5 (71.4%) of post-PBT seizures occurred in patients with meningiomas located in the middle fossa. Median follow-up ranged from 11 to 145.2 months.

Conclusions: PBT has become an increasingly applied modality for meningiomas. The side effect profile has not been well established. Seizures are a rare but reported adverse event following PBT and anti-seizure medication should be considered in select cases especially those involving middle fossa meningiomas where the temporal lobes may be subject to increased radiation.

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No conflict of interest has been declared by the author(s).

Publication History

Article published online:
05 February 2024