Peritumoral edema after stereotactic radiosurgery for meningioma

Peritumoral edema induced by radiosurgery after the treatment of intracranial meningioma has been reported and its mechanism remains unclear. A 65-year-old woman presented with a history of intermittent dizziness. A CT scan and MRI of the brain revealed an extra-axial space-occupying lesion in the left frontal region. She was treated by stereotactic radiosurgery (SRS). Seven months later, the patient began experiencing general weakness and drowsiness. She developed peritumoral edema around the left frontal tumor. Similarly, a 55-year-old woman complained of unstable gait and dizziness 1 month prior to admission. A CT scan and MRI of the brain revealed an extra-axial space-occupying lesion in the right posterior temporal region. Six months after SRS, this patient experienced deteriorated consciousness and general weakness. Peritumoral edema in the right temporal region was noted. We report these two patients, discuss possible causes and review the relevant literature.