Endoscope-assisted treatment for delayed cystic radiation necrosis after stereotactic radiosurgery for metastatic brain tumors: illustrative cases.

Background: Cystic formation due to radiation necrosis in metastatic brain tumors is a rare condition. Surgical intervention is necessary if symptoms develop. Additionally, excising radiation necrosis lesions within the cyst is essential to prevent recurrence. Neuroendoscopic surgery is a minimally invasive method suitable for treating cystic diseases and accessing deep lesions in the brain. The authors herein present a method for removing radiation necrotic tissue from deep lesions of cystic radiation necrosis using neuroendoscopy.

Observations: Endoscopic surgery was performed in two patients with symptomatic cystic radiation necrosis. Both cases involved multilocular cysts, with radiation necrosis located deep within the cyst. The authors performed a small craniotomy of approximately 3 cm and opened the cyst. After removing its contents, an endoscope was used to closely observe the interior of the cyst. Removal of the septum within the cyst allowed the endoscope to be inserted deeply. The authors identified and excised the nodular lesion diagnosed as radiation necrosis in the deep tissue. Following the surgery, the cyst shrank rapidly, and symptoms disappeared. Both patients showed no recurrence of the lesions.

Lessons: The authors performed minimally invasive surgery and achieved good outcomes. Endoscopic surgery was considered beneficial for treating cystic radiation necrosis. https://thejns.org/doi/10.3171/CASE24250.