Objectives Radiation-induced aneurysm is a rare complication for head and neck tumors. Only seven cases of an aneurysm after stereotactic radiosurgery and/or stereotactic radiotherapy (SRT) have been described. We report two patients with a ruptured internal carotid artery (ICA) aneurysm presenting with catastrophic epistaxis after repeated SRT for an anterior skull base tumor. Results Two male patients received repeated SRT in various combinations following surgery for an anterior skull base tumor. They presented with significant epistaxis due to rupture of the aneurysm of the ICA 6 and 77 months after the final SRT, respectively. The aneurysms were located within the radiation field. Preoperative angiography had revealed no aneurysms. Thus the aneurysms in these cases were most likely induced by the repeated SRT. Conclusions This is a proven report of aneurysm formation following repeated SRT without conventional radiotherapy. SRT may be very effective to control malignant skull base tumors. However, the possible development of radiation-induced aneurysm of the ICA should be considered in the case of repeated SRT. The surviving patients who have received SRT should undergo sequential follow-up for possible vascular involvement.
Keywords: anterior skull base tumor; carotid artery aneurysm; radiation-induced aneurysm; stereotactic radiosurgery; stereotactic radiotherapy.