Intracranial giant aneurysm due to the effects of radiation

: Two cases of intracranial giant aneurysms of the carotid artery are presented, probably caused by radiation damage. Both patients had been treated for hypophyseal adenoma by transfrontal implantation of yttrium seeds (35 and 45 mCi). Preoperative carotid angiographies had shown no vascular abnormalities; the aneurysms were revealed 8 and 11 years after these examinations. No identical cases could be found in the literature. Further etiological hypotheses are discussed.