[Post-radiotherapy stenosis of the supraclinoid internal carotid artery. Moyamoya network]

A 36 year-old caucasian woman was operated and then irradiated for a pituitary adenoma. Two years later, a left anterior temporal lobectomy for a grade I astrocytoma was performed. Four years later, she experienced right hemiparesis and aphasia. CT scan showed a left temporo-occipital low density area. A left carotid angiogram showed a narrowing of the left carotid artery beginning in the lower part of the siphon and progressing to a complete supraclinoid occlusion. There was a collateral circulation of the Moyamoya type. Radiation-induced narrowing or occlusion of the intracranial internal carotid artery is an infrequent finding. Most cases appear in young subjects, several years after a high dose of radiation therapy (30 to 60 grays). Some cases may show a network of the Moyamoya type. Usually, the absence of vascular abnormalities prior to radiation cannot be demonstrated. In our case, as in 3 other cases of the literature, the intracranial vessels were of normal appearance before irradiation. The vascular lesions can thus be considered as acquired and secondary to radiation therapy.