Occlusion of the internal carotid artery after radiation therapy for the chiasmal lesion.

Occlusion of the intracranial portion of the internal carotid artery were encountered in two cases with suprasellar tumours, who had received irradiation therapy previously and shown excellent clinical improvement postoperatively. Clinical features and the angiographic characteristics were analysed in these two cases and the results were compared with reports in the literature. The occlusive effect of radiation on the arterial wall was conceived as the cause of carotid obstruction. In order to avoid this side effect of radiation therapy, especially for brain tumours of low malignancy in childhood, careful estimation of the radiation dose should be required and cerebral angiographic follow-up during and after the treatment with radiation is indicated, particularly when the patient develops cerebral transient ischaemic symptoms.