CEREBELLAR ARTERIES ORIGINATING FROM THE INTERNAL CAROTID-ARTERY

PURPOSE: To study the incidence of cerebellar arteries originating dir ectly from the internal carotid artery, and to discuss the probable em bryological origin and clinical implications of this anatomical anomal y. METHODS: We reviewed 5500 angiographic studies done at our institut ion in the last 4 years, searching for these anomalous vessels as well as for other anatomical variants. RESULTS: Eleven cerebellar arteries originating directly from the internal carotid artery and nine embryo nic cerebral arteries were found. CONCLUSION: These arteries are consi dered persistent trigeminal artery variants and seem to occur as the r esult of the persistence of a primitive trigeminal artery associated w ith an incomplete fusion of the longitudinal neural arteries. These an omalous vessels are clinically significant particularly becuase of the ir role in endovascular therapeutic and surgical complications and the paradoxical lesions in the cerebellum that occur as a result of carot id disease.