On the Clinical Significance of the Primitive Trigeminal Artery

The clinical syndrome and the arterio-graphical findings in seven patients with a primitive trigeminal artery are described. The primitive trigeminal artery is associated with other congenital anomalies, usually of the vascular system. A large primitive trigeminal artery can be associated with hypoplastic vertebral arteries and absence of posterior communicating arteries. In such cases the brainstem circulation may depend on the primitive trigeminal artery. The clinical significance of such a situation is discussed.