Successful recanalization for internal carotid artery occlusion with persistent primitive trigeminal artery manifesting only as ischemia of the posterior circulation.

BACKGROUND Internal carotid artery (ICA) occlusion mainly manifests as ischemia of the anterior circulation. There are very few reports of ICA occlusion manifesting as only ischemia of the posterior circulation related to a fetal type posterior communicating artery or other arteries. CASE PRESENTATION The authors experienced a case of ICA occlusion with persistent primitive trigeminal artery (PPTA) manifesting only as ischemia of the posterior circulation. In this case, the initial NIHSS score was high (35/42 points). Additionally, cross flow of the anterior communicating artery, ICA occlusion and basilar artery (BA) occlusion were represented on the initial head MRA. Therefore, our first impression was a presumptive diagnosis of BA occlusion. Prior head MRI/MRA performed for screening purposes, had incidentally demonstrated a right PPTA. Based on this understanding, we were able to determine the exact angioarchitectural mechanism of the ICA occlusion. Because of the presence of the PPTA, successful recanalization was accomplished expeditiously. CONCLUSION Although the presence of PPTA is rare and ICA occlusion patients with PPTA is even more unusual, if ICA occlusion and BA occlusion appear simultaneously on MRA, the presence of PPTA should be considered.