Vascular supply of the hindbrain: Basic longitudinal and axial angioarchitecture

The basic pattern of arterial vascularization is highly conserved across vertebrates and develops under neuromeric rules. The hindbrain has an angioarchitecture that is homologous to that of the spinal cord, and the hindbrain vascular system can be analyzed at the longitudinal and axial structures. During development, there are two main longitudinal arteries: the longitudinal neural artery and primitive lateral basilovertebral anastomosis. This review discusses the basic pattern of the blood supply of the hindbrain, the development of vascularization, and the anatomical variations, with a special reference to the embryological point of view of two main longitudinal anastomoses (longitudinal neural artery and primitive lateral basilovertebral anastomosis). The formation of commonly observed variations, such as fenestration and duplication of the vertebrobasilar artery, or primitive trigeminal artery variant, can be explained by the partial persistence of the primitive lateral basilovertebral anastomosis. Understanding the pattern and the development of the blood supply of the hindbrain provides useful information of the various anomalies of the vertebrobasilar junction and cerebellar arteries.

Fenestration of the cavernous internal carotid artery associated with a persistent primitive trigeminal artery

Fenestration of the cavernous segment of the internal carotid artery (ICA) is an extremely rare variant with unknown clinical significance. We present two cases of this variant, both of which were associated with a persistent primitive trigeminal artery (PPTA). Large dual channels of the ICA were seen extending from the part immediately distal to the origin of the PPTA to the C3 segment of the ICA. We speculate that coexistence of the two vascular anomalies might be due to failed regression or a remnant of the primitive arterial network during the same early gestation period in which development of the PTA takes place (3-5 mm crown-rump length stage).

Successful mechanical thrombectomy using a combined technique for internal carotid artery occlusion with persistent primitive trigeminal artery

Background: The prevalence of persistent primitive trigeminal artery (PPTA) has been reported to be 0.1–0.6%. We report the successful recanalization of internal carotid artery (ICA) without embolization to new vascular territory (ENT) using a combined technique in a case of ICA occlusion with PPTA. Case Description: A 65-year-old female presented with sudden consciousness disorder. The Glasgow Coma Scale score was 7 (E1, V1, M5) and National Institutes of Health Stroke Scale score was 28. Magnetic resonance diffusion-weighted imaging showed areas of high signal intensity in the left frontal lobe, parietal lobe, insular cortex, and corona radiata. Magnetic resonance angiography showed occlusion of the left ICA distal to a PPTA. We performed mechanical thrombectomy (MT) using a combined technique with a balloon guide catheter (BGC), aspiration catheter, and stent retriever and achieved complete recanalization without ENT. The patient experienced a good postoperative recovery course. At 6 months, her Modified Rankin Scale score was 2. Conclusion: MT using a combined technique with BGC would be useful to prevent embolization to the posterior circulation through the PPTA in cases of ICA occlusion with PPTA.