A Study on the Persistent Trigeminal Artery and Its Classification Based on Magnetic Resonance Angiograph Images

The persistent trigeminal artery (PTA) is the most common remnant of primitive circulation, communicating the developing carotid and vertebrobasilar junction.This study aimed to evaluate the implementation of magnetic resonance angiography for the detection of PTA and to reclassify the variations based on Weon typing. Moreover, the correlation of various Weon types with the posterior cerebral artery (PCA), Willis ring, basilar artery (BA) dysplasia, and the relationship between PTA and arteriosclerosis were analyzed.From November 2017 to October 2019, a total of 48,184 patients underwent magnetic resonance angiography examination in our hospital, and 79 patients were diagnosed with PTA. Of these, 70 patients with complete radiological and clinical information were included in this study.Among the 70 patients with complete data, 27 were classified as Weon type I (38.6%), 7 as type II (10%), 14 as type III (20%), 8 as type IV (11.4%), and 3 as type V (4.3%: type Va, 1 case; type Vb, 2 cases). The remaining 11 cases were PCA with mixed blood supply, so the new type VI was divided into 3 subtypes: type VIa, type VIb, and type VIc, and each subtype of type V was further refined into 4 subtypes. There were 32 cases of PTA with BA dysplasia, including 14 with type I (51.9%), 5 with type II (71.4%), 2 with type III (14.3%), 5 with type IV (62.5%), and 6 with type VI (54.5%). Cerebral infarction was found in 55 cases (78.6%) of PTA, among which 11 had a cerebral infarction in the posterior circulation blood supply area. There were 46 cases (65.7%) accompanied by intracranial arteriosclerosis, and in 6 cases, arteriosclerosis mainly occurred in the posterior circulation.We redefined the classification of PTA based on Weon typing for a better understanding of clinical symptoms and surgical risks. Moreover, PTA was correlated with the fetal origin of PCA, BA dysplasia, and posterior circulation arteriosclerosis. These factors may increase the incidence of cerebral infarction in the posterior circulation blood supply area.