Persistent primitive trigeminal arteries (PTA) and its variant (PTAV): analysis of 103 cases detected in 16,415 cases of MRA over 3 years

Selective Transarterial Embolization for a Ruptured Persistent Trigeminal Artery Variant Aneurysm

We report a male patient with a ruptured persistent primitive trigeminal artery variant aneurysm that resulted in a fistula with the cavernous sinus. He presented with left conjunctival hyperemia and exophthalmos. Cerebral angiography revealed a left direct carotid-cavernous fistula; however, a balloon occlusion test determined that the source was actually a ruptured aneurysm located on the trunk of a persistent primitive trigeminal artery. Endovascular trapping of the persistent primitive trigeminal artery was performed, which resulted in fistula occlusion and symptom resolution.

Watershed cerebral infarction in a patient with a persistent primitive trigeminal artery and contralateral internal carotid artery stenosis: A case report

Patients with a persistent primitive trigeminal artery frequently have a poorly developed vertebrobasilar arterial system. However, they are not at higher risk of stroke and most are asymptomatic. Left cerebral watershed infarction was identified in a 75-year-old man who presented with aphasia and disorientation on magnetic resonance image (MRI). Additional imaging studies also demonstrated a right persistent primitive trigeminal artery, aplastic basilar artery, and 47% left internal carotid artery stenosis. Antiplatelet medication was administered and he was discharged 2 weeks after admission on aspirin. At the 4-month follow-up, cerebral blood flow in the left watershed territory was still decreased; however, no recurrent stroke had occurred. Although the indication for surgical or endovascular intervention for internal carotid artery stenosis is primarily determined by the degree of stenosis, cerebral blood flow evaluation is recommended in patients with internal carotid artery stenosis and a persistent primitive trigeminal artery.

A Case of Cerebral Infarction due to Internal Carotid Artery Occlusion Accompanied by Persistent Primitive Trigeminal Artery

An 85-year-old woman with a history of diabetes mellitus became aware of motor weakness of the left lower extremity. Magnetic resonance imaging showed multiple small cerebral infarctions in the right corona radiata. Angiography revealed persistent primitive trigeminal artery (PPTA) originating from the right internal carotid artery (ICA) and connecting to basilar artery, and the right ICA occluded distal to PPTA. Collateral blood circulation had developed, and sufficient collateral blood flow was expected. From these findings, the right ICA was considered to show stenosis due to atherosclerotic changes before occlusion. Conservative treatment was conducted with the transoral administration of rivaroxaban. It is important to correctly diagnose the anatomy and existence of an anomalous vessel in a stroke patient, not only when endovascular treatment is planned, but also for conservative medical treatment. Rapid and accurate radiological examinations facilitate safe and effective treatment.

Ruptured Anterior Inferior Cerebellar Artery Aneurysm From a Persistent Trigeminal Artery: A Case Report

Persistent trigeminal artery (PTA) is the most common remnant of the primitive carotid-vertebrobasilar anastomoses, which typically form and obliterate during the early stages of human embryonic development. While PTA can be non-pathologic and is usually an incidental finding, it is also associated with various other vascular abnormalities, such as arteriovenous malformations and fistulae, but most commonly cerebral aneurysms. In these cases, aneurysms are usually reported in the anterior cerebral circulation or in the PTA trunk itself; to date, only one report exists of an associated aneurysm in the posterior circulation (basilar artery). These associated vascular pathologies are not only a source of morbidity and mortality but can also complicate subsequent endovascular treatment due to different flow patterns and increased vessel tortuosity. In this case report, we present the first reported case of PTA-associated aneurysm in the anterior inferior cerebellar artery and its resulting impact on the endovascular treatment of this aneurysm.

Incidental Finding of Persistent Trigeminal Artery in a Young Woman: A Case Report

Persistent trigeminal artery disease is one of the most common types of persistent carotid-vertebrobasilar anastomoses. Usually, it is unilateral, and it can be discovered with a magnetic resonance angiography (MRA), computed tomography angiography (angioCT), or classic angiography exam. It can be associated with non-specific symptoms, such as headaches, or more specific ones, such as III or VI nerve palsy or trigeminal neuralgia, but most of the time it goes undetected, being an incidental finding and not causing any symptoms. On MRA and angioCT, it has the characteristic "tau" sign. We present the case of a young woman who, incidentally, discovered this malformation after undergoing an MRA. She had been experiencing a persistent headache without a known cause, which did not improve despite medication.

Persistent trigeminal artery variant and presumed ophthalmic artery simultaneously arising from the inferolateral trunk incidentally diagnosed by magnetic resonance angiography

PURPOSE

To describe a case of persistent trigeminal artery variant (PTAV) and presumed ophthalmic artery (OA) simultaneously arising from the inferolateral trunk (ILT).

METHODS

A 53-year-old woman with an initial episode of convulsion underwent cranial magnetic resonance imaging (MRI) and MR angiography (MRA) of the intracranial region for the evaluation of brain and vascular lesions. The MR machine was a 3-T scanner.

RESULTS

MRI revealed no pathological brain lesions. On MRA, the left anterior inferior cerebellar artery (AICA) arose from the cavernous segment of the internal carotid artery (ICA), indicative of the PTAV. The arising point was more distal than the usual point, and the presumed OA also arose simultaneously from the short common trunk, which was considered the ILT.

CONCLUSION

There are two types of PTA: lateral (usual) and medial (intrasellar) PTA. The lateral-type PTA and PTAV arise from the ICA of the distal precavernous-proximal cavernous segment and take a course similar to that of the posterior fossa. The medial type arises slightly more in the distal cavernous segment than in the lateral type. The OA rarely arises from the cavernous segment of the ICA and enters the orbit via the superior orbital fissure. The origin of this type of OA is considered to be the ILT. We herein report a case of a PTAV and presumed OA arising simultaneously from an ILT. No similar case has been reported in the relevant English language literature.

Medial-type persistent trigeminal artery and ipsilateral posterior communicating artery supplying bilateral posterior cerebral arteries combined with an aberrant right subclavian artery and bicarotid trunk

PURPOSE

To describe a case of a medial-type persistent trigeminal artery (PTA) associated with multiple arterial variations.

METHODS

A 34-year-old woman with multiple sclerosis underwent cranial magnetic resonance (MR) angiography from the aortic arch to the neck region and intracranial region for the evaluation of an unruptured cerebral aneurysm that was previously detected on MR imaging. The MR machine was a 3-T scanner.

RESULTS

There was an aberrant right subclavian artery and bicarotid trunk, medial-type left PTA and ipsilateral posterior communicating artery (PCoA) supplying bilateral posterior cerebral arteries (PCAs). The unruptured aneurysm was located at the paraclinoid segment of the left internal carotid artery and was treated successfully by coil embolization via a transfemoral approach.

CONCLUSION

Only 10% of PTAs are classified as the medial type. The association with extremely large ipsilateral PCoA, which supplies the bilateral PCAs, has not been previously reported. Aberrant right subclavian arteries are common and are frequently associated with a bicarotid trunk. Before catheterization of the cerebral arteries, the aortic arch and its branches must be evaluated by MR angiography or computed tomography angiography to prevent catheterization failure via the right transradial approach.

Intracranial Angioplasty via Type II Proatlantal Intersegmental Artery

A proatlantal intersegmental artery (PIA) is an exceedingly rare primitive anastomosis between the carotid and vertebrobasilar circulations. PIAs may be accompanied by ipsilateral or bilateral vertebral artery (VA) agenesis and can originate from the cervical internal carotid artery (ICA, type I) or external carotid artery (ECA, type II) before eventually joining the vertebrobasilar system. Several authors have described this anomaly in different clinical scenarios, but to our knowledge, there are no studies documenting VA angioplasty through a type II PIA in the setting of vertebrobasilar stroke. We present the case of vertebrobasilar stroke in which the right VA did not originate from the right subclavian artery but instead from the ECA. The patient was subsequently determined to have a type II PIA. We performed right VA angioplasty via the PIA, followed by partial restoration of vertebrobasilar blood flow. This is the first documented case of intracranial vertebral angioplasty through a type II PIA and serves as a reminder for neuroendovascular surgeons about persistent fetal circulation. In such instances, an angiogram of both the ICA and ECA should be performed to exclude right VA stenosis and visualize persistent fetal circulation. This case underscores the complexity of arterial thrombotic events, the beneficial role of endovascular intervention, and the necessity of future studies to identify the optimal treatment methods for vertebrobasilar stroke.

Interventions and imaging in patients with anatomic variations of cerebral circulation: a pictorial review

The cerebral arterial system shows a wide spectrum of variations. Minor degrees of anatomic differences can be seen in almost all patients. Recognition of these anatomic variants is essential for the following: evaluating collateral circulation; some anatomic variants may mimic pathology; increased risk for aneurysm formation with some variants (e.g. fenestration, persistent trigeminal artery); dealing with pathologies that can arise with these variations; and for preoperative planning. The anterior and posterior groups of intracranial circulation show numerous anastomoses that play a major role in maintaining adequate blood supply to the cerebral parenchyma. This review focuses on the imaging features of these variants as seen on computed tomography and magnetic resonance imaging with relevant digital subtraction angiography imaging. We also present some case illustrations where understanding of these variants contributed to providing appropriate management.

Persistent trigeminal artery-superior cerebellar artery segmental fusion diagnosed using magnetic resonance angiography

PURPOSE

To describe a case of persistent trigeminal artery (PTA)-superior cerebellar artery (SCA) segmental fusion incidentally diagnosed on magnetic resonance (MR) angiography.

CASE REPORT

A 53-year-old woman with a history of facial pain underwent cranial MR imaging and MR angiography. MR angiography showed a left lateral-type PTA arising from the precavernous portion of the left internal carotid artery (ICA). PTA branched into the left distal SCA and showed segmental fusion with the proximal SCA at the distal part of the PTA. We also diagnosed an unruptured cerebral aneurysm at the junction between the left ICA and PTA.

DISCUSSION

PTA is the most frequent type of carotid-vertebrobasilar anastomosis. The reported prevalence rate is 0.2% by angiography and 0.34% by MR angiography. There are two types of PTA-lateral (usual) and medial (intrasellar). SCA arising from the lateral-type PTA has rarely been reported. Further, a PTA from which the distal SCA branches and segmentally fuses with the proximal SCA at the distal part of the PTA has not been reported.

CONCLUSION

Using MR angiography, we diagnosed a rare type of PTA that fused segmentally with SCA. No similar case has been reported in relevant English-language literature.

An anatomical study of persistent trigeminal artery detected by computed tomography angiography and magnetic resonance angiography: proposal for a modified classification and a novel basilar artery grading system

PURPOSE

The purpose of this study is to investigate the anatomical characteristics of persistent trigeminal artery (PTA) detected by computed tomography angiography (CTA) and magnetic resonance angiography (MRA), propose a modified classification and a novel grading system for basilar artery (BA).

METHODS

Patients who underwent head CTA or MRA in our hospital between August 2014 and August 2022 were reviewed retrospectively. The prevalence, sex, and course of PTA were evaluated. PTA types were modified based on Weon's classification. Type I to IV were similar to those in Weon's classification except the presence of intermed fetal-type posterior cerebral artery (IF-PCA). Type V was the same as that in Weon's classification. Type VI included subtypes of VIa (concomitant IF-PCA based on type I to IV) and VIb (other variants). BA was assessed based on a scale of 0 to 5 compared with PTA's caliber (0, BA aplasia; 1 and 2, BA non-dominant; 3, equilibrium; 4 and 5, BA dominant).

RESULTS

A total of 57 patients (0.06%) with PTA, including 36 females and 21 males, were detected in 94,487 patients. Six patients (10.5%) were medial type and 51 patients (89.5%) were lateral type. Thirty-seven patients (64.9%) were type I, 1 (1.8%) as type II, 13 (22.8%) as type III, 3 (5.3%) as type IV, 1 (1.8%) as type V, and 2 (3.5%) as type VI. For BA grading, 4 (7.0%), 21 (36.8%), 17 (29.8%), 6 (10.5%), 6 (10.5%), and 3 (5.3%) of the patients were grade 0, 1, 2, 3, 4, and 5, respectively. Fifteen patients (26.3%) had intracranial aneurysms. One cases (1.8%) had a fenestration of the PTA.

CONCLUSION

The prevalence of PTA in our study was lower than that in most previous reports. The modified PTA classification and BA grading system can be used to better understand the vascular structure of PTA patients.

Large persistent trigeminal artery variant that supplied the subtotal cerebellar hemisphere and caused trigeminal neuralgia, which was diagnosed by magnetic resonance (MR) angiography and MR cisternography

PURPOSE

To describe a case of large persistent trigeminal artery (PTA) variant that caused trigeminal neuralgia, which was diagnosed by magnetic resonance (MR) angiography and MR cisternography.

CASE REPORT

An 82-year-old woman with left trigeminal neuralgia underwent cranial MR imaging, MR angiography and MR cisternography. MR imaging revealed no significant abnormality. MR angiography showed that a relatively large artery arose from the precavernous segment of the left internal carotid artery (ICA) without connection to the basilar artery, which is indicative of a PTA variant. This artery supplied the left cerebellar arteries, except for the rostral branch of the superior cerebellar artery. MR cisternography showed that the inferior surface of the left trigeminal nerve was compressed by the PTA variant. She was treated by microvascular decompression surgery and her symptoms disappeared.

DISCUSSION

According to a meta-analysis, the prevalence of the PTA variants is reported to be 0.2%. The majority of PTA variants are small arteries and are classified as the anterior inferior cerebellar artery type. The present case involved a relatively large artery that supplied large territories of the cerebellar hemisphere. PTA and PTA variants rarely cause trigeminal neuralgia.

CONCLUSION

Using MR angiography and MR cisternography, the author diagnosed a case of large PTA variant that caused trigeminal neuralgia. No similar case has been reported in the relevant English language literature.

Persistent Trigeminal Artery Causing an Abducens Nerve Palsy: A Case Report

We present a case of a 50-year-old female who was diagnosed with an isolated right abducens nerve palsy and was found to have a persistent trigeminal artery (PTA). The trigeminal artery is the most common persistent embryological carotid-vertebrobasilar anastomosis. A PTA can be picked up as an incidental finding on magnetic resonance imaging (MRI) or angiography. It has been reported that a PTA can be found in 0.1 to 0.6% of all cerebral angiograms. PTA has been linked to several rare abnormalities such as vascular aneurysms and cranial nerve compression. Our patient presented with diplopia and was found to have a paresis of the right lateral rectus muscle consistent with a right abducens nerve palsy. MRI found a right-sided PTA indenting the ventral surface of the pons. This case investigates and highlights that neurovascular compression from a PTA can cause an isolated abducens nerve palsy. Further research is required to investigate if surgical intervention for non-aneurysmal PTA would be beneficial for patients.

Duplicated superior cerebellar arteries, one of which was supplied by a persistent trigeminal artery variant diagnosed by magnetic resonance angiography

PURPOSE

The purpose of the study was to describe a case of duplicated superior cerebellar arteries (SCAs), whose caudal branch was supplied by a persistent trigeminal artery (PTA) variant, diagnosed by magnetic resonance (MR) angiography.

CASE REPORT

A 74-year-old woman with a history of cerebral infarction underwent cranial MR imaging and MR angiography. MR imaging revealed chronic-stage left cerebellar and right basal ganglionic infarctions. MR angiography showed no steno-occlusive lesions in the intracranial arteries; however, duplicated left SCAs were observed and the caudal branch arose from the precavernous segment of the left internal carotid artery, which is indicative of a PTA variant.

DISCUSSION

Variations of the SCA (e.g., duplication, early bifurcation, and common trunk of the posterior cerebral artery and SCA) are frequently seen. A cerebellar artery arising from the precavernous segment of the internal carotid artery without connection to the basilar artery is regarded as a PTA variant. According to a meta-analysis, the prevalence is reported to be 0.2%. The majority of PTA variants are classified as the anterior inferior cerebellar artery type. PTA and PTA variants are frequently associated with other cerebral variations. A case of duplicated posterior inferior cerebellar artery, in which one of the branches was supplied by a PTA variant, was reported previously. However, the combination of duplicated SCA and PTA variants has not been reported.

CONCLUSION

Using MR angiography, the author diagnosed a case of duplicated SCA, whose caudal branch was supplied by a PTA variant. No similar case has been reported in the relevant English-language literature.

A persistent trigeminal artery demonstrates cerebrovascular embryologic development

Background

Cerebrovascular embryologic development is characterized by the presence of four well-described carotid-vertebrobasilar (VB) anastomoses. As the fetal hindbrain matures and the VB system develops, these connections involute, yet some may persist into adulthood. The persistent primitive trigeminal artery (PPTA) is the most common of these anastomoses. In this report, we describe a unique variant of the PPTA and a four-way division of the VB circulation.

Case Description

A female in her 70s presented with a Fisher Grade 4 subarachnoid hemorrhage. Catheter angiography revealed a fetal origin of the left posterior cerebral artery (PCA) giving rise to a left P2 aneurysm which was coiled. A PPTA arose from the left internal carotid artery and supplied the distal basilar artery (BA) including the superior cerebellar arteries bilaterally and the right but not left PCA. The mid-BA was atretic and the anterior inferior cerebellar artery-posterior inferior cerebellar artery complexes were fed solely from the right vertebral artery.

Conclusion

Our patient's cerebrovascular anatomy represents a unique variant of the PPTA not well described in the literature. This demonstrates how hemodynamic capture of the distal VB territory by a PPTA is sufficient to prevent fusion of the BA.

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.

Sequential aneurysms with incidental persistent primitive trigeminal artery: Is this association purely coincidental? A case study and review of the literature in search for a pathobiological mechanism

Background:

The appearance of sequential bilateral aneurysms in patients with persistent primitive trigeminal artery (PTA) is not described in the literature. No clear guidelines on screening and follow-up of patients with incidental PTAs for the detection of associated lesions have been established.

Case Description:

A 55-year-old lady presented with occasional headaches. Detailed evaluation showed a left ophthalmic segment internal carotid artery (ICA) aneurysm measuring (11.2 × 5.5) mm. A bovine aortic arch configuration (type III) and a persistent left PTA were identified. A pipeline flex flow diverter was placed and aneurysm was coiled. Follow-up angiography after 6 months showed a completely occluded aneurysm with preserved PTA and a new aneurysm in the right ICA ophthalmic segment measuring 3.5 × 1.5 mm. It was followed up serially with angiography which revealed significant increase in 6 months. The base measured 5.4 mm and two blebs 3.1 mm and 2.5 mm had appeared on the dome. A SUPRASS flow diverter was placed across this aneurysm. Serial follow-up showed complete occlusion of the left aneurysm and significant reduction in filling of the right aneurysm. A review of the literature identified 34 cases of incidental PTAs associated with 50 aneurysms with increased prevalence of anterior circulation aneurysms in patients with incidental PTA.

Conclusion:

Sequential angiography of a patient with incidental PTA and an ICA aneurysm shows presence of a new aneurysm in contralateral circulation and its progression in size and morphology. Detailed large-scale studies are needed to assess the impact of incidental PTA on aneurysm development and management.

Clinical Importance of the Persistent Primitive Trigeminal Artery in Vascular Lesions and Its Role in Endovascular Treatment

The persistent primitive trigeminal artery (PPTA) extends from the internal carotid artery to the basilar artery between the origins of the anterior inferior cerebellar artery and superior cerebellar artery. PPTAs have complex anatomical characteristics. Salas and Saltzman classifications are most often used in PPTAs. The PPTA can play many roles in vascular lesions, including intracranial aneurysms, brain arteriovenous malformations, trigeminal artery-cavernous fistulas, Moyamoya disease, and large vessel occlusion. For these lesions, surgical treatment is difficult due to the deep location and complex anatomy of the PPTA, but endovascular treatment (EVT) has emerged as a good alternative. Currently, a complete review of the clinical importance of the PPTA in terms of its role in the development and EVT of vascular lesions is lacking. Therefore, we conducted a PubMed search, performed a review of the relevant extracted literature and cataloged our experience with PPTAs. By review, we found that a thorough understanding of the anatomical and angiographic features of this PPTA is of utmost importance when making therapeutic decisions for any of these pathological conditions.

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

BACKGROUND

The persistent trigeminal artery (PTA) is the most common remnant of primitive circulation, communicating the developing carotid and vertebrobasilar junction.

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Persistent trigeminal artery variant associated with ipsilateral hypoplasia of the internal carotid artery

A persistent trigeminal artery is the most common persistent carotid-vertebrobasilar anastomosis, while persistent trigeminal artery variants involve termination at the cerebellar artery without connecting to the basilar artery. Internal carotid artery hyperplasia is also a rare congenital anomaly. To the best of our knowledge, there are no reports of persistent trigeminal artery variant associated with ipsilateral hypoplasia of the internal carotid artery. Herein, we report a case of a 44 year-old woman who visited a neurosurgical clinic because of chronic headaches. Magnetic resonance angiography showed impaired delineation of the left internal carotid artery, and she was referred to our hospital for catheter angiography. Angiogram revealed left internal carotid artery hypoplasia and a left persistent trigeminal artery variant that terminated at the left anterior inferior cerebellar artery. Computed tomography bone images showed a narrow left carotid canal. We diagnosed congenital hypoplasia of the left internal carotid artery concomitant with ipsilateral persistent trigeminal artery variant. Careful imaging assessment is important for identifying persistent trigeminal artery variant when associated with ipsilateral internal carotid artery hypoplasia.

Carotid-cavernous Fistula Associated with a Ruptured Persistent Primitive Trigeminal Artery Aneurysm: A Case Report and Review of Literature

Carotid-cavernous sinus fistula (CCF) caused by a ruptured aneurysm of the persistent primitive trigeminal artery (PPTA) is rarely reported. A 69-year-old woman presented with progressive ptosis and pulsating tinnitus. Vertebral angiography under flow control of the internal carotid artery revealed CCF associated with a ruptured PPTA-trunk aneurysm, and PPTA was divided into Saltzman type 2. Endovascular treatment was performed by coil embolization of the aneurysm and parent artery occlusion of the PPTA, preserving the basilar artery (BA) side of PPTA, without complications. In the case of ruptured aneurysms originating from the Saltzman type 2 PPTA trunk, parent artery occlusion of the PPTA might be a treatment option and preservation of the BA side of PPTA is necessary to avoid ischemic complication of pons.

Carotid artery stenting in patients with chronic internal carotid artery occlusion

BACKGROUND

The risk of ischemic stroke in patients with chronic total occlusion (CTO) of the internal carotid artery (ICA) on best medical treatment has been estimated to be 5.5% per year. The purpose of this study was to assess early and mid-term outcome of patients who underwent an attempt at transfemoral carotid artery stenting (CAS) for CTO of the ICA.

METHODS

Clinical data of symptomatic patients who underwent attempt at CAS for CTO of the ICA between January 1, 2010 and July 1, 2020 were retrospectively reviewed. Clinical success, perioperative and mid-term stroke and death rates were recorded. Descriptive statistics were used.

RESULTS

There were 27 patients, 14 females, 13 males, with a mean age of 66.8 years, range: 57 to 79. All patients had symptoms within 6 months prior to the procedure. 16 had ipsilateral stroke at a mean of 2.8 months, ranges: 1.5-4 months, two had transient ischemic attack (TIA), at 1 week and at 6 months, one had amaurosis fugax at one week, two had chronic ocular ischemia and six had chronic cerebral hypoperfusion. Technical success was 52% (14/27). One patient developed a minor reversible stroke (1/27, 3.7%) there was no early death, for an overall 30-day stroke and death rate of 3.7% (1/27). Two patients had perioperative TIAs. Among 14 patients with successful CAS (group A) one had minor, reversible ipsilateral stroke during a follow-up of 29 months (range: 4-112), two had contralateral stroke. There was no death. One patient developed asymptomatic stent occlusion, three had asymptomatic in-stent restenosis >50%, two had reinterventions. Among patients with unsuccessful attempt at CAS (group B), 31% (4/13) had stroke at 4, 10, 14 and 22 months, respectively. One stroke patient died at 10 months.

CONCLUSIONS

Transfemoral CAS of symptomatic patients with CTO of the ICA was feasible in half of the patients, with no mortality or major stroke, for an overall early stroke/death rate of 3.7%. Since one third of the patients with unsuccessful stenting developed stroke during follow-up, further studies to investigate the safety, efficacy and durability of CAS for CTO of the ICA are needed.

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.

Trigeminal neuralgia associated with a variant of persistent trigeminal artery

A persistent trigeminal artery variant (PTAV) is an anomalous vessel that originates from the internal carotid artery and directly supplies the cerebellum without interposition of the basilar artery. This anatomic variant is usually found incidentally on imaging but can rarely have clinical implications. We describe a case of a 74-year-old woman presenting with multiple years of lower jaw pain attributed to trigeminal neuralgia, unresolved with medication. A persistent trigeminal artery variant compressing the trigeminal nerve was identified on magnetic resonance imaging and magnetic resonance angiography. The characteristic imaging findings of PTAV are essential for identifying an etiology of medically refractory trigeminal neuralgia and may assist with preoperative planning.

Treatment of Aneurysms in Persistent Primitive Trigeminal Arteries with Stent-Assisted Coil Embolization

Objective

Persistent primitive trigeminal artery (PPTA) is a rare condition in which a fetal carotid-basilar anastomosis persists into adulthood. PPTA aneurysms often necessitate endovascular treatment and adjunctive techniques, such as stent- or balloon-assisted techniques, are sometimes selected. This case report describes two women in their sixties with unruptured right PPTA aneurysms who underwent stent-assisted coil embolization procedures, with consideration of the anatomical features in each case.

Case Presentations

One patient presented with an aneurysm at the bifurcation of the PPTA and the basilar artery (BA), which was classified as Saltzman type 1 with a hypoplastic vertebral artery (VA)-BA system. A stent was deployed from the BA to the PPTA to cover the neck of the aneurysm and coil embolization was performed. The second patient presented with an aneurysm at the bifurcation of the PPTA and the internal carotid artery (ICA), which was classified as Saltzman type 2 with a hypoplastic VA-BA system. A stent was deployed from the PPTA to the petrous segment of the ICA covering the neck of the aneurysm and coil embolization was performed. In both patients, the 1-year follow-up digital subtraction angiography (DSA) showed that the aneurysms had not recurred.

Conclusion

The PPTA aneurysms were successfully treated with stent-assisted coil embolization. The treatment strategy should be devised in accordance with both the lesion site and the PPTA variant.

MN1 C-terminal truncation syndrome is a novel neurodevelopmental and craniofacial disorder with partial rhombencephalosynapsis

MN1 encodes a transcriptional co-regulator without homology to other proteins, previously implicated in acute myeloid leukaemia and development of the palate. Large deletions encompassing MN1 have been reported in individuals with variable neurodevelopmental anomalies and non-specific facial features. We identified a cluster of de novo truncating mutations in MN1 in a cohort of 23 individuals with strikingly similar dysmorphic facial features, especially midface hypoplasia, and intellectual disability with severe expressive language delay. Imaging revealed an atypical form of rhombencephalosynapsis, a distinctive brain malformation characterized by partial or complete loss of the cerebellar vermis with fusion of the cerebellar hemispheres, in 8/10 individuals. Rhombencephalosynapsis has no previously known definitive genetic or environmental causes. Other frequent features included perisylvian polymicrogyria, abnormal posterior clinoid processes and persistent trigeminal artery. MN1 is encoded by only two exons. All mutations, including the recurrent variant p.Arg1295* observed in 8/21 probands, fall in the terminal exon or the extreme 3' region of exon 1, and are therefore predicted to result in escape from nonsense-mediated mRNA decay. This was confirmed in fibroblasts from three individuals. We propose that the condition described here, MN1 C-terminal truncation (MCTT) syndrome, is not due to MN1 haploinsufficiency but rather is the result of dominantly acting C-terminally truncated MN1 protein. Our data show that MN1 plays a critical role in human craniofacial and brain development, and opens the door to understanding the biological mechanisms underlying rhombencephalosynapsis.

Trigeminal Neuralgia Due to Compression of Primitive Trigeminal Artery Variant: Usefulness of Fusion Images of Constructive Interference in Steady-State Magnetic Resonance Imaging and Computed Tomography Angiography

BACKGROUND

Trigeminal neuralgia (TN) is one of the neuropathic pain syndromes, most commonly caused by vascular compression in the root entry zone of the trigeminal nerve in the cerebellopontine angle. It was rare as offending artery that primitive trigeminal artery and primitive trigeminal artery variant (PTAv) as an anomaly that occurs carotid-basilar anastomosis. We report a case of TN caused by the PTAv, and usefulness of fusion images of magnetic resonance imaging (MRI) and computed tomography angiography (CTA).

CASE DESCRIPTION

A 65-year-old man presented with a 2-year history of left paroxysmal facial pain in the second division of the trigeminal nerve. We diagnosed left TN due to PTAv using constructive interference in steady state magnetic resonance imaging (CISS MRI) and CTA. Microvascular decompression surgery disclosed trigeminal nerve compressed by PTAv consisted with findings from preoperative neuroimaging. We report a case of TN caused by PTAv, and usefulness of fusion images of CISS MRI and CTA to understand the neurovascular and bony structure during the perioperative period.

CONCLUSIONS

The fusion image created by CISS MRI and 3-dimensional CTA was useful to identify the offending vessel and to clearly understand the neurovascular structure preoperatively.

Cerebellar artery arising from the cavernous segment of the internal carotid artery and persistent trigeminal artery: a spectrum of incomplete longitudinal fusion

Background

The embryological relationship between cerebellar arteries originating directly from the cavernous segment of the internal carotid artery and persistent trigeminal artery is not well understood.

Purpose

To evaluate the incidence and pattern of cerebellar arteries originating from the internal carotid artery and persistent trigeminal artery, and to discuss their probable embryological relationship.

Material and Methods

We reviewed 5113 angiographic studies from 5093 patients at our institution over the last eight years, searching for patients with persistent trigeminal artery and cerebellar arteries originating from a cavernous segment of internal carotid artery (persistent trigeminal artery variant).

Results

Of the 5093 patients, 27 patients had persistent trigeminal artery or persistent trigeminal artery variant (0.53%). Twenty patients (6 men, 14 women; median age = 54 years) had persistent trigeminal artery (0.39%). Seven patients (2 men, 5 women, age range = 37–72 years; median age = 57 years) had a persistent trigeminal artery variant with persistent trigeminal artery terminating in a cerebellar artery without direct connection to the basilar artery (persistent trigeminal artery variant; 0.14%). The terminal branch of the persistent trigeminal artery variant was an anterior inferior carotid artery in five patients and a superior cerebellar artery in two patients. Of the seven patients having persistent trigeminal artery variant, four patients had another artery from the basilar artery to the anterior inferior carotid artery territory. In 6/20 patients with persistent trigeminal artery, there was an anterior inferior carotid artery arising from the persistent trigeminal artery. One of these patients showed another arterial branch from the basilar artery to the anterior inferior carotid artery territory.

Conclusion

Persistent trigeminal artery variant and cerebellar arteries originating from the persistent trigeminal artery are both believed to be a spectrum of incomplete fusion of the longitudinal neural arteries. Understanding the precise anatomy is important in diagnostic and therapeutic settings for related vascular disease.

Persistence of a trigeminal artery associated with a posterior meningeal artery aneurysm: case report and literature review

A 59-year-old female presented with severe headache and trouble of consciousness. The CT showed a subarachnoid hemorrhage FISHER IV with a hematoma of the right cerebellum. The angiography discovered a persistent left trigeminal artery associated with an aneurysm of the right posterior meningeal artery. The attempt of embolization failed and the patient suffered cerebral vasospasm and died. The persistence of a trigeminal artery is found in 0.1–0.6% of the population. It is the most frequent embryological carotid-vertebral anastomosis. It appears at the fifth week of development and disappears when the embryo reaches 5–7 mm. This embryological persistence is associated with numerous vascular abnormalities. The literature review showed the presence of those aneurysms in the trigeminal artery itself or the communicating artery. The association that we described is the first to our knowledge. Therefore, this association is particular and interesting to expose.

Persistent trigeminal artery in a patient with posterior circulation stroke treated with rt-PA: case report

BACKGROUND

A persistent trigeminal artery (PTA) is a non-involuted embryonic vessel that connects the cavernous part of the internal carotid artery with the posterior circulation. In the adult it is associated with multiple pathological conditions including trigeminal neuralgia, ophthalmoplegia, hypopituitarism, intracavernous fistula, brain aneurysms and posterior circulation strokes. The latter may occur through steal phenomena or thrombosis in the anterior circulation. PTA associated vertebrobasilar hypoplasia has yet to be associated to TIA like events, however, in the reported case, that seems to be the case with reported vertigo being probably linked to vertebrobasilar insufficiency.

CASE REPORT

We present a case of an 82-year-old man with sudden onset neurological deficits, including left hemiparesis with crural predominance, vertical nystagmus, right internuclear ophthalmoplegia, dysarthria and dysmetria on the left arm. CT angiography disclosed basilar artery hypoplasia in the proximal two thirds and a persistent trigeminal artery. He was diagnosed with acute ischemic stroke. He was submitted to rt-PA with partial reversion of deficits.

CONCLUSION

The ischemic events related to PTA remain a rare cause of stroke with specific pathophysiological mechanisms and implications. They may occur through steal phenomena or thrombosis in the anterior circulation. Upon literature review, in the described case both mechanisms seem possible, however the transient episodes of vertigo could have been the first sign of vertebrobasilar insufficiency.

Persistent Trigeminal Artery: Neuroanatomic and Clinical Relevance

INTRODUCTION

Persistent trigeminal artery (PTA) is the most common remnant of primitive circulation communicating the developing carotid and vertebrobasilar junction. Although discovered incidentally, an altered hemodynamic may lead to an increased association of aneurysms, vascular malformations, and stroke. Neurosurgeons should be aware of the presence and significance of PTA when interpreting imaging and planning interventions.

METHODS

We retrospectively reviewed all magnetic resonance angiography and cerebral digital subtraction angiography performed between 2012 and 2017 for the presence of PTA. The radiologic and anatomic details were noted and analyzed along with the clinical profiles. We categorized the radiologic findings with respect to the available classification systems. A review of the available literature was done comparing our results.

RESULTS

We found 33 cases of incidentally detected PTA. The average age of the patients was 45.42 years. The lateral surface of the proximal cavernous internal carotid artery was the most common origin (n = 23). Only 3 cases had a medial/transsellar course. Most cases were Saltzman/Weon type I (19/33). Intracranial aneurysms were associated with 6 patients (18.18%). Trigeminal neuralgia (TN) was a presenting feature in 5 patients. None had a direct neurovascular conflict at the root entry zone.

CONCLUSIONS

Our study is one of the largest to describe the incidence of PTA. We emphasized the importance of PTA to the neurosurgeons; increased association of aneurysms, as a route for intervention in occlusive disease of the posterior fossa; risk of injury and bleeding during transsphenoidal surgery; and the association with TN. However, we found that only PTA variants are likely to be associated with TN because of their cisternal course causing NV conflict.

Prevalence and Clinical Implications of the Primitive Trigeminal Artery and its Variants: A Meta-Analysis

BACKGROUND

The primitive trigeminal artery (PTA) is the most common and the largest persistent carotid-basilar anastomosis. Primitive trigeminal artery variants (PTAVs) are anastomoses between the internal carotid artery and cerebellar arteries. These vessels pose a risk of hemorrhagic or ischemic complications during neurosurgical procedures in the parasellar and intrasellar regions. The aim of this study was to determine the prevalence of both PTA and PTAVs and their clinically important anatomic features.

METHODS

Major electronic databases were thoroughly searched for studies on PTA and PTAV. References in the included articles were also evaluated. Data regarding prevalence, laterality, origin, course patterns, and associated anomalies were extracted and pooled into a meta-analysis.

RESULTS

A total of 39 studies (110,866 patients) were included in the meta-analysis. The total pooled prevalence estimate of PTA and PTAVs combined was 0.4% (95% confidence interval [CI], 0.3-0.5). Individually, PTA was present in 0.3% of patients and PTAV in 0.2%. Both arteries most often originated from the C4 internal carotid artery and took a course lateral to the dorsum sellae. The anterior inferior cerebellar artery type was the predominant PTAV (72.1%). Basilar artery hypoplasia was found in 42.5% of patients with a PTA.

CONCLUSIONS

PTA and PTAVs are rare vessels, but they are clinically important because they can contribute to trigeminal neuralgia. Knowledge of the potential course of these arteries is essential in neuroradiology and neurosurgery, especially in minimally invasive procedures such as the endoscopic endonasal transsphenoidal approach to the pituitary gland and the percutaneous gasserian ganglion procedure.

Persistent trigeminal artery aneurysms: case report and systematic review

Background

The persistent trigeminal artery (PTA) is an adult carotid-basilar anastomosis with debated pathologic aspects, such as its association with brain aneurysms. True trigeminal artery aneurysms are rare vascular anomalies, reported in a few case reports.

Objective

To report our experience with a ruptured trigeminal artery aneurysm and to provide a systematic review of the literature in order to analyse potential links between the anatomic configuration of the PTA and PTA aneurysm (PTAA) type, and implications of each PTAA type for the diagnostic and therapeutic approach.

Methods

We reviewed the medical literature on trigeminal artery aneurysms according to the PRISMA guidelines. Population characteristics, aneurysms features, and PTA type and side were assessed.

Results

40 previously published cases of PTAAs were included in the analysis. The mean age of subjects was 55 years, with a strong female predominance (77%). Four PTAAs were accidentally discovered, while 16 caused compressive symptoms and 20 were ruptured. Successful endovascular treatment was performed in 62% of cases.

Conclusions

PTAAs are rare vascular anomalies, underdiagnosed in the presence of a trigemino-cavernous fistula. Parent vessel occlusion seems to be the best therapeutic option for ruptured or symptomatic unruptured PTAAs in Saltzman type II and III PTAs. Patency of the parent vessel is the main target in Saltzman type I PTA.

Coil embolisation of multiple cerebral aneurysms with lateral type I persistent primitive trigeminal artery: A case report and literature review

The primitive trigeminal artery is an anastomotic vessel of the carotid-basilar artery system that occurs only transiently during the embryonic period. Persistent primitive trigeminal artery occurs in approximately 0.1-0.6% of the population. Here, we report the case of a 60-year-old woman with Fisher II grade subarachnoid haemorrhage. Computed tomography angiography demonstrated a lateral, Saltzman type I persistent primitive trigeminal artery with three cerebral aneurysms, including one anterior communicating artery aneurysm, one suspicious right anterior choroidal artery aneurysm and one distal basilar artery aneurysm supplied by the persistent primitive trigeminal artery. All three aneurysms were treated with coil embolisation. At the 8-month follow-up, the anterior communicating artery aneurysm had a neck remnant, the other two aneurysms exhibited complete occlusion. Persistent primitive trigeminal artery with multiple cerebral aneurysms is extremely rare, and only seven cases of persistent primitive trigeminal artery with multiple cerebral aneurysms have previously been reported in publications that included information on treatment. Most aneurysms were treated by open surgery. This is the first report of coil embolisation treatment of multiple aneurysms in persistent primitive trigeminal artery patients with follow-up results, and provides relevant and valuable information about the persistent primitive trigeminal artery and the endovascular treatment of multiple aneurysms in persistent primitive trigeminal artery patients.

Carotid-vertebrobasilar anastomosis: magnetic resonance and computed tomographic angiographic demonstration

Carotid-vertebrobasilar (VB) anastomoses are rare and usually found incidentally, but they can have clinical significance. Their variance can represent aneurysm formation at the origin of the anomalous artery, cerebral ischemia due to unique blood flow, or other complications. Thus, recognition and correct diagnosis of these anomalous vessels are important when interpreting magnetic resonance (MR) and computed tomography (CT) angiography. This pictorial essay presents MR and CT angiographic images of several types of persistent fetal carotid-VB anastomoses, including those involving the proatlantal, hypoglossal, and trigeminal arteries as well as their variants. Images depict types 1 and 2 proatlantal arteries, persistent second cervical intersegmental artery, persistent hypoglossal artery (PHA), PHA of external carotid origin, two types of the PHA variant, posterior inferior cerebellar artery arising from the jugular branch of the ascending pharyngeal artery, lateral and medial types of persistent trigeminal arteries (PTAs), and four types of PTA variants.

Endovascular treatment for unruptured aneurysm associated with persistent primitive trigeminal artery: a case report and literature review

The persistent primitive trigeminal artery (PPTA) is the most common carotid-basilar anastomosis, and the incidence of cerebral aneurysms associated with the PPTA is approximately 4%. Since PPTA aneurysms often have a wide neck and other vascular anomalies, endovascular treatment using an adjunctive technique is the current first-line therapy. Here, we report a case of PPTA aneurysm treated by coil embolization with a stent-assisted technique. A detailed evaluation of the size and course of all vessels and collateral flow, including the Allcock test and balloon test occlusion, is necessary when deciding on the treatment strategy.

Persistent primitive trigeminal artery associated with a cavernous carotid aneurysm. Case report and literature review

The persistent primitive trigeminal artery is the most common persistent carotid-vertebrobasilar anastomosis. Patients are usually asymptomatic and the persistent primitive trigeminal artery is commonly found incidentally on imaging. Rarely, they may present with symptoms of neurovascular conflict or cranial nerve compression syndromes as the artery may be intimately related to the cranial nerves. The basilar artery is often hypoplastic in this condition and blood supply to the posterior circulation is predominantly via the persistent primitive trigeminal artery. Recognizing the persistent primitive trigeminal artery is imperative as disease of the artery may result in ischemia of the posterior circulation. To date, there is no clear association between this artery and cerebral aneurysms. We present a rare case of a patient with a persistent primitive trigeminal artery and a concomitant cavernous carotid aneurysm together with a literature review.

Spontaneous direct carotid-cavernous sinus fistula secondary to a persistent primitive trigeminal artery treated by trans-venous coil embolisation

A healthy 51-year-old female presented with a spontaneous direct carotid-cavernous sinus fistula associated with a persistent primitive trigeminal artery. She had no history of connective tissue or cerebrovascular disorders or significant head trauma. This is a rare lesion with only 18 previously reported cases. It had similar clinical presentation and imaging appearance to a high-flow direct carotid-cavernous fistula and was uncovered after successful trans-venous coil embolisation of the fistula. It therefore needs to be considered in cases of direct carotid-cavernous fistula without history of trauma. Knowledge of types of persistent primitive trigeminal artery is also important for their critical treatment implications.

Carotid Endarterectomy in a Patient with Severe Internal Carotid Artery Stenosis with Persistent Trigeminal Artery and Ischemia of the Anterior and Posterior Circulation

Occurrence of cerebral ischemia in the posterior circulation as a result of severe internal carotid artery disease and persistent trigeminal artery is rare. An 81-year-old man with medical history of hypertension and ischemic stroke presented with dizziness, nausea, and mild dysarthria. Magnetic resonance imaging of the brain revealed acute infarcts in the left internal carotid artery territory. CT angiogram revealed a persistent trigeminal artery (PTA) and severe atherosclerosis. The patient developed new neurological symptoms and repeat imaging revealed new acute infarcts in the PTA distribution. After undergoing a left carotid endarterectomy with no complications, the patient was discharged to a skilled nursing facility with no recurrence of ischemic stroke. This case adds a rare complication of an infrequent vascular anomaly to the limited body of the literature.

Treatment of Large or Giant Cavernous Aneurysm Associated with Persistent Trigeminal Artery: Case Report and Review of Literature

BACKGROUND

Primitive trigeminal artery (PTA) is the most common anomaly of primitive carotid-basilar anastomosis and is associated with cerebrovascular anomalies, such as aneurysm. Large or giant cavernous aneurysm associated with PTA is rare, and the treatment strategies differ in comparison with large or giant aneurysm without PTA. In this article, we report an unusual case of a giant cavernous aneurysm associated with PTA and review treatment strategies for large or giant cavernous aneurysm associated with PTA.

CASE DESCRIPTION

A 38-year-old woman suffered from double vision. Magnetic resonance imaging revealed a mass lesion in the left cavernous sinus, and magnetic resonance angiography showed a giant aneurysm at the cavernous portion of the left internal carotid artery, associated with PTA. Coil embolization, distal to the PTA, was scheduled after high-flow bypass on the same day. Computed tomography scan showed no definite infarction after treatment. A 3-dimensional computed tomography showed disappearance of the aneurysm and good patency of bypass and PTA. The patient experienced improvements in symptoms and was discharged without neurologic deficits (modified Rankin Scale 0).

CONCLUSIONS

The treatment strategy for large or giant cavernous aneurysm associated with PTA is different from strategies used for large or giant cavernous aneurysm without PTA. Simple ligation of internal carotid artery is inadequate because the aneurysm is supplied through the PTA, from the vertebrobasilar system. Furthermore, the treatment strategy has to be revised according to whether the PTA can be occluded. Keeping in mind PTA preservation, an appropriate strategy should be selected.

Carotid-vertebrobasilar Anastomoses with Reference to Their Segmental Property

The primitive carotid-vertebrobasilar anastomoses are primitive embryonic cerebral vessels that temporarily provide arterial supply from the internal carotid artery to the longitudinal neural artery, the future vertebrobasilar artery in the hindbrain. Four types known are the trigeminal, otic, hypoglossal, and proatlantal intersegmental arteries. The arteries are accompanied by their corresponding nerves and resemble an intersegmental pattern. These vessels exist in the very early period of cerebral arterial development and rapidly involute within a week. Occasionally, persistence of the carotid to vertebrobasilar anastomosis is discovered in the adult period, and is considered as the vestige of the corresponding primitive embryonic vessel. The embryonic development and the segmental property of the primitive carotid-vertebrobasilar anastomoses are discussed. This is followed by a brief description of the persisting anastomoses in adults.

Right persistent trigeminal artery variant (PTAV) and tiny left PTA associated with bilateral ophthalmic arteries arising from the cavernous segments of the internal carotid arteries

Persistent trigeminal artery (PTA) and its variant (PTAV) are the most prevalent types of carotid-vertebrobasilar anastomosis, but bilateral anastomoses are exceedingly rare. We report a case of a right PTAV and tiny left lateral-type PTA from which the cerebellar artery (presumed anterior inferior cerebellar artery) arose. And also, bilateral ophthalmic arteries arose from the cavernous segments of the internal carotid arteries and entered the orbits via the superior orbital fissures. Selective cerebral angiography, especially 3-dimensional angiography, is superior to magnetic resonance (MR) angiography to identify rare variations of the cerebral arteries. Careful observation of MR angiographic source images is important for identifying unique arterial coursing.

Persistent trigeminal artery communicating with a fetal posterior communicating artery: A case report

A persistent trigeminal artery (PTA) is the most common carotid-vertebrobasilar anastomosis. PTA variants terminating on cerebellar arteries instead of the basilar artery have been reported previously. We present the first case of a PTA communicating with a fetal posterior communicating artery identified on a magnetic resonance angiogram. An understanding of these anatomical variants is important to clarify pathological processes that can help guide neurosurgical and endovascular procedures.