Two anatomical autopsy cases of direct communication between a persistent primitive trigeminal artery and an anterior inferior cerebellar artery

Disappearing Cerebral Communicating Vessels in Embryonic Development-With a Case of Carotid-Vertebrobasilar Artery Anastomosis

In early embryonic development, anastomoses between carotid and basilar arteries occur in the primitive trigeminal, primitive otic, primitive hypoglossal, and primitive proatlantal arteries, and these anastomoses gradually disappear as the embryo continues to develop. This article reported a case of vascular anastomosis occurring between the external carotid artery and vertebral artery.

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.

ATHEROMATOSIS OF THE BRAIN-SUPPLYING ARTERIES: CIRCLE OF WILLIS, BASILAR, VERTEBRAL AND THEIR BRANCHES

PURPOSE

Atherosclerotic plaques in the brain-supplying arteries are slowly-developing alterations of vascular structures that can lead to neurological impairment due to stenosis and insufficient oxygenation of eloquent brain areas. The aim of this study is to provide detailed demographic information related to the incidence of atherosclerotic plaques in the cerebral arteries.

MATERIAL AND METHODS

Forty-eight circles of Willis (21 men, 21 women, mean age: 70.26, six samples unknown) were macroscopically analyzed for length, diameter, and presence of atherosclerotic plaques. Statistical analysis was used to identify potential differences in the locations and frequencies of atherosclerotic plaques in relation to age and sex.

RESULTS

The study sample revealed 261 atherosclerotic plaques. The key findings were significant correlations between plaque development and age and between plaque location and age; however, there was no significant sex difference.

CONCLUSION

The upper and lower branches of the middle cerebral artery (MCA) were novel locations predisposing to plaque development. A cut-off value at 60 years revealed a significant difference in plaque development and distribution. There were no significant sex differences in the occurrence of atherosclerotic plaques.

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.

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.

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.

Bilateral persistent trigeminal artery variants diagnosed by MR angiography

A persistent trigeminal artery (PTA) is the most common anastomosis between the carotid and vertebrobasilar system. A PTA variant (PTAV) is a rare anomaly in which the cerebellar artery arises from the internal carotid artery (ICA) without connection with the basilar artery (BA). I present what I believe is the first report of bilateral PTAVs diagnosed using magnetic resonance (MR) angiography and briefly discuss the embryology of this rare anomaly. An 81-year-old woman with small infarctions underwent cerebral MR imaging and MR angiography with a 1.5-tesla imager for the evaluation of brain lesions. An MR angiography was obtained using the standard noncontrast three-dimensional time-of-flight technique. The MR angiographic demonstration of bilateral anterior inferior cerebellar arteries arising from the precavernous segment of the ICA without anastomosis to the BA indicated bilateral PTAVs. This is the first report of bilateral PTAVs diagnosed by MR angiography. The literature review indicates that an estimated prevalence of bilateral PTAVs is about 0.0012%.

Trigeminal artery: a review of normal and pathological features

OBJECTS

Carotid-vertebrobasilar anastomoses-the trigeminal, otic, hypoglossal, and proatlantal intersegmental arteries-serve as transitory channels between primitive internal carotid arteries and bilateral longitudinal neural arterial plexus, which is the precursor of future basilar artery, when the human embryo reaches about 4-mm length.

MATERIAL AND METHODS

Normal and/or abnormal morphofunctional aspects of the prenatal and postnatal forms of the trigeminal artery are described according to personal and literature data. Many arteries of similar origin and course are also noted in the differential diagnosis of the trigeminal artery.

CONCLUSIONS

The persistent primitive trigeminal artery, as the most commonly carotid-vertebrobasilar anastomosis, has a reported incidence of 0.03-2.2% in the literature. There is female sex predilection, and it may be discovered in patients of any age, on either side, and in association with many vascular variants. Although the significance of persistent primitive trigeminal artery regarding the development of an aneurysm or association with another pathological condition may not be clear, its (ab)normal morphology is the inspiration for anatomists, especially for neurosurgeons, before planning diagnostic and therapeutic procedures.

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

INTRODUCTION

The primitive persistent trigeminal artery (PTA) is the most common carotid-basilar anastomosis, but because of its extremely low incidence, it is poorly understood. The purpose of this study is to clarify the features of PTA and its variants (PTAV) based on a large magnetic resonance angiography (MRA) series.

METHODS

MRA was performed on continuous 16,415 patients (8,610 males and 7,805 females) between October 2005 and September 2008 using two 1.5-T systems and one 1.0-T system. These all MRAs were evaluated by neuroradiologists.

RESULTS

The incidence of both PTA and PTAV was 0.68% (48 cases of PTA, 50 cases of PTAV, and five unclassified). Among them, 65 cases originated from the left internal carotid artery and 38 from the right. There were 44 cases of lateral type PTA and four cases of medial type. Hypoplasia of the basilar artery proximal to the union of PTA was recognized as follows: no hypoplasia in 12 cases, moderate hypoplasia in 22 cases, and severe hypoplasia in 13 cases. Distance from SCA and the union was an average of 6.7 mm. Four cases of pre- and postoperative cerebral aneurysms were recognized in 103 cases (3.9%).

CONCLUSION

We have identified details of both PTA/PTAV. The incidence of PTA was similar to previous studies, and the co-existence of cerebral aneurysm was also similar when compared to patients in the general population without PTA or PTAV.

A rare variant of persistent trigeminal artery: cavernous carotid-cerebellar artery anastomosis--a case report and a systematic review

We report a very rare anomalous anatomic variant of the cavernous internal carotid artery supplying directly the posterior inferior cerebellar artery, with no basilar artery opacification. A systematic review as well as a description of other variants of trigeminal-cerebellar anastomosis is given.