[Basilar Artery, Anterior Inferior Cerebellar Artery, Superior Cerebellar Artery].

The basilar artery(BA)is formed by the fusion of two longitudinal arteries, and incomplete development may lead to BA fenestration. The BA provides many short perforating arteries and long lateral pontine arteries to the brain stem. The anterior inferior cerebellar artery(AICA)usually branches from the proximal third of the BA and primarily perfuses the ventral, inferior and lateral aspect of the cerebellum and inner ear organ. However, there are many variations to the AICA that depend on the degree of posterior inferior cerebellar artery development. The superior cerebellar artery(SCA)branches into not only to the rostral, ventral aspect of the cerebellar hemisphere, but also to the deeper cerebellar nucleus and brain stem. Duplications within this vessel are frequently identified, but it is not missing.

Characterization of posterior circulation blood perfusion in patients with different degrees of basilar artery tortuosity.

OBJECTIVE: The morphology of basilar artery (BA) may affect posterior circulation blood perfusion. We aimed to investigate whether different degrees of BA tortuosity could lead to the alterations of posterior circulation perfusion. METHODS: We collected 138 subjects with different BA tortuosity scores, including 32 cases of score 0, 45 cases of score 1, 43 cases of score 2, and 18 cases of score 3. A higher score represented a higher degree of BA tortuosity. Ordered logistic regression analysis was performed to investigate the risk factors for BA tortuosity. We quantitatively measured the cerebral blood flow (CBF) in eight posterior circulation brain regions using arterial spin labeling. SPSS 25.0 was used for statistical analysis. The correlation between the CBF and BA tortuosity was corrected by the Bonferroni method. The significance level was set at 0.006 (0.05/8). RESULTS: Hypertension (HR: 2.39; 95%CI: 1.23-4.71; P = 0.01) and vertebral artery dominance (HR: 2.38; 95%CI: 1.10-4.67; P = 0.03) were risk factors for BA tortuosity. CBF in occipital gray matter (R = -0.383, P < 0.001), occipital white matter (R = -0.377, P < 0.001), temporal gray matter (R = -0.292, P = 0.001), temporal white matter (R = -0.297, P < 0.001), and cerebellum (R = -0.328, P < 0.001) were negatively correlated with BA tortuosity degree. No significant correlation was found between the BA tortuosity degree and CBF in hippocampus (R = -0.208, P = 0.014), thalamus (R = -0.001, P = 0.988) and brainstem (R = -0.204, P = 0.016). CONCLUSIONS: BA tortuosity could affect posterior circulation blood perfusion. CBF was negatively correlated with BA tortuosity degree. The morphology of BA may serve as a biomarker for posterior circulation and the severity of posterior circulation ischemia.

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.

Case of Amaurosis Fugax in the Setting of a Persistent Primitive Hypoglossal Artery Requiring Carotid Endarterectomy with Regional Anesthesia.

BACKGROUND A persistent primitive hypoglossal artery (PPHA) is a rare congenital anomaly leading to persistent carotid-basilar anastomosis. This is a report of an 83-year-old man with a PPHA presenting with amaurosis fugax of the left eye requiring carotid endarterectomy under regional anesthesia. CASE REPORT An 83-year-old man presented with 2 weeks of intermittent self-resolving visual disturbances, followed by an episode of left eye amaurosis fugax. The patient had been referred to the hospital for further investigation of symptoms 1 day following the amaurosis fugax event. Carotid Doppler ultrasound demonstrated a greater than 90% stenosis of the left internal carotid artery. Computed tomography carotid and Circle of Willis angiography confirmed a mixed, ulcerated plaque and revealed a persistent left hypoglossal artery originating from the left internal carotid artery and continuing as the basilar artery. On day 3 of admission, left carotid endarterectomy was performed under conscious sedation and regional anesthesia to permit continuous monitoring of neurological status and avoid the need for intraoperative shunting. "Permissive hypertension" by targeting a systolic blood pressure of 190 to 200 mmHg was sought for the duration of clamp time. There was no deterioration of neurological function during clamping of the carotid vessels. The patient recovered well and was discharged 2 days after surgery, with no residual neurology. CONCLUSIONS This report has presented a rare case of PPHA to highlight awareness of this congenital vascular anomaly when undertaking carotid endarterectomy.

Vertebrobasilar artery elongation in migraine-a retrospective cross-sectional study.

BACKGROUND: Numerous but inconclusive findings have sparked an ongoing debate about whether the arteries of migraine patients undergo vascular alterations. The outlet angle of the superior cerebellar artery (SUCA) and the lateral displacement of basilar arteries are good surrogate parameters for determining elongation of the vertebrobasilar arteries. METHODS: We retrospectively determined the SUCA outlet angle and the lateral displacement of the basilar artery in 63 patients with migraine (30.6 ± 8.9 years, 84% women, 16% chronic migraine, 60% migraine with aura) and compared these with 126 age- and sex-matched control subjects. RESULTS: In patients with migraine, the SUCA outlet angle was lower (159 ± 26° vs. 169 ± 29°, p = 0.020) and the lateral displacement of the basilar artery was greater (3.7 ± 2.7 mm vs. 2.8 ± 2.4 mm, p = 0.020) than in the control subjects. Age, gender, migraine characteristics and presence of any cardiovascular risk factors did not affect the SUCA outlet angle or lateral displacement of the basilar artery. CONCLUSION: Migraine patients exhibited a lower SUCA outlet angle and greater lateral displacement of the basilar arteries. Both may be attributable to the elongation of the vertebrobasilar arteries, which is an indication of arterial wall pathology in migraine.

Persistent trigeminal artery associated with an occipital arteriovenous malformation: a case report and literature review.

BACKGROUND: Persistent trigeminal artery or persistent primitive trigeminal artery (PTA) is the most common carotid-basilar anastomosis in both cadaveric and live patient studies, followed by persistent hypoglossal and persistent otic arteries. Approximately 0.2% of all angiographies reported this finding. CASE REPORT: We present the case of a 21-year-old male who arrived at the emergency department with tonic‒clonic seizures. After performing diagnostic contrast magnetic resonance imaging and digital subtraction angiography, the patient was diagnosed with a right occipital arteriovenous malformations (AVM) fed by the right calcarine artery associated with an ipsilateral PTA. After considering surgical and endovascular treatment options, the patient was selected for watchful waiting. We included a literature review of the PTA, the results of a PubMed search regarding the combined presence of these findings, and a brief discussion providing insight into the implications for treatment. CONCLUSIONS: Although several studies have linked PTA to different vascular pathologies, such as cerebral aneurysms, the association between PTA and AVMs remains scarce. This case, along with the literature review, shows that further research is needed to characterize the relationship between these findings.

Duplicated posterior inferior cerebellar arteries one of which was supplied by the jugular branch of the ascending pharyngeal artery.

PURPOSE: To describe a case of duplicated posterior inferior cerebellar arteries (PICAs), one of which was supplied by the jugular branch of the ascending pharyngeal artery (APA). CASE REPORT: A 62-year-old man with cerebral infarction underwent cranial magnetic resonance (MR) imaging and MR angiography. MR angiography showed a hyperplastic left APA, that was found to enter the posterior cranial fossa and continue to the PICA. Another left PICA arising from the V4 segment of the left vertebral artery (VA) and a tiny left anterior inferior cerebellar artery (AICA) were also identified. The source images of MR angiography revealed that the anomalous artery was passing through the medial side of the jugular foramen pars vascularis. The two left PICAs did not fuse to each other. DISCUSSION: There are four types of the PICA arising from the carotid system: (1) the PICA arises from the cavernous segment of the internal carotid artery (ICA) (persistent trigeminal artery variant); (2) the PICA arises from the cervical segment of the ICA (persistent hypoglossal artery variant); (3) the PICA arises from the APA via the hypoglossal canal; and (4) the PICA arises from the APA via the jugular foramen. Two PICAs sometimes arise from the V4 segment of the VA. In this common variation, the AICA is usually absent. This is the first reported case involving the association of (4) and a duplicated PICA with a tiny AICA. CONCLUSION: To identify this variation, careful observation of source images and creation of partial maximum-intensity-projection images of MR angiography are important.

Acute pontine infarction in a patient with 8-shaped basilar artery fenestration malformation: A case report.

INTRODUCTION: Cerebrovascular fenestration malformation is a relatively rare vascular dysplasia, and an 8-shaped basilar artery fenestration malformation is even rarer. The characteristics of transcranial Doppler cerebral blood flow in cerebrovascular fenestration malformations have rarely been studied or reported. PATIENT CONCERNS: A 58-year-old woman presented with hypertension, diabetes, with no history of smoking or drinking. The patient had no relevant family history. The patient experienced left limb weakness for 2 days, which gradually worsened. DIAGNOSIS: Head and neck computed tomography angiography revealed an 8-shaped fenestration deformity of the lower segment of the basilar artery with multiple stenoses of the local vessels. Transcranial Doppler cerebral blood flow examination at a depth of 85 cm revealed an eddy current in the lower segment of the basilar artery. INTERVENTIONS: Tirofiban was administered intravenously for 3 days and subsequently changed to oral clopidogrel antiplatelet treatment. OUTCOMES: The modified Rankin Scale score at 3 months after disease onset was 0, indicating that the patient recovered well after treatment. CONCLUSION: A basilar artery 8-shaped fenestration is extremely rare and has seldom been reported. Cerebral vascular fenestration can lead to an acute cerebral infarction and its pathogenesis may include local hemodynamic abnormalities and thrombosis. Eddy currents can be detected by transcranial Doppler cerebral blood flow examination.

Association of cerebral infarction with vertebral arterial fenestration using non-Newtonian hemodynamic evaluation.

PURPOSE: Cerebral artery fenestration is a rare vascular anomaly, but its existence has been increasingly documented. The association of cerebral infarction and fenestration is of great clinical interest, and the exact underlying mechanism remains unclear. This study aims to identify risk factors contributing to cerebral infarction by computational hemodynamics analysis. METHODS: Eight patients with image findings of fenestration structure were recruited in this research, in which four suffered fenestration-related cerebral infarction (A series) while the other four (B series) were set as control matched by the fenestration size. Three-dimensional models were reconstructed from the MRA images and computational simulations with non-Newtonian flow model were performed to get interested hemodynamic characteristics. RESULTS: The blood flow pattern was relatively separated along two channels of fenestration in series A compared with series B cases in Group 1-2, however, no significant difference was shown in Group 3-4. Quantitatively, planes were cut in the middle of fenestrations and the ratio of mass flow rate and area was calculated at systolic peak. Results showed that the side of the dominant blood supply was opposite between A and B series, and the dominant side was also opposite between small and large fenestrations. In infarction cases, the basilar top was distributed with larger areas of detrimental hemodynamic indicators and a larger concentrated high viscosity region. CONCLUSION: The flow division condition throughout the fenestration structure has a key impact on further flow redistribution and flow pattern. The blood viscosity has the potential to be a useful tool in identifying the risk factors for cerebral infarction and more emphasis should be placed on the hemodynamic environment at superior cerebellar arteries.

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.

Arterial abnormalities and associated variations of the vertebrobasilar system on the brain base: apropos of a rare case / Anomalías arteriales y variaciones asociadas del sistema vertebrobasilar en la base del cerebro: un caso raro

SUMMARY: The presented case characterizes an association of primitive and definitive arteries with variations on the cadaveric brain base of a very old man. This case is found by the retrospective review of the data archive obtained during many years of cooperation of the author and co-authors. Fenestration of the (ectatic) basilar artery, partial and total duplication of some cerebellar arteries was associated with other variations of the vertebrobasilar and carotid systems. Although this is a case autopsied because of the myocardial infarction, the peculiarity of the case lies in the absence of the aneurysm based on the fenestration or dissection of one of the cerebral arteries.

RESUMEN: El caso presentado caracteriza una asociación de arterias primitivas y definitivas con variaciones sobre la base cerebral cadavérica de un anciano. Este caso se encuentra mediante la revisión retrospectiva de datos obtenidos durante muchos años de un trabajo de cooperación del autor y coautores. La fenestración de la arteria basilar (ectásica), la duplicación parcial y total de algunas arterias cerebelosas se asoció con otras variaciones de los sistemas vertebrobasilar y carotídeo. Si bien se trata de un caso de autopsia a causa de un infarto del miocardio, la peculiaridad del caso radica en la ausencia del aneurisma en base a la fenestración o disección de una de las arterias cerebrales.

Persistent trigeminal artery as a rare cause of vertebrobasilar insufficiency.

The persistent trigeminal artery (PTA) is the most common foetal carotid-basilar anastomosis which may persist into adult life. In the literature there are numerous papers referring to the anatomical characteristics of this anomalous vessel. In the majority of cases PTA is an incidental finding and its clinical significance has been debated. Some authors describe the coincidence of PTA with various clinical syndromes. However, there are few reports linking PTA with the symptoms of vertebrobasilar insufficiency. We present a patient with a 3-year history of recurrent dizziness and impaired vision, precipitated by physical activity, in whom neuroimaging techniques revealed a left PTA. In our case the occurrence of PTA might have been related to the clinical manifestation and the potential mechanism will be discussed.

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.

Persistent Stapedial Artery Resulting in Direct Communication Between the Middle Meningeal and Basilar Arteries: Clinical Image.

A persistent stapedial artery originates from the petrous segment of the internal carotid artery due to failure of the regression of the embryonic stapedial artery. During embryologic development, the stapedial artery supplies the middle meningeal artery through the ventral pharyngeal artery. The presence of a persistent stapedial artery can result in direct communication between the basilar and middle meningeal arteries. We present a cerebral angiogram image of an adult patient that shows a right-sided persistent stapedial artery with communication between the right middle meningeal and basilar arteries. It is important to recognize such rare anatomic variants during endovascular interventions to avoid catastrophic complications such as nontarget embolization of the posterior circulation.

Persistent Primitive Hypoglossal Artery with Ipsilateral Symptomatic Carotid Artery Stenosis and Cerebral Aneurysm.

OBJECTIVE: Persistent primitive hypoglossal artery (PPHA) is a rare type of persistent carotid-basilar anastomosis sometimes associated with other vascular lesions. We treated an extremely rare case of PPHA with concomitant ipsilateral symptomatic cervical internal carotid artery (ICA) stenosis and unruptured aneurysm. CASE PRESENTATION: A 67-year-old woman visited our institution with acute onset of diplopia. Magnetic resonance imaging revealed multiple acute infarctions in the right anterior and posterior circulations. Digital subtraction angiography demonstrated the right PPHA concomitant with ipsilateral cervical ICA stenosis and an unruptured ICA aneurysm with maximum diameter of 8 mm. The multiple infarctions were considered to result from artery-to-artery embolism due to microthrombi from the ICA plaque passed along the PPHA, so carotid endarterectomy was performed as the first step with preoperative modified Rankin Scale (mRS) grade 1. During the operation, the patient had impaired ICA perfusion due to internal shunt catheter migration into the PPHA followed by acute infarction in the right hemisphere causing mild left hemiparesis. The patient was transferred to the rehabilitation hospital with mRS grade 3. After 3 months of rehabilitation, the patient recovered to mRS grade 1 and clipping surgery for the unruptured right ICA aneurysm was performed as the second step with uneventful postoperative course. CONCLUSION: The treatment strategy should be carefully considered depending on the specific blood circulation for such cases of PPHA with unique vasculature.

Persistent Trigeminal Artery as Collateral Circulation in Ischemic Stroke.

The persistent trigeminal artery is the most frequent of the persistent embryonic carotid-basilar artery anastomoses. In the literature, it has most often been described in relation to cerebrovascular pathologies such as aneurysms, vascular nerve compression, trigeminal cavernous fistulas, and thromboembolic ischemia. Its role as collateral circulation, thus supplying brain perfusion during main arterial trunk occlusion, has seldom been described. We describe the case of a patient who presented with a stroke due to a traumatic dissection of the internal carotid artery at the neck, in which the infarction may have been limited by a persistent trigeminal artery.

Medial type persistent trigeminal artery associated with a saccular aneurysm at its trunk.

There are four types of fetal anastomosis between the carotid and vertebrobasilar arteries at 5 weeks gestation; from caudal to cranial position, these involve the proatlantal intersegmental, hypoglossal, otic, and trigeminal arteries. Excluding otic artery, these arteries may persist rarely. Persistent trigeminal artery (PTA) is the most common carotid-vertebrobasilar anastomosis, and the medial type (intrasellar) PTA is quite rare, accounting for approximately 10% of all PTA cases. An aneurysm is occasionally found at the origin of the PTA. Rarely, an aneurysm arises at the trunk of the PTA. Using magnetic resonance angiography, we identified a case of medial type PTA with an unruptured saccular aneurysm at its trunk.

Asymmetry of P1 and vertebral arteries is not related to basilar tip aneurysm development or rupture.

OBJECTIVE: Lately, morphological parameters of the surrounding vasculature aside from aneurysm size, specific for the aneurysm location, e.g., posterior cerebral artery angle for basilar artery tip aneurysms, could be identified to correlate with the risk of rupture. We examined further image-based morphological parameters of the aneurysm surrounding vasculature that could correlate with the growth or the risk of rupture of basilar artery tip aneurysms. METHODS: Data from 83 patients with basilar tip aneurysms (27 not ruptured; 56 ruptured) and 100 control patients were assessed (50 without aneurysms and 50 with aneurysms of the anterior circle of Willis). Anatomical parameters of the aneurysms were assessed and analyzed, as well as of the surrounding vasculature, namely the asymmetry of P1 and the vertebral arteries. RESULTS: Patients with basilar tip aneurysm showed no significant increase in P1 or vertebral artery asymmetry compared with the control patients or patients with aneurysms of the anterior circulation, neither was there a significant difference in asymmetry between cases with ruptured and unruptured aneurysms. Furthermore, we observed no significant correlations between P1 asymmetry and the aneurysm size or number of lobuli in the aneurysms. CONCLUSION: We observed no significant difference in aneurysm size, rupture, or lobulation associated with P1 or vertebral artery (surrounding vasculature) asymmetry. Therefore, the asymmetry of the surrounding vessels does not seem to be a promising morphological parameter for the evaluation of probability of rupture and growth in basilar tip aneurysms in future studies.

A unique finding of the basilar artery.

Variants of the posterior intracranial circulation are important for surgeon, interventionalists and radiologists. Herein, a unique configuration of the basilar artery is reported. A 54-year-old man with a history of COPD, hypothyroidism, smoking, and hyperlipidemia presented to an outside institution with nausea, confusion, altered mental status, and ataxia. The patient was evaluated for stroke. Imaging revealed rotation of the basilar apex of 180 degrees, fetal configuration of the posterior communicating artery, right posterior cerebral artery filling from the left vertebral artery, and duplication of the left and right superior cerebellar arteries. The patient continued to deteriorate neurologically and MRI revealed multifocal and symmetric signal abnormalities in the brain stem, thalami, basal ganglia, and hippocampi. The differential diagnosis included acute disseminated myeloencephalitis. Despite plasma exchange and steroid therapy, the patient died a few days later. This case report demonstrates a rare variation of the basilar apex.