Cerebrovascular Anomalies: Perspectives From Immunology and Cerebrospinal Fluid Flow.

Appropriate vascular function is essential for the maintenance of central nervous system homeostasis and is achieved through virtue of the blood-brain barrier; a specialized structure consisting of endothelial, mural, and astrocytic interactions. While appropriate blood-brain barrier function is typically achieved, the central nervous system vasculature is not infallible and cerebrovascular anomalies, a collective terminology for diverse vascular lesions, are present in meningeal and cerebral vasculature supplying and draining the brain. These conditions, including aneurysmal formation and rupture, arteriovenous malformations, dural arteriovenous fistulas, and cerebral cavernous malformations, and their associated neurological sequelae, are typically managed with neurosurgical or pharmacological approaches. However, increasing evidence implicates interacting roles for inflammatory responses and disrupted central nervous system fluid flow with respect to vascular perturbations. Here, we discuss cerebrovascular anomalies from an immunologic angle and fluid flow perspective. We describe immune contributions, both common and distinct, to the formation and progression of diverse cerebrovascular anomalies. Next, we summarize how cerebrovascular anomalies precipitate diverse neurological sequelae, including seizures, hydrocephalus, and cognitive effects and possible contributions through the recently identified lymphatic and glymphatic systems. Finally, we speculate on and provide testable hypotheses for novel nonsurgical therapeutic approaches for alleviating neurological impairments arising from cerebrovascular anomalies, with a particular emphasis on the normalization of fluid flow and alleviation of inflammation through manipulations of the lymphatic and glymphatic central nervous system clearance pathways.

Changes in Angioarchitecture After Stereotactic Radiosurgery for Dural Arteriovenous Fistula.

INTRODUCTION: Dural arteriovenous fistulae (DAVF) are intracranial vascular abnormalities encountered in neurosurgery practice. Treatment options are microsurgical disconnection, endovascular embolization and/or radiosurgery. Past studies have reported the efficacy, safety, and predictors of success of radiosurgery. In this study, we investigated the angioarchitecture of fistulae at the time of radiosurgery and how the anatomy changed in the time after treatment based on angiogram follow-ups. METHODS: A retrospective analysis was performed on patients with angiographic diagnosis of DAVF treated with Gamma Knife radiosurgery (GKRS) between 2013 and 2018. Data collection included demographics, symptoms, grading scores, vascular anatomy, radiation data, treatment strategy, angiographic results, and length of patient follow-up. RESULTS: Our study reports data on 10 patients with a total of 14 fistulae. On follow-up angiography, 8 (57%) had complete occlusion of the fistula with a median time to follow up of 19.5 months. The remaining 6 (43%) were deemed as near-complete occlusion of fistula with a median time to follow up of 12.0 months. Time from radiosurgery to angiogram revealing incomplete vs. angiogram revealing complete obliteration was significantly different (p=0.045). Nearly all AVFs had decreased feeders over time after treatment with only one AVF developing an additional feeder post-treatment. Arterial feeders, drainage site, sex, Borden type, lesion volume and treatment volume had no predictive value of obliteration outcome. CONCLUSIONS: This study provides data on the angioarchitecture of fistulae treated with GKRS and also serves as an extension of previous studies reporting the safety and efficacy of GKRS treatment for DAVF in a specific patient population.

De Novo Dural Arteriovenous Fistula on Draining Veins of Previously Treated Pial Arteriovenous Malformation: a Case Report.

A 71-year-old man, with a pial micro-arteriovenous malformation (pAVM) draining into the confluence of the vein of Trolard and the vein of Labbé was surgically removed, sparing these cortical veins. 4-months MR and angiographic controls showed a de novo dural arteriovenous fistula (dAVF) draining into the previously spared cortical veins. It was removed using intraoperative motor evoked potentials (MEP). This is the first case of iatrogenic dAVF developing on the same draining vein of a previously treated pAVM. De novo dAVFs are generally iatrogenic. This case suggests that the unresected venous drainage of an AVM might be the substratum for neo-angiogenetic processes; moreover inflammation related to surgery might be the trigger factor for the development of the dAVF.

Additive Manufacturing of 3D Biomodels as Adjuvant in Intracranial Aneurysm Clipping.

One of the main difficulties in intracranial aneurysms (IA) surgery refers to the choice of the appropriate clip(s) to be implanted. Although the imaging exams currently available ensure visualization of IA's morphology, they do not bring an accurate reference positioning for the surgeon in executing the surgery procedure nor efficiently contribute to planning the surgery. Unfortunately, for IA's largely inaccessible regions, there is not an efficient method of treatment planning. Therefore, we propose a novel method that allows the generation of a 3D biomodel of the IA region under investigation using additive manufacturing technology (AM). Thus, a physical copy of the IA is produced and offers the surgeon a full view of the anatomy of that region of the brain. The aim of this study is the creation of a flexible 3D physical model (elastomer) through the AM technique, in order to allow the clip selection prior to the surgery. DICOM angio-CT images from eight patients who underwent IA surgery were transformed into STL format and then built on a 3D printer. Preoperative surgical clip selection was performed and then compared with those used in surgery. At the end of the study, all 3D IA biomodels were reproduced for microsurgical clipping selection and it was possible to predict the metal clip to be used in the surgery. In addition, the proposed methodology helps to clarify the surgical anatomy and to avoid excessive manipulation of the intracranial arteries and prolonged surgical time. The major advantage of this technology is that the surgeon can closely study complex cerebrovascular anatomy from any perspective using realistic 3D biomodels, which can be handheld, allowing simulation of intraoperative situations and anticipation of surgical challenges.

Persistent Primitive Olfactory Artery as Novel Collateral Channel to the Anterior Cerebral Artery in Moyamoya Disease.

BACKGROUND: There are a variety of collateral routes to compensate persistent cerebral ischemia in moyamoya disease. However, there is no report presenting the persistent primitive olfactory artery (POA) as a spontaneous collateral route to the anterior cerebral artery (ACA) in moyamoya disease. METHODS: We precisely examined cerebral angiography in 84 patients with moyamoya disease to identify the collateral channel through the persistent POA. Its anatomy was evaluated on pre- and postoperative angiography. RESULTS: Of 84 patients, four (4.8%) had spontaneous collateral channel through the persistent POA. All of these four hemispheres were categorized into Stage 5. In all four patients, the collateral blood flow arose from the ophthalmic artery and run to the persistent POA through the ethmoidal moyamoya. The persistent POA provided collateral blood flow from the ophthalmic artery to the ACA in all four patients. Superficial temporal artery to middle cerebral artery anastomosis and encephalo-duro-myo-arterio-pericranial synangiosis was performed in three of four patients. After surgery, the collateral channel through the persistent POA completely disappeared or markedly regressed, suggesting a significant improvement of cerebral hemodynamics in the territory of not only the MCA but also the ACA. CONCLUSION: The persistent POA can potentially provide collateral blood flow to the ACA in about 5% of patients with moyamoya disease, and should be recognized as a novel collateral channel in moyamoya disease. The persistent POA may be useful to evaluate therapeutic effects of surgical revascularization on the ACA territory.

Rare Case of Absent Common Carotid Artery Likely Associated with Intracranial Aneurysm Development.

Congenital absence of the common carotid artery without separate origin of internal carotid artery and external carotid artery from the aortic arch is a very rare anomaly. A persistent proatlantal intersegmental artery into adult life is also a rare condition. We report a patient with the coexistence of such rare conditions who presented with cerebral infarctions and intracranial aneurysms.

Risk factors for neurological deficits after surgical treatment of brain arteriovenous malformations supplied by deep perforating arteries.

The treatment of brain arteriovenous malformations supplied by deep perforating arteries (PA) (P-BAVM) remains challenging. The aims of this study were to determine the outcomes after surgical treatment in patients with P-BAVMs and to identify the risk factors associated with postoperative neurological deficits. We retrospectively reviewed the medical charts and imaging records of 228 consecutive patients with BAVMs who underwent microsurgical resection of their BAVMs at Beijing Tiantan Hospital between September 2012 and March 2016. Patients were included if the BAVMs were totally or partially supplied by PA. All patients had undergone preoperative diffusion tensor imaging (DTI), MRI, 3D time-of-flight MRA (3D TOF-MRA) and digital subtraction angiography (DSA) followed by resection. Both functional and angioarchitectural factors were analysed with respect to the postoperative neurological deficits, including motor deficits, visual field deficits and aphasia. Statistical analysis was performed using the statistical package SPSS (version 20.0.0, IBM Corp.). Fifty-nine patients with P-BAVMs were enrolled. Radical obliteration was achieved in all P-BAVMs according to postoperative DSA. Forty-five (76.3%) patients obtained neurological deficits 1 week after surgery. At a mean follow-up of 14.7 ± 9.4 (3-30) months after surgery, 34 patients (57.6%) had long-term neurological deficits. Multivariable logistic regression analyses showed that a shorter lesion-to-eloquent fibre tracts distance (LFD) was an independent risk factor for short- (P = 0.014) and long-term (P = 0.013) neurological deficits. The cut-off point of LFD for long-term neurological deficits was 5.20 mm. The predominant supply of the PA (P = 0.008) was an independent risk factor for long-term neurological deficits. This study identified a high risk of surgical morbidity for P-BAVMs. The predominant supply of the PA and a shorter LFD are crucial risk factors for postoperative neurological deficits in patients with P-BAVMs.

Persistent trigeminal artery variant terminating in the posterior inferior cerebellar artery: a case report.

Persistent trigeminal artery (PTA) is a rare cerebrovascular variation of remnant fetal carotid-vertebrobasilar anastomoses. The PTA variant terminates in the cerebellar artery with no direct connection to the basilar artery. We present a rare case of a PTA variant that terminated directly into the ipsilateral posterior inferior cerebellar artery.

Communicating Segment Aneurysm of Internal Carotid Artery Associated with Saltzman's Type III Persistent Trigeminal Artery: A Case Report.

Persistent trigeminal artery (PTA), also called primitive trigeminal artery, represents the most common embryonic remnant of fetal circulation in adulthood, (only after fetal pattern of posterior communicating artery [PComA]) with an estimated incidence of between 0.1% and 0.76%. The permanence of this fetal pattern constitutes an incidental finding in most cases, however, may be associated with aneurysms, arteriovenous malformations, trigeminal neuralgia, and other types of fetal circulation persistency. A patient with giant aneurysm in the communicating segment of the right internal carotid artery, associated with the presence of PTA and fetal pattern of PComA, also on the right side is reported.

Multiple variations of the cerebral arteries associated with tetralogy of Fallot: a case report.

Tetralogy of Fallot (TOF) can be associated with vascular malformations or variations, especially of the aortic arch or supracardiac major venous systems. We report its association with an extremely rare combination of three such variations of the cerebral arteries-a right persistent hypoglossal artery, an extremely rare left carotid-right anterior cerebral artery (ACA) anastomosis, and a left accessory middle cerebral artery arising from the A1-A2 junction of the left ACA-which were diagnosed by magnetic resonance angiography in a 9-year-old girl during evaluation of multiple acute cerebral infarctions.

[Vascular pathologies and vascular anatomical variants of the posterior cranial fossa]. / Gefäßpathologien und -normvarianten der hinteren Schädelgrube.

CLINICAL/METHODICAL ISSUE: The posterior fossa is the location of some specific vascular pathologies and vascular anatomical variants that are important for radiologists to know and recognize. Vascular malformations that are also found in the supratentorial region have some divergent characteristics in the posterior fossa. PRACTICAL RECOMMENDATIONS: Knowledge of the vascular anatomy of the posterior fossa and its variants is important for an understanding of vascular pathologies.

Fast 4D flow MRI intracranial segmentation and quantification in tortuous arteries.

PURPOSE: To describe, validate, and implement a centerline processing scheme (CPS) for semiautomated segmentation and quantification in carotid siphons of healthy subjects. 4D flow MRI enables blood flow measurement in all major cerebral arteries with one scan. Clinical translational hurdles are time demanding postprocessing and user-dependence induced variability during analysis. MATERIALS AND METHODS: A CPS for 4D flow data was developed to automatically separate cerebral artery trees. Flow parameters were quantified at planes along the centerline oriented perpendicular to the vessel path. At 3T, validation against 2D phase-contrast (PC) magnetic resonance imaging (MRI) and 4D flow manual processing was performed on an intracranial flow phantom for constant flow, while pulsatile flow validation was performed in the internal carotid artery (ICA) of 10 healthy volunteers. The CPS and 4D manual processing times were measured and compared. Flow and area measurements were also demonstrated along the length of the ICA siphon. RESULTS: Phantom measurements for area and flow were highly correlated between the CPS and 2D measurements (area: R = 0.95, flow: R = 0.94), while in vivo waveforms were highly correlated (R = 0.93). Processing time was reduced by a factor of 4.6 compared with manual processing. Whole ICA measurements revealed a significantly decreased area in the most distal segment of the carotid siphon (P = 0.0017), with flow unchanged (P = 0.84). CONCLUSION: This study exhibits fast semiautomated analysis of intracranial 4D flow MRI. Internal consistency was shown through flow conservation along the tortuous ICA siphon, which is typically difficult to assess.

Extremely long posterior communicating artery diagnosed by MR angiography: report of two cases.

We report two cases of an extremely long left posterior communicating artery (PCoA) diagnosed by magnetic resonance (MR) angiography. The PCoA arose from the normal point of the supraclinoid internal carotid artery and fused with the posterior cerebral artery (PCA) at its posterior ambient segment, forming an extremely long PCoA and extremely long precommunicating segment of the PCA. To our knowledge, this is the first report of such variation. Careful observation of MR angiographic images is important for detecting rare arterial variations. To identify these anomalous arteries on MR angiography, partial maximum-intensity-projection images are useful.

Variable relations of the trochlear nerve with the pontomesencephalic segment of the superior cerebellar artery.

The superior cerebellar artery (SCA) is, perhaps, the most anatomically constant cerebellar artery which, in its lateral pontomesencephalic course, is crossed above by the trochlear nerve (CNIV). The SCA may determine, as an offending vessel, CNIV compression and superior oblique myokymia and thus surgical decompression may be indicated. In this regard an accurate knowledge of the variational possibilities of the SCA-CNIV is needed. Such rare neurovascular variants are reported here. The variables are determined by the length of the SCA, and the course of the CNIV as referred to the rostral (RT) and caudal (CT) trunks of the SCA. The CNIV may be pinched between the origins of the RT and CT, may pass above the RT or the SCA main trunk, and even between the primary branches of the RT. The CNIV was found compressed between the RT and the brainstem. Perhaps the most spectacular variation was a CNIV coursing through an arterial ring formed by the RT and CT which were anastomosed distally to the CNIV. The possibilities of neurovascular relations between the CNIV and the SCA should be considered when CNIV palsy, or surgical decompression, are estimated.

Double origin and early bifurcation of the anterior inferior cerebellar artery diagnosed by CT angiography.

Due to the technical improvements, anatomical variations of the small arteries, those were previously reported on cadaveric series, can also be evaluated on CT angiography. Absence of the anterior inferior cerebellar artery (AICA) is the most common variation of the AICA. Duplication and fenestration of the AICA can be rarely seen. In this report, two new variations, early bifurcation and double origin of the AICA, were described on CT angiography.

Missing relationship of moyamoya and persistent primitive artery in Europeans. Another distinctive feature or artifact?

PURPOSE: Previous studies found higher incidence of persistent primitive arteries in Asian moyamoya (MM) patients than in the general population, which was thought to be a characteristic trait of the MM entity in general. We analyzed incidence of persistent primitive arteries and demographics of patients with European MM treated in one single center. First, we compared our large dataset to existing literature and second, we raised the question whether European MM demonstrates similar high prevalence of persistent primitive arteries as it was previously presented within Asian MM. METHODS: All European MM on whom revascularization surgery was performed from 1999 to 2013 were included. Demographics and associated diseases were obtained by retrospective chart review. Two independent readers evaluated 122 MM angiograms to determine the occurrence of persistent primitive arteries as well as the Suzuki score. RESULTS: We identified 112 cases with MM disease, 10 with MM syndrome. Mean age at time of diagnosis was 38.2 (range 6-64 years); a peak incidence in early childhood was not observed. Ninety (73.8%) were women, associated systemic diseases were found in four patients. Seven cases (5.7%) presented with unilaterally affected vessels. The majority of patients (71; 58.2%) were graded Suzuki Score 3. One 14-year-old boy with moyamoya presented with a primitive trigeminal artery (0.89%). CONCLUSIONS: We did not find a bimodal age distribution, but only a second peak during adulthood. Unlike previous studies on Asian moyamoya patients, our collective does not exhibit a higher prevalence of persistent primitive arteries than the normal population.

An unusual, duplicate origin of the anterior choroidal artery with aneurysm: a case report.

BACKGROUND AND IMPORTANCE: Aneurysms of the anterior choroidal artery (AChoA) are rare and often difficult to treat. Variations may be present and must be identified prior to treatment. We report a unique case of a ruptured aneurysm located at the origin of a duplicate branch of the AChoA. CLINICAL PRESENTATION: A 56-year-old male was admitted to our university hospital for coma. A brain CT scan showed a subarachnoid hemorrhage, and CT angiography revealed a duplication of the right AChoA, with an aneurysm located at the branch's origin. We decided to embolize this aneurysm. Four weeks later, our patient was able to transfer to the rehabilitation unit. CONCLUSION: To the best of our knowledge, this is one of the first descriptions of an aneurysm located at the origin of a duplicate branch of the AChoA.

Persistent hypoglossal artery aneurysm located in the hypoglossal canal with associated subarachnoid hemorrhage.

The hypoglossal artery is one of four primitive anastomoses between the internal carotid artery and vertebrobasilar system that regresses in the sixth week of fetal development. A persistent hypoglossal artery (PHA) is generally an incidental finding but may also be associated with aneurysms or arteriovenous malformations. We present a rare case of a PHA with an associated bleeding intracranial PHA aneurysm located in the hypoglossal canal.

Intracranial arterial variations: a comprehensive evaluation using CT angiography.

Background Intracranial arterial variations are a frequent finding in the general population. Knowledge of these vascular variations has significant clinical impact because some of them predispose patients to development of an aneurysm or cerebrovascular ischemic disease. The purpose of this study was to evaluate the frequency of intracranial vascular variations and associated vascular lesions on computed tomography angiography (CTA) examinations. Material and Methods CTA examinations performed by 16-detector computed tomography were prospectively reviewed in 455 patients for the presence of fenestrations, duplications, hypoplasia, aplasia, aneurysms, and other vascular lesions. Results Arterial fenestrations were found in 2.4% of patients, with the vertebrobasilar system as the most common location. The remaining fenestrations were located on the middle cerebral artery M1 segment (0.2%), anterior communicating artery (0.4%), and anterior cerebral artery A1 segment (0.6%). No associated aneurysms were noted in these patients. The prevalence of an azygos anterior cerebral artery was 1.5%. Bihemispheric anterior cerebral artery was found in 0.9%, hypoplastic A1 segment in 17.6%, and congenital absence of A1 segment in 0.4% of patients. Fetal origin of the posterior cerebral artery was found in 37% of cases. Hypoplastic vertebral artery terminating as posterior inferior cerebellar artery was observed in 9 patients, while transversal anastomosis between vertebral arteries was seen in only 1 patient. Conclusions CTA precisely demonstrates the diversity of intracranial arterial variations, whose overall frequency in this study is similar to previous radiological reports. Furthermore, our results do not show significant association between the frequency of aneurysms and cerebral arterial anomalies.