Vascular stability of brain arteriovenous malformations after partial embolization.

INTRODUCTION: Brain arteriovenous malformation (bAVM) might have a higher risk of rupture after partial embolization, and previous studies have shown that some metrics of vascular stability are related to bAVM rupture risk. OBJECTIVE: To analyze vascular stability of bAVM in patients after partial embolization. METHODS: Twenty-four patients who underwent partial embolization were classified into the short-term, medium-term, and long-term groups, according to the time interval between partial embolization and surgery. The control group consisted of 9 bAVM patients who underwent surgery alone. Hemodynamic changes after partial embolization were measured by angiogram. The inflammatory infiltrates and cell-cell junctions were evaluated by MMP-9 and VE-cadherin. At the protein level, the proliferative and apoptotic events of bAVMs were analyzed by immunohistochemical staining of VEGFA, eNOS, and caspase-3. Finally, neovascularity and apoptotic cells were assessed by CD31 staining and TUNEL staining. RESULTS: Immediately after partial embolization, the blood flow velocity of most bAVMs increased. The quantity of MMP-9 in the medium-term group was the highest, and VE-cadherin in the medium-term group was the lowest. The expression levels of VEGFA, eNOS, and neovascularity were highest in the medium-term group. Similarly, the expression level of caspase-3 and the number of apoptotic cells were highest in the medium-term group. CONCLUSION: The biomarkers for bAVM vascular stability were most abnormal between 1 and 28 days after partial embolization.

The Lateral Supraorbital Approach: 2-Dimensional Operative Video.

INDICATIONS: The lateral supraorbital approach (LSO), a minimally invasive alternative to the pterional approach, can be used for anterior circulation aneurysms (except distal anterior cerebral artery), some posterior circulation aneurysms, and tumors located around the sellar and suprasellar regions. ANATOMIC ESSENTIALS: Performing one-layer myocutaneous flap that is retracted anteriorly, exposure of the superior temporal line, and zygomatic process of the frontal bone and the inferior limit of the craniotomy represent the upper edge of the Sylvian fissure, exposing the anterolateral skull base. ESSENTIALS STEPS: Skin incision behind the hairline, one-layer myocutaneous flap retracted anteriorly, minimal detachment of the temporalis muscle, burr hole over the superior temporal line, and craniotomy of 4 cm in diameter (inferior limit of the craniotomy represents the Sylvian fissure). PITFALLS/AVOIDANCE OF COMPLICATIONS: Potential risks include opening of the frontal sinus, entering the orbit and exposure of the orbital fat, wrong craniotomy location, and limited exposure. Inadequate craniotomy size limits instruments maneuverability. To avoid complication, identification of anatomic landmarks, sinus closure, preoperative evaluation of computed tomography scans, and use of neuronavigation are necessary. This requires surgical expertise and familiarity of minimal invasive craniotomies. VARIANTS/REASONS: Anatomic limitations of the LSO include temporomesial region, distal Sylvian +/-, posterior communicating artery aneurysms medial projection, retro carotid space, and carotid cave. For pathologies requiring an additional lateral trajectory, we use an extended LSO, drilling the sphenoid wing through the fronto-pterio-orbital window without drilling of the temporal bone. Additional variations include performing an intradural or extradural clinoidectomy. The patient consented to the procedure and to the publication of their image.

Tracking tumor evolution during the first-line treatment in brain glioma via serial profiling of cell-free tumor DNA from tumor in situ fluid.

Objective: Tumor in situ fluid (TISF) refers to the fluid within surgical cavities of glioma. Several studies preliminarily proved the value of cell-free tumor DNA (cf-tDNA) from TISF in the dynamic characterization of the glioma genome. Here, we assessed the potential utility of TISF cf-tDNA in broad aspects of tumor evolution under therapeutic pressure. Methods: This study was conducted under an Institutional Review Board-approved protocol at Henan Provincial People's Hospital (China). Cf-tDNA samples were sequenced with a designed 68-gene panel. A total of 205 cf-tDNA samples from 107 patients were studied. The clinical relevance of serial cf-tDNA profiling during the postoperative course was analyzed. Results: At least one tumor mutations were detected in 179/205 (87.3%) TISF cf-tDNA samples. Serial cf-tDNA was complementary to molecular residual disease and to initial tumors. Serial cf-tDNA revealed the selection of pre-existing mismatch repair-deficient cells by temozolomide as a resistant mechanism. Cf-tDNA parameters during treatment were predictive of recurrence, and serial cf-tDNA monitoring had diagnostic value for early recurrence. A total of 223 potentially actionable genomic alterations were assessed in cf-tDNA samples, wherein 78% were not found in any tumor tissue. Conclusions: In conclusion, serial TISF cf-tDNA profiling is valuable in tracking the tumor evolution of glioma during treatment and may be a feasible non-invasive option for monitoring glioma in future prospective studies and clinical practice.

Case Report: Curative effect of OA-PICA protected bypass in severe PICA-complicated vertebral artery stenosis treatment: Results in 3 cases.

Objectives: We aimed to explore the results of OA-PICA-protected bypass grafting in patients with severe stenosis of the vertebral artery combined with PICA. Methods: Three patients with vertebral artery stenosis involving the posterior inferior cerebellar artery, treated by the Department of Neurosurgery of Henan Provincial People's Hospital from January 2018 to December 2021, were retrospectively analyzed. All the patients underwent Occipital Artery-Posterior Inferior Cerebellar Artery (OA-PICA) bypass surgery followed by elective vertebral artery stenting. Intraoperative indocyanine green fluorescence angiography (ICGA) showed patency of the bridge-vessel anastomosis. Postoperatively, the ANSYS software was used to assess the flow pressure changes and vascular shear in combination with the reviewed DSA angiogram. CTA or DSA was reviewed 1-2 years postoperatively, and the prognosis was evaluated by the modified Rankin Scale (mRS) one year postoperatively. Results: OA-PICA bypass surgery was completed in all patients, with intraoperative ICGA showing a patent bridge anastomosis, followed by stenting of the vertebral artery, and a review of the DSA angiogram. We also employed ANSYS software evaluation of the bypass vessel, which showed stable pressure and low turnover angle, suggesting a low rate of long-term occlusion of the vessel. All patients had no procedure-related complications during their hospitalization, and were followed up for a mean of 24 months postoperatively, with a good prognosis (mRS score of 1) at 1 year postoperatively. Conclusion: OA-PICA-protected bypass grafting is an effective treatment for patients with severe stenosis of the vertebral artery combined with PICA.

A meta-analysis of Lateral supraorbital vs mini Pterional approach in the outcome of rupture and unruptured noncomplex aneurysms' surgery.

To determine the characteristics and to compare the functional outcomes and safety of different subfrontal approaches versus mini Pterional (MPT) approaches mainly for the treatment of ruptured noncomplex intracranial aneurysms. This meta-analysis included articles comparing outcomes of brain aneurysms (BAs) - most for the anterior circulation-, using Lateral supraorbital & Supraorbital keyhole (LSO) versus MPT approach. There were six articles left into the final article pool and the total number of patients was 683 (322 in LSO and 361 in the MPT group). In terms of the early and late time of surgery, the LSO seems to be superior over the MPT approach but with heterogeneity (OR -0.21, CI 95% -0.59 to 0.18, and p=0.04) or (OR -0.21, CI 95% -0.69 to 0.28, and p=0.05), and (p=0.02 and I2=68.97%) or (p=0.05 and I2=61.74%) respectively. Regarding the subgroup of patients with the supra-early time of surgery, surgical duration, completed occlusion, technical intraoperative complications, postoperative infection, intraoperative rupture, vasospasm, good and poor neurological outcomes and clinical deterioration, there was no superiority of the one method over the other. Mini or keyhole craniotomy even challenging might be a good option for neurosurgeons. Particularly in ruptured noncomplex aneurysms' surgery LSO seems to be superior over the MPT approach in terms of the early time and in the late time of surgery but with heterogeneity.

Safety and efficacy of the SeparGateTM balloon-guiding catheter in neurointerventional surgery: A prospective, multicenter, single-arm clinical trial.

Objective: To evaluate the safety and efficacy of the SeparGate™ balloon-guiding catheter (BGC) for blocking flow and delivering devices in neurointerventional surgery. Method: This prospective multicenter single-arm trial enrolled patients who received BGC adjuvant therapy to provide temporary blood flow arrest of the supra-aortic arch arteries and their branch vessels in interventional therapy. The primary endpoint was immediate procedural success rate in flow arrest, device delivery, and withdrawal. The efficacy endpoints were intraoperative product performance, including rigidity, smoothness, fracture resistance of the catheter wall, catheter push performance, compatibility and radiopaque display, integrity, adhesion thrombus after withdrawal and balloon rupture. The safety endpoints were adverse and serious adverse events associated with the test device and serious adverse events resulting in death or serious health deterioration. Result: A total of 129 patients were included; of them, 128 were analyzed in the full analysis set (FAS) and per protocol set (PPS). Immediate procedural success was achieved in 97.7% of patients with FAS and PPS. The lower bound of the 95% confidence interval was 94.6%, higher than the preset efficacy margin of 94%. Device-related adverse events occurred in 2 (1.6%) cases. One was mild adverse event of vasospasm, which resolved spontaneously. The other was serious adverse event of dissection aggravation, which was treated with stenting angioplasty. No device defects were observed. Conclusion: In neurointerventional surgery, the SeparGate™ BGC can be used to temporarily block the flow of the supra-aortic arch arteries and their branch vessels and guide the interventional device to the target vascular position.

Risk factors and predictive models of poor prognosis and delayed cerebral ischemia in aneurysmal subarachnoid hemorrhage complicated with hydrocephalus.

Objective: To evaluate the correlation of serum biological markers and related scales to the occurrence of delayed cerebral ischemia and clinical prognosis in patients with aneurysmal subarachnoid hemorrhage (aSAH) complicated with acute hydrocephalus before admission. Methods: The clinical data of 227 patients with pre-admission aSAH complicated with acute hydrocephalus admitted to Henan Provincial People's Hospital from April 2017 to December 2020 were retrospectively analyzed. Patients were grouped according to the presence or absence of delayed cerebral ischemia (DCI) after surgery and the prognosis at 6 months after discharge. Univariate and multivariable logistic regression analysis were performed to analyze the relationship between serum biological indicators combined with aneurysm related clinical score scale and the occurrence and prognosis of delayed cerebral ischemia. ROC curves and nomogram were drawn. Results: Multivariable Logistic regression analysis showed that high Hunt-Hess grade and surgical clipping were independent risk factors for postoperative DCI (P < 0.05). Older age, higher Hunt-Hess grade, higher CRP and neutrophil levels were independent risk factors for poor prognosis at 6 months after surgery (P < 0.05). ROC curve analysis showed that the area under the curve (AUC) of Hunt-Hess grade and surgical method for predicting DCI in patients with aSAH combined with hydrocephalus after surgery were 0.665 and 0.593. The combined AUC of Hunt-Hess grade and surgical method was 0.685, the sensitivity was 64.9%, and the specificity was 64.7%. The AUC of CRP, neutrophil, age and Hunt-Hess grade for predicting poor prognosis in patients with aSAH combined with hydrocephalus at 6 months after surgery were 0.804, 0.735, 0.596, 0.757, respectively. The combined AUC of CRP, neutrophil, age, Hunt-Hess grade was 0.879, the sensitivity was 79%, and the specificity was 84.5%. According to the correction curve, the predicted probability of the nomogram is basically consistent with the actual probability. Conclusion: Hunt-Hess grade and surgical method are independent predictors of postoperative DCI in patients with aSAH complicated with hydrocephalus. "CRP," "neutrophil," "age" and "Hunt-Hess grade" at admission are independent predictors of clinical prognosis in patients with aSAH complicated with hydrocephalus. The combination of the above indicators has high predictive value.

Vascular Lesions of the Pineal Region: A Comprehensive Review of the Therapeutic Options.

OBJECTIVE: Vascular lesions of the pineal region comprise aneurysms of the pineal region, arteriovenous malformations, cavernous malformations, and vein of Galen malformations. In the present report, we have offered an extensive review of each vascular pineal region lesion. METHODS: We performed an extensive literature review, focusing on the current therapeutic options available for the different vascular lesions of the pineal region. RESULTS: Vascular lesions of the pineal region are rare. Microneurosurgery remains a valid treatment of cavernomas, arteriovenous malformations, and aneurysms. Endovascular treatments seem to be the first option for the vein of Galen malformations, followed by microneurosurgery. Radiosurgery seems beneficial for small-size arteriovenous malformations. Complex and large vascular lesions will require a combination of multiple treatments. CONCLUSIONS: Vascular lesions of the pineal region are complex, uncommon diseases. Thus, definitive therapeutic modalities for these lesions require further research.

Surgical treatment of brainstem cavernous malformations: an international Delphi consensus.

OBJECTIVE: Indication for surgery in brainstem cavernous malformations (BSCMs) is based on many case series, few comparative studies, and no randomized controlled trials. The objective of this study was to seek consensus about surgical management aspects of BSCM. METHODS: A total of 29 experts were invited to participate in a multistep Delphi consensus process on the surgical treatment of BSCM. RESULTS: Twenty-two (76%) of 29 experts participated in the consensus. Qualitative analysis (content analysis) of an initial open-ended question survey resulted in 99 statements regarding surgical treatment of BSCM. By using a multistep survey with 100% participation in each round, consensus was reached on 52 (53%) of 99 statements. These were grouped into 4 categories: 1) definitions and reporting standards (7/14, 50%); 2) general and patient-related aspects (11/16, 69%); 3) anatomical-, timing of surgery-, and BSCM-related aspects (22/37, 59%); and 4) clinical situation-based decision-making (12/32, 38%). Among other things, a consensus was reached for surgical timing, handling of associated developmental venous anomalies, handling of postoperative BSCM remnants, assessment of specific anatomical BSCM localizations, and treatment decisions in typical clinical BSCM scenarios. CONCLUSIONS: A summary of typical clinical scenarios and a catalog of various BSCM- and patient-related aspects that influence the surgical treatment decision have been defined, rated, and interpreted.

Occlusion of the Anterior Cerebral Artery Mimicking a Cerebral Aneurysm: Clinical Presentation and Literature Review.

BACKGROUND: Intracranial aneurysms may be misdiagnosed with other vascular lesions such as vascular loops, infundibulum, or the stump of an occluded artery (very rare and reported compromising only the middle cerebral artery and the posterior circulation territory). Our aim was to describe a unique case of occlusion of an anterior cerebral artery mimicking a cerebral aneurysm in a probable moyamoya disease patient, and to highlight its clinical presentation, diagnosis, and management, and to perform an extensive literature review. CASE: A 67-year-old man suffering from recurrent dizziness for 3 months. Previous medical history was unremarkable. Brain magnetic resonance angiography (MRA) and digital subtraction angiography (DSA) demonstrated occlusion of the right middle cerebral artery (MCA) associated with a "probable moyamoya disease" and an aneurysm-like shadow protruding lesion at the anterior communicating artery (AcomA). Perfusion images showed ischemia along the right temporo-occipital lobe. Due to MCA occlusion with perfusion deficits and unspecific symptoms, we offered a right side encephalo-duro-myo-synangiosis (EDMS) and clipping of the AcomA aneurysm in one session. Intraoperatively, there was no evidence of the AcomA aneurysm; instead, this finding corresponded to the stump of the occluded right anterior cerebral artery (A1 segment). This segment appeared to be of yellowish color due to atherosclerosis and lacked blood flow. The patient underwent as previously planned a right side EDMS and the perioperative course was uneventful without the presence of additional ischemic attacks. CONCLUSION: Arterial branch occlusions can sometimes present atypical angiographic characteristics that can mimic a saccular intracranial aneurysm. It is relevant to consider this radiographic differential diagnosis, especially when aneurysm treatment is planned.

Surgical treatment of symptomatic pineal cysts without hydrocephalus-meta-analysis of the published literature.

BACKGROUND: To examine published data and assess evidence relating to safety and efficacy of surgical management of symptomatic pineal cysts without hydrocephalus (nhSPC), we performed a systematic review of the literature and meta-analysis. METHODS: Following the PRISMA guidelines, we searched Pubmed and SCOPUS for all reports with the query 'Pineal Cyst' AND 'Surgery' as of March 2021, without constraints on study design, publication year or status (PROSPERO_CRD:42,021,242,517). Assessment of 1537 hits identified 26 reports that met inclusion and exclusion criteria. RESULTS: All 26 input studies were either case reports or single-centre retrospective cohorts. The majority of outcome data were derived from routine physician-recorded notes. A total of 294 patients with surgically managed nhSPC were identified. Demographics: Mean age was 29 (range: 4-63) with 77% females. Mean cyst size was 15 mm (5-35). Supracerebellar-infratentorial approach was adopted in 90% of cases, occipital-transtentorial in 9%, and was not reported in 1%. Most patients were managed by cyst resection (96%), and the remainder by fenestration. Mean post-operative follow-up was 35 months (0-228). PRESENTATION: Headache was the commonest symptom (87%), followed by visual (54%), nausea/vomit (34%) and vertigo/dizziness (31%). Other symptoms included focal neurology (25%), sleep disturbance (17%), cognitive impairment (16%), loss of consciousness (11%), gait disturbance (11%), fatigue (10%), 'psychiatric' (2%) and seizures (1%). Mean number of symptoms reported at presentation was 3 (0-9). OUTCOMES: Improvement rate was 93% (to minimise reporting bias only consecutive cases from cohort studies were considered, N = 280) and was independent of presentation. Predictors of better outcomes were large cyst size (OR = 5.76; 95% CI: 1.74-19.02) and resection over fenestration (OR = 12.64; 3.07-52.01). Age predicted worse outcomes (OR = 0.95; 0.91-0.99). Overall complication rate was 17% and this was independent of any patient characteristics. Complications with long-term consequences occurred in 10 cases (3.6%): visual disturbance (3), chronic incisional pain (2), sensory disturbance (1), fatigue (1), cervicalgia (1), cerebellar stroke (1) and mortality due to myocardial infarction (1). CONCLUSIONS: Although the results support the role of surgery in the management of nhSPCs, they have to be interpreted with a great deal of caution as the current evidence is limited, consisting only of case reports and retrospective surgical series. Inherent to such studies are inhomogeneity and incompleteness of data, selection bias and bias related to assessment of outcome carried out by the treating surgeon in the majority of cases. Prospective studies with patient-reported and objective outcome assessment are needed to provide higher level of evidence.

Magnetically Guided Catheters, Micro- and Nanorobots for Spinal Cord Stimulation.

Spinal cord stimulation (SCS) is an established treatment for refractory pain syndromes and has recently been applied to improve locomotion. Several technical challenges are faced by surgeons during SCS lead implantation, particularly in the confined dorsal epidural spaces in patients with spinal degenerative disease, scarring and while targeting challenging structures such as the dorsal root ganglion. Magnetic navigation systems (MNS) represent a novel technology that uses externally placed magnets to precisely steer tethered and untethered devices. This innovation offers several benefits for SCS electrode placement, including enhanced navigation control during tip placement, and the ability to position and reposition the lead in an outpatient setting. Here, we describe the challenges of SCS implant surgery and how MNS can be used to overcome these hurdles. In addition to tethered electrode steering, we discuss the navigation of untethered micro- and nanorobots for wireless and remote neuromodulation. The use of these small-scale devices can potentially change the current standard of practice by omitting the need for electrode and pulse generator implantation or replacement. Open questions include whether small-scale robots can generate an electrical field sufficient to activate neuronal tissue, as well as testing precise navigation, placement, anchoring, and biodegradation of micro- and nanorobots in the in vivo environment.

Case Report: Internal Carotid Artery Thrombosis: A Rare Complication After Fibrin Glue Injection for Cavernous Sinus Hemostasis.

Background: Fibrin glue injection within the cavernous sinus (CS) is a demonstrably safe and simple technique to control venous bleeding with a low complication rate. However, this technique does have inherent risks. We illustrate 2 cases of internal carotid artery (ICA) thrombosis after fibrin glue injection in the CS for hemostasis. Methods: After encountering this complication recently, we conducted a retrospective review of the surgical database of 2 senior neurosurgeons who specialize in cerebrovascular and skull base surgery to identify patients with any complications associated with the use of fibrin glue injection for hemostasis. Approval was given by respective institutional review boards, and patient consent was obtained. Results: Of more than 10,000 microsurgery procedures performed by 2 senior neurosurgeons with a combined experience of 40 years, including procedures for aneurysms and skull base tumors, 2 cases were identified involving ICA thrombosis after fibrin glue injection in the CS for hemostasis. Both cases involved severe ischemic complications as a result of the ICA thrombosis. In this article, we present their clinical presentation, characteristics, management, and outcomes. Conclusion: Direct injection of fibrin glue into the CS for hemostasis can effectively control venous bleeding and facilitate complex dissections. However, it can be associated with ICA thrombosis, with subsequent serious ischemia and poor prognosis. Although this complication appears to be rare, increased awareness of this problem should temper the routine use of fibrin glue in anterior clinoidectomy and transcavernous approaches.

Tumor DNA From Tumor In Situ Fluid Reveals Mutation Landscape of Minimal Residual Disease After Glioma Surgery and Risk of Early Recurrence.

The recurrence of glioma is a difficult problem in clinical treatment. The molecular markers of primary tumors after resection cannot fully represent the characteristics of recurrent tumors. Here, abundant tumor DNA was detected in tumor in situ fluid (TISF). We report that TISF-derived tumor DNA (TISF-DNA) can detect genomic changes in recurrent tumors and facilitate recurrence risk analysis, providing valuable information for diagnosis and prognosis. The tumor DNA in TISF is more representative and sensitive than that in cerebrospinal fluid. It reveals the mutational landscape of minimal residual disease after glioma surgery and the risk of early recurrence, contributing to the clinical management and clinical research of glioma patients.

Constrained-Spherical Deconvolution Tractography in the Evaluation of the Corticospinal Tract in Glioma Surgery.

Introduction: Tractography has demonstrated utility for surgical resection in the setting of primary brain tumors involving eloquent white matter (WM) pathways. Methods: Twelve patients with glioma in or near eloquent motor areas were analyzed. The motor status was recorded before and after surgery. Two different tractography approaches were used to generate the motor corticospinal tract (CST): Constrained spherical deconvolution probabilistic tractography (CSD-Prob) and single tensor deterministic tractography (Tens-DET). To define the degree of disruption of the CST after surgical resection of the tumor, we calculated the percentage of the CST affected by surgical resection, which was then correlated with the postoperative motor status. Moreover, the fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) of the CST generated by the CSD-Prob and the Tens-DET was measured and compared between the ipsilesional and contralesional side. Results: The CST was identified in all patients and its trajectory was displaced by the tumor. Only the CSD-Prob approach showed the CST with the characteristic fan-like projections from the precentral gyrus to the brainstem. Disruption of the CST was identified in 6/6 with postoperative motor deficit by CSD-Prob approach and in 5/6 in the Tens-DET. The degree of disruption was significantly associated with the motor deficit with the CSD-Prob approach (rho = -0.88, p = 0.021). However, with the Tens-DET approach the CST disruption did not show significant association with the motor function (rho = -0.27, p = 0.6). There was a significant decrease in FA (p = 0.006) and a significant increase in MD (p = 0.0004) and RD (p = 0.005) on the ipsilesional CST compared with the contralesional CST only with the CSD-Prob approach. Conclusion: CSD-Prob accurately represented the known anatomy of the CST and provided a meaningful estimate of microstructural changes of the CST affected by the tumor and its macrostructural damage after surgery. Newer surgical planning stations should include advanced models and algorithms of tractography in order to obtain more meaningful reconstructions of the WM pathways during glioma surgery.

Microsurgical Neurovascular Anatomy of the Brain: The Posterior Circulation (Part II).

Introduction Vascular complications of posterior fossa surgery are often deadly although widely preventable through in-depth knowledge of the microsurgical neurovascular anatomy of the infratentorial region and careful surgical planning.   The target of this study is to provide a synoptic overview of the normal anatomy and anatomic variants of the infratentorial neurovascular system, critical to safely operate tumors and neurovascular pathologies of the posterior fossa. Methods Two fresh-frozen and five formalin-fixed cadaveric heads were used. Cervical arteries and internal jugular veins were injected with red and blue latex, respectively. The heads were dissected under a surgical microscope, with magnifications ranging between 3× to 40×, focusing on the infratentorial region. The infratentorial arteries, their collaterals and perforating branches, the brainstem and cerebellar veins, the tentorial venous sinuses, and the relative vascular territories were summarized according to a synoptic approach.    Results The vertebral artery, basilar artery (BA), and posterior cerebral artery (PCA) are the main sources of the arterial supply of the brainstem and cerebellum through the posterior inferior cerebellar artery (PICA), the anterior inferior cerebellar artery (AICA), the superior cerebellar artery (SCA), and the perforating arteries. The perforating arteries of the vertebrobasilar system derive from the PICA, BA, AICA, SCA, and PCA, and provide for a key contribution to the vascularization of the midbrain, pons, medulla oblongata, fourth ventricle, cerebellar and cerebral peduncles, thalamus, hypothalamus, subthalamus, posterior part of the internal capsule, and optic tract. The distal segments and branches of the PCA also add a significant arterial supply to the temporal, occipital, and parietal lobes. The venous outflow of the posterior fossa is a prerogative of the internal jugular veins via the tentorial venous sinuses. Conclusion A perfect mastery of the arterial, venous, and cisternal anatomy of the infratentorial region is vital for the planning and execution of the whole range of posterior fossa approaches.

Microsurgical Neurovascular Anatomy of the Brain: The Anterior Circulation (Part I).

Introduction Treatment of cranial neurovascular pathology requires a detailed understanding of the brain, head, and neck vasculature. This study aims at a comprehensive overview of the microsurgical anatomy of the anterior cerebral circulation. Methods Five formalin-fixed adult cadaveric heads were used. Common carotid arteries, vertebral arteries, and internal jugular veins were injected with colored latex (red for arteries and blue for veins). The heads were dissected under a surgical microscope with magnifications ranging between 3× to 40× focusing on the anterior circulation. A synoptic approach was used to describe in detail the segments, branches, perforating arteries, veins, and vascular territories of the cerebral arteries and veins. Results The anterior arterial circulation of the brain is provided by the internal carotid artery (ICA), anterior cerebral artery (ACA), middle cerebral artery (MCA), anterior communicating artery (ACoA), and perforating arteries. Perforating arteries of the anterior circulation arise from the ICA, ACA, MCA, ACoA, and posterior communicating artery (PCoA). The distal segments and collateral branches of the ICA, ACA, and MCA give the arterial supply to the largest part of the forebrain, whereas perforating arteries of the anterior circulation are related to the striatum, thalamus, and basal ganglia. The ACoA is the core functional anastomosis between the left and right ICA systems. The external carotid artery provides the vascular supply to the region of the face, head, and neck, and most of the meninges. The internal jugular venous system is composed of the internal and external jugular veins, which constitutes the outflow of the cerebral and facial venous system, respectively. Conclusion Thorough knowledge of the topographic, cisternal, and functional anatomy of the anterior circulation of the brain is critical for surgery of the supratentorial lesions.

Shedding the Light on the Natural History of Intracranial Aneurysms: An Updated Overview.

The exact molecular pathways underlying the multifactorial natural history of intracranial aneurysms (IAs) are still largely unknown, to the point that their understanding represents an imperative challenge in neurovascular research. Wall shear stress (WSS) promotes the genesis of IAs through an endothelial dysfunction causing an inflammatory cascade, vessel remodeling, phenotypic switching of the smooth muscle cells, and myointimal hyperplasia. Aneurysm growth is supported by endothelial oxidative stress and inflammatory mediators, whereas low and high WSS determine the rupture in sidewall and endwall IAs, respectively. Angioarchitecture, age older than 60 years, female gender, hypertension, cigarette smoking, alcohol abuse, and hypercholesterolemia also contribute to growth and rupture. The improvements of aneurysm wall imaging techniques and the implementation of target therapies targeted against inflammatory cascade may contribute to significantly modify the natural history of IAs. This narrative review strives to summarize the recent advances in the comprehension of the mechanisms underlying the genesis, growth, and rupture of IAs.