Mapping the Fine-Scale Organization and Plasticity of the Brain Vasculature.

The cerebral vasculature is a dense network of arteries, capillaries, and veins. Quantifying variations of the vascular organization across individuals, brain regions, or disease models is challenging. We used immunolabeling and tissue clearing to image the vascular network of adult mouse brains and developed a pipeline to segment terabyte-sized multichannel images from light sheet microscopy, enabling the construction, analysis, and visualization of vascular graphs composed of over 100 million vessel segments. We generated datasets from over 20 mouse brains, with labeled arteries, veins, and capillaries according to their anatomical regions. We characterized the organization of the vascular network across brain regions, highlighting local adaptations and functional correlates. We propose a classification of cortical regions based on the vascular topology. Finally, we analysed brain-wide rearrangements of the vasculature in animal models of congenital deafness and ischemic stroke, revealing that vascular plasticity and remodeling adopt diverging rules in different models.

The neurosurgeon's familiarity with the vein of Rolando.

The vein of Rolando, also known as the central sulcal vein, is a critical superficial cerebral vein located in the central sulcus, playing a pivotal role in the venous drainage of the motor and sensory cortices. Named after the Italian anatomist Luigi Rolando, this vein serves as a crucial anatomical landmark in neurosurgery, guiding surgeons to approach critical brain structures with minimal damage. This article explores the anatomy and clinical significance of the vein of Rolando, emphasizing its role in neurosurgery and neuroimaging. Advanced imaging techniques such as functional MRI (fMRI), Magnetic Resonance Venography (MRV), and CT Angiography have enhanced the ability to diagnose and preserve this vein, reducing surgical risks. The article also discusses the interconnectedness of the vein of Rolando with other cerebral veins like the vein of Trolard and underscores the importance of understanding venous variations and drainage patterns for successful surgical outcomes. Preventive measures to protect the vein during neurosurgery are essential to prevent complications such as venous congestion and intracranial pressure. This overview highlights the necessity for precise anatomical knowledge and advanced diagnostic tools in optimizing neurosurgical procedures and patient care.

Prevalence and Morphometry of Occipital Foramen in Dry Skulls and its Clinical Implications.

The occipital emissary foramen (OEF) located on the occipital bone transmits the occipital emissary vein, which connects the occipital vein to the confluence of cranial venous sinuses. The OEF varies in incidence, number, size, and location. Knowledge of this foramen is essential for carrying out suboccipital and transcondylar surgeries without clinical implications. Hence, the study was planned. The aim of the present study is to elaborate on incidence, location, and morphometry consisting of the number and size of this foramen in light of clinical bearing in the context of the Indian population. The study was carried out in the Department of Anatomy using 80 skulls of unknown age and sex. The occipital bone of the skull was observed for the incidence, number, size, and location of the occipital emissary vein and associated clinical implications were elaborated. The incidence of occipital foramen was 36.25% and detected in 29 skulls. All these occipital foramina were patent. The mean diameter of this foramen was 0.6 mm. The most common location of these foramina was the left side of the foramen magnum, followed by the left side of the external occipital crest. The information about the incidence, number, size, and location of OEF is important to prevent catastrophic bleeding during surgery in the region of the occipital bone. The awareness of differential morphometry and morphology of occipital foramina is of great importance for neurosurgeons during suboccipital craniotomy and skull base surgeries, including far lateral and transcondylar approaches to access posterior cranial fossa for management of pathologies in the cranial cavity.

Angulation of the dural venous sinuses of the posterior cranial fossa: Anatomical study with clinical and surgical applications.

Cerebral vein and dural venous sinus thromboses (CVST) account for 0.5%-1% of all strokes. Some structural factors associated with a potentially higher risk for developing CVST have been described. However, angulation of the dural venous sinuses (DVS) has yet to be studied as a structural factor. The current study was performed because this variable could be related to alterations in venous flow, thus predisposing to a greater risk of CVST development. Additionally, such information could help shed light on venous sinus stenosis (VSS) at or near the transverse-sigmoid junction. The angulations formed in the different segments of the grooves of the transverse (TS), sigmoid (SS), and superior sagittal sinuses (SSS) were measured in 52 skulls (104 sides). The overall angulation of the TS groove was measured using two reference points. Other variables were examined, such as the communication pattern at the sinuses' confluence and the sinus grooves' lengths and widths. The patterns of communication between sides were compared statistically. The most typical communication pattern at the sinuses' confluence was a right-dominant TS groove (82.98%). The mean angulations of the entire left TS groove at two different points (A and B) were 46° and 43°. Those of the right TS groove were 44° and 45°. The median angulations of the left and right SSS-transverse sinus junction grooves were 127° and 124°. The mean angulations of the left and right TS-SSJsv grooves were 111° (range 82°-152°) and 103° (range 79°-130°). Differentiating normal and abnormal angulations of the DVSs of the posterior cranial fossa can help to explain why some patients are more susceptible to pathologies affecting the DVSs, such as CVST and VSS. Future application of these findings to patients with such pathologies is now necessary to extrapolate our results.

[Anatomy of the Cavernous Sinus].

The cavernous sinus is the crossroad of veins from various embryological origins, including the brain, eye, pituitary gland, dura, and cranium. Embryologically, the cavernous sinus is mainly formed from the pro-otic sinus; secondary anastomosis between the cavernous sinus and primitive tentorial sinus results in various anatomical variations in the drainage patterns of the superficial middle cerebral vein. Moreover, connections between the cavernous sinus and basal vein via the uncal vein, bridging vein, and petrosal vein from the superior petrosal sinus may exist. Retrograde drainage from the cavernous sinus into the cerebral veins is often observed in arteriovenous shunts involving the cavernous sinus, such as dural and carotid-cavernous fistulas, which are primarily treated using transvenous embolization. Understanding the anatomy of the cavernous sinus and its associated veins is essential for safe and reliable endovascular treatment.

[Venous Anatomy of the Superior and Inferior Sagittal Sinuses].

The superior sagittal sinus(SSS)is contained within the dura, which consists of the dura propria and osteal dura at the junction of the falx cerebri, in addition to the attachment of the falx to the cranial vault. The SSS extends anteriorly from the foramen cecum and posteriorly to the torcular Herophili. The superior cerebral veins flow into the SSS, coursing under the lateral venous lacunae via bridging veins. Most of the bridging veins reach the dura and empty directly into the SSS. However, some are attached to the dural or existed in it for some distance before their sinus entrance. The venous structures of the junctional zone between the bridging vein and the SSS existed in the dura are referred to as dural venous channels. The SSS communicates with the lateral venous lacunae connecting the meningeal and diploic veins, as well as the emissary veins. These anatomical variations of the SSS are defined by the embryological processes of fusion and withdrawal of the sagittal plexus and marginal sinus.

[Inferior Petrosal Sinus and Anterior Condylar Confluence and Surrounding Venous Anatomy].

Veins at the craniocervical junction are complex network structures. They empty into two main brain venous drainages, the internal jugular vein and internal vertebral venous plexus, and reroute venous blood according to postural changes. They are also involved in the etiology of dural arteriovenous shunts in this region. Hence, regional venous anatomy is crucial for interventional neuroradiologists to understand the pathophysiology and formulate therapeutic strategies. This article aims to provide a summary on venous anatomy, radiological findings, and related pathological conditions, especially for young and inexperienced interventional neuroradiologists.

Ring-shaped Dandy's superior petrosal vein.

BACKGROUND: Dandy's superior petrosal vein (SPV) anatomy is highly relevant for neurosurgeons. The SPV drains into the superior petrosal sinus (SPS), closely related to the trigeminal and internal auditory pores. METHOD: The archived enhanced MRI files of a male patient were studied. RESULTS: An infratentorial ring-shaped (RS) SPV was found on the petrosal surface of the right cerebellar hemisphere. It was inserted in the SPS above the internal auditory pore, postero-lateral to the trigeminal pore. The anterior arm of that venous ring received a delicate supratrigeminal plexus of veins from the pontine surface and continued as a single venous trunk on the cerebellar surface. CONCLUSION: Such previously unreported RS-SPV is of utmost importance to be identified before subtemporal transtentorial and retrosigmoid approaches for different neurosurgical reasons.

Preoperative assessment of the individual anatomy of the superior petrosal vein complex using balanced fast field echo magnetic resonance imaging.

BACKGROUND: Here, we sought to examine the validity and reproducibility of balanced fast field echo (bFFE) for assessing superior petrosal vein (SPV) complex (SPVC) anatomy. METHODS: Preoperative bFFE or equivalent scans and operative videos were studied and directly compared with regard to the individual anatomical features of SPVCs and their relation to the operative field. The anatomical details of the bFFE findings of the non-operated side (group 2) of all 50 patients were then reviewed, including the presence of petrosal-galenic anastomosis, and finally compared to the operated SPVCs (group 1). RESULTS: A complete correlation between bFFE and intraoperative findings was observed in 62% of cases and had a significant correlation with 3 Tesla magnet strength and higher pixel bandwidth (rbis = - 0.47; p = 0.005). The sensitivity and specificity of bFFE magnetic resonance imaging were 93.7 and 95.2%, respectively, for detecting an SPV disturbing the operative field, and 97.3% and 95% for a disturbing tributary, respectively. Each group had 50 SPVCs, with a total of 70 and 64 SPVs, 10 and 11 general SPVC configurations, as well as 29 and 28 different individual anatomical variations in groups 1 and 2, respectively. Both groups had 1-3 SPVs with a similar distribution of frequencies [Chi-square (4) = 27.56; p = 0.0145 (Fisher's exact test)]. The similarity of the general configurations was not statistically significant. The same four predominant configurations constituted 80% of the SPVCs in each group. The vein of the cerebellopontine fissure was most frequently found in 86% and 88% of cases, and a petrosal-galenic anastomosis was seen in 38% and 40% of groups 1 and 2, respectively. CONCLUSIONS: Individual SPVC variations are extensive. Good quality bFFE or equivalents are feasible for preoperative SPVC assessments. However, methods improving vascular visualization are recommended.

Acute cerebral venous outflow obstruction during convexity meningioma resection.

BACKGROUND: Cerebral venous outflow obstruction involves idiopathic intracranial hypertension, and the most common related condition is dural venous sinus stenosis or, in other words, an obstruction of the dural venous sinuses. In these cases, the pathological process is often chronic, displays only mild symptoms, and rarely requires urgent surgical intervention. In this study, we present a unique case involving an acute cerebral venous outflow obstruction that occurred during meningioma resection that ultimately had catastrophic consequences. MATERIALS AND METHODS: The patient's preoperative imaging only revealed an unremarkable frontal convexity meningioma with an average diameter exceeding 8 cm. She was admitted for a scheduled right frontoparietal craniotomy for lesion resection. RESULTS: The patient's unique congenital dural venous sinus structure along with a non-surgical epidural hematoma both contributed to a catastrophic outcome, causing a progressive hemispheric encephalocele, significant blood loss, and wound closure difficulties. CONCLUSION: Neurosurgeons should place an additional focus on cerebral venous outflow patency during tumor resection, even if the tumor does not involve the transverse or sigmoid sinuses. It is well known that the tacking sutures play an essential role in preventing an epidural hematoma, but the procedure to mitigate hematomas occurring outside the surgical field of view is not fully recognized by neurosurgeons. If dural tacking sutures are placed after complete tumor resection, the prophylactic effect for preventing EDH in the non-surgical areas may not be guaranteed. Therefore, we strongly advocate for the tacking sutures to be accurately placed before dural incisions are made.

CT angiographic study of the cerebral deep veins around the vein of Galen.

Research on the anatomy of cerebral deep veins (CDVs) around the vein of Galen (VG) is very important and has fundamental clinical significance. Large-scale anatomical studies of CDVs using computed tomography angiography (CTA) are rarely reported. A retrospective study of the CDVs around the VG was conducted in Chinese patients of Han nationality. One hundred cases were included in the final analysis. The patients were aged from 17 to 78 years (mean: 42.3 years). Also, 46% of the patients were female. The diameter of the internal cerebral vein (ICV) at its beginning and termination points ranged from 0.4 to 2.8 mm (1.49 ± 0.39 mm) and 0.4 to 3.5 mm (2.05 ± 0.47 mm), respectively. There was statistical significance regarding the diameter of the ICV at its beginning and termination points (P <0.01). The ICV length ranged from 28.5 to 47.9 mm (36.86 ± 3.74 mm). The length of the straight sinus (SS) ranged from 30.2 to 57.8 mm (43.6 ± 6.37 mm). The length of the VG ranged from 1.5 to 41.8 mm (9.30 ± 4.76 mm). The angle at the VG and SS transition area ranged from 25.4 to 110.6° (77.2 ± 18.0°). This study was a meaningful attempt to conduct anatomical research of CDVs using CTA. Preoperative familiarity with the normal venous structure and its variation around the VG would be helpful for endovascular treatment.

Bridging veins of the cerebellum: a magnetic resonance imaging study.

PURPOSE: To date, no study has yet explored the bridging veins (BVs) of the cerebellum using neuroimaging modalities. Therefore, this study aimed to characterize them using magnetic resonance imaging (MRI). METHODS: A total of 90 patients with intact cerebellar hemispheres and intracranial dural sinuses underwent thin-sliced, contrast-enhanced MRI. RESULTS: The BVs were classified into six routes based on the draining pattern into the dural sinuses. The superior vermian vein emptying into the straight sinus was delineated in 100% of the patients. The inferior vermian vein emptying into the confluence of the sinuses was identified in 66.7% of the patients. The inferior hemispheric and cerebellar cortical veins emptying into the transverse sinus were identified in 54.4% and 26.7% of the patients, respectively. The inferior vermian and cerebellar cortical veins emptying into the straight sinus were identified in 77.8% and 12.2% of the patients, respectively. The cerebellar cortical vein emptying into the tentorial sinus was identified in 83.3% of the patients; it was delineated on 54 sides with an average number per right hemisphere of 1.9 and 63 sides with an average number per left hemisphere of 2. The pontine-trigeminal and anterior hemispheric veins emptying into the superior petrosal sinus were identified in 42.2% of the patients. CONCLUSIONS: The BVs of the cerebellum can be classified into six distinct routes. Radiological classification may be useful for understanding the drainage pattern of the cerebellum.

Cortical and bridging veins of the upper cerebral convexity: a magnetic resonance imaging study.

PURPOSE: There is no study exploring the cortical veins (CVs) and connecting bridging veins (BVs) with neuroimaging modalities. The present study aimed to characterize these veins of the upper cerebral convexity. METHODS: A total of 89 patients with intact cerebral hemispheres and covering meninges underwent thin-sliced, contrast magnetic resonance imaging (MRI). In addition, three injected specimens were dissected in this study. RESULTS: In cadaver dissection, the BVs were observed to course in the arachnoid sheaths, suspended from the dura mater. The medial parts of the BVs, located near the superior sagittal sinus (SSS)-BV junction site, were occasionally exposed subdurally. The CVs were formed by venous channels arising from the cerebral gyri and those emerging from the sulci. On MRI, the CVs and connecting BVs were identified in the medial and latera convexity areas and medial surface of the cerebrum. These veins were highly variable in number, thickness, length, course, and distribution. In the medial convexity area, the CVs arising from the gyri were identified in 58% of patients, while they were found only in 11% of patients in the lateral convexity area. CONCLUSION: In the medial convexity area, involving the parasagittal region, the CVs connect more densely with the BVs that may predispose to injury during neurosurgical procedures. Mechanical impact exerted the area, diameter of the veins in the craniocaudal direction, and number of venous afferences may affect the SSS-BV junctional region in an indirect manner and lead to the development of acute subdural hematoma.

Individual variations of the superior petrosal vein complex and their microsurgical relevance in 50 cases of trigeminal microvascular decompression.

BACKGROUND: We investigated the understudied anatomical variations of the superior petrosal vein (SPV) complex (SPVC), which may play some role in dictating the individual complication risk following SPVC injury. METHODS: Microvascular decompressions of the trigeminal nerve between September 2012 and July 2016. All operations utilized an SPVC preserving technique. Preoperative balanced fast field echo (bFFE) magnetic resonance imaging, or equivalent sequences, and operative videos were studied for individual SPVC anatomical features. RESULTS: Applied imaging and operative SPVC anatomy were described for fifty patients (mean age, 67.18 years; female sex and right-sided operations, 58% each). An SPVC component was sacrificed intentionally in 6 and unintentionally in only 7 cases. Twenty-nine different individual variations were observed; 80% of SPVCs had either 2 SPVs with 3 or 1 SPV with 2, 3, or 4 direct tributaries. Most SPVCs had 1 SPV (64%) and 2 SPVs (32%). The SPV drainage point into the superior petrosal sinus was predominantly between the internal auditory meatus and Meckel cave (85.7% of cases). The vein of the cerebellopontine fissure was the most frequent direct tributary (86%), followed by the pontotrigeminal vein in 80% of SPVCs. Petrosal-galenic anastomosis was detected in at least 38% of cases. At least 1 SPV in 54% of the cases and at least 1 direct tributary in 90% disturbed the operative field. The tributaries were more commonly sacrificed. CONCLUSIONS: The extensive anatomical variation of SPVC is depicted. Most SPVCs fall into 4 common general configurations and can usually be preserved. BFFE or equivalent sequences remarkably facilitated the intraoperative understanding of the individual SPVC in most cases.

Pediatric otitic hydrocephalus: Report of two unusual cases and literature review.

Otitic hydrocephalus (OH) comprises a form of benign intracranial hypertension, which is secondary to otogenic lateral sinus thrombosis (LST). Only a small percentage of the patients with otogenic LST go into developing OH, and this may be associated with the multiplicity of anatomic variations of the cerebral venous drainage pathways. We present two pediatric cases of OH, along with a comprehensive review of the relevant literature. Both cases discussed in this article had concomitantly a rather rare anatomical variation; a high-riding, dehiscent jugular bulb, which might have played a role in the development of their clinical syndrome. The pediatric population with this particular imaging finding should receive special attention. Clinical implications of this concurrence are fitly discussed.

The condylar canal and emissary vein-a comprehensive and pictorial review of its anatomy and variation.

The condylar canal and its associated emissary vein serve as vital landmarks during surgical interventions involving skull base surgery. The condylar canal serves to function as a bridge of communication from the intracranial to extracranial space. Variations of the condylar canal are extremely prevalent and can present as either bilateral, unilateral, or completely absent. Anatomical variations of the condylar canal pose as a potential risk to surgeons and radiologist during diagnosis as it could be misinterpreted for a glomus jugular tumor and require surgical intervention when one is not needed. Few literature reviews have articulated the condylar canal and its associated emissary vein through extensive imaging. This present paper aims to further the knowledge of anatomical variations and surgical anatomy involving the condylar canal through high-quality computed tomography (CT) images with cadaveric and dry bone specimens that have been injected with latex to highlight emissary veins arising from the condylar canal.

Diploic veins of the cranial base: an anatomical study using magnetic resonance imaging.

PURPOSE: The anatomy and distribution of the diploic veins (DVs) of the cranial base have not been fully documented. The aim of this study was to characterize these veins using contrast magnetic resonance imaging (MRI). METHODS: In total, 95 patients underwent thin-sliced, contrast MRI. Coronal and sagittal images were used for the analysis. The cranial base was divided into the anterior, middle, and posterior bases. Then, each base was further subdivided into three equal parts in the anteroposterior and lateromedial directions. The anteroposterior parts were evaluated on coronal images, while the lateromedial parts were evaluated on sagittal images. RESULTS: The DVs were identified over the entire cranial base. However, they were more frequent in the posterior-third of the lateral-third region of the anterior, middle-third of the lateral and middle-third regions of the middle, and middle-third region of the posterior cranial base, and sparse in the posterior and medial-third regions of the middle cranial base. The DVs showed marked morphological variability. For instance, the DVs of the pterional area were generally well defined, as pivotal channels connecting the lateral parts of the anterior and middle cranial base, but were highly varied in appearance. CONCLUSIONS: The DVs of the cranial base are distinct structures characterized by morphological variability and topographical predilection. Contrast MRI is useful for delineating these veins.

Dynamic assessment of venous anatomy and function in neurosurgery with real-time intraoperative multimodal ultrasound: technical note.

The relevance of the cerebral venous system is often underestimated during neurosurgical procedures. Damage to this draining system can have catastrophic implications for the patient. Surgical decision-making and planning must consider each component of the venous compartment, from the medullary draining vein to the dural sinuses and extracranial veins. Intraoperative ultrasound (ioUS) permits the real-time study of venous compartments using different modalities, thus allowing complete characterization of their anatomical and functional features. The B-mode (brightness mode) offers a high-resolution anatomical representation of veins and their relationships with lesions. Doppler modalities (color, power, spectral) allow the study of blood flow and identification of vessels to distinguish their functional characteristics. Contrast-enhanced US allows one to perform real-time angiosonography showing both the functional and the anatomical aspects of vessels. In this technical report, the authors demonstrate the different applications of multimodal ioUS in neurosurgery for identifying the anatomical and functional characteristics of the venous compartment. They discuss the general principles and technical nuances of ioUS and analyze their potential implications for the study of various venous districts during neurosurgical procedures.

Quantification of Surgical Route Parameters for Exposure of the Jugular Foramen Via a Trans-Mastoidal Approach Exposing Jugular Foramen in Three-Dimensional Visualization Model.

OBJECTIVE: Surgical operation within the region of the jugular foramen presents a great challenge. The authors characterized the quantitative impact of surgical window parameters on the exposure of the jugular foramen via a trans-mastoidal approach. METHODS: Computed tomography and magnetic resonance imaging data were used to establish a 3-dimensional model of the jugular foramen region. The mastoidale, posterior edge of the mastoid, and the superior edge of the bony external acoustic meatus were selected as points a, b, and c. The anterior edge of the tuberculum jugulare was selected as point d. The midpoints of line segments ab, ac, and bc were selected as points e, f, and g. Triangle abc was divided into triangles aef, beg, cfg, and efg. Surgical corridors of the triangular pyramid were outlined by connecting the above triangles to point d. Anatomic exposure was evaluated by measuring the area and volume of various structures within each route. Statistical comparisons were performed via analysis of variance. RESULTS: The model allowed for adequate visualization of all structures. The areas of triangles beg and efg were greater than those of triangles aef and cfg (P < 0.05). The volumes of triangular pyramids d-beg and d-cfg were greater than those of triangular pyramids d-aef and d-efg (P = 0.000). Statistically significant differences were also observed for volumes of osseous, venous, and cranial nerve structures in all divided routes (P = 0.000). CONCLUSION: Our results indicate that 3-dimensional modeling may aid in the quantification of surgical exposure and that division of the craniotomy window may allow for more precise operation.

Standardization of the technique of silicon injection of human cadaveric heads for opacification of cerebral vasculature in Indian conditions.

A surgeon's understanding of the surgical anatomy can be greatly enhanced by the dissection of preserved cadaveric specimens. A reliable and inexpensive biological model for testing and standardization of dye injection concentrations is proposed utilizing the goat's head as a biological model. The first phase was concerned with standardization of the dye by titrating its concentration and injecting various amounts into cerebral vessels of a goat's head until an optimal concentration had been ascertained. In the second phase, this optimum concentration of the dye was injected into four human cadaveric heads following the same technique standardized using the goat's head. Upon dissecting the four cadaveric human heads which were injected with silicon dyes and preserved in 10% formalin, the vessels were all well-opacified and the brain was of near normal consistency and good for dissection, without showing any features of putrefaction. The goat model, having similar color, texture, and the handling as the cadaveric head, offers an opportunity to test indigenously manufactured polymerizing dyes in the future. This biological model, therefore, has the potential to considerably reduce the cost of cadaver preparation.