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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., (© 2023. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

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 (r bis  = - 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., (© 2023. The Author(s), under exclusive licence to Springer-Verlag France SAS, part of Springer Nature.)

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.

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.

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.

Background: Changes in head position are thought to cause a degree of brain shift in the intracranial cavity. However, little is known on the concurrent shift of the cerebral veins. The present study aimed to investigate the positional shift of the cerebral veins that accompanies brain shift., Methods: Sagittal T2-weighted magnetic resonance imaging was performed on 21 consecutive patients lying in the supine and prone positions, using the same sequence. For each patient, imaging data were obtained for the two positions as a pair of images with morphologically best-matched cerebral contours., Results: The subarachnoid spaces in the parasagittal frontal convexity showed variable reductions related to a postural change from a supine to a prone position, with a mean percent reduction (%Δ) of 17.8 ± 11.7%. Additionally, cerebral cisterns ventral to the brainstem and upper cervical cord were reduced in most patients when lying in a prone position, with a mean %Δ of 16.6 ± 8.7%. In contrast, none of these 130 pairs of identical venous segments located in the parasagittal cerebral convexity showed positional shift. Cadaveric dissections found that the major cortical veins were superficially upheld by the arachnoid membranes., Conclusions: The parasagittal major cortical and bridging veins do not seem to show positional shifts. Positional change in the posterior-anterior direction causes a shearing between the frontal cortices and the distributing veins and can be a risk factor for acute subdural hemorrhage, in case of severe head trauma.

Purpose: Arachnoid granulations (AGs) occasionally appear to protrude into the calvarial convexity, lying close to the bridging veins (BVs). This study aims to characterize such AGs and BVs using magnetic resonance imaging (MRI)., Methods: Ninety-five patients were enrolled in this study. Initially, stepwise frontal craniotomy was performed in an injected cadaver head. Next, examinations with contrast MRI were performed involving the whole cranial vault., Results: In cadaveric dissection, the AGs located in the parasagittal regions appeared as outward protrusions through the dura mater and in contact with the diploic veins. Forming tent-shaped sleeves, these AGs and the continuous arachnoid membranes suspended the BVs coursing just below. A total of 237 AGs were identified on contrast MRI that protruded into the skull, lying close to the BVs. Among them, 78 % were located in parasagittal regions as AG-BV pairs. These pairs were most frequently found in the middle third of the calvarial hemisphere, followed by the anterior and posterior thirds. In 34 %, the BV segments were lodged in the AGs., Conclusions: Some AGs located in the parasagittal regions and cerebral convexity pass through the dura mater and pile drive into the skull, which contribute to forming hanging-type arachnoid sleeves suspending the BVs. These structures may underpin the predisposition of BVs to injury following mechanical impacts.

Purpose: The mastoid emissary vein (MEV) is a small venous channel connecting the intracranial and extracranial venous systems. Most current knowledge about the MEV has been obtained through cadaver studies. This study aimed to explore the MEV in vivo, using magnetic resonance imaging (MRI)., Methods: Ninety-six patients were enrolled in this study. The initial examinations used the conventional MRI sequences; contrast examinations were performed using thin-sliced sections., Results: The MEVs were identified bilaterally in 59.3 % of the 96 patients and unilaterally in 29.2 %. The original site, size, and intraosseous course of the MEVs were highly variable. On coronal images, the MEVs originated from a variable height on the posterior wall of the sigmoid sinus, most frequently from the lower third of the wall. Intraosseous MEV courses were classified as straight, curved, or tortuous, with the straight type occurring most frequently. The MEVs were dominant on the right side in 51.8 % of cases and on the left side in 24.7 % of cases. Two patients had two MEVs on the same side. Furthermore, on eight sides (5.6 %), the diploic venous channel was found to communicate with the MEV., Conclusions: The MEV is a structure with diverse morphologies and right-sided dominancy. MEVs should be evaluated before performing surgical and endovascular procedures around the suboccipital region.

Developmental venous variations (DVVs) are anatomic variations of normal transmedullary veins which are often discovered incidentally. Although they are accepted as benign compensatory venous drainage systems, they may become symptomatic or clinically significant due to flow-related causes. The fragile venous drainage systems increase vulnerability to in-out flow alterations. Increased inflow or decreased outflow causes rise in venous pressure, which may subsequently produce ischemic symptoms. Obstruction or stenosis of the collector vein is the most common cause of decreased outflow of a DVV. However, in the absence of collecting vein stenosis, venous hypertension may still exist due to volume overload. In case of multiple DVVs with single combined drainage pathway, functional outflow restriction may occur due to diminished capability of the vessel to adapt to pressure changes. In this report, we present a case with bilateral thalamic DVVs, which cause parenchymal amorphous calcification and drain into the left internal cerebral vein. A review of the literature on DVVs with outflow restriction including pathophysiological mechanisms is also discussed.

Purpose: Little attention has been paid to the superficial anastomotic veins but severe post-operative complications can be related to iatrogenic venous damage. The importance of the position of VL (vein of Labbé) relates with the lateral accesses to skull base and medial tentorial lesions by posterior temporal approaches. The aim of this study was to characterize and deepen knowledge on the VL anatomy., Methods: We reviewed retrospectively 101 hemispheres from cerebral angiographic studies in 59 patients (42 patients with bilateral angiography)., Results: VL duplication was found in 13 patients (31 %) and it was predominant on the left side. The absence of VL was rare (3 of 101 hemispheres). The mean location of the VL entry point in the transverse sinus was almost the middle of the distance between the inion and external acoustic meatus. The mean angle for this entry point was 69°. The mean VL caliber for the patients studied was 3.2 mm. Regarding the relation between VL and vein of Trolard, we found VL dominance in 31 % of the cases. About left-right intrapersonal variability we found a tendency for left VL dominance., Conclusions: We emphasized not only the interindividual differences but also the great intrapersonal variability of VL anatomy. The adequate study of the cerebral venous system particularities is of crucial importance for pre-operative planning to avoid severe complications.

Purpose: The configurations of cerebral veins and dural venous sinuses differ not only between individuals, but also between the two brain hemispheres of an individual, making the anatomical classification of the cerebral veins difficult. We evaluated the superior dural venous sinuses and classified their types and variations using magnetic resonance venography (MRV) and digital substraction angiography (DSA)., Methods: A total of 394 patients were studied retrospectively. Superior dural venous sinuses were evaluated and the confluence of the sinuses was classified on 2-dimensional time-of-flight MRV, contrast-enhanced 3-dimensional spoiled gradient recalled echo magnetic resonance imaging, and/or cerebral DSA. Confluens sinuum was divided into three types: true confluence, partial confluence, and non-confluence., Results: Of the three types, partial confluence (type II) was most frequently seen. Co-dominance of the transverse sinuses was most frequently observed. An occipital sinus was observed in 15 % of the patients. There were statistically significant differences between the left transverse sinus agenesis and the presence of the occipital sinus (p < 0.001), between the co-presence of the partial confluence type torcular and the occipital sinus (p = 0.040), and between the co-presence of the fenestrated straight sinus and the occipital sinus (p = 0.010)., Conclusions: Although anatomical variations of dural venous sinuses are seen frequently, classification of venous sinuses helps surgeons in preoperative evaluation and management, and prevention of possible complications. In this study, we think that a comprehensive evaluation and classification of dural venous sinuses is a significant contribution to the literature.

Background: The calvarial diploic venous channels (CDVCs) are well-known intraosseous structures, but their distribution and anatomofunctional implications are not fully understood., Objective: To investigate the architecture of CDVCs using high-resolution magnetic resonance (MR) imaging., Method: This prospective study enrolled 43 male and 37 female outpatients who underwent a 3.0-T MR imaging equipped by a 32-channel head coil. T1-weighted imaging covering the whole cranial vault was performed after gadolinium injection. In addition, one-piece orbitozygomatic craniotomy was performed in three cadaveric heads to observe the interruption of the CDVCs., Results: The CDVCs showed irregular contours and peculiar branching patterns with four common major pathways: the pteriofrontparietal (PFP), frontoorbital (FO), occipitoparietal (OP), and occipitocervical (OC) routes. The proximal PFP coursed as a single trunk and divided into several branches at the level of the frontal eminence. The orbital part of the FO continued to the subcutaneous vein via the supraorbital rim. The PFP and the pterional part of the FO fused proximally with the sphenoparietal sinus and descended as the middle meningeal vein. The OP coursed in the superoinferior direction and connected the junction part of the transverse-sigmoid sinus to the parietal superior sagittal sinus. The OC occurred as a single trunk in the median occipital bone, drained extracranially, and joined the suboccipital venous channels., Conclusions: The CDVCs seem to be a relatively consistent network functioning not only as conduits connecting the intracranial dural sinuses but also as pathways to the extracranial venous systems. High-resolution MR imaging is useful for investigating the CDVCs.

The existing classifications of cerebral veins have certain problems, including limited adequacy to uniquely describe neurovascular networks in three dimensions (3D), mixture of deep and superficial veins, and ambiguity of territories-based parcellations as veins may course on multiple territories. Classification discrepancies exist in subdivision, region drained, and parcellation criteria. Recent developments in diagnostic imaging and computers enable to acquire, create, and manipulate complete vascular networks, which also call for a new classification of cerebral veins. We propose a new classification suitable for the description of the complete cerebral veins, providing a clear separation of the superficial cortical veins from deep veins, and facilitating presentation and exploration of cerebral veins in 3D with respect to surrounding neuroanatomy. It is based on terminating vascular subsystems (rather than draining regions). It divides the cerebral veins into cortical, deep, and posterior fossa veins. The cortical veins are subdivided into two groups: terminating in dural sinuses and terminating in deep veins. The posterior fossa veins are subdivided also into two groups: terminating in dural sinuses and terminating in deep veins. This classification was illustrated with a cerebrovascular model containing over 1,300 vessels. This new classification has many advantages. It is simple, clear and didactically useful; avoids mixture of superficial and deep veins; shows overall hierarchical structure and topographical relationships including tributaries; is useful in analysis of 3D vascular trees extracted from imaging; and may be used in conjunction with the existing parcellations.

Objective: Venous drainage of the temporal lobe is of great importance in various neurosurgical and combined skull base approaches. The most significant draining vein of the temporal lobe is the inferior anastomotic vein (vein of Labbé). The purpose of this study was to examine the detailed anatomy and variations of the vein of Labbé (VL) from microsurgical perspective., Methods: Fourteen fixed human cadaver heads (28 sides) with perfused vessels were included to define microsurgical anatomy and variations of the VL., Results: The main findings of the present study were as follows: (1) drainage pattern of the VL was found to be very variable in cadaveric dissections; (2) VL drained around the sinus confluence at the tentorium in one specimen (3.5%), into the large meningeal vein in the occipital dura mater in another specimen (3.5%). The VL rarely (7%) drains into the superior petrosal sinus (SPS) which may make combined skull base approaches very difficult or impossible., Conclusion: Results of this study suggest that careful and thorough evaluation of the VL is of great importance, especially in surgeries combining a subtemporal route with petrosal approaches by sectioning the SPS and the tentorium.

Purpose: To evaluate the capability of venography based on MR phase-sensitive imaging (PSI) in the visualization of internal cerebral veins (ICV) and their tributaries, and to concurrently describe their anatomical variants., Patients and Methods: A total of 100 consecutive patients underwent PSI MR examination. A minimum intensity projection image from PSI was generated and evaluated by two radiologists. Veins included in this study were ICV, thalamostriate veins (TSV), septal veins (SV), anterior caudate nucleus veins, medial atrial veins and lateral direct veins., Results: With PSI-based venography, we clearly delineated ICV, SV, TSV, anterior caudate nucleus veins, medial atrial veins and lateral direct veins in 100, 98.5, 100, 92.5, 92 and 32% of 200 sides, respectively, within a group of 100 patients. In 80.5% of the sides, the TSV-SV-ICV junction was located adjacent to the posterior margin of the foramen of Monro; in 19.5% the junction was located beyond the foramen of Monro; and in 70.8%, the anterior caudate nucleus veins drained into TSV. In 21.6% of the sides, the SV, TSV and anterior caudate nucleus veins joined together to form the ICV. In 7.6% of the sides, the anterior caudate nucleus veins and TSV separately conjoined with SV or ICV. The pattern that the anterior caudate nucleus veins drain into SV or ICV is more frequent in the sides with TSV-SV-ICV in the posterior location. Of the 64 lateral direct veins, 59.4% of the sides were accompanied by an insufficient development of the TSV and 40.6% sides were normal. Enlarged direct lateral veins frequently accompany an insufficient development of TSV., Conclusions: Phase-sensitive imaging-based venography showed its extraordinary detectability in demonstrating the anatomy and variants of ICV and their tributaries. The advantages of this technique are a relatively short examination time, and a non-invasive and contrast-free procedure. We propose that PSI-based venography may be a promising method to study the anatomy of subependymal veins, especially the tiny and tortuous ones.

Introduction: Detailed descriptions of the mastoid emissary veins (MEVs) and the foramina through which they travel are lacking in the literature. Therefore, the aim of our study was to explore and delineate the morphology, topography and morphometry of the MEV, mastoid foramen (MF) and occipital foramen (OF). One hundred cadaver heads and 100 dried human skulls were grossly examined, Results: The MF and OF varied from being absent to having as many as four small openings, each transmitting an emissary vein. The overall prevalence of MEV was 98% on the right and 72% on the left. The overall prevalence of OF was 7% on the right and 4% on the left. The mean length of the MEV from its point of origin to its point of termination was found to be 7.2 cm with a range of 3.8-11.8 cm. The mean diameter of the MEV at the mastoid emissary foramen was 3.5 mm with a range of 1.1-5.6 mm. In the majority of the cadavers (85%) it was observed that mastoid and occipital emissary veins formed a confluent venous system, while in the remaining 15%, they remained as single vessels., Conclusions: The MEV may be a significant source of bleeding during surgery of the skull base or middle ear, particularly during retrosigmoid and far-lateral approaches and detailed anatomical knowledge may help to prevent these complications. Endovascular treatment of dural arteriovenous fistulas is often extremely difficult due to limited access, however, the use of the MEV represents a unique and potentially valuable technique for accessing an isolated or inaccessible transverse or sigmoid sinus system.

The nucleus lentiformis vascular networks were studied in 30 brains by injecting the vascular system with gelatinous Indian ink. The nucleus lentiformis is divided into a medial part, the globus pallidus, and a lateral part, the putamen. These two parts differ completely from one another in their embryology, structure and functions. For these reasons, each part presents a specific vascular network. The putaminal network is dense and shows many similarities with the cerebral cortex vascular network; the pallidal one is simpler and less dense. These two vascular networks are located close to each other without overlapping. Their specificity may be in relation with the histological structure, with the morphogenetic evolution or with the functional activity of both nuclei to which they provide the vascularization.

The trans-cerebral v. have long been described, but there is little or no knowledge of their function and dysfunction. They are the site of fundamental interchange across the blood-brain barrier, a unique process within the organism. Two systems can be structurally distinguished: the venous system draining the white matter and the trans-cerebral anastomotic system. The former seems to be associated with the nutrition and drainage of the parenchyma, and is rendered visible at angiography by anatomic variations based on developmental venous anomalies. The anastomotic trans-cerebral ventriculo-cortical system seems concerned with the regulation of reabsorption of the cerebrospinal fluid. It is visualized only in exceptional situations where an increased flow (arteriovenous shunt) is combined with obstruction of the normal routes of venous drainage and collateral circulation. It usually functions in the ventriculo-cortical direction. No specific dysfunction of this system is currently recognized.

The authors report a case of tentorial sinus draining the telencephalic and diencephalic tributaries of the basal vein. Dorsally the sinus joined the straight sinus and later the confluence of the sinuses. Attention should be paid to this normal variation whenever a transtentorial surgical approach is considered.