Microsurgical anatomy of the superficial veins of the cerebrum

Anatomic Eponyms in Neuroradiology: Brain, Cerebral Vasculature, and Calvarium

Medical eponyms are ubiquitous, numerous, and at times controversial. They are often useful for succinctly conveying complex concepts, and familiarity with eponyms is important for proper usage and appropriate communication. In this historical review, we identify 18 anatomic eponyms used to describe structures of the brain, cerebral vasculature, and calvarium. For each structure, we first offer a biographical sketch of the individual for whom the structure is named. This is followed by a description of the anatomic structure and a brief discussion of its clinical relevance.

Isolated cortical vein thrombosis: case series

OBJECT

Isolated cortical vein thrombosis (ICVT) accounts for less than 1% of all cerebral infarctions. ICVT may cause irreversible parenchymal damage, rendering early and accurate diagnosis critical. This case series and literature review presents the clinical and radiological findings in 7 patients with ICVT, and highlights risk factors and imaging modalities that may be most beneficial in rendering an accurate and timely diagnosis.

METHODS

Patients with CT and MRI findings consistent with ICVT examined between January 2011 and June 2014 were included in this retrospective review.

RESULTS

Seven patients (5 females, 2 males), ranging in age from 11 months to 34 years, met the inclusion criteria. The most common clinical presentations were headaches (n = 4) and seizures (n = 3). The most common comorbidities noted in these patients were hypercoagulable states (n = 4) and intracranial hypotension (n = 3). Five patients had intraparenchymal involvement. CT suggested the correct diagnosis in 4 patients, and MRI confirmed the diagnosis in all 7 patients. All patients who received anticoagulation therapy (n = 5) experienced complete resolution of their symptoms.

CONCLUSIONS

The majority of these patients were adult females, consistent with published data. Seizures and headaches were the most common presenting symptoms. Hypercoagulable state and intracranial hypotension, both known risk factors for thrombosis, were the most commonly noted ICVT risk factors. Intraparenchymal involvement was prevalent in nearly all ICVT cases and presented as vasogenic edema, early intraparenchymal hemorrhage, or hemorrhagic venous infarction. Susceptibility-weighted imaging was the most sensitive imaging technique in diagnosing ICVT.

Microstructural Characterization of the Pia-Arachnoid Complex Using Optical Coherence Tomography

Traumatic brain injury (TBI) is one of the leading causes of death and disability in the world, and is often identified by the presence of subdural and/or subarachnoid hemorrhages that develop from ruptured cortical vessels during brain-skull displacement. The pia-arachnoid complex (PAC), also known as the leptomeninges, is the major mechanical connection between the brain and skull, and influences cortical vessel deformation and rupture following brain trauma. This complex consists of cerebrospinal fluid, arachnoid trabeculae, and subarachnoid vasculature sandwiched between the arachnoid and pia mater membranes. Remarkably, studies of the tissues in the PAC are largely qualitative and do not provide numerical metrics of population density and variability of the arachnoid trabeculae and subarachnoid vasculature. In this study, microstructural imaging was performed on the PAC to numerically quantify these metrics. Five porcine brains were perfusion-fixed and imaged in situ using optical coherence tomography with micrometer resolution. Image processing was performed to estimate the volume fraction (VF) of the arachnoid trabeculae and subarachnoid vasculature in 12 regions of the brain. High regional variability was found within each brain, with individual brains exhibiting up to a 38.4 percentage-point range in VF. Regions with high VF were often next to regions with low VF. This suggests that some areas of the brain may be mechanically weaker, increasing their susceptibility to hemorrhage during TBI events. This study provides the first quantifiable data of arachnoid trabeculae and subarachnoid vasculature distribution within the PAC and will be valuable to understanding brain biomechanics during head trauma.

Japanese neurosurgeons and microsurgical anatomy: a historical review

Research in microneurosurgical anatomy has contributed to great advances in neurosurgery in the last 40 years. Many Japanese neurosurgeons have traveled abroad to study microsurgical anatomy and played major roles in advancing and spreading the knowledge of anatomy, overcoming their disadvantage that the cadaver study has been strictly limited inside Japan. In Japan, they initiated an educational system for surgical anatomy that has contributed to the development and standardization of Japanese neurosurgery. For example, the Japanese Society for Microsurgical Anatomy started an annual educational meeting in the middle of 1980s and published its proceedings in Japanese every year for approximately 20 years. These are some of the achievements that bring worldwide credit to Japanese neurosurgeons. Not only should Japanese neurosurgeons improve their educational system but they should also contribute to the international education in this field, particularly in Asia.

Venous system in acute brain injury: Mechanisms of pathophysiological change and function

Cerebral vascular injury is a major component of acute brain injury. Currently, neuroprotective strategies primarily focus on the recanalization of cerebral arteries and capillaries, and the protection of insulted neurons. Hitherto, the role of vein drainage in the pathophysiology of acute brain injury has been overlooked, due to an under appreciation of the magnitude of the impact of veins in circulation. In this review, we summarize the changes in the vein morphology and functions that are known, or likely to occur related to acute brain injury, and aim to advance the therapeutic management of acute brain injury by shifting the focus from reperfusion to another term: recirculation. Recent progress in the neurobiological understanding of the vascular neural network has demonstrated that cerebral venous systems are able to respond to acute brain injury by regulating the blood flow disharmony following brain edema, blood brain barrier disruption, ischemia, and hemorrhage. With the evidence presented in this review, future clinical management of acutely brain injured patients will expand to include the recirculation concept, establishing a harmony between arterial and venous systems, in addition to the established recanalization and reperfusion strategies.

Superficial Anastomotic Veins: Neurosurgical View Depending on 251 Cranitotomies

Background:

Superficial anastomotic veins (SAVs) have been studied extensively but little attention has been paid to clinical studies. The aim of this study is to provide variations in the drainage patterns of SAVs depending on the intraoperative findings.

Methods:

A total of 251 craniotomies due to intractable temporal lobe epilepsy were performed between 1972 and 1987 at the Montreal Neurological Institute. The courses of the three largest SAVs including the vein of Trolard (VT), vein of Labbe (VL) and superficial Sylvian vein (SSV) were studied.

Results:

All three veins showed variable courses. The most common predominant vein was the combination of the VL + SSV. The VT and VL were frequently coursed at the level of the central vein and middle temporal vein, respectively. On the right hemisphere the SSV was the predominant type while the VL tended to be predominant on the left hemisphere. A combination of VL and SSV was predominant in patients with right and/or left hemispheric dominance.

Conclusions:

The SAVs showed considerable variation in their courses and it is difficult to define an exact pattern although some courses showed constant directions. Attention should be paid not to damage these veins since in a considerable number of cases a single dominant vein may be responsible for draining a majority of the lateral surface of cerebral hemisphere.

Structural and mechanical characterisation of bridging veins: A review

Bridging veins drain the venous blood from the cerebral cortex into the superior sagittal sinus (SSS) and doing so they bridge the subdural space. Despite their importance in head impact biomechanics, little is known about their properties with respect to histology, morphology and mechanical behaviour. Knowledge of these characteristics is essential for creating a biofidelic finite element model to study the biomechanics of head impact, ultimately leading to the improved design of protective devices by setting up tolerance criteria. This paper presents a comprehensive review of the state-of-the-art knowledge on bridging veins. Tolerance criteria to prevent head injury through impact have been set by a number of research groups, either directly through impact experiments or by means of finite element (FE) simulations. Current state-of-the-art FE head models still lack a biofidelic representation of the bridging veins. To achieve this, a thorough insight into their nature and behaviour is required. Therefore, an overview of the general morphology and histology is provided here, showing the clearly heterogeneous nature of the bridging vein complex, with its three different layers and distinct morphological and histological changes at the region of outflow into the superior sagittal sinus. Apart from a complex morphology, bridging veins also exhibit complex mechanical behaviour, being nonlinear, viscoelastic and prone to damage. Existing material models capable of capturing these properties, as well as methods for experimental characterisation, are discussed. Future work required in bridging vein research is firstly to achieve consensus on aspects regarding morphology and histology, especially in the outflow cuff segment. Secondly, the advised material models need to be populated with realistic parameters through biaxial mechanical experiments adapted to the dimensions of the bridging vein samples. Finally, updating the existing finite element head models with these parameters will render them truly biofidelic, allowing the establishment of accurate tolerance criteria and, ultimately, better head protection devices.

Acute subdural hematoma from bridging vein rupture: a potential mechanism for growth

Most acute subdural hematomas (ASDHs) develop after rupture of a bridging vein or veins. The anatomy of the bridging vein predisposes to its tearing within the border cell layer of the dura mater. Thus, the subdural hematoma actually forms within the dura. The hematoma grows by continued bleeding into the border cell layer. However, the venous pressure would not be expected to cause a large hematoma. Therefore, some type of mechanism must account for the hematoma's expansion.

Cerebral venous pressure (CVP) has been demonstrated in animal models to be slightly higher than intracranial pressure (ICP), and CVP tracks the ICP as pressure variations occur. The elevation of CVP as the ICP increases is thought to result from an increase in outflow resistance of the terminal portion of the bridging veins. This probably results from a Starling resistor model or, less likely, from a muscular sphincter.

A hypothesis is derived to explain the mechanism of ASDH enlargement. Tearing of one or more bridging veins causes these vessels to bleed into the dural border cell layer. Subsequent ICP elevation from the ASDH, cerebral swelling, or other cause results in elevation of the CVP by increased outflow resistance in the intact bridging veins. The increased ICP causes further bleeding into the hematoma cavity via the torn bridging veins. Thus, the ASDH enlarges via a positive feedback mechanism.

Enlargement of an ASDH would cease as blood within the hematoma cavity coagulates. This would stop the dissection of the dural border cell layer, and pressure within the hematoma cavity would equalize with that in the torn bridging vein or veins.

Surgical treatment of parasagittal and falcine meningiomas invading the superior sagittal sinus

OBJECTIVE

We present our experience with surgery of parasagittal and falcine meningiomas invading the superior sagittal sinus with special consideration of the surgical complications and the incidence of tumour recurrence.

MATERIALS AND METHODS

The analysis included 37 patients with parasagittal and falcine meningiomas invading the superior sagittal sinus. In 13 cases, the sinus was ligated and resected with tumour. In 14 cases, the sinus was entered with the goal of tumour resection and the sinus was reconstructed, while in 10 patients the sinus was not entered and the remaining residual tumour was observed for growth.

RESULTS

Out of 13 patients after radical resection of the tumour and invaded part of sinus, 9 revealed haemodynamic complications: venous infarction (4), significant brain oedema (3) and hypoperfusion syndrome (2). 2 out of 14 patients after resection of the tumour from the lumen of the superior sagittal sinus with subsequent sinus repair developed venous infarction after surgery. Among 27 patients after radical tumour excision the remote follow-up revealed recurrence in 2 patients. There were no significant haemodynamic complications in none of 10 cases, in which the residual tumour was left after surgery in the superior sagittal sinus. In this group, 3 cases were subjected to early post-operative radiotherapy and local recurrence was observed in 4 patients.

CONCLUSIONS

The aggressive surgical treatment of meningiomas infiltrating the superior sagittal sinus is associated with a high surgical risk. The incidence of recurrence of these tumours increases significantly in the case of non-radical excision of the tumour.

Cerebral malaria in children: using the retina to study the brain

Cerebral malaria is a dangerous complication of Plasmodium falciparum infection, which takes a devastating toll on children in sub-Saharan Africa. Although autopsy studies have improved understanding of cerebral malaria pathology in fatal cases, information about in vivo neurovascular pathogenesis is scarce because brain tissue is inaccessible in life. Surrogate markers may provide insight into pathogenesis and thereby facilitate clinical studies with the ultimate aim of improving the treatment and prognosis of cerebral malaria. The retina is an attractive source of potential surrogate markers for paediatric cerebral malaria because, in this condition, the retina seems to sustain microvascular damage similar to that of the brain. In paediatric cerebral malaria a combination of retinal signs correlates, in fatal cases, with the severity of brain pathology, and has diagnostic and prognostic significance. Unlike the brain, the retina is accessible to high-resolution, non-invasive imaging. We aimed to determine the extent to which paediatric malarial retinopathy reflects cerebrovascular damage by reviewing the literature to compare retinal and cerebral manifestations of retinopathy-positive paediatric cerebral malaria. We then compared retina and brain in terms of anatomical and physiological features that could help to account for similarities and differences in vascular pathology. These comparisons address the question of whether it is biologically plausible to draw conclusions about unseen cerebral vascular pathogenesis from the visible retinal vasculature in retinopathy-positive paediatric cerebral malaria. Our work addresses an important cause of death and neurodisability in sub-Saharan Africa. We critically appraise evidence for associations between retina and brain neurovasculature in health and disease, and in the process we develop new hypotheses about why these vascular beds are susceptible to sequestration of parasitized erythrocytes.

Drainage Pathway of the Superior Petrosal Vein Evaluated by CT Venography in Petroclival Meningioma Surgery

Objectives This study aimed to clarify the drainage location of the superior petrosal vein (SPV) in relation to Meckel's cave and the internal acoustic meatus (IAM) and to discuss its significance in petroclival meningioma surgery. Design Prospective clinical study. Setting Hospital-based. Participants Five patients with petroclival meningioma and 50 patients (primarily unruptured supratentorial aneurysm patients, with a few hemifacial spasm patients) with no posterior fossa lesions. Main Outcome Measures On computed tomography venography (CTV), the drainage site was classified into three patterns based on its relationship to Meckel's cave and the IAM: Meckel's cave type, Intermediate type, and Meatal type. Results In all patients, the SPV was patent and emptied into the superior petrosal sinus (SPS). In patients without posterior fossa lesions, 35% had Meckel's cave type, 54% had Intermediate type, and 11% had Meatal type. Of the five patients with petroclival meningioma, three had Intermediate type, and two had Meckel's cave type. Conclusion The SPV is a significant vein that should be preserved to prevent venous complications. Preoperative knowledge of the SPV drainage site is helpful for planning the approach and preserving the SPV in petroclival meningioma surgery.

Development of a Finite Element Human Head Model Partially Validated With Thirty Five Experimental Cases

This study is aimed to develop a high quality, extensively validated finite element (FE) human head model for enhanced head injury prediction and prevention. The geometry of the model was based on computed tomography (CT) and magnetic resonance imaging scans of an adult male who has the average height and weight of an American. A feature-based multiblock technique was adopted to develop hexahedral brain meshes including the cerebrum, cerebellum, brainstem, corpus callosum, ventricles, and thalamus. Conventional meshing methods were used to create the bridging veins, cerebrospinal fluid, skull, facial bones, flesh, skin, and membranes—including falx, tentorium, pia, arachnoid, and dura. The head model has 270,552 elements in total. Thirty five loading cases were selected from a range of experimental head impacts to check the robustness of the model predictions based on responses including the brain pressure, relative skull-brain motion, skull response, and facial response. The brain pressure was validated against intracranial pressure data reported by Nahum et al. (1977, “Intracranial Pressure Dynamics During Head Impact,” Proc. 21st Stapp Car Crash Conference, SAE Technical Paper No. 770922) and Trosseille et al. (1992, “Development of a F.E.M. of the Human Head According to a Specific Test Protocol,” Proc. 36th Stapp Car Crash Conference, SAE Technical Paper No. 922527). The brain motion was validated against brain displacements under sagittal, coronal, and horizontal blunt impacts performed by Hardy et al. (2001, “Investigation of Head Injury Mechanisms Using Neutral Density Technology and High-Speed Biplanar X-Ray,” Stapp Car Crash Journal, 45, pp. 337–368; and 2007, “A Study of the Response of the Human Cadaver Head to Impact,” Stapp Car Crash Journal, 51, pp. 17–80). The facial bone responses were validated under nasal impact (Nyquist et al. 1986, “Facial Impact Tolerance and Response,” Proc. 30th Stapp Car Crash Conference, SAE Technical Paper No. 861896), zygoma and maxilla impact (Allsop et al. 1988, “Facial Impact Response – A Comparison of the Hybrid III Dummy and Human Cadaver,” Proc. 32nd Stapp Car Crash Conference, SAE Technical Paper No. 881719)]. The skull bones were validated under frontal angled impact, vertical impact, and occipital impact (Yoganandan et al. 1995, “Biomechanics of Skull Fracture,” J Neurotrauma, 12(4), pp. 659–668) and frontal horizontal impact (Hodgson et al. 1970, “Fracture Behavior of the Skull Frontal Bone Against Cylindrical Surfaces,” 14th Stapp Car Crash Conference, SAE International, Warrendale, PA). The FE head model was further used to study injury mechanisms and tolerances for brain contusion (Nahum et al. 1976, “An Experimental Model for Closed Head Impact Injury,” 20th Stapp Car Crash Conference, SAE International, Warrendale, PA). Studies from 35 loading cases demonstrated that the FE head model could predict head responses which were comparable to experimental measurements in terms of pattern, peak values, or time histories. Furthermore, tissue-level injury tolerances were proposed. A maximum principal strain of 0.42% was adopted for skull cortical layer fracture and maximum principal stress of 20 MPa was used for skull diploë layer fracture. Additionally, a plastic strain threshold of 1.2% was used for facial bone fracture. For brain contusion, 277 kPa of brain pressure was calculated from reconstruction of one contusion case.

Cerebral venous infarction: a potentially avoidable complication of deep brain stimulation surgery

OBJECT

Despite numerous reports on the morbidity and mortality of deep brain stimulation (DBS), cerebral venous infarction has rarely been reported. We present four cases of venous infarct secondary to DBS surgery.

METHODS

The diagnosis of venous infarction was based on 1) delayed onset of new neurologic deficits on postoperative day 1 or 2; 2) significant edema surrounding the superficial aspect of the implanted lead, with or without subcortical hemorrhage on CT scan.

RESULTS

Four cases (0.8% per lead, 1.3% per patient) of symptomatic cerebral venous infarction were identified out of 500 DBS lead implantation procedures between July 2002 and August 2009. All four patients had Parkinson's disease. Their DBS leads were implanted in the subthalamic nucleus (n = 2), and the globus pallidus internus (n = 2). Retrospective review of the targeting confirmed that the planned trajectory passed within 3 mm of a cortical vein in two cases for which contrast-enhanced preoperative magnetic resonance (MR) imaging was available. In the other two cases, contrasted targeting images were not obtained preoperatively.

CONCLUSION

Cerebral venous infarction is a potentially avoidable, but serious complication. To minimize its incidence, we propose the use of high-resolution, contrast-enhanced, T1-weighted MR images to delineate cerebral venous anatomy, along with careful stereotactic planning of the lead trajectory to avoid injury to venous structures.

Congenital pial arteriovenous fistula in the temporal region draining into cavernous sinus: a case report

This report concerns a 4-month-old infant with progressive prominent and redness of his left eye since birth. This report concerns a 4-month-old infant with progressive prominent redness of his left eye since birth. Angiography revealed a congenital pial arteriovenous fistula between the temporal branch of the left posterior cerebral artery and left cavernous sinus through the sphenoparietal sinus, a condition not reported in the literature. The fistula was successfully occluded with two micro-coils by vertebrobasilar approach.

The pterional craniotomy: tips and tricks

This review intended to describe in a didactic and practical manner the frontotemporosphenoidal craniotomy, which is usually known as pterional craniotomy and constitute the cranial approach mostly utilized in the modern neurosurgery. This is, then, basically a descriptive text, divided according to the main stages involved in this procedure, and describes with details how the authors currently perform this craniotomy.

A perfusion-metabolic mismatch in Sturge-Weber syndrome: a multimodality imaging study

OBJECTIVE

We combined perfusion weighted imaging (PWI) with 2-deoxy-2[(18)F]fluoro-D-glucose (FDG) positron emission tomography (PET) to study the relationship between regional metabolic and perfusion abnormalities and their clinical correlates in children with Sturge-Weber syndrome (SWS).

METHODS

Fifteen children (age: 0.9-10 years) with unilateral SWS underwent high-resolution PWI and FDG PET prospectively. Regional (lobar) asymmetry indices (AIs) of subcortical white matter (WM) cerebral blood flow (CBF) were correlated with corresponding cortical FDG uptake asymmetries, extent of leptomeningeal vascular malformation and clinical seizure variables.

RESULTS

Abnormal cortical glucose metabolism and/or subcortical WM CBF were seen in all lobes affected by vascular malformation and extended to lobes not affected by abnormal pial vessels in 6 patients. Lower CBF was associated with lower cortical glucose metabolism in the temporal, parietal and occipital lobes (p≤0.02). While decreased perfusion was associated with hypometabolism in most cases, increased regional CBF (found in 6 patients) was commonly associated with relatively mild or no hypometabolism. Ten of 24 cerebral lobes with normal glucose metabolism in the affected hemisphere showed abnormal perfusion. High seizure frequency was associated with severe parieto-occipital hypoperfusion (p≤0.03), while long duration of epilepsy was related to frontal lobe hypometabolism (p=0.015).

CONCLUSIONS

Regional perfusion and cortical metabolic abnormalities can extend beyond lobes affected by leptomeningeal vascular malformations and are related to epilepsy in SWS. Despite a general correlation between perfusion and metabolism, increased WM perfusion with preserved cortical metabolism in overlying cortex is a common pattern of a perfusion/metabolic mismatch. This may represent a disease stage where cortical function is preserved while increased WM perfusion provides collateral drainage of cortex via the deep vein system.

Epidural anterior petrosectomy with subdural visualization of sphenobasal vein via the anterior transpetrosal approach--technical case report

The drainage of the superficial middle cerebral vein (SMCV) is classified into four subtypes. The sphenobasal vein (SBV) drains from the SMCV to the pterygoid venous plexus at the temporal skull base. Epidural procedures in the standard anterior transpetrosal approach (ATPA) may damage the route of the SBV. We report a case in which modified surgical procedures via the ATPA were used to preserve the SBV. A 45-year-old man complained of right facial pain. Magnetic resonance images revealed a right cerebellopontine tumor suggestive of an epidermoid cyst. Right carotid angiography revealed that the SMCV drained into the pterygoid venous plexus via the SBV. The convexity dura mater of the temporal lobe was cut and the anterior part of the temporal lobe was retracted subdurally. The SBV was visualized from the subdural side. The basal dura mater of the temporal lobe posterior to the SBV was cut and the posterior part of the temporal lobe was retracted epidurally. After dissecting the dura mater medial to the greater petrosal nerve and to the edge of the petrous apex, the petrous apex was exposed and drilled out without injuring the SBV. The superior petrous sinus and the tentorium were cut. The tumor compressed the root exit zone of the trigeminal nerve. The tumor was grossly totally removed. The modified ATPA (epidural anterior petrosectomy with subdural visualization of the SBV) is effective in preserving the SBV.

Variations of the superior sagittal sinus and bridging veins in human dissections and computed tomography venography

OBJECTIVES

The aim of the present study was to examine the superior sagittal sinus (SSS) and bridging veins (BVs) from an anatomical, neurosurgical and radiological perspective.

METHODS

Computed tomography venographies (CTVs) of 30 patients and 9 cadaveric dissections of human SSS were analyzed.

RESULTS

CTV and cadavers showed most BVs emptying into the SSS close by (±3 cm) and distal to the coronary suture (74% in CTV, 62% in cadavers).

CONCLUSIONS

Important anatomical information can be drawn from cerebral CTV for neurosurgical preoperative planning.

The cranial dura mater: a review of its history, embryology, and anatomy

INTRODUCTION

The dura mater is important to the clinician as a barrier to the internal environment of the brain, and surgically, its anatomy should be well known to the neurosurgeon and clinician who interpret imaging.

METHODS

The medical literature was reviewed in regard to the morphology and embryology of specifically, the intracranial dura mater. A historic review of this meningeal layer is also provided.

CONCLUSIONS

Knowledge of the cranial dura mater has a rich history. The embryology is complex, and the surgical anatomy of this layer and its specializations are important to the neurosurgeon.

Microsurgical anatomy of the temporal lobe and its implications on temporal lobe epilepsy surgery

Objective. We review the neuroanatomical aspects of the temporal lobe related to the temporal lobe epilepsy. The neuronal, the ventricular, and the vascular structures are demonstrated. Methods. The previous articles published from the laboratory of the senior author are reviewed. Results. The temporal lobe has four surfaces. The medial surface has a complicated microanatomy showing close relation to the intraventricular structures, such as the amygdala or the hippocampus. There are many white matter bundles in the temporal lobe showing relation to the extra- and intraventricular structures. The surgical approaches commonly performed to treat temporal lobe epilepsy are discussed under the light of these data. Conclusion. A thorough knowledge of the microanatomy is necessary in cortical, subcortical, and intraventricular structures of the temporal lobe to achieve better results.

Differentiation of transverse sinus thrombosis from congenitally atretic cerebral transverse sinus with CT

BACKGROUND AND PURPOSE

Transverse sinus thrombosis can have nonspecific clinical and radiographic signs. We hypothesized that the novel "sigmoid notch sign" (on head CT) can help differentiate transverse sinus thrombosis from a congenitally atretic sinus among individuals with absent signal in 1 transverse sinus by MR venography.

METHODS

We retrospectively evaluated 53 subjects with a unilaterally absent transverse sinus signal on MR venography. Eleven had true transverse sinus thrombosis and 42 had an atretic transverse sinus. Reviewers were trained in the sigmoid notch sign: "positive" if 1 of the sigmoid notches was asymmetrically smaller than the other, consistent with a congenitally absent transverse sinus on that side. This sign was scored on CT scans by 2 blinded reviewers to determine if signal dropout was clot or atretic sinus. A consensus rating was reached when the reviewers disagreed. Characteristics of the sigmoid notch sign as a diagnostic test were compared with a gold standard of full chart review by an independent reviewer.

RESULTS

Each reviewer had a sensitivity of 91% (detecting 10 of 11 clots based on a negative sigmoid notch sign) and specificity of 71% to 81%; consensus specificity increased to 86% (36 of 42 individuals with an atretic sinus had a positive notch sign, detecting atretic sinuses based on presence of the sign).

CONCLUSIONS

Asymmetries of the sigmoid notches on noncontrast brain CT is a very sensitive and specific measure of differentiating transverse sinus thrombosis from an atretic transverse sinus when absence of transverse sinus flow is visualized on MR venography.

Bilateral chronic subdural haematomas in a patient with meningioma of the superior sagittal sinus - case report and pathophysiological study

Bilateral chronic subdural haemorrhage accompanying meningioma is a very rare clinical condition. We present a case of a 69-year-old female patient with large meningioma completely obliterating the posterior third part of the superior sagittal sinus with accompanying bilateral chronic subdural haematomas. Three anatomical zones of venous collateral circulation were revealed by the preoperative digital subtraction angiography. The tumour and haematomas were removed completely with no major complications. The most likely pathomechanism of the development of bilateral chronic subdural haematomas was venous hypertension caused by an occlusion of major cerebral venous trunks. As a result of a minor thrombotic incident or insignificant head injury, the distended veins of collateral circulation that were volumetrically burdened could have been damaged. Patients with large tumours occluding the superior sagittal sinus, who did not qualify for or refused surgery, should be carefully monitored clinically and neuroradiologically because of possibly increased risk of an intracranial haemorrhage.

Cadaveric dissection identifying the left superior anastomotic vein of Trolard communicating indirectly with the superior sagittal sinus via a lateral lacuna

A cadaveric dissection of the calvarium of a 90 year old woman demonstrated a left superior anastomotic vein of Trolard communicating indirectly with the superior sagittal sinus via a left lateral lacunae. This is an anatomical variant contrary to the textbook description of a direct communication between the vein of Trolard and the superior sagittal sinus. A literature search failed to identify a previous description of this variation. Possible clinical implications of this finding will be discussed.

Proposition of a new classification of the cerebral veins based on their termination

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.

The vulnerability of the vein of labbé during combined craniotomies of the middle and posterior fossae

During combined middle and posterior cranial fossae ("petrosal") approaches to the skull base, the anastamotic vein of Labbe, which bridges between the inferior surface of the temporal lobe and the transverse sinus is placed at risk. Occlusion of this vein, which may drain a large section of the temporal and parietal lobes, may lead to speech, memory, and/or other cognitive disorders. Labbe may be injured along its course on the inferior aspect of the temporal lobe where it may be laceraed during dural incision or thrombosed due to prolonged or overly vigorous retraction. The anastamotic segment of the vein, which bridges between the temporal lobe and transverse sinus, may be avulsed during elevation of the temporal lobe or injured during tentorial division. Labbé may course in close proximity to the upper surface of the tentorium or even travel within it for a short segment of its course en route to the transverse sinus. This article reviews the anatomy of the vein of Labbé, discusses its clinical significance, and highlights the technical points relevant to the preservation of this important structure.

Incidence of venous infarction after sacrificing middle-third superior sagittal sinus cortical bridging veins in a pediatric population

OBJECT

The interhemispheric transcallosal approach offers an excellent surgical corridor for the treatment of deep-seated midline lesions. The approach typically requires the sacrifice of one or more middle-third superior sagittal sinus (SSS) cortical bridging veins, which introduces the risk of venous infarction and associated neurological injury. The authors studied the incidence of venous infarcts following this operative approach in a pediatric population.

METHODS

The authors performed a retrospective review of surgical cases involving pediatric patients treated at the Children's Hospital Los Angeles between 1990 and 2007, in which an interhemispheric transcallosal operative procedure was performed and one or more middle-third SSS cortical bridging veins were occluded. Postoperative MR imaging studies done 1-3 days following the procedure were analyzed and compared with preoperative studies.

RESULTS

Sixty-three patients met the inclusion criteria. No patient developed MR imaging evidence of venous infarction.

CONCLUSIONS

The occlusion of one or more middle-third SSS cortical bridging veins related to the interhemispheric transcallosal approach resulted in no incidence of cerebral venous infarction in this pediatric population.

Perioperative and Long-term Outcomes From the Management of Parasagittal Meningiomas Invading the Superior Sagittal Sinus

BACKGROUND:

Parasagittal meningiomas invading the superior sagittal sinus (SSS) pose formidable obstacles to surgical management. Invasion is often considered a contraindication to surgery because of associated morbidity, such as cerebral venous thrombosis.

OBJECTIVE:

We report our most recent experience with the resection of parasagittal meningiomas invading the SSS.

METHODS:

Between 1992 and 2004, 110 patients with parasagittal meningiomas underwent surgery at the Johns Hopkins Medical Institutions. Clinical charts, radiological studies, pathological features, and operative notes were retrospectively analyzed; only those patients with minimum 24 months follow-up (n = 61) were further studied.

RESULTS:

Tumor distribution by location along the SSS was: 21% anterior, 62% middle, and 17% posterior. All patients were managed with initial surgical resection with radiosurgery for residual/recurrent disease if indicated (19.6%). Pathological examination revealed 80% grade I meningiomas, 13% grade II meningiomas, and 7% grade III meningiomas. Simpson grade I/II resection was achieved in 81% of patients. Major complications included venous thrombosis/infarction (7%), intraoperative air embolism (1.5%), and death (1.5%); long-term outcomes assessed included recurrence (11%) and improvement in Karnofsky Performance Score (85%).

CONCLUSION:

On the basis of our study, the incidence of postoperative venous sinus thrombosis is 7% in the setting of a recurrence rate of 11% with a mean follow-up of 41 months. In comparison with the published literature, the data corroborate the rationale for our treatment paradigm; lesions invading the sinus can initially be resected to the greatest extent possible without excessive manipulation of vascular structures, whereas residual/recurrent disease can be observed and managed with radiosurgery.

Dural Entrance of the Bridging Vein in the Middle Cranial Fossa: A Novel Classification of the Cerebral Veins for Preoperative Planning

BACKGROUND AND IMPORTANCE:

Understanding of the intracranial venous anatomy is essential for preoperative planning.

OBJECTIVE:

To identify anatomic features of the dural entrance of the bridging veins (BVs) into the dural sinuses in the middle cranial fossa on the cadaver and to correlate such features with those of digital subtraction venogram, computed tomographic venogram, and magnetic resonance venogram.

CLINICAL PRESENTATION:

A total of 30 adult cadavers and 86 patients were examined with anatomic dissection or neuroimages. The number, diameter, and location of the BVs entering the dural sinuses in the middle cranial fossa were recorded and compared between the cadavers and neuroimages. The dural entrances of the BVs were identifiable on neuroimages and distributed mainly at the anteromedial area of the fossa. Morphological features of the dural sinuses and meningeal veins in the fossa indicated that the techniques of lengthening the BV by dissecting it away from the dura mater or cutting a small area of the dura along the sides of the BV may not be applicable for the management of BVs in the anteromedial middle cranial fossa.

CONCLUSION:

Unique anatomic features of the dural entrance of BVs entering the dural sinuses in the cadaver are correlated to those on neuroimages. Identification of the dural entrance of BVs with neuroimaging modalities provides a reliable measure for preoperative planning.

Venous anatomy and imaging of the first centimeter

The outermost centimeter of the head contains multiple layers ranging from the skin to the meninges. The venous drainage of this region is complex and with wide anatomical variation. With advances in imaging techniques, delineation of this venous system has become better appreciated. Understanding the anatomy of the superficial venous system is fundamental in being able to differentiate pathology from normal variants and structures. This review aims to characterize the basic venous architecture of the first centimeter. In addition, it hopes to give an introduction to and examples of the methods employed to image it.

The termination of superior sagittal sinus and drainage patterns of the lateral, occipital at confluens sinuum in newborns: clinical and embryological implications

Drainage patterns of dural venous sinuses at confluens sinuum are variable and clinically significant. It has been generally investigated in adults; however, we thought that neonatal cadaver study might be more informative in views of embryological and clinical. A total of 33 skull bases of neonatal cadavers were resected to identify termination patterns of lateral sinus (LS), superior sagittal sinus (SSS) and occipital sinus (OS) at the confluens sinuum. Termination patterns of these sinuses were classified into six types: the SSS showed continuity with right transverse sinus (TS) (with OSs) (30.3%) (Type I); or multiple OSs (21.2%) (Type II). The SSS continued with left TS (with OSs) (12.1% (Type III); or with multiple OSs (6.1%) (Type IV). The SSS shows continuity with both TS (9.1%) (Type V). SSS symmetrically bifurcated, the confluens sinuum has a large OS (21.2%) (Type VI). Understanding of the cerebral venous drainage and large variation of the posterior fossa dural sinuses is crucially important for planning surgical intervention to some tumors in the neck which may require ligation of the internal jugular vein.

Cortical vein thrombosis: the diagnostic value of different imaging modalities

INTRODUCTION

Cortical vein thrombosis (CVT) is a rare disorder, and its diagnosis is challenging. The aim of our study was to evaluate the value of different imaging modalities for the detection of CVT.

METHODS

Thirteen patients with CVT, either isolated (n = 3) or in combination with sinus thrombosis (n = 10), and 20 control patients without any venous pathologies were included in this study. The analysis was performed independently by three blinded readers who evaluated the following imaging modalities and sequences separately: non-enhanced computed tomography (NCCT); multi-detector row CT angiography (MDCTA); diffusion-weighted (DWI), T1-weighted (T1w), PD-weighted (PDw), T2*-weighted (T2*w), and fluid-attenuated inversion recovery-weighted (FLAIRw) magnetic resonance (MR) sequences; as well as venous MR angiography (vMRA). The sensitivity, specificity, positive (PPV) and negative predictive values, and interobserver agreement of the different modalities were calculated.

RESULTS

T2*w showed the highest sensitivity for the detection of CVT (97.4%), followed by T1w (70%). FLAIRw and vMRA had a sensitivity of 50% and 41.7%, respectively, whereas the sensitivity of NCCT, MDCTA, DWI, and PDw was below 30%. The specificity and PPV of all modalities was 100%, with good to perfect interobserver agreement.

CONCLUSION

T2*w was the superior MR imaging sequence for diagnosing CVT. Besides T2*w, only T1w reached a sensitivity of over 50% for CVT, followed by FLAIRw, and vMRA. On the contrary, our results suggest that NCCT but also MDCTA might not be suitable for diagnosing CVT.

The relationship between parasagittal and falcine meningiomas and the superficial cortical veins: a virtual reality study

OBJECTIVES

Surgery for parasagittal and falcine meningiomas requires meticulous preservation of the cortical veins that surround the tumour; thus, knowledge of the relevant venous anatomy would be extremely helpful during surgery.

METHODS

This study utilises virtual reality technology to determine the number, size and disposition of the veins in relation to the tumour in 8 patients with parasagittal and falcine meningiomas. The same data were also collected from the scans of 8 normal subjects and compared with the data from the meningioma patients.

RESULTS

Our results show that the average number of veins is comparable in the tumour and control groups, and that the number of veins on either side does not differ significantly for both groups. On measurement, the size of the veins is approximately the same on either side of the superior sagittal sinus for both the control and the tumour groups. It was also observed that regardless of size, most of the parasagittal and falcine meningiomas demonstrated no significant anatomical distortion effects on the adjacent venous structures, with the exception of one parasagittal meningioma with invasion of the superior sagittal sinus and concomitant engulfment of the draining veins.

CONCLUSION

Data from a larger population would have to be collected in order to determine the effect of the growth of these tumours on the surrounding venous anatomy. With virtual reality technology, the parasagittal veins are clearly discerned, and knowing their location and relationship to the tumour would contribute towards safe and effective surgery.

Microvascular repair of an injured cortical draining vein

BACKGROUND

Cortical venous injury can occur during any intracranial procedure with potentially severe consequences. We describe a simple technique that allowed for successful repair of a large cortical draining vein.

CASE DESCRIPTION

A 43-year-old, right-handed woman presented with 6 months of headaches and progressive difficulty with right-sided hemiparesis. She had significant loss of hand coordination and writing ability. Computed tomography and MR imaging revealed a parasagittal meningioma in the left, posterior frontal region. The patient underwent craniotomy with resection of the lesion.

CONCLUSION

When a cortical vein is injured, collateral drainage pathways may prevent the development of a clinical problem. Because of the unpredictability of these collateral channels, venous reconstruction may be feasible and even straightforward in some cases.

The cerebrum. Anatomy

The cerebrum is the crown jewel of creation and evolution. It is a remarkably delicate, intricate, and beautiful structure. The goal of this chapter is to provide the information needed to permit the neurosurgeon to navigate accurately, gently, and safely around and through the cerebrum and intracranial space. The location of deep structures is frequently described in relation to cranial and superficial cerebral landmarks in order to develop the concept of see-through, x-ray type knowledge of the cerebrum. In numerous illustrations, stepwise dissections are used to clarify the relationship between structures in different layers. Important clinical and surgical concepts are intermixed with the description of the cerebrum and its arteries, veins, and ventricles.

Frequency and topographic distribution of brain lesions in pediatric cerebral venous thrombosis

BACKGROUND AND PURPOSE

Cerebral sinovenous thrombosis (CSVT) is increasingly encountered in children, including neonates. The purpose of this study was to assess the frequency and topographic distribution of parenchymal brain lesions associated with CSVT in children and to compare these with the known anatomic venous drainage pathways.

MATERIALS AND METHODS

Brain CT/CT venograms and/or MR imaging/MR venograms of 71 consecutive patients with CSVT were reviewed retrospectively. The patients were grouped into neonates, infants, and older children. The site of CSVT, the location and size of the brain lesions, and the presence of hemorrhage were documented. The frequency of the brain lesions was calculated.

RESULTS

There were 34 neonates, 10 infants, and 27 older children with CSVT who were included. The most common sites of CSVT were the transverse sinuses, the superior sagittal sinus, and the straight sinus. Overall, 37 of 71 children with CSVT had parenchymal brain lesions. There were 21 of 34 neonates, 4 of 10 infants, and 12 of 27 older children who had brain lesions. The most common locations were in the frontal and parietal lobes. The topographic distribution of lesions correlated with the corresponding venous drainage territory in 16 of 21 neonates, all infants, and all older children. The neonates had smaller-sized lesions. Brain lesions were hemorrhagic in 76% of neonates, 75% of infants, and 33% of older children.

CONCLUSION

The topographic distribution of brain lesions associated with CSVT correlates with the known drainage territories of the dural venous sinus in children.