Torcular Herophili classification and evaluation of dural venous sinus variations using digital subtraction angiography and magnetic resonance venographies

Advanced Surgical Techniques for Dural Venous Sinus Repair: A Comprehensive Literature Review

The dural venous sinus (DVS) is a thin-walled blood channel composed of dura mater that is susceptible to injury during common neurosurgical approaches. DVS injuries are highly underreported, which is reflected by a lack of literature on the topic. Neurosurgeons should be familiar with appropriate techniques to successfully repair an injured DVS and prevent associated complications. This study presents a literature review on the surgical techniques for DVS repair after DVS injury during common neurosurgical approaches. The databases PubMed and Scopus were queried using the terms "cranial sinuses," "superior sagittal sinus," "transverse sinuses," "injury," and "surgery." A total of 117 articles underwent full-text review and were analyzed for surgical approach, craniotomy, lesion location, lesion characteristics, and surgical repair techniques. A literature review was performed, and a comprehensive summary is presented. Data from publications describing DVS lacerations related to pathological conditions (eg, meningioma) were excluded. A total of 9 techniques aiding with bleeding control, hemostasis, and sinus repair and reconstruction were identified, including compression, hemostatic agents, bipolar cautery, dural tenting and tack-up suturing, dural flap, direct suturing, autologous patch, venous bypass, and ligation. The advantages and drawbacks of each technique are described. Multiple options to treat DVS injuries are available to the neurosurgeon. Treatment type is based on anatomic location, complexity of the laceration, cardiovascular status, the presence of air embolism, and the dexterity and experience of the surgeon.

Multimodality imaging in cerebral venous thrombosis: a synopsis for emergency radiologist

Cerebral venous thrombosis (CVT) is an uncommon but potentially fatal condition which presents with a wide range of symptoms. Some of these presenting features are vague thus contributing to the delay in diagnosis. A prompt diagnosis and initiation of appropriate therapy are therefore of paramount importance. In this pictorial, we have tried to illustrate the direct and indirect imaging features of CVT in detail on multiple imaging modalities, along with the potential pitfalls of imaging.

The effect of the occipital sinus on the torcular Herophili and neighboring structures

Objective

The occipital sinus (OS) has many variations. It is unknown whether OS can change the angioarchitecture of torcular Herophili. Therefore, we performed magnetic resonance venography (MRV) in a cohort of Han Chinese individuals to determine whether OS can change the angioarchitecture of torcular Herophili.

Methods

Participants were divided into a normal OS group and a hyperplastic OS group. Parameters of the OS and torcular Herophili and its neighboring structures were recorded. Statistical analysis was used to determine the effects of OS on torcular Herophili and neighboring structures.

Results

One hundred forty-five healthy participants were enrolled. One hundred patients were in the normal OS group, and 45 were in the hyperplastic OS group. In the normal OS group, the diameters at the transverse sinus (TS) origin were 5.8 ± 2.3 mm on the left side and 7.5 ± 2.2 mm on the right side. In the hyperplastic OS group, the diameters at the TS origin were 6.0 ± 2.1 mm on the left side and 7.0 ± 2.7 mm on the right side. Fenestration was observed in 33% of the torculars in the normal OS group and 6.7% of the torculars in the hyperplastic group. An unpaired t-test revealed a significant difference between bilateral TSs in the normal OS group (P < 0.05) but no difference in the hyperplastic OS group. The chi-square test revealed a significant difference in torcular Herophili fenestration between the normal and hyperplastic OS groups (P < 0.05).

Conclusions

Hyperplastic OS makes bilateral TSs equal in diameter and weakens the predominance of the right TS. A hyperplastic OS reduces the occurrence of torcular Herophili fenestration.

Absence of the torcular, review of venous sinus anatomy, and the simplified dural sinus classification

BACKGROUND

Classically, the torcular Herophili is described as the symmetric junction between the superior sagittal sinus (SSS), transverse sinuses (TSs), and straight sinus (SS). However, finding this pattern in practice is not standard. Anatomical variations are common, and different drainage patterns should be expected. Existing literature proposes highly detailed descriptions and classifications of this region. Still, a simplified and practical categorization is not available.

METHODS

We present an anatomical finding of the torcular Herophili discovered on a cadaveric dissection. Then, we conducted a retrospective study examining the 100 most recent cranial magnetic resonance venographies (MRVs) from the Mayo Clinic, labeling them with a new proposed dural sinus classification system. Images were initially classified by two authors and further validated by a board-certified neurosurgeon and a board-certified neuroradiologist from our institution. To measure consistency in image identification, two additional international neurosurgeons were asked to classify a subset of the same MRV images, and their answers were compared.

RESULTS

Of the MRV cohort, 33 patients were male and 67 were female. Their ages ranged from 18 to 86 years, with a mean of 47.35 years and a median of 49 years. Upon examination, 53 patients presented as confluent (53%), 9 as SSS divergent (9%), 25 as SS divergent (25%), 11 as circular (11%), and 2 as trifurcated (2%). The inter-rater reliability ranked very good; agreement between the two neurosurgeons was 83% (κ = 0.830, p < 0.0005).

CONCLUSION

The confluence of the venous sinuses is a highly variable anatomical area that is rarely evaluated with neuroimaging before surgery. The classic textbook configuration is not the rule. Using a simplified classification system may increase awareness and hopefully patient safety by preparing the physician for anatomical variations that they will encounter in a surgical or clinical scenario.

MRI and MR angiography evaluation of pulsatile tinnitus: A focused, physiology-based protocol

BACKGROUND AND PURPOSE

Pulsatile tinnitus (PT) is the subjective sensation of a pulse-synchronous sound, most often due to a cerebrovascular etiology. PT can severely impact quality of life and may indicate a life-threatening process, yet a timely and accurate diagnosis can often lead to effective treatment. Clinical assessment with a history and physical examination can often suggest a diagnosis for PT, but is rarely definitive. Therefore, PT should be evaluated with a comprehensive and targeted radiographic imaging protocol. MR imaging provides a safe and effective means to evaluate PT. Specific MR sequences may be used to highlight different elements of cerebrovascular anatomy and physiology. However, routine MR evaluation of PT must comply with economic and practical constraints, while effectively capturing both common and rarer, life-threatening etiologies of PT.

METHODS

In this state-of-the-art review, we describe our institutional MR protocol for evaluating PT.

RESULTS

This protocol includes the following dedicated sequences: time-of-flight magnetic resonance angiography; arterial spin labeling; spoiled gradient recalled acquisition in the steady state; time-resolved imaging of contrast kinetics; diffusion weighted imaging, and 3-dimensional fluid-attenuated inversion recovery.

CONCLUSIONS

We describe the physiologic and clinical rationale for including each MR sequence in a comprehensive PT imaging protocol, and detail the role of MR within the broader evaluation of PT, from clinical presentation to treatment.

Skull Base Neurointerventional Techniques

Neurodiagnostic and neurointerventional radiology (NIR) play a central role in the diagnosis and treatment of skull base disorders. Noninvasive imaging modalities, including computed tomography and magnetic resonance imaging, are important in lesion localization, evaluation of lesion extent, and diagnosis, but cannot always be definitive. Image-guided skull base biopsy and percutaneous and endovascular treatment options are important tools in the diagnosis and treatment of head, neck, and skull base disorders. NIR plays an important role in the treatment of vascular disorders of the skull base. This article summarizes the imaging evaluation and interventional therapies pertinent to the skull base.

Effectiveness of Transvenous Aspiration Thrombectomy for Cerebral Venous Sinus Thrombosis: A Report of Three Cases

Objective

We report three patients successfully treated by emergent transvenous thrombectomy for cerebral venous sinus thrombosis (CVST).

Case Presentation

(Case 1) A 77-year-old man presented with vomiting, dizziness, and headache. CT revealed local subarachnoid hemorrhage (l-SAH), and angiography confirmed occlusion of the right transverse sigmoid sinus and superior sagittal sinus (SSS). Emergent transvenous aspiration thrombectomy using a Penumbra catheter (PC) resulted in effective reperfusion. (Case 2) A 60-year-old man developed disorientation, sensory aphasia, and right hemiparesis. MRI demonstrated extensive cerebral edema caused by venous congestion in both thalami, and angiography revealed poor opacification of the SSS, straight sinus, and bilateral transverse sinuses. Venous sinus flow was restored by catheter aspiration using a PC and topical infusion of urokinase (UK). (Case 3) A 19-year-old man developed a headache, numbness of the right upper limb, motor paralysis, and convulsions. CT revealed l-SAH and dense clot sign in the SSS. The SSS was poorly delineated on angiography. Thrombus aspiration using a PC and topical UK administration achieved partial recanalization.

Conclusion

Transvenous aspiration thrombectomy using large lumen catheters for patients with CVST is effective and safe. In particular, this method may be a better option than anti-coagulation therapy alone for patients presenting with a severe neurological condition or intracranial hemorrhage.

Angiographic cerebral venous sinus calibers and drainage patterns in patients with normal intracranial pressure and idiopathic intracranial hypertension

BACKGROUND

Normative venous sinus diameters are not well established. This study seeks to compare two-dimensional digital subtraction cerebral angiographic (DSA) venous sinus calibers for patients with normal intracranial pressure (ICP) and with idiopathic intracranial hypertension (IIH).

METHODS

Patients who underwent diagnostic cerebral angiography from 2016 to 2020 were retrospectively identified. Two independent reviewers measured venous sinus calibers from anteroposterior (AP) and lateral carotid injection delayed venous phase in patients from two groups (group 1: patients with normal ICP; group 2: patients with IIH) after receiving training in a standardized measurement protocol, with measurements obtained from the superior sagittal sinus (SSS) through the sigmoid sinuses (SS).

RESULTS

97 patients from group 1 and 30 patients from group 2 were included. Interrater reliability was greater than 0.75 for all measured sites. Both groups had similar anatomical subtypes with most being right transverse sinus (TS) dominant or codominant. In group 1, men had significantly larger SSS on lateral view (p<0.001) and dominant TS calibers on AP view (p=0.02) compared with women. Both dominant TS measurements and SSS measurements (lateral plane) were significantly smaller among group 2 compared with group 1 (p<0.001 and 0.02, respectively). Patients with IIH had significantly larger dominant SS measurements (p=0.01). Bifid SSS anatomy was present in 9% of patients with mean caudal width 31 mm (range 19-49 mm).

CONCLUSIONS

This study is the first to provide two-dimensional DSA dural venous sinus calibers in patients with and without IIH and to compare anatomical drainage types and calibers among groups.

Variability in Wall Thickness and Related Structures of Major Dural Sinuses in Posterior Cranial Fossa: A Microscopic Anatomical Study and Clinical Implications

BACKGROUND

Regional variability in dural sinus (DS) wall thickness in posterior cranial fossa (PCF) have not been studied in detail yet.

OBJECTIVE

To clarify the possible regional variability in DS wall thickness and determine the occurrence and localization of the chordae Willisii (CW) in PCF.

METHODS

Fifty-nine human cadaveric DSs of PCF were investigated. A measurement of the DS walls/dura mater/CW thickness of parafin-embedded/hematoxylin-eosin stained axial sections was performed by using Cell Sens Science Imaging Software (Olympus Corporation, Tokyo, Japan).

RESULTS

The osseus wall (OW) was the thickest one in the confluens sinuum (CS) and the thinnest one in the jugular bulb (JB) and sigmoid sinus (P < .05). The biggest differences between individual walls were observed in the JB where the superior wall was almost twice as thick as the OW. At the transverse-sigmoid junction, the thickness of the walls was comparable. In the CS and transverse sinuses, the OW was even thicker than the surrounding dura mater. The occurrence and thickness of the CW increased from the JB towards CS and prevailed on the right side. An overall number of the CW in PCF was comparable to that observed in the superior sagittal sinus.

CONCLUSION

The present study displayed for the first time the regional variability in the DS walls thickness and occurrence of the CW in PCF. Application of these findings may afford greater freedom in exposure of the DSs or neoplasms adhering to the DSs.

Idiopathic intracranial hypertension with stenosis of a solitary occipital venous sinus treated with stenting

A 47-year-old live kidney-donor woman presented with headaches and blurred vision. Neuro-ophthalmological examination demonstrated papilledema and right eye inferior nasal defect. Brain MRV showed no sinus thrombosis but solitary right venous sinus draining the torcular Herophili to right jugular bulb. Lumbar puncture revealed elevated CSF opening pressure of 40 cm H₂O with normal composition. She was diagnosed with idiopathic intracranial hypertension (IIH). She did not tolerate medical management and declined CSF diversion surgery. Cerebral angiography and venography showed venous outflow drainage from torcular Herophili through a solitary occipital sinus which has distal severe stenosis and pressure gradient of 10 mmHg. Balloon angioplasty and stenting of the occipital sinus were performed. Post-stenting, the stenosis and pressure gradient resolved. At 3-months follow-up, her symptoms and papilledema had resolved and CSF opening pressure was normal at 15 cm H2O. Aberrant cerebral venous anatomy may cause IIH and can be treatable with neuroendovascular techniques.

Dural Venous Sinuses: What We Need to Know

BACKGROUND

The dural venous sinuses (DVS), in general, are frequently asymmetrical and display far more anatomical variations than arterial systems. A comprehensive study of the anatomy and variants of the DVS can help surgeons in the preoperative evaluation and management as well as minimizing possible complications in the following treatment.

METHODS

The current review was designed to provide a general overview of the normal anatomy and notable variants of the cerebral venous system as surveyed from the available literature. The pros and cons of different multimodal imaging methods for investigating DVS are also outlined. Finally, cases of various pathological entities are illustrated from our clinical practice.

CONCLUSION

There are many anatomical variations and lesions involving the DVS. MRI examination can provide essential information both on anatomical variation and morphological or functional change of the offending DVS in most circumstances. Multimodal non-invasive venography protocols may become a feasible alternative to the classical digital subtraction angiography and would improve the diagnostic accuracy in future studies.

A Preliminary Study of Neonatal Cranial Venous System by Color Doppler

Aim

To present anatomic data in the ultrasound planes for the identification of the major veins and the venous sinuses in cerebrum and to establish the sonographic normal reference values for the visualization of vein vessels and vein sinuses and blood flow velocities.

Methods

This study involved 55 healthy full-term neonates for transfontanellar color Doppler sonography. The imaging included both sagittal and coronal planes with LA332E probe, supplemented with PA240 probe as necessary. As low as reasonably achievable (ALARA) principle was obeyed, limiting Doppler exposure time and maximizing signal intensity by increasing gain rather than outputting transducer power settings. The output power was kept at a minimum level consistent with recording an adequate signal. Keeping the newborns in calm state, the total examination time which every neonate required was less than 5 min. All images were stored also in a workstation for further analysis. The description statistics and t-test for statistical analysis were used.

Result

In all studied cases (100% cases), subependymal veins (SV), internal cerebral veins (ICV), Galen vein (GV), straight sinus (SS), superior sagittal sinus (SSS), and transverse sinuses (TS) were visualized. The visualization percentages of inferior sagittal sinus (ISS) or basal veins/Rosenthal veins (BV/RV) were lower than 100%. Based on vessel visualization percentage from high to low, the vessels were ordered as follows: SV, ICV, BV, SS, TS, ISS, and SSS. In SSS and TS, the pulsation percentage was 100%. The descending percentages of vessel pulsation were noted in SS, BV, ICV, and SV. On the basis of the mean of maximum velocities of the vessels from low to high, the vessels were ordered as follows: ISS, BV-L, BV-R, ICV-R, ICV-L, SV-L, SV-R, SSS, TS-L, TS-R, and SS.

Conclusion

The measurements percent of visualization of cerebral deep veins was higher than the percent of cerebral venous sinuses. The pulsation percent of measurement and the velocities of cerebral venous sinuses were absolutely higher than the cerebral deep venous system. The pairs of vascular blood flow velocities were nonsignificantly different from one another.

Evaluation of the inion and asterion as neurosurgical landmarks for dural venous sinuses: osteological study on a sample of South African skull specimens

BACKGROUND

Sub-Saharan neurosurgeons most likely need to perform invasive procedures without the latest imaging and navigation technology in the operating room. Therefore, these surgeons need to utilize other methods such as superficial surface landmarks for neuro-navigation. Bony landmarks, including the inion and asterion, are commonly used during invasive procedures to pinpoint the location of the confluence of sinuses and transverse-sigmoid sinus junction, respectively. The purpose of this study was to investigate whether the inion and asterion can be used as superficial landmarks for the confluence of sinuses and the transverse-sigmoid sinus junction, respectively, in a South African population.

METHODS

Fifty South African human skulls were used (25 male, 25 female). The micro-focus X-ray radiography and tomography facility (MIXRAD) at Necsa scanned and created three-dimensional virtual images of the skull specimens. Reference points were then inserted on the images and the relation between bony landmarks and venous sinuses was documented.

RESULTS

The inion was directly related to the confluence of sinuses in 4% of the sample, whereas the asterion was directly related to the transverse-sigmoid sinus junction in 28% of the cases, on both the right and left sides.

CONCLUSIONS

This study confirmed that neither the inion, nor the asterion, are directly related the confluence of sinuses and transverse-sigmoid sinus junction, respectively. These bony landmarks are more likely to be located either inferior, or not related at all, to the investigated dural venous sinuses.

Evaluation of dural venous sinuses and confluence of sinuses via MRI venography: anatomy, anatomic variations, and the classification of variations

PURPOSE

We aimed to determine the anatomical variations more comprehensively particularly at the level of superior sagittal sinus (SSS), confluence of sinuses (CS), transverse sinuses (TS), straight sinuses (SS) and occipital sinuses (OS) with the help of the images obtained via MRI venography, and to contribute to the classification efforts.

METHODS

In our retrospective study, we evaluated 211 patients who admitted to our hospital with various complaints and cerebral MRI venography has been performed. All investigations were performed by using 1.5-T MRIscanner (Achiva, Philips) with a VEN-3D -PCA MR venous angiography technique. Section thickness was 0.8 mm and axial plane was used. Other parameters were as follows: 17/7.1 (TR/TE), flip angle, 10.00, FOV, 220-mm, and matrix 244x140.

RESULTS

We divided our cases into 3 types but we increased the number of subgroups. Type I was divided into 4 subgroups (Type IA, IB, IC, ID), Type II into 9 (Type IIA1, IIA2, IIB1, IIB2, IIC, IID1, IID2, IIE1, IIE2) and Type III into 2 (Type IIIA, IIIB). Type I constitutes a 26.06% of whole cases, and Type II 59.71%, Type III 14.21%. In our cases R-TS wasn't revealed in 10 cases (4.73%) whereas in 37 cases (17.53%) it was hypoplastic. L-TSwasn't shown in 26 cases (12.32%) and in 85 cases (49.09%) it was hypoplastic. R-Sig S wasn't revealed in 7 (3,31%) and was hypoplastic in 34 (16.11%) whereas L-Sig S wasn't present in 2 (0.94%) and hypoplastic in 72 (34.12%). Among these cases 14 had bilateral hypoplastic TS (6.63%). In cases with hypoplastic TS or Sig S, as an alternative pathway 30 patients had OS (14.21%). Two of these patients had double OS.

CONCLUSION

Our wish is to contribute to the efforts of clarifying and classifying the intracranial venous structures and their anatomical variations. We hope our study enlightens a path in this field for future studies.

A Severe Case of Aneurysmal Malformation of the Vein of Galen, Cardiac Failure and Intrauterine Fetal Death

Aneurism of the vein of Galen is a rare congenital anomaly, where complex arteriovenous malformation are identified between multiple choroidal arteries and the median prosencephalic vein of Markowski, which is a precursor of the vein of Galen, with subsequent aneurysmal enlargement of the respective arteriovenous system. The congenital malformation develops during week 6 to 11 of fetal development. Infants often die from high-output congestive heart failure. We present a case of a 40 years old patient, presented the first time at hospital at 28 weeks of gestation for lower perception of fetal movements. The patient was referred to our Prenatal Diagnosis Unit for a suspected cardiac malformation. We diagnosed cardiomegaly along vein of Galen aneurysmal malformation (VGAM) with severe cardiac failure, ascites, and critical fetal distress. Fetal demise was noted 24 hours later, during the corticosteroid procedures for fetal maturation. A stillborn weighting 2000g with a severe hydropic aspect was born after labor induction. Autopsy was performed following injection of colored gelatin in carotid vessels. The aneurysmal defect was evident in the vein of Galen and straight sinus. We also found the transverse, sagittal and the occipital sinus seriously dilated. We could not highlight the communication with the middle cerebral artery, because of the degradation of the cerebral tissue, despite an optimal preparation

Fate of the three embryonic dural sinuses in infants: the primitive tentorial sinus, occipital sinus, and falcine sinus

PURPOSE

The primitive tentorial, occipital, and falcine sinuses are thought to attain the adult pattern or regress between the fetal stage and adulthood. The anatomy of these three primitive dural sinuses has seldom been studied in the infant population, and it remains unclear when these dural sinuses reach the adult condition. Using computed tomography digital subtraction venography (CT-DSV), we analyzed the anatomy of these embryonic dural sinuses in infants.

METHODS

We included 13 infants who underwent CT-DSV prior to neurosurgery and 35 cases with unruptured cerebral aneurysms as normal adult controls. Three embryonic dural sinuses, i.e., the primitive tentorial, occipital, and falcine sinuses, were retrospectively analyzed in CT-DSV images of infants and adults. We also analyzed the drainage patterns of the superficial middle cerebral vein (SMCV), determined by the connection between the primitive tentorial sinus and the cavernous sinus.

RESULTS

The primitive tentorial, occipital, and falcine sinuses were present in 15.4%, 46.2%, and none of the infants, respectively, and in 10.0, 8.6, and 2.9% of the adults, respectively. The difference in SMCV draining pattern between infants and adults was insignificant. The incidence of the occipital sinus was significantly higher in infants than in adults.

CONCLUSIONS

The connection between the primitive tentorial sinus and the cavernous sinus appears to be established before birth. The occipital sinus is formed at the embryonic stage and mostly regresses after infancy. The falcine sinus is usually obliterated prenatally. Our findings form the basis for interventions by pediatric interventional neuroradiologists and neurosurgeons.

Pressure Mapping and Hemodynamic Assessment of Intracranial Dural Sinuses and Dural Arteriovenous Fistulas with 4D Flow MRI

The feasibility of 4D flow MR imaging to visualize flow patterns and generate relative pressure maps in the dural venous sinus in healthy subjects (n = 60) and patients with dural arteriovenous fistulas (n = 7) was investigated. Dural venous drainage was classified based on torcular Herophili anatomy by using 4D flow MR imaging-derived angiograms and magnitude images. Subjects were scanned in a 3T clinical MR imaging system. 4D flow MR imaging enabled noninvasive characterization of dural sinus anatomy and mapping of relative pressure differences.

Cranial venous sinus dominance: what to expect? Analysis of 100 cerebral angiographies

Methods

Data of 100 cerebral angiographies were retrospectively analyzed (p = 0.05).

Results

Mean age was 56.3 years, 62% female and 38% male. Measurements and dominance are shown in the Tables. There was no association between age or gender and dominance. Right parasagittal division of the superior sagittal sinus was associated with right dominance of the transverse sinus, sigmoid sinus and internal jugular vein; and left parasagittal division of the superior sagittal sinus was associated with left dominance of the transverse sinus, sigmoid sinus and internal jugular vein.

Conclusion

A dominance pattern of cranial venous sinuses was found. Age and gender did not influence this pattern. Angiographic findings, such as division of the superior sagittal sinus, were associated with a pattern of cranial venous dominance. We hope this article can add information and assist in preoperative venous analysis for neurosurgeons and neuroradiologists.

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.

Extraordinary cerebral venous drainage pathway with mastoid emissary and posterior external jugular veins detected by contrast-enhanced neck computed tomography

An extraordinary cerebral venous drainage pathway and dilated vein at the left posterior cervical region were detected with routine contrast-enhanced neck computed tomography exam. The left sigmoid sinus was drained by dilated mastoid emissary vein (MEV). The MEV continued as posterior auricular and posterior external jugular veins (PEJVs). The left PEJV directly drained into subclavian vein. Atretic right transverse sinus, left facial vein forming the external jugular vein, atresia and hypoplasia of upper internal jugular veins at the right and left sides, respectively, were the other uncommon findings in our case. Detecting venous variations may prevent complications during surgical and interventional procedures, so the radiologists should examine the superficial cervical veins closely.