Relation between bilateral differences in internal jugular vein caliber and flow patterns of dural venous sinuses

Quantification of the Dynamics of the Vascular Flows in the Cerebral Arterial and Venous Trees

Objective: Cerebral vascularization is made of the symmetrical arterial system, with muscular walls, and the venous system, more variable and dominated by sinuses and jugular veins. Factors like age and posture influence this network, complicating its study. Phase-contrast MRI is the gold standard for quantifying cerebral circulation. This study aimed to quantify the dynamics of the cerebral blood system using PC-MRI. Materials and Methods: Thirty-six healthy adults participated. Imaging was performed on a 3T MRI (Philips Achieva) in a supine position. Two slices were acquired: intracranial and extracranial. In-house software analyzed flow curves over a cardiac cycle. Each vessel's contribution was evaluated. Results: Extracranial venous drainage was categorized as jugular-dominant, equivalent, or peripheral-dominant. A similar classification applied intracranially. Intracranial flows showed low variability (5-9%), while extracranial venous flows, especially in the internal jugular veins, had higher variability (17-21%). Some extracranial veins were absent. Conclusions: There is significant venous heterogeneity in the extracranial region. PC-MRI enables the quantification of cerebral dynamics.

Phase-contrast MRI analysis of cerebral blood and CSF flow dynamic interactions

BACKGROUND

Following the Monro-Kellie doctrine, the Cerebral Blood Volume Changes (CB_VC) should be mirrored by the Cerebrospinal Fluid Volume Changes (CSF_VC) at the spinal canal. Cervical level is often chosen to estimate CB_VC during the cardiac cycle. However, due to the heterogeneity in the anatomy of extracranial internal jugular veins and their high compliance, we hypothesize that the intracranial level could be a better choice to investigate blood and cerebrospinal fluid (CSF) interactions. This study aims to determine which level, intracranial or extracranial, is more suitable for measuring arterial and venous flows to study cerebral blood and CSF dynamics interactions.

METHODS

The spinal CSF and cerebral blood flow measured at intracranial and extracranial levels were quantified using cine phase-contrast magnetic resonance imaging (PC-MRI) in 38 healthy young adults. Subsequently, CSF_VC and CB_VC were calculated, and by linear regression analysis (R2 and slope), the relationship between CB_VC at both levels and the spinal CSF_VC was compared. The differences between extracranial and intracranial measurements were assessed using either a paired Student's t-test or Wilcoxon's test, depending on the normality of the data distribution.

RESULTS

The CB_VC amplitude was significantly higher at the extracranial level (0.89 ± 0.28 ml/CC) compared to the intracranial level (0.73 ± 0.19 ml/CC; p < 0.001). CSF oscillations through the spinal canal do not completely balance blood volume changes. The R2 and the slope values obtained from the linear regression analysis between CSF and blood flows were significantly higher in magnitude for the intracranial CB_VC (R2: 0.82 ± 0.16; slope: - 0.74 ± 0.19) compared to the extracranial CB_VC (R2: 0.47 ± 0.37; slope: -0.36 ± 0.33; p < 0.001). Interestingly, extracranial CB_VC showed a greater variability compared to intracranial CB_VC.

CONCLUSION

Our results confirmed that CSF does not completely and instantaneously balance cerebral blood expansion during the cardiac cycle. Nevertheless, the resting volume is very small compared to the total intracranial volume. To our knowledge, this study is the first to demonstrate these findings using cerebral blood flow measured intracranially below the Circle of Willis. Additionally, our findings show that cerebral arterial and venous flow dynamic measurements during the cardiac cycle obtained by PC-MRI at the intracranial plane strongly correlate with CSF oscillations measured in the spinal canal. Therefore, the intracranial vascular plane is more relevant for analyzing cerebral blood and CSF interactions during the cardiac cycle compared to measurements taken at the cervical vascular level.

Enlarged Perivascular Space in the Basal Ganglia is Associated with Cerebral Venous Reflux in Patients with Recent Small Subcortical Infarction

BACKGROUND

Research has linked enlarged perivascular spaces (EPVS) to cerebral venous reflux (CVR) in patients with hypertensive intracerebral hemorrhage, but it is unclear whether this association exists in recent small subcortical infarct (RSSI) patients.

OBJECTIVE

This study aimed to investigate the correlation between EPVS and CVR in patients with RSSI.

METHOD

This study included 297 patients, selected from patients with RSSI in the lenticulostriate artery admitted to the Department of Neurology of the First Affiliated Hospital of Zhengzhou University. CVR was assessed by time-of-flight magnetic resonance angiography (TOF-MRA). The relationship between EPVS and CVR was studied using multiple logistic regression analysis.

RESULTS

This study included patients with an average age of 59.84±12.27 years, including 201 males (67.7%). CVR was observed in 40 (13.5%) patients. Compared to the group without CVR, the proportions of male patients and patients with a history of smoking and drinking were higher in the CVR group. The proportions of high-grade EPVS in the centrum semiovale region [23 cases (57.5%) vs. 108 cases (42.0%), p =0.067] and the basal ganglia region [30 cases (75.0%) vs. 133 cases (51.8%), p =0.006] were higher in the CVR group. After multiple logistic regression analysis, high-grade EPVS in the basal ganglia region was still associated with CVR (OR, 2.68; 95% CI, 1.22-5.87;p=0.014).

CONCLUSION

In the population with RSSI, EPVS in basal ganglia is significantly associated with CVR, suggesting a close relationship between venous dysfunction and the formation of EPVS.

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.

Can occipital lobe bending, Gibraltar sign of superior sagittal sinus groove and jugular foramen dimensions predict transverse sinus dominance?

BACKGROUND

Asymmetry between the transverse sinuses (TS) is quite common. We sought to test the possible hypothesis that certain anatomical features - namely, occipital lobe bending, Gibraltar sign of superior sagittal sinus groove (SSS) and jugular foramen (JF) dimensions - can predict dominance of the transverse sinuses on routine axial T1- and T2-weighted images.

MATERIALS AND METHODS

One hundred consecutively acquired combined MRI-MRV studies of brain were reviewed. On non-contrast axial T1WI, each reviewer assessed the occipital lobe bending, and Gibraltar sign of SSS groove; on axial T2-weighted images, JF dimensions were measured. TS cross-sectional area was measured on non-contrast sagittal 2-dimensional phase contrast MRV images and served as the reference standard.

RESULTS

Of the 51 subjects with right-dominant TS, 37 had occipital bending to the right side and 35 showed sloping of the Gibraltar sign to right side. Of the 18 subjects with left dominant TS, 10 had occipital bending to left side and 13 showed left-sided sloping of the Gibraltar sign. Of the 31 subjects with co-dominant TS, 15 had no occipital bending and 20 showed no sloping of the Gibraltar sign. Mean right and left JF dimensions were higher in the right and left dominant TS respectively with no significant differences in patients with co-dominant sinus (p < 0.02).

CONCLUSION

Right occipital bending had a good association with right TS dominance. The other two parameters- Gibraltar sign of superior sagittal sinus groove and jugular foramen dimensions - did not have a very good association with respect to TS dominance.

Gravitational effects on carotid and jugular characteristics in graded head-up and head-down tilt

Altered gravity affects hemodynamics and blood flow in the neck. At least one incidence of jugular venous thrombosis has been reported in an astronaut on the International Space Station. This investigation explores the impact of changes in the direction of the gravitational vector on the characteristics of the neck arteries and veins. Twelve subjects underwent graded tilt from 45° head-up to 45° head-down in 15° increments in both supine and prone positions. At each angle, the cross-sectional area of the left and right common carotid arteries (ACCA) and internal jugular veins (AIJV) were measured by ultrasound. Internal jugular venous pressure (IJVP) was also measured by compression sonography. Gravitational dose-response curves were generated from experimental data. ACCA did not show any gravitational dependence. Conversely, both AIJV and IJVP increased in a nonlinear fashion with head-down tilt. AIJV was significantly larger on the right side than the left side at all tilt angles. In addition, IJVP was significantly elevated in the prone position compared with the supine position, most likely because of raised intrathoracic pressure while prone. Dose-response curves were compared with existing experimental data from parabolic flight and spaceflight studies, showing good agreement on an acute timescale. The quantification of jugular hemodynamics as a function of changes in the gravitational vector presented here provides a terrestrial model to reference spaceflight-induced changes, contributes to the assessment of the pathogenesis of spaceflight venous thromboembolism events, and informs the development of countermeasures.NEW & NOTEWORTHY Flow stasis and thrombosis have been identified in the jugular vein during spaceflight. We measured the area and pressure of the internal jugular vein and the area of the common carotid artery in graded head-up and head-down tilt. Experimental data are used to generate gravitational dose-response curves for the measured variables, demonstrating that jugular vein area and pressure exhibit a nonlinear response to altered gravity. Gravitational dose-response curves show good agreement with spaceflight and parabolic flight studies.

Henle Fiber Layer Hemorrhage in Macular Telangiectasia Type 2: Is Right Eye Dominance Coincidence or Consequence?

PURPOSE

To summarize all reported cases of Henle fiber layer (HFL) hemorrhage in the absence of subretinal neovascularization (SRNV) in patients with macular telangiectasia type 2 (MacTel2) and to propose a mechanism for the right-sided predominance of this unique presentation.

DESIGN

Perspective.

METHODS

Collection, review, and analysis of all cases in the literature and in the authors' databases of HFL hemorrhage in MacTel2, including analysis of baseline and follow-up multimodal retinal imaging findings of selected cases. Elucidation of the complex interplay of systemic venous pressure with the deep retinal capillary plexus and hypothesis regarding the right-sided predilection of HFL hemorrhage complicating MacTel2.

RESULTS

Ten patients presented with a unilateral, characteristic radial macular hemorrhage within the HFL that affected only the right eye in all cases. Absence of SRNV was confirmed by fluorescein angiography and/or optical coherence tomography angiography. The hemorrhage resolved spontaneously in at least 7 of the 10 eyes. The HFL hemorrhage may plausibly be explained by dysfunction of the deep capillary plexus in MacTel2 combined with an acute rise in central venous pressure, for which the right side may be at increased risk.

CONCLUSIONS

HFL hemorrhage can complicate MacTel2 in the absence of SRNV, and the radial pattern of blood affecting only the right eye is remarkable. The right eye predominance may be multifactorial in etiology. Related factors may include the right-sided predilection of MacTel2 and/or increased right-sided dural sinus drainage related to normal anatomical variation.

The Right Internal Jugular at the Cricoid Cartilage Level May Represent the Optimal Central Vein Puncture Site in Pediatric Patients

OBJECTIVE

Internal jugular vein puncture or cannulation is far more difficult in children compared with adults. Anthropometric measures of the internal jugular vein acquired by two-dimensional ultrasound are useful in the practice of puncture and catheterization. The aim of this study is to measure anthropometric parameters of bilateral internal jugular veins in children and to determine the best puncture site based on these parameters.

MATERIALS

A total of 107 pediatric patients undergoing elective operation were included. Ultrasound-visible evaluation of bilateral internal jugular veins was used to obtain the depth from skin, maximum antero-posterior diameter, and cross-sectional area at the levels of the superior border of thyroid cartilage and cricoid cartilage. Statistical analysis was performed using these anthropometric data and demographic variables of all studied pediatric patients, such as age, height, and weight.

RESULTS

A very weak correlation was noted between the depth, maximal antero-posterior diameter, and cross-sectional area of both internal jugular veins and the age, height, weight, and body surface index of all included children. All Pearson's R correlation coefficients were <0.45. The largest diameter and cross-sectional area were in the right internal jugular vein at the cricoid cartilage level (p < 0.01) followed by the left internal jugular vein at this level (p < 0.01). In addition, the internal jugular vein at the cricoid cartilage level was more superficial than that of the superior border of the thyroid cartilage (p < 0.01).

CONCLUSION

The right internal jugular vein at the cricoid cartilage level is the best site for puncture. The most appropriate alternative site is the left internal jugular vein on the same level. Better correlation was not observed between the anthropometric parameters of the internal jugular vein and children's biological characteristics. This finding should be confirmed in a larger-scale demographical study in the future.

Vascular effects on the BOLD response and the retinotopic mapping of hV4

Despite general acceptance that the retinotopic organisation of human V4 (hV4) takes the form of a single, uninterrupted ventral hemifield, measured retinotopic maps of this visual area are often incomplete. Here, we test hypotheses that artefact from draining veins close to hV4 cause inverted BOLD responses that may serve to obscure a portion of the lower visual quarterfield—including the lower vertical meridian—in some hemispheres. We further test whether correcting such responses can restore the ‘missing’ retinotopic coverage in hV4. Subjects (N = 10) viewed bowtie, ring, drifting bar and full field flash stimuli. Functional EPIs were acquired over approximately 1.5h and analysed to reveal retinotopic maps of early visual cortex, including hV4. Normalised mean maps (which show the average EPI signal amplitude) were constructed by voxel-wise averaging of the EPI time course and used to locate venous eclipses, which can be identified by a decrease in the EPI signal caused by deoxygenated blood. Inverted responses are shown to cluster in these regions and correcting these responses improves maps of hV4 in some hemispheres, including restoring a complete hemifield map in one. A leftwards bias was found whereby 6/10 left hemisphere hV4 maps were incomplete, while this was the case in only 1/10 right hemisphere maps. Incomplete hV4 maps did not correspond with venous artefact in every instance, with incomplete maps being present in the absence of a venous eclipse and complete maps coexisting with a proximate venous eclipse. We also show that mean maps of upper surfaces (near the boundary between cortical grey matter and CSF) provide highly detailed maps of veins on the cortical surface. Results suggest that venous eclipses and inverted voxels can explain some incomplete hV4 maps, but cannot explain the remainder nor the leftwards bias in hV4 coverage reported here.

Occipital petalia as a predictive imaging sign for transverse sinus dominance

OBJECTIVES

Occipital petalia is an anatomic description where one of the occipital lobes protrudes towards the contralateral side. Transverse sinus (TS) asymmetry might cause diagnostic challenges with regards to thrombotic or compressive pathologies involving these sinuses. In this study, we investigated the association between occipital petalia and TS hypoplasia on MRI studies.

METHODS

In 264 subjects with no neurological complaints, occipital bending was determined on T1-weighted images based on the angulation of interhemispheric fissure between occipital lobes with respect to an imaginary midline. TS asymmetry was evaluated visually. Information on handedness and ocular dominance was also gathered from all participants.

RESULTS

Rightwards bending was observed in 72 subjects (27%), whereas leftwards bending was present in only 10 participants (4%). The presence or direction of bending was related neither to hand nor ocular dominance. In participants with rightwards bending, 72% had a larger TS on the right-side, while only a single subject had a left-sided predilection for venous drainage. In subjects with leftwards bending, 70% had a left-dominant TS drainage system and none had a larger TS on the right. Overall, the direction of bending was predictive of TS dominance on the ipsilateral side with a PPV of 72% (95%CI, 60-82%) for right and 70% (95%CI, 35-92%) for left.

DISCUSSION

The direction of bending, a relatively straightforward radiologic diagnosis, is closely linked to the side of TS hypoplasia, and thereby might provide physicians with an additional diagnostic clue regarding the interpretation of imaging findings related to TSs and their pathologies.

Surgical review of the anatomical variations of the internal jugular vein: an update for head and neck surgeons

BACKGROUND

The internal jugular vein is one of the major vessels of the neck. The anatomy of this vessel is considered to be relatively stable. It is an important landmark for head and neck surgeons as well as the anaesthetists for both diagnostic and therapeutic purposes.

METHODS

We present two case reports of the posterior tributary of the internal jugular vein and review the surgical literature regarding anatomical variations of the vein.

FINDINGS

A total of 1197 patients from 27 published papers were included in this review. Of these patients, 99.6% had neck surgery and the rest were cadaveric dissections. Anatomical variations of the internal jugular vein were found in 2% of the patient cohort (n = 40). The majority of these patients had either bifurcation or fenestration of the vein. The posterior tributary of the internal jugular vein is unusual and is scarcely reported in the literature (three cases). Knowledge of variations in the anatomy of the internal jugular vein assists surgeons in avoiding complications during neck surgery and preventing morbidity. Two rare cases of posterior branching of the internal jugular vein and experience of other surgeons are demonstrated in this extensive review.

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

Ultrasound diagnosis of transverse sinus hypoplasia using flow profiles of the internal jugular vein

Accurate diagnosis of subtypes of transverse sinus (TS) hypoplasia requires more expensive methods like magnetic resonance (MR) imaging. We hypothesized ultrasound findings of the internal jugular vein (IJV) can be surrogate indicators for diagnosis of TS hypoplasia. MR images were reviewed in 131 subjects to evaluate TS diameter and the location and degree of venous flow stenosis and obstruction. Ultrasound parameters including the cross-sectional lumen area (CSA), time-average-mean velocity (TAMV), and flow volume (FV) at each IJV segment were also evaluated. Sixty-nine subjects had TS hypoplasia based on MRV criteria, of which 39 TS hypoplasia were considered a subtype of TS hypoplasia, which is secondary to the downstream venous compression/stenosis or left brachiocephalic vein. In the ultrasound study, the CSA of the IJV ipsilateral to TS hypoplasia was significantly smaller. Further, a contralateral/ipsilateral IJV CSA ratio >1.55 provided good sensitivity, specificity, and positive predictive value for discriminating TS hypoplasia.

Intrapetrous Anastomosis between the Internal Jugular Vein and the Superior Petrosal Sinus: Cone Beam Computed Tomography Incidental Finding

This is a case report of a 62-year-old male who presented to the Ear, Nose, and Throat clinic for a follow-up exam for hearing loss stemming from a fall from a horse in his infancy. A Cone Beam Computed Tomography (CBCT) examination revealed an intrapetrous communication between the internal jugular vein bulb and the superior petrosal sinus. Three-dimensional bone and soft tissues volume renderings were generated to demonstrate this incidental anatomical variant.

An anatomy-based lumped parameter model of cerebrospinal venous circulation: can an extracranial anatomical change impact intracranial hemodynamics?

BACKGROUND

The relationship between extracranial venous system abnormalities and central nervous system disorders has been recently theorized. In this paper we delve into this hypothesis by modeling the venous drainage in brain and spinal column areas and simulating the intracranial flow changes due to extracranial morphological stenoses.

METHODS

A lumped parameter model of the cerebro-spinal venous drainage was created based on anatomical knowledge and vessels diameters and lengths taken from literature. Each vein was modeled as a hydraulic resistance, calculated through Poiseuille's law. The inputs of the model were arterial flow rates of the intracranial, vertebral and lumbar districts. The effects of the obstruction of the main venous outflows were simulated. A database comprising 112 Multiple Sclerosis patients (Male/Female = 42/70; median age ± standard deviation = 43.7 ± 10.5 years) was retrospectively analyzed.

RESULTS

The flow rate of the main veins estimated with the model was similar to the measures of 21 healthy controls (Male/Female = 10/11; mean age ± standard deviation = 31 ± 11 years), obtained with a 1.5 T Magnetic Resonance scanner. The intracranial reflux topography predicted with the model in cases of internal jugular vein diameter reduction was similar to those observed in the patients with internal jugular vein obstacles.

CONCLUSIONS

The proposed model can predict physiological and pathological behaviors with good fidelity. Despite the simplifications introduced in cerebrospinal venous circulation modeling, the key anatomical feature of the lumped parameter model allowed for a detailed analysis of the consequences of extracranial venous impairments on intracranial pressure and hemodynamics.