Potential involvement of the extracranial venous system in central nervous system disorders and aging

Cerebral venous congestion alters CNS homeostatic plasticity, evoking tinnitus-like behavior

BACKGROUND

Brain function and neuronal activity depend on a constant supply of blood from the cerebral circulation. The cerebral venous system (CVS) contains approximately 70% of the total cerebral blood volume; similar to the cerebral arterial system, the CVS plays a prominent role in the maintenance of central nervous system (CNS) homeostasis. Impaired venous autoregulation, which can appear in forms such as cerebral venous congestion, may lead to metabolic abnormalities in the brain, causing severe cerebral functional defects and even chronic tinnitus. However, the role of cerebral venous congestion in the progression of tinnitus is underrecognized, and its pathophysiology is still incompletely understood. This study elucidated the specific pathogenetic role of cerebral venous congestion in the onset and persistence of tinnitus and the possible neurophysiological mechanisms.

RESULTS

We found that a rat model of cerebral venous congestion exhibited tinnitus-like behavioral manifestations at 14 days postoperatively; from that point onward, they showed signs of persistent tinnitus without significant hearing impairment. Subsequent neuroimaging and neurochemical findings showed CNS homeostatic plasticity disturbance in rats with cerebral venous congestion, reflected in increased neural metabolic activity, ultrastructural synaptic changes, upregulated synaptic efficacy, reduced inhibitory synaptic transmission (due to GABA deficiency), and elevated expression of neuroplasticity-related proteins in central auditory and extra-auditory pathways.

CONCLUSION

Collectively, our data suggest that alternations in CNS homeostatic plasticity may play a vital role in tinnitus pathology caused by cerebral venous congestion. These findings provide a new perspective on tinnitus related to cerebral venous congestion and may facilitate the development of precise interventions to interrupt its pathogenesis.

Extreme lateral infracondylar approach for internal jugular vein compression syndrome: A case series with preliminary clinical outcomes

BACKGROUND AND OBJECTIVES

Internal jugular vein (IJV) stenosis is associated with several neurological disorders including idiopathic intracranial hypertension (IIH) and pulsatile tinnitus. In cases of extreme bony compression causing stenosis in the infracondylar region, surgical decompression might be necessary. We aim to examine the safety and efficacy of surgical IJV decompression.

METHODS

We retrospectively reviewed patients who received surgical IJV decompression via the extreme lateral infracondylar (ELI) approach between July 2020 and February 2022.

RESULTS

Fourteen patients with IJV stenosis were identified, all with persistent headache and/or tinnitus. Six patients were diagnosed with IIH, three of whom failed previous treatment. Of the eight remaining patients, two failed previous treatment. All underwent surgical IJV decompression via styloidectomy, release of soft tissue, and removal of the C1 transverse process (TP). Follow-up imaging showed significant improvement of IJV stenosis in eleven patients and mild improvement in three. Eight patients had significant improvement in their presenting symptoms, and three had partial improvement. Two patients received IJV stenting after a lack of initial improvement. Two patients experienced cranial nerve paresis, and one developed a superficial wound infection.

CONCLUSION

The ELI approach for IJV decompression appears to be safe for patients who are not ideal endovascular candidates due to bony anatomy. Confirming long-term efficacy in relieving debilitating clinical symptoms requires longer follow-up and a larger patient cohort. Carefully selected patients with symptomatic bony IJV compression for whom there are no effective medical or endovascular options may benefit from surgical IJV decompression.

Cerebral venous congestion alters brain metabolite profiles, impairing cognitive function

Vascular cognitive impairment (VCI) represents the second most common cause of dementia after Alzheimer's disease, and pathological changes in cerebral vascular structure and function are pivotal causes of VCI. Cognitive impairment caused by arterial ischemia has been extensively studied the whole time; the influence of cerebral venous congestion on cognitive impairment draws doctors' attention in recent clinical practice, but the underlying neuropathophysiological alterations are not completely understood. This study elucidated the specific pathogenetic role of cerebral venous congestion in cognitive-behavioral deterioration and possible electrophysiological mechanisms. Using cerebral venous congestion rat models, we found these rats exhibited decreased long-term potentiation (LTP) in the hippocampal dentate gyrus and impaired spatial learning and memory. Based on untargeted metabolomics, N-acetyl-L-cysteine (NAC) deficiency was detected in cerebral venous congestion rats; supplementation with NAC appeared to ameliorate synaptic deficits, rescue impaired LTP, and mitigate cognitive impairment. In a cohort of cerebral venous congestion patients, NAC levels were decreased; NAC concentration was negatively correlated with subjective cognitive decline (SCD) score but positively correlated with mini-mental state examination (MMSE) score. These findings provide a new perspective on cognitive impairment and support further exploration of NAC as a therapeutic target for the prevention and treatment of VCI.

Long-term safety and efficacy of stenting on correcting internal jugular vein and cerebral venous sinus stenosis

OBJECTIVES

To compare the long-term safety and efficacy of stenting in correcting cerebral venous sinus stenosis (CVSS) and internal jugular venous stenosis (IJVS).

METHODS

Patients confirmed with CVSS or IJVS by imaging were enrolled in this real-world study from 2014 through 2021. Clinical characteristics and long-term outcomes of these two diseases entities post-stenting were followed up and compared.

RESULTS

Three hundred and nineteen patients were enrolled in this study, with a mean age of 48.83 years and a BMI of 25.08 on average. In which, 144 patients underwent stenting, the stenotic segments were corrected and the venous blood flow was restored immediately post-stenting. At 6.15 ± 1.67 days follow-up, significant improvement was observed in headache, tinnitus, insomnia, ICP, and mean pressure gradient in both groups (all p < 0.05). At 30.53 ± 4.41 months follow-up post-stenting, the headache, tinnitus, visual loss, papilledema, and insomnia were attenuated remarkably or even completely disappeared. The Frisen papilledema grade scores declined from 2 (0-4) to 1 (0-3) in IJVS group and from 4 (1-5) to 1 (0-4) in CVSS group compared to the baseline. One hundred and twenty-seven out of the 144 patients (95.5%) maintained sufficient blood flow verified by followed up computed tomographic venography or contrast-enhanced magnetic resonance angiography. Adverse events related to stenting included three cases of intraluminal restenosis and three cases of in-stent thrombosis, no intracranial hemorrhage, venous thromboembolisms, stent-adjacent stenosis, and stent displacement occurred.

INTERPRETATION

Using stents to correct IH and related neurological issues has shown to be a safe and effective approach for both IJVS and CVSS.

Whether jugular venous reflux relates to more serious ischemic white matter lesions?

OBJECTIVE

To evaluate whether jugular venous reflux (JVR) relates to more serious ischemic white matter lesions (WMLs).

PATIENTS AND METHODS

Fifty cases were enrolled and divided into absent to mild ischemic WMLs group and moderate to severe ischemic WMLs group. Then the univariate and multivariate analyses were conducted to evaluate the relationship between JVR and moderate to severe ischemic WMLs, and a receiver operating characteristic (ROC) curve was used to evaluate the predictive value of JVR for moderate to severe ischemic WMLs.

RESULTS

There were 28 patients in the absent to mild ischemic WMLs group and 22 patients in the moderate to severe ischemic WMLs group. There was no significant difference between the two groups in gender, blood lipid indexes, proportions of diabetes, and abnormal deep cerebral veins (all p > 0.05). However, compared with the absent to mild ischemic WMLs group, the moderate to severe ischemic WMLs group was older and had a higher proportion of hypertension and JVR (p = 0.005; p < 0.001; p < 0.001, respectively). Multivariate logistic regression analysis showed that JVR was an independent risk factor for moderate to severe ischemic WMLs (OR = 17.679, 95 % CI: 3.056-102.286, p = 0.001). Furthermore, the area under curve of JVR combined with hypertension was 0.912 (p < 0.001), and the specificity of predicting moderate to severe ischemic WMLs was 92.9 %.

CONCLUSION

Our study suggested that JVR might relate to more severe ischemic WMLs.

Results of Numerical Modeling of Blood Flow in the Internal Jugular Vein Exhibiting Different Types of Strictures

The clinical relevance of nozzle-like strictures in upper parts of the internal jugular veins remains unclear. This study was aimed at understanding flow disturbances caused by such stenoses. Computational fluid dynamics software, COMSOL Multiphysics, was used. Two-dimensional computational domain involved stenosis at the beginning of modeled veins, and a flexible valve downstream. The material of the venous valve was considered to be hyperelastic. In the vein models with symmetric 2-leaflets valve without upstream stenosis or with minor 30% stenosis, the flow was undisturbed. In the case of major 60% and 75% upstream stenosis, centerline velocity was positioned asymmetrically, and areas of reverse flow and flow separation developed. In the 2-leaflet models with major stenosis, vortices evoking flow asymmetry were present for the entire course of the model, while the valve leaflets were distorted by asymmetric flow. Our computational fluid dynamics modeling suggests that an impaired outflow from the brain through the internal jugular veins is likely to be primarily caused by pathological strictures in their upper parts. In addition, the jugular valve pathology can be exacerbated by strictures located in the upper segments of these veins.

Cerebral venous congestion exacerbates cerebral microhemorrhages in mice

Cerebral microhemorrhages (CMHs; microbleeds), which are small focal intracerebral hemorrhages, importantly contribute to the pathogenesis of cognitive decline and dementia in older adults. Although recently it has been increasingly recognized that the venous side of the cerebral circulation likely plays a fundamental role in the pathogenesis of a wide spectrum of cerebrovascular and brain disorders, its role in the pathogenesis of CMHs has never been studied. The present study was designed to experimentally test the hypothesis that venous congestion can exacerbate the genesis of CMHs. Increased cerebral venous pressure was induced by internal and external jugular vein ligation (JVL) in C57BL/6 mice in which systemic hypertension was induced by treatment with angiotensin II plus L-NAME. Histological analysis (diaminobenzidine staining) showed that mice with JVL developed multiple CMHs. CMHs in mice with JVL were often localized adjacent to veins and venules and their morphology was consistent with venous origin of the bleeds. In brains of mice with JVL, a higher total count of CMHs was observed compared to control mice. CMHs were distributed widely in the brain of mice with JVL, including the cortical gray matter, brain stem, the basal ganglia, subcortical white matter, cerebellum, and the hippocampi. In mice with JVL, there were more CMHs predominantly in cerebral cortex, brain stem, and cerebellum than in control mice. CMH burden, defined as total CMH volume, also significantly increased in mice with JVL. Thus, cerebral venous congestion can exacerbate CMHs. These observations have relevance to the pathogenesis of cognitive impairment associated with right heart failure as well as elevated cerebral venous pressure due to jugular venous reflux in older adults.

Combination of Genomic and Transcriptomic Approaches Highlights Vascular and Circadian Clock Components in Multiple Sclerosis

Aiming at exploring vascular components in multiple sclerosis (MS) with brain outflow disturbance, we combined transcriptome analysis in MS internal jugular vein (IJV) wall with WES in MS families with vertical transmission of disease. Main results were the differential expression in IJV wall of 16 MS-GWAS genes and of seven genes (GRIN2A, GRIN2B, IL20RB, IL26, PER3, PITX2, and PPARGC1A) not previously indicated by GWAS but encoding for proteins functionally interacting with MS candidate gene products. Strikingly, 22/23 genes have been previously associated with vascular or neuronal traits/diseases, nine encoded for transcriptional factors/regulators and six (CAMK2G, GRIN2A, GRIN2B, N1RD1, PER3, PPARGC1A) for circadian entrainment/rhythm components. Among the WES low-frequency (MAF ≤ 0.04) SNPs (n = 7) filtered in the 16 genes, the NR1D1 rs17616365 showed significantly different MAF in the Network for Italian Genomes affected cohort than in the 1000 Genome Project Tuscany samples. This pattern was also detected in five nonintronic variants (GRIN2B rs1805482, PER3 rs2640909, PPARGC1A rs2970847, rs8192678, and rs3755863) in genes coding for functional partners. Overall, the study proposes specific markers and low-frequency variants that might help (i) to understand perturbed biological processes in vascular tissues contributing to MS disease, and (ii) to characterize MS susceptibility genes for functional association with disease-pathways.

The aging venous system: from varicosities to vascular cognitive impairment

Aging-induced pathological alterations of the circulatory system play a critical role in morbidity and mortality of older adults. While the importance of cellular and molecular mechanisms of arterial aging for increased cardiovascular risk in older adults is increasingly appreciated, aging processes of veins are much less studied and understood than those of arteries. In this review, age-related cellular and morphological alterations in the venous system are presented. Similarities and dissimilarities between arterial and venous aging are highlighted, and shared molecular mechanisms of arterial and venous aging are considered. The pathogenesis of venous diseases affecting older adults, including varicose veins, chronic venous insufficiency, and deep vein thrombosis, is discussed, and the potential contribution of venous pathologies to the onset of vascular cognitive impairment and neurodegenerative diseases is emphasized. It is our hope that a greater appreciation of the cellular and molecular processes of vascular aging will stimulate further investigation into strategies aimed at preventing or retarding age-related venous pathologies.

Eye-Neck Integrated Ultrasound in Idiopathic Intracranial Hypertension and Cerebral Venous Sinus Thrombosis

Background: The clinical presentation of cerebral venous sinus thrombosis (CVST) overlaps with that of idiopathic intracranial hypertension (IIH), but no screening tool exists. We investigated the role of eye-neck integrated ultrasound in the diagnosis and differentiation of IIH and CVST. Methods: Twenty IIH patients, 30 CVST patients, and 40 healthy controls were retrospectively analyzed. The ultrasonographic optic nerve sheath diameter (ONSD) and hemodynamic characteristics of the internal jugular veins (IJVs) were recorded. The cerebrospinal fluid opening pressure was measured after ultrasonic examination. Results: The ONSD was significantly larger in IIH patients than in controls (4.71 ± 0.41 vs. 3.93 ± 0.24 mm, p < 0.001). The ONSD cut-off for IIH diagnosis was 4.25 mm (AUC = 0.978; 95% CI: 0.95-1.0, p < 0.001, sensitivity: 90%, specificity: 93%). In the CVST group, 22 (73.3%) patients had elevated intracranial pressure (ICP); the mean ONSD was significantly higher in patients with increased ICP than in those without (4.43 ± 0.33 vs. 3.95 ± 0.17 mm, p < 0.001). The mean blood flow volume (BFV) was significantly reduced in CVST patients (425.17 ± 349.83 mL/min) compared to that in controls (680.37 ± 233.03 mL/min, p < 0.001) and IIH patients (617.67 ± 282.96 mL/min, p = 0.008). The optimal BFV cut-off for predicting CVST was 527.28 mL/min (AUC = 0.804, 95% CI: 0.68-0.93, p < 0.001, sensitivity: 80%, specificity: 78%). The velocity of the unilateral IJVs-J3 segment decreased or remained constant during deep inspiration (abnormal respiratory modulate blood flow test, ARMT) in 32.5% of controls, with no bilateral ARMT. The prevalence of bilateral ARMT was 25% in IIH patients (χ2 = 12.9, p = 0.005) and 27% in CVST patients (χ2 = 17.6, p = 0.001). Conclusion: Eye-neck integrated ultrasound is an easily available bedside technique to assess ICP and hemodynamic characteristics of IJVs. ONSD measurement can identify patients with increased ICP, and reduced IJV BFV may aid the differentiation of CVST and IIH.

The association between transthoracic echocardiogram parameters and white matter hyperintensities

OBJECTIVE

Identify abnormal cardiac chamber size and hemodynamic parameters on transthoracic echocardiogram (TTE) as predictors of advancing cerebral small vessel disease (CSVD) on brain magnetic resonance imaging (MRI).

MATERIALS AND METHODS

A retrospective chart review of adults with a brain MRI and a 2-dimensional TTE was performed. WMH measured by the Fazekas score served as the primary outcome. We fit multivariate ordinal logistic regression models to the Fazekas score with the individual predictors of the TTE measurements and adjusted for potential confounders.

RESULTS

132 individuals were included. Cardiac functional markers were not significant, including tricuspid annular plane systolic excursion (p = 0.818), right ventricular ejection fraction (p = 0.818) and left ventricular ejection fraction (p = 0.673). Cardiac structural markers included right atrial area (p = 0.247), right ventricular internal diameter (RVID, p = 0.020) and left atrial area (LAA, p = 0.041). RVID and LAA were identified as being predictors, although the direction of the association suggested that normal values resulted in more WMH. Analysis of isolated DWM or PVWM Fazekas scores were not associated with cardiac structure or function.

CONCLUSIONS

In our study, we found that normal LAA and RVID values were associated with an increased degree of WMH on MRI. This finding may represent earlier identification of WMH prior to TTE cardiac changes. Future studies are needed for more robust quantitative comparison as well as evaluation prospectively of the association between cardiac chamber sizes and development of WMH.

Numerical modeling of blood flow in the internal jugular vein with the use of computational fluid mechanics software

OBJECTIVES

To determine the site and nature of altered hemodynamics in pathological internal jugular veins.

METHOD

With the use of computational fluid mechanics software we simulated blood flow in 3 D models of the internal jugular veins that exhibited different morphologies, including nozzle-like strictures in their upper parts and valves in the lower parts.

RESULTS

In a majority of models with nozzle-like strictures, especially those positioned asymmetrically, abnormal flow pattern was revealed, with significant flow separation and regions with reversed flow. Abnormal valves had no significant impact on flow in a case of already altered flow evoked by stricture in upper part of the vein.

CONCLUSIONS

In our jugular model, cranially-located stenoses, which in clinical practice are primarily caused by external compression, cause more significant outflow impact respect to endoluminal defects and pathological valves located more caudally.

Pathogenesis and Management in Cerebrovenous Outflow Disorders

In keeping with its status as one of the major causes of disability and mortality worldwide, brain damage induced by cerebral arterial disease has been the subject of several decades of scientific investigation, which has resulted in a vastly improved understanding of its pathogenesis. Brain injury mediated by venous etiologies, however, such as cerebral, jugular, and vertebral venous outflow disturbance, have been largely ignored by clinicians. Unfortunately, this inattention is not proportional to the severity of cerebral venous diseases, as the impact they exact on the quality of life of affected patients may be no less than that of arterial diseases. This is evident in disease sequelae such as cerebral venous thrombosis (CVT)-mediated visual impairment, epilepsy, and intracranial hypertension; and the long-term unbearable head noise, tinnitus, headache, dizziness, sleeping disorder, and even severe intracranial hypertension induced by non-thrombotic cerebral venous sinus (CVS) stenosis and/or internal jugular venous (IJV) stenosis. In addition, the vertebral venous system (VVS), a large volume, valveless vascular network that stretches from the brain to the pelvis, provides a conduit for diffuse transmission of tumors, infections, or emboli, with potentially devastating clinical consequences. Moreover, the lack of specific features and focal neurologic signs seen with arterial etiologies render cerebral venous disease prone to both to misdiagnoses and missed diagnoses. It is therefore imperative that awareness be raised, and that as comprehensive an understanding as possible of these issues be cultivated. In this review, we attempt to facilitate these goals by systematically summarizing recent advances in the diagnosis and treatment of these entities, including CVT, CVS stenosis, and IJV stenosis, with the aim of providing a valid, practical reference for clinicians.

Normobaric Oxygen May Ameliorate Cerebral Venous Outflow Disturbance-Related Neurological Symptoms

Cerebral venous outflow disturbance (CVOD) has begun to garner the attention of researches owing to a series of clinical symptoms that impose a significant impact on people's quality of life. Herein, we aimed to investigate whether normobaric oxygen (NBO) can ameliorate CVOD-induced neurological symptoms. This was one part of the prospective trial registered in ClinicalTrials.gov (NCT03373292). A total of 37 CVOD patients were divided into the NBO group (5–8 L/min of oxygen inhalation, 1 h per time, 3 times daily, n = 19) and the control group (without oxygen inhalation, n = 18) randomly. The assessments were performed at admission, 1-week hospitalization, and 6-month follow-up. Quantitative electroencephalogram (qEEG) data were recorded prior to and post 1 h of NBO in some patients. R software was used for data analysis. No NBO-related adverse events were observed during the whole NBO intervention process. The 1-week Patient Global Impression of Change (PGIC) scale showed that the symptom improvement occurred in nine patients in the NBO group (47.4%) while none in the control group (p = 0.001). NBO could improve headache evaluated with visual analog scale (pre-NBO vs. post-NBO: 4.70 ± 2.16 vs. 2.90 ± 2.03, p = 0.024) and Headache Impact Test-6 (53.40 ± 12.15 vs. 50.30 ± 13.04, p = 0.041). As for 6-month PGIC follow-up, eight out of 14 cases (57.1%) in the NBO group reported improvement, while only one out of 12 patients in the control group replied mild improvement (p = 0.014). The qEEG revealed that NBO reduced the ratio of theta to alpha power (0.65 ± 0.38 vs. 0.56 ± 0.35, p = 0.030) over the fronto-central electrodes. To sum up, NBO may be a safe and effective approach to attenuate CVOD-related symptoms (especially for headache) by brain functional improvement resulting from increasing oxygen supply to the brain tissues.

Cerebral Venous Thrombosis: A Comprehensive Review

BACKGROUND

Cerebral sinus venous thrombosis (CSVT) is a relatively rare, potentially fatal neurological condition that can be frequently overlooked due to the vague nature of its clinical and radiological presentation. A literature search on PubMed using the keyword "Cerebral sinus venous thrombosis" was performed. We searched for the epidemiology, risk factors, pathophysiology, clinical features, diagnosis, and treatment of CSVT. All full-text articles in the last 10 years, in adults (>18 years), and the English language were included. We aim to give a comprehensive review of CSVT, with a primary focus on the management of the disease.

SUMMARY

The literature search revealed 404 articles that met our criteria. CSVT is a relatively rare condition that accounts for approximately 1% of all forms of stroke. They can be subdivided into acute, subacute, and chronic forms based on the time of onset of clinical symptoms. It is a multifactorial disease, and the major forms of clinical presentation include isolated intracranial hypertension syndrome, focal neurological deficits, and cavernous sinus syndrome. MRI with magnetic resonance venogram (MRV) is considered the gold standard for diagnosis. Anticoagulation with heparin or low-molecular-weight heparin is the mainstay of treatment. Endovascular management is indicated for those cases with severe symptoms or worsening of symptoms despite anticoagulation therapy. Favorable outcomes have been reported in patients who receive early diagnosis and treatment.

CONCLUSION

CSVT is a potentially fatal neurological condition that is often under-diagnosed due to its nonspecific presentation. Timely diagnosis and treatment can reduce morbidity and mortality, remarkably improving the outcome in affected individuals.

Venous and Arterial Responses to Partial Gravity

Introduction: Chronic exposure to the weightlessness-induced cephalad fluid shift is hypothesized to be a primary contributor to the development of spaceflight-associated neuro-ocular syndrome (SANS) and may be associated with an increased risk of venous thrombosis in the jugular vein. This study characterized the relationship between gravitational level (G_z-level) and acute vascular changes.

Methods: Internal jugular vein (IJV) cross-sectional area, inferior vena cava (IVC) diameter, and common carotid artery (CCA) flow were measured using ultrasound in nine subjects (5F, 4M) while seated when exposed to 1.00-G_z, 0.75-G_z, 0.50-G_z, and 0.25-G_z during parabolic flight and while supine before flight (0-G analog). Additionally, IJV flow patterns were characterized.

Results: IJV cross-sectional area progressively increased from 12 (95% CI: 9–16) mm² during 1.00-G_z seated to 24 (13–35), 34 (21–46), 68 (40–97), and 103 (75–131) mm² during 0.75-G_z, 0.50-G_z, and 0.25-G_z seated and 1.00-G_z supine, respectively. Also, IJV flow pattern shifted from the continuous forward flow observed during 1.00-G_z and 0.75-G_z seated to pulsatile flow during 0.50-G_z seated, 0.25-G_z seated, and 1.00-G_z supine. In contrast, we were unable to detect differences in IVC diameter measured during 1.00-G seated and any level of partial gravity or during 1.00-G_z supine. CCA blood flow during 1.00-G seated was significantly less than 0.75-G_z and 1.00-G_z supine but differences were not detected at partial gravity levels 0.50-G_z and 0.25-G_z.

Conclusions: Acute exposure to decreasing G_z-levels is associated with an expansion of the IJV and flow patterns that become similar to those observed in supine subjects and in astronauts during spaceflight. These data suggest that G_z-levels greater than 0.50-G_z may be required to reduce the weightlessness-induced headward fluid shift that may contribute to the risks of SANS and venous thrombosis during spaceflight.

Expression profiles of the internal jugular and saphenous veins: Focus on hemostasis genes

INTRODUCTION

Venous bed specificity could contribute to differential vulnerability to thrombus formation, and is potentially reflected in mRNA profiles.

MATERIALS AND METHODS

Microarray-based transcriptome analysis in wall and valve specimens from internal jugular (IJV) and saphenous (SV) veins collected during IJV surgical reconstruction in patients with impaired brain outflow. Multiplex antigenic assay in paired jugular and peripheral plasma samples.

RESULTS

Most of the top differentially expressed transcripts have been previously associated with both vascular and neurological disorders. Large expression differences of HOX genes, organ patterning regulators, pinpointed the vein positional identity. The "complement and coagulation cascade" emerged among enriched pathways. In IJV, upregulation of genes for coagulation inhibitors (TFPI, PROS1), activated protein C pathway receptors (THBD, PROCR), fibrinolysis activators (PLAT, PLAUR), and downregulation of the fibrinolysis inhibitor (SERPINE1) and of contact/amplification pathway genes (F11, F12), would be compatible with a thromboprotective profile in respect to SV. Further, in SV valve the prothrombinase complex genes (F5, F2) were up-regulated and the VWF showed the highest expression. Differential expression of several VWF regulators (ABO, ST3GAL4, SCARA5, CLEC4M) was also observed. Among other differentially expressed hemostasis-related genes, heparanase (HPSE)/heparanase inhibitor (HPSE2) were up-/down-regulated in IJV, which might support procoagulant features and disease conditions. The jugular plasma levels of several proteins, encoded by differentially expressed genes, were lower and highly correlated with peripheral levels.

CONCLUSIONS

The IJV and SV rely on differential expression of many hemostasis and hemostasis-related genes to balance local hemostasis, potentially related to differences in vulnerability to thrombosis.

Probable risk factors of internal jugular vein stenosis in Chinese patients-A real-world cohort study

OBJECTIVES

Extracranial venous anomalies, especially internal jugular vein stenosis (IJVS), have recently received increasing attention, however, its etiologies are uncertain. This study aimed to explore the probable risk factors of IJVS in Chinese PATIENTS AND METHODS: Eligible patients with IJVS confirmed by contrast-enhanced magnetic resonance venography (CE-MRV) were enrolled from October 2017 through October 2018. Probable risk factors were analyzed, including the conditions that may result in IJV wall damage, extraluminal compression, gender and age.

RESULTS

A total of 133 patients enrolled in the final analysis, including 73 females and 60 males, the mean age were 54.83 ± 15.25 years. In this IJVS cohort, the top two risks were previous hepatitis B virus (HBV) infection (48.9 %) and osseous compression (41.4 %). The IJVS cohort was divided into two subsets: extraluminal compression and non-compression. In the former, osseous compression (80.9 %) was the top risk factor, other risks including arterial (22.1 %) and lymph node compression (2.9 %). While, in the latter subset, the most common risk factor was previous HBV infection (46.2 %). In addition, cerebral venous sinus thrombosis (CVST) in non-compression subset was more common than that in extraluminal compression subset (21.5 % VS. 2.9 %, p = 0.001). When considered the gender (Male vs. Female), the ratios were 28.3 % vs. 0 % of smoking, p < 0.001, 16.67 % vs. 1.37 % of hyperhomocysteinemia, p = 0.002, and 11.67 % vs. 1.37 % of hyperuricemia, p = 0.023. In the subset with age less than 45 years, the top three risks included CVST (56.25 %), immunological diseases (55.56 %), and hyperhomocysteinemia (50.00 %), while, in the subset with the ages over 60 years, type-2 diabetes (66.66 %), carotid artery compression (53.33 %), previous HBV infection (52.31 %), and osseous compression (49.09 %) were more common than others.

CONCLUSION

This study illustrates the probable risks of IJVS may be diverse, in which osseous compression and previous HBV infection may be the top two probable risks of IJVS in Chinese. This is the biggest difference from previous reports based on Caucasian.

Probable factors affecting clinical outcomes of internal jugular vein stenosis

Background

Internal jugular vein stenosis (IJVS) has recently aroused increasing interests, whereas, the factors affecting its clinical outcomes are not clear. This study aims to explore the probable factors affected clinical prognosis by evaluating the IJVS with different etiologies and strategies.

Methods

Patients with IJVS confirmed by contrast-enhanced magnetic resonance venography (CE-MRV) were enrolled from October 2017 through October 2018. One-year clinical outcomes of the IJVS cases enrolled in this study were assessed by outpatient and telephone follow-up using the Patient Global Impression of Change (PGIC) scores. According to the etiologies, patients were divided into thrombotic IJVS and non-thrombotic IJVS groups. And further, non-thrombotic IJVS group was divided into external compression and non-external compression subgroups. Outcomes of IJVS with different etiologies and strategies were compared and the probable prognostic factors were analyzed.

Results

A total of 118 eligible patients enrolled in this study, including 76 females and 42 males, mean aged 55.07±14.61 years. The average follow-up duration after discharge was 13.22±3.80 months. According to the PGIC scores, we categorized patients as good outcome and poor outcome groups. For thrombotic IJVS, patients underwent standard anticoagulant obtained remarkable PGIC improvement (100.0% vs. 33.3%, P=0.038). For non-thrombotic IJVS, stenting showed benefit in non-external compression subgroup (26.9% vs. 3.3%, P=0.019) but not in external compression subgroup. In addition, we found that in this Chinese IJVS cohort, poor outcomes involved old age (P=0.004), type 2 diabetes mellitus (P=0.036), previous hepatitis B virus (HBV) infection (P=0.027), and head noises (P=0.002). Multivariate logistic regression analysis indicated that continuous head noises [P=0.045, odds ratio (OR): 2.412, 95% confidence interval (CI): 1.019-5.711], as a unique symptom of IJVS may be significantly related to poor outcomes.

Conclusions

In this Chinese cohort, elderly degenerative bone compression, type 2 diabetes mellitus, and previous HBV infection are the top-three probable etiologies of non-thrombotic IJVS and may involve poor outcome. Long-term head noises may predict IJVS and with poor outcome. Thrombosis-induced IJVS may get benefit from standard anticoagulation. Non-external compression IJVS can be corrected by stenting.

Blood-brain Barrier Disruption May Contribute to White Matter Lesions in the Setting of Internal Jugular Venous Stenosis

BACKGROUND AND PURPOSE

Cloudy white matter lesions are associated imaging features of internal jugular venous stenosis (IJVS). However, the mechanism of the IJVS associated cloudy white matter lesions is still unclear. This study aims to evaluate blood-brain barrier integrity of the patients with IJVS.

MATERIALS AND METHODS

A total of 45 eligible patients with IJVS confirmed by computed tomography venography (CTV) and 45 healthy controls were enrolled into this study. The levels of serum MMP-9 and the markers of tight junctions, including occludin and ZO-1 obtained from IJVS patients and control group were tested by enzyme-linked immune-sorbent assay and compared.

RESULTS

Both the levels of serum MMP-9 (0.2ng/ml) and occludin (0.05ng/ml) in IJVS group were higher than in the control group (0.01ng/ml vs. 0 ng/ml, all p<0.001). While, the levels of serum ZO-1 showed no statistical significance between the two groups (0.55ng/ml vs 0.735ng/ml, P=0.34). The levels of serum MMP-9 between the subset with or without white matter lesions in IJVS group showed a significant difference (0.22 [0.06, 0.43] vs. 0.01 [0.01, 0.06], P =0.019).

CONCLUSION

BBB disruption may participate in the formation of IJVS-associated white matter lesions; the mechanism of BBB disruption may involve MMP-9 and occludin.

Cerebral venous congestion promotes blood-brain barrier disruption and neuroinflammation, impairing cognitive function in mice

Cognitive impairment is one of the most common co-occurring chronic conditions among elderly heart failure patients (incidence: up to ~ 80%); however, the underlying mechanisms are not completely understood. It is hypothesized that in addition to decreased cardiac output, increases in central-and consequentially, cerebral-venous pressure (backward failure) also contribute significantly to the genesis of cognitive impairment. To test this hypothesis and elucidate the specific pathogenic role of venous congestion in the brain, we have established a novel model of increased cerebral venous pressure: mice with jugular vein ligation (JVL). To test the hypothesis that increased venous pressure in the brain contributes to the development of cognitive deficits by causing blood-brain barrier disruption, dysregulation of blood flow, and/or promoting neuroinflammation, in C57BL/6 mice, the internal and external jugular veins were ligated. Cognitive function (radial arm water maze), gait function (CatWalk), and motor coordination (rotarod) were tested post-JVL. Neurovascular coupling responses were assessed by measuring changes in cerebral blood flow in the whisker barrel cortex in response to contralateral whisker stimulation by laser speckle contrast imaging through a closed cranial window. Blood-brain barrier integrity (IgG extravasation) and microglia activation (Iba1 staining) were assessed in brain slices by immunohistochemistry. Neuroinflammation-related gene expression profile was assessed by a targeted qPCR array. After jugular vein ligation, mice exhibited impaired spatial learning and memory, altered motor coordination, and impaired gait function, mimicking important aspects of altered brain function observed in human heart failure patients. JVL did not alter neurovascular coupling responses. In the brains of mice with JVL, significant extravasation of IgG was detected, indicating blood-brain barrier disruption, which was associated with histological markers of neuroinflammation (increased presence of activated microglia) and a pro-inflammatory shift in gene expression profile. Thus, cerebral venous congestion per se can cause blood-brain barrier disruption and neuroinflammation, which likely contribute to the genesis of cognitive impairment. These findings have relevance to the pathogenesis of cognitive decline associated with heart failure as well as increased cerebal venous pressure due to increased jugular venous reflux in elderly human patients.

No association between variations in extracranial venous anatomy and clinical outcomes in multiple sclerosis patients over 5 years

Background

No longitudinal, long-term, follow-up studies have explored the association between presence and severity of variations in extracranial venous anatomy, and clinical outcomes in patients with multiple sclerosis (MS).

Objective

This prospective 5-year follow-up study assessed the relationship of variations in extracranial venous anatomy, indicative of chronic cerebrospinal venous insufficiency (CCSVI) on Doppler sonography, according to the International Society for Neurovascular Disease (ISNVD) proposed consensus criteria, with clinical outcomes and disease progression in MS patients.

Methods

90 MS patients (52 relapsing-remitting, RRMS and 38 secondary-progressive, SPMS) and 38 age- and sex-matched HIs were prospectively followed for 5.5 years. Extracranial and transcranial Doppler-based venous hemodynamic assessment was conducted at baseline and follow-up to determine the extent of variations in extracranial venous anatomy. Change in Expanded Disability Status Scale (∆EDSS), development of disability progression (DP) and annualized relapse rate (ARR) were assessed.

Results

No significant differences were observed in MS patients, based on their presence of variations in extracranial venous anatomy at baseline or at the follow-up, in ∆EDSS, development of DP or ARR. While more MS patients had ISNVD CCSVI criteria fulfilled at baseline compared to HIs (58% vs. 37%, p = 0.03), no differences were found at the 5-year follow-up (61% vs. 56%, p = 0.486).

Discussion

This is the longest follow-up study assessing the longitudinal relationship between the presence of variations in extracranial venous anatomy and clinical outcomes in MS patients. Conclusion: The presence of variations in extracranial venous anatomy does not influence clinical outcomes over the 5-year follow-up in MS patients.

Electronic supplementary material

The online version of this article (10.1186/s12883-019-1350-2) contains supplementary material, which is available to authorized users.

Cervical spondylotic internal jugular venous compression syndrome

Aims

This study aimed to identify the clinical profiles of cervical spondylosis‐related internal jugular vein stenosis (IJVS) comprehensively.

Methods

A total of 46 patients, who were diagnosed as IJVS induced by cervical spondylotic compression were recruited. The clinical manifestations and imaging features of IJVS were presented particularly in this study.

Results

Vascular stenosis was present in 69 out of the 92 internal jugular veins, in which, 50.7% (35/69) of the stenotic vessels were compressed by the transverse process of C1, and 44.9% (31/69) by the transverse process of C1 combined with the styloid process. The transverse process of C1 compression was more common in unilateral IJVS (69.6% vs 41.3%, P = 0.027) while the transverse process of C1 combined with the styloid process compression had a higher propensity to occur in bilateral IJVS (52.2% vs 30.4%, P = 0.087). A representative case underwent the resection of the elongated left lateral mass of C1 and styloid process. His symptoms were ameliorated obviously at 6‐month follow‐up.

Conclusions

This study proposes cervical spondylotic internal jugular venous compression syndrome as a brand‐new cervical spondylotic subtype. A better understanding of this disease entity can be of great relevance to clinicians in making a proper diagnosis.

Role of age-related alterations of the cerebral venous circulation in the pathogenesis of vascular cognitive impairment

There has been an increasing appreciation of the role of vascular contributions to cognitive impairment and dementia (VCID) associated with old age. Strong preclinical and translational evidence links age-related dysfunction and structural alterations of the cerebral arteries, arterioles, and capillaries to the pathogenesis of many types of dementia in the elderly, including Alzheimer's disease. The low-pressure, low-velocity, and large-volume venous circulation of the brain also plays critical roles in the maintenance of homeostasis in the central nervous system. Despite its physiological importance, the role of age-related alterations of the brain venous circulation in the pathogenesis of vascular cognitive impairment and dementia is much less understood. This overview discusses the role of cerebral veins in the pathogenesis of VCID. Pathophysiological consequences of age-related dysregulation of the cerebral venous circulation are explored, including blood-brain barrier disruption, neuroinflammation, exacerbation of neurodegeneration, development of cerebral microhemorrhages of venous origin, altered production of cerebrospinal fluid, impaired function of the glymphatics system, dysregulation of cerebral blood flow, and ischemic neuronal dysfunction and damage. Understanding the age-related functional and phenotypic alterations of the cerebral venous circulation is critical for developing new preventive, diagnostic, and therapeutic approaches to preserve brain health in older individuals.

Potential Involvement of Impaired Venous Outflow from the Brain in Neurodegeneration: Lessons Learned from the Research on Chronic Cerebrospinal Venous Insufficiency

About 10 years ago, the so-called chronic cerebrospinal venous insufficiency syndrome was discovered. This clinical entity, which is associated with extracranial venous abnormalities that impair venous outflow from the brain, was initially found exclusively in multiple sclerosis patients. Currently, we know that such venous lesions can also be revealed in other neurological pathologies, including Alzheimer's and Parkinson's diseases. Although direct causative role of chronic cerebrospinal venous insufficiency in these neurological diseases still remains elusive, in this paper, we suggest that perhaps an abnormal venous drainage of the brain affects functioning of the glymphatic system, which in turn results in the accumulation of pathological proteins in the cerebral tissue (such as β-synuclein, β-amyloid and α-synuclein) and triggers the venous outflow from the cranial cavity and circulation of the cerebrospinal fluid in the settings of neurodegenerative disease.

Assessment of Hemodynamic Alterations in Cerebral Veins in Patients With Intracerebral Hemorrhage Using Duplex Color-Coded Sonography

OBJECTIVES

To investigate the contributions of hemodynamic alterations in cerebral veins to the prognosis of patients with primary intracerebral hemorrhage (ICH).

METHODS

Duplex color-coded sonography was performed on 87 ICH patients between July 2016 and October 2017. The time-averaged peak velocity, the time-averaged mean velocity (TAMV), the blood flow volume (BFV) of bilateral internal jugular veins (IJVs) and vertebral veins (VVs), and the mean velocities of bilateral basal veins of Rosenthal, straight sinus, and bilateral transverse sinuses were calculated to understand the relationship of hemodynamic data with prognosis in patients with ICH.

RESULTS

The study revealed that the time-averaged peak velocities, TAMVs and BFVs of both right IJV and VV in ICH patients with good clinical outcomes were higher than those of the left IJV and VV, whereas statistically significant differences were not found in the mean velocity of bilateral veins of Rosenthal. The perihematomal edema volume, time-averaged peak velocities, TAMVs, and BFVs of the bilateral IJVs and right VV and the TAMV of the left VV were associated with the prognosis of ICH patients in the univariate analysis. However, the TAMV of the right IJV and BFV of the left IJV were the independent factors that predicted prognosis in multivariate analysis. Partial correlation showed that there was a linear dependence between the differences in TAMV and BFV between bilateral IJVs.

CONCLUSIONS

The presence of hemodynamic changes in cerebral veins in patients with ICH has an impact on prognosis.

Repeated Valsalva maneuvers promote symptomatic manifestations of cerebral microhemorrhages: implications for the pathogenesis of vascular cognitive impairment in older adults

Multifocal cerebral microhemorrhages (CMHs, also known as "cerebral microbleeds"), which are associated with rupture of small intracerebral vessels, have been recognized as an important cause for cognitive decline in older adults. Although recent studies demonstrate that CMHs are highly prevalent in patients 65 and older, many aspects of the pathogenesis and clinical significance of CMHs remain obscure. In this longitudinal observational study, a case of a 77-year-old man with multifocal CMHs is described, in whom the rupture of intracerebral vessels could be linked to repeatedly performing extended Valsalva maneuvers. This patient was initially seen with acute aphasia after performing a prolonged Valsalva maneuver during underwater swimming. T2-weighted magnetic resonance imaging revealed a left acute frontal intracerebral hemorrhage (ICH) with multiple CMHs. The aphasia was resolved and no cognitive impairment was present. Two years later, he developed unsteadiness and confusion after performing two prolonged Valsalva maneuvers during underwater swimming separated by about 12 days. Repeat brain imaging revealed an acute right and a subacute left ICH, with a marked interval increase in the number of CMHs. The patient also exhibited manifest memory loss after the second admission and was diagnosed with dementia. These observations suggest that prolonged Valsalva maneuver is potentially a common precipitating cause of both CMHs and symptomatic ICHs. The Valsalva maneuver both increases the systolic arterial pressure and gives rise to a venous pressure wave transmitted to the brain in the absence of the competent antireflux jugular vein valves. This pressure increase is superimposed on existing hypertension and/or increases in blood pressure due to exercise and increased venous return due to immersion of the body in water. We advocate that further studies are needed to distinguish between CMHs with arterial and venous origins and their potential to lead to ICH induced by Valsalva maneuver as well as to determine whether these lesions have a predilection for a particular location.

Possible Role of Glymphatic System of the Brain in the Pathogenesis of High-Altitude Cerebral Edema

In this article, we suggest that the glymphatic system of the brain can play an important role in the pathogenesis of high-altitude cerebral edema (HACE). Water enters the intercellular space of the brain primarily through aquaporin-4 (AQP-4) water channels, the main component of the glymphatic system, whereas acetazolamide, pharmacological agent used in the prevention of HACE, is the blocker of the AQP-4 molecule. In animal experiments, cerebral edema caused by hypobaric hypoxia was associated with an increased expression of AQP-4 by astrocytes. Also, the glymphatic system is primarily active during sleep, although sleep at high altitude is a well-known risk factor of developing HACE. All these findings support our hypothesis. We suggest that future research on the prevention and treatment of HACE should involve factors that are already known to modify activity of the glymphatic system, such as angiotensin-converting enzyme inhibitors or other pharmaceutical agents affecting noradrenergic system of the brain, body posture during sleep, anatomy of the veins draining the cranial cavity, and the influence of physical activity before and during exposure to high altitude, especially in relation to sleep.

Centralized and Local Color Doppler Ultrasound Reading Agreement for Diagnosis of the Chronic Cerebrospinal Venous Insufficiency in Patients with Multiple Sclerosis

Background:

An impaired cerebrospinal venous drainage was postulated to be a cofactor in the multifactorial path-ogenesis of multiple sclerosis (MS). Chronic cerebrospinal venous insufficiency (CCSVI) is characterized by abnormalities of the main extracranial cerebrospinal venous outflow routes, which can be detected by color Doppler Ultrasound (CDUS) using 5 venous hemodynamic (VH) criteria. Discrepant results between different investigators were reported in the past, therefore the usefulness and applicability of the CCSVI CDUS-based diagnosis in clinical research and practice has been questioned.

The reproducibility of proposed criteria for CCSVI detection depends on the blinding, training level, skills of the operator and interpretation of VH criteria.

Objectives:

To assess agreement between centralized and local reading of CDUS examination for diagnosis of CCSVI in trained Doppler sonologists.

Methods:

This study was performed in 78 MS patients and 28 age- and sex-matched healthy controls (HCs). Extracranial and transcranial CDUS venous hemodynamic assessment was conducted, according to International Society of Neurovascu-lar Disease (ISNVD) recommended criteria, by a single CCSVI-trained expert sonologist blinded to the subject disease sta-tus. After the local Doppler sonologist performed the investigation, all images and video clips of the CDUS examination were sent to the centralized reading center, where a second blinded reading was performed by two CCSVI-trained expert sonologists. Statistical analyses were performed comparing accuracy of CCSVI diagnosis (≥2 VH criteria) and each of the 5 individual VH criteria using Cohen kappa statistic, along with positive/negative agreement and Odds ratio (OR) with 95% confidence intervals (95% CI).

Results:

Diagnosis of CCSVI was obtained in 59.7% of local and 64.3% centralized readers (Kappa, 0.67, p<0.001). Simi-lar Kappa values were obtained for CCSVI diagnosis and individual CCSVI criteria in both MS patients and HCs. The high-est Kappa between local and centralized readers was observed for VH criteria 5 (0.93) followed by VH criteria 4 (0.70), VH criteria 1 (0.66), VH criteria 2 (0.64) and VH criteria 3 (0.58). The positive predictive value (PPV) and negative predictive value (NPV) for CCSVI diagnosis were 82.7% and 86,7%, respectively with an OR of 31.1 (95% CI 11.1-87.5, p<0.001). The highest agreement between local and centralized readers was observed for VH criteria 4 (OR 98.7, 95% CI 17.1-569.9, p<0.001) with 72.7% PPV and 97.3% NPV followed by VH criteria 5 (53, 95% CI 13.4-209.2, p<0.001) with 98.1% PPV and 100% NPV value.

Conclusion:

Centralized reading of the CDUS examination for the diagnosis of CCSVI is feasible with high accuracy in CCSVI-trained Doppler sonologists. The most reproducible VH criteria between local and centralized readers were VH cri-teria 4 and 5.

Understanding jugular venous outflow disturbance

Extracranial venous abnormalities, especially jugular venous outflow disturbance, were originally viewed as nonpathological phenomena due to a lack of realization and exploration of their feature and clinical significance. The etiology and pathogenesis are still unclear, whereas a couple of causal factors have been conjectured. The clinical presentation of this condition is highly variable, ranging from insidious to symptomatic, such as headaches, dizziness, pulsatile tinnitus, visual impairment, sleep disturbance, and neck discomfort or pain. Standard diagnostic criteria are not available, and current diagnosis largely depends on a combinatory use of imaging modalities. Although few researches have been conducted to gain evidence-based therapeutic approach, several recent advances indicate that intravenous angioplasty in combination with stenting implantation may be a safe and efficient way to restore normal blood circulation, alleviate the discomfort symptoms, and enhance patients' quality of life. In addition, surgical removal of structures that constrain the internal jugular vein may serve as an alternative or adjunctive management when endovascular intervention is not feasible. Notably, discussion on every aspect of this newly recognized disease entity is in the infant stage and efforts with more rigorous designed, randomized controlled studies in attempt to identify the pathophysiology, diagnostic criteria, and effective approaches to its treatment will provide a profound insight into this issue.

Heritability of the dimensions, compliance and distensibility of the human internal jugular vein wall

Aims

The elasticity of the internal jugular vein (IJV) is a major determinant of cerebral venous drainage and right atrium venous return. However, the level of genetic determination of IJV dimensions, compliance and distensibility has not been studied yet.

Methods

170 adult Caucasian twins (43 monozygotic [MZ] and 42 dizygotic [DZ] pairs) were involved from the Italian twin registry. Anteroposterior and mediolateral diameters of the IJV were measured bilaterally by ultrasonography. Measurements were made both in the sitting and supine positions, with or without Valsalva maneuver. Univariate quantitative genetic modeling was performed.

Results

Genetic factors are responsible for 30–70% of the measured properties of IJV at higher venous pressure even after adjustment for age and gender. The highest level of inheritance was found in the supine position regarding compliance (62%) and venous diameter during Valsalva (69%). Environmental and measurement-related factors instead are more important in the sitting position, when the venous pressure is low and the venous lumen is almost collapsed. The range of capacity changes between the lowest and highest intraluminal venous pressure (full distension range) are mainly determined by genetic factors (58%).

Conclusions

Our study has shown substantial heritability of IJV biomechanics at higher venous pressures even after adjustment for age and gender. These findings yield an important insight to what degree the geometric and elastic properties of the vascular wall are formed by genetic and by environmental factors in humans.

Recanalization, reperfusion, and recirculation in stroke

Recirculation, from arterial inflow routes through venous outflow pathways, was conceptualized in stroke research 50 years ago. As new technologies were developed, blocked arteries could be reopened, capillaries could be reperfused, and the use of recanalization and reperfusion grew to dominate therapeutic strategies. These approaches overwhelmingly focused on restoration of arterial and capillary inflow, but not on veins even though venous disorders may initiate or exacerbate brain injury. In this commentary, we advance the term "recirculation" after "recanalization" and "reperfusion" as a primary concept of stroke pathophysiology that targets the restoration of both the arterial and venous cerebral circulations.

Jugular Anomalies in Multiple Sclerosis Are Associated with Increased Collateral Venous Flow

BACKGROUND AND PURPOSE

To date, research on extracranial venous collaterals has been focused on structure, with relatively little attention paid to hemodynamics. We addressed this limitation by quantitatively comparing collateral flow in patients with multiple sclerosis and healthy controls by using phase-contrast MR imaging. We hypothesize that patients with MS with structurally anomalous internal jugular veins will have elevated collateral venous flow compared with healthy controls.

MATERIALS AND METHODS

The sample consisted of 276 patients with MS and 106 healthy controls. We used MRV to classify internal jugular veins as stenotic and nonstenotic based on an absolute cross-sectional area threshold in 276 patients with MS and 60 healthy controls; 46 healthy controls lacked this imaging. Individual and total vessel flows were quantified by using phase-contrast MR imaging on all patients. Veins were classified by extracranial drainage type: internal jugular veins (I), paraspinal (II), and superficial (III). Differences among healthy controls, patients with MS, nonstenotic patients, and stenotic subgroups in total venous flow by vessel type were evaluated in a general linear model for statistical analysis.

RESULTS

In the MS group, 153 patients (55%) evidenced stenosis, whereas 12 (20%) healthy controls were classified as stenotic (P < .001). Compared with healthy controls, the MS group showed lower type I flow and increased type II flow. Stenosis was associated with reduced flow in the type I vessels [F(1272) = 68; P < .001]. The stenotic MS group had increased flow in the type II vessels compared with the nonstenotic MS group [F(1272) = 67; P < .001].

CONCLUSIONS

Compared with healthy controls, patients with MS exhibit reduced venous flow in the main extracerebral drainage vein (internal jugular vein). In contrast, flow in the paraspinal venous collaterals is elevated in patients with MS and exacerbated by venous stenosis. Collateral drainage may be a compensatory response to internal jugular vein flow reduction.

Jugular Venous Reflux Is Associated with Perihematomal Edema after Intracerebral Hemorrhage

The purpose of this study was to determine whether jugular venous reflux (JVR) is associated with perihematomal edema (PHE) in individuals with intracerebral hemorrhage (ICH). Patients with spontaneous supratentorial ICH within 72 h of symptom onset were enrolled. Baseline brain computed tomography (CT) scan was performed, with a follow-up CT examination at 12 ± 3 days after onset. Jugular venous color Doppler ultrasound was performed at 12 ± 3 days after onset to examine the JVR status. A total of 65 patients with ICH were enrolled. In logistic regression analysis, absolute PHE volume was significantly associated with JVR (OR, 5.46; 95% CI, 1.04–28.63; p = 0.044) and baseline hematoma volume (OR, 1.14; 95% CI, 1.03–1.26; p = 0.009) within 72 h of onset. It was also correlated with JVR (OR, 15.32; 95% CI, 2.52–92.99; p = 0.003) and baseline hematoma volume (OR, 1.14; 95% CI, 1.04–1.24; p = 0.006) at 12 ± 3 days after onset. In a similar manner, relative PHE volume was significantly associated with JVR (OR, 14.85; 95% CI, 3.28–67.17; p < 0.001) within 72 h of onset and at 12 ± 3 days after onset (OR, 5.87; 95% CI, 1.94–17.77; p = 0.002). JVR is associated with both absolute and relative PHE volumes after ICH.

Cardiac, Respiratory and Postural Influences on Venous Return of Internal Jugular and Vertebral Veins

It is known from physiology that heartbeat and respiration influence venous return, but little is known regarding the extent to which these two factors affect flow. In this study, we estimated the prevalence of cardiac- and breathing-induced venous flow modulations in the internal jugular vein (IJV) and vertebral vein (VV) and the effects of posture. In 19 healthy patients, neck vein flow was examined with pulsed wave Doppler. Electrocardiogram and respiratory signals were simultaneously acquired. In supine position, heart contraction always influenced venous flow, whereas breathing influenced 68% of IJV and 34% of VV flow. In sitting position, heart contraction influenced 74% of IJV and 42% of VV flow; breathing influenced 68% of IJV and 61% of VV measures. Thus, cardiac influence is greatly present in supine position, whereas breathing influence prevails in the VV while sitting. This setup allowed us to observe that in some patients, expiration may cause an unexpected increase in venous flow.

Cerebral microhemorrhages: mechanisms, consequences, and prevention

The increasing prevalence of multifocal cerebral microhemorrhages (CMHs, also known as "cerebral microbleeds") is a significant, newly recognized problem in the aging population of the Western world. CMHs are associated with rupture of small intracerebral vessels and are thought to progressively impair neuronal function, potentially contributing to cognitive decline, geriatric psychiatric syndromes, and gait disorders. Clinical studies show that aging and hypertension significantly increase prevalence of CMHs. CMHs are also now recognized by the National Institutes of Health as a major factor in Alzheimer's disease pathology. Moreover, the presence of CMHs is an independent risk factor for subsequent larger intracerebral hemorrhages. In this article, we review the epidemiology, detection, risk factors, clinical significance, and pathogenesis of CMHs. The potential age-related cellular mechanisms underlying the development of CMHs are discussed, with a focus on the structural determinants of microvascular fragility, age-related alterations in cerebrovascular adaptation to hypertension, the role of oxidative stress and matrix metalloproteinase activation, and the deleterious effects of arterial stiffening, increased pulse pressure, and impaired myogenic autoregulatory protection on the brain microvasculature. Finally, we examine potential treatments for the prevention of CMHs based on the proposed model of aging- and hypertension-dependent activation of the reactive oxygen species-matrix metalloproteinases axis, and we discuss critical questions to be addressed by future studies.

Age differences in arterial and venous extra-cerebral blood flow in healthy adults: contributions of vascular risk factors and genetic variants

Sufficient cerebral blood flow (CBF) and venous drainage are critical for normal brain function, and their alterations can affect brain aging. However, to date, most studies focused on arterial CBF (inflow) with little attention paid to the age differences in venous outflow. We measured extra-cerebral arterial and venous blood flow rates with phase-contrast MRI and assessed the influence of vascular risk factors and genetic polymorphisms (ACE insertion/deletion, COMT val158met, and APOEε4) in 73 adults (age 18-74 years). Advanced age, elevated vascular risk, ACE Deletion, and COMT met alleles were linked to lower in- and outflow, with no effects of APOE ε4 noted. Lower age-related CBF rate was unrelated to brain volume and was observed only in val homozygotes of COMTval158met. Thus, in a disease-free population, age differences in CBF may be notable only in persons with high vascular risk and carriers of genetic variants associated with vasoconstriction and lower dopamine availability. It remains to be established if treatments targeting alleviation of the mutable factors can improve the course of cerebrovascular aging in spite of the immutable genetic influence.

Clinical Applicability of Assessment of Jugular Flow over the Individual Cardiac Cycle Compared with Current Ultrasound Methodology

There is growing interest in measuring cerebral venous outflow with ultrasound (US). However, results obtained with the current US Doppler methodology, which uses just a single value of cross-sectional area (CSA) of the vessel, are highly variable and inconclusive. The product of CSA and time-averaged velocity in the case of pulsatile vessels may be a possible source of error, particularly for a pulsatile vein like the internal jugular vein (IJV), where the cardiac pump transmits a sequence of well-established waves along the conduit. We herein propose a novel technique for US IJV flow assessment that accurately accounts for IJV CSA variations during the cardiac cycle. Five subjects were investigated with a high-resolution real-time B-mode video, synchronized with an electrocardiography trace. In this approach, CSA variations representing the pulsatility of the IJV are overlapped with the velocity curve obtained by the usual spectral Doppler trace. The overlap is then phased point by point using the electrocardiography pacemaker. This allows us to experimentally measure the velocity variation in relation to the change in CSA precisely, ultimately enabling calculation of IJV flow. (i) The sequence of CSA variation with respect to the electrocardiography waves corresponds exactly to the jugular venous pulse as measured in physiology. (ii) The methodology permits us to phase the velocity and CSA, which is ultimately what is currently lacking to precisely calculate the flow in the IJV with US. (iii) The time-averaged flow, calculated with the described technique, is very close to that calculated assuming a constant IJV CSA, whereas the time-dependent flow shows differs as much as 40%. (iv) Finally, we tested the accuracy of the technique with a methodology that may allow for universal assessment of the accuracy of each personal US-based evaluation of flow rate.

Original Research: Feasibility and safety of two surgical techniques for the development of an animal model of jugular vein occlusion

To date, no studies have explored the effect of abnormal cerebral venous circulation on brain disorders, whereas many studies have investigated neurodegenerative brain anomalies associated with arterial diseases. The aim of our study was to demonstrate the feasibility of different surgical techniques to induce venous obstruction of cerebral brain drainage. Six C57/black mice underwent bilateral occlusion of the external jugular vein (group EJV), six underwent bilateral occlusion of the internal jugular vein (group IJV), and six underwent bilateral occlusion of both the EJV and the IJV (group EJV/IJV). Within each group, the interruption of blood flow was obtained via monopolar electro-coagulation (ME) in three mice and via surgical ligation (SL) in the remaining three mice. A "sham group" of two mice was used as the control. High-frequency ultrasound (HFUS) was used to detect the absence of blood flow in the examined vessel. The ME procedure led to successful results in two of nine (22%) mice, one in the EJV group, one in the EJV/IJV group, and zero in the IJV group, and 4 of 18 (22%) mice when considering individual veins (i.e., total number of EJVs and IJVs occluded). The SL procedure was successful in two of three (67%) mice in the EJV group, in three of three (100%) mice in the IJV and in three of four (75%) mice in the EJV/IJV group. Therefore, the overall success rate was 8/10 (80%) when considering mice, and 20/26 (77%) when considering individual veins. The monopolar electro-coagulation method exhibited a high mortality due to cardiorespiratory arrest, while the results of the bilateral surgical ligation of EJVs and IJVs show that it is technically feasible and safe.

Intra- and Extracranial MR Venography: Technical Notes, Clinical Application, and Imaging Development

Scientific debate over chronic cerebrospinal venous insufficiency (CCSVI) has drawn attention to venous system involvement in a series of pathologic brain conditions. In the last few decades, the MRI venography (MRV) field has developed a number of valuable sequences to better investigate structural anatomy, vessel patency, and flow characteristics of venous drainage in the intra- and extracranial systems. A brief two-tier protocol is proposed to encompass the study of intra- and extracranial venous drainage with and without contrast administration, respectively. Contrast-enhanced protocol is based on time-resolved contrast-enhanced MRV of the whole region plus extracranial flow quantification through 2D Cine phase contrast (PC); non-contrast-enhanced protocol includes intracranial 3D PC, extracranial 2D time of flight (TOF), and 2D Cine PC flow quantification. Total scanning time is reasonable for clinical applications: approximately seven minutes is allocated for the contrast protocol (most of which is due to 2D Cine PC), while the noncontrast protocol accounts for around twenty minutes. We believe that a short though exhaustive MRI scan of the whole intra- and extracranial venous drainage system can be valuable for a variety of pathologic conditions, given the possible venous implication in several neurological conditions.

Internal Jugular Vein Cross-Sectional Area Enlargement Is Associated with Aging in Healthy Individuals

Background

Internal jugular vein (IJV) narrowing has been implicated in central nervous system pathologies, however normal physiological age- and gender-related IJV variance in healthy individuals (HIs) has not been adequately assessed.

Objectives

We assessed the relationship between IJV cross-sectional area (CSA) and aging.

Materials and Methods

This study involved 193 HIs (63 males and 130 females) who received 2-dimensional magnetic resonance venography at 3T. The minimum CSA of the IJVs at cervical levels C2/C3, C4, C5/C6, and C7/T1 was obtained using a semi-automated contouring-thresholding technique. Subjects were grouped by decade. Pearson and partial correlation (controlled for cardiovascular risk factors, including hypertension, heart disease, smoking and body mass index) and analysis of variance analyses were used, with paired t-tests comparing side differences.

Results

Mean right IJV CSA ranges were: in males, 41.6 mm² (C2/C3) to 82.0 mm² (C7/T1); in females, 38.0 mm² (C2/C3) to 62.3 mm² (C7/T1), while the equivalent left side ranges were: in males, 28.0 mm² (C2/C3) to 52.2 mm² (C7/T1); in females, 27.2 mm² (C2/C3) to 47.8 mm² (C7/T1). The CSA of the right IJVs was significantly larger (p<0.001) than the left at all cervical levels. Controlling for cardiovascular risk factors, the correlation between age and IJV CSA was more robust in males than in the females for all cervical levels.

Conclusions

In HIs age, gender, hand side and cervical location all affect IJV CSA. These findings suggest that any definition of IJV stenosis needs to account for these factors.

The Oscillating Component of the Internal Jugular Vein Flow: The Overlooked Element of Cerebral Circulation

The jugular venous pulse (JVP) provides valuable information about cardiac haemodynamics and filling pressures and is an indirect estimate of the central venous pressure (CVP). Recently it has been proven that JVP can be obtained by measuring the cross-sectional area (CSA) of the IJV on each sonogram of an ultrasound B-mode sonogram sequence. It has also been proven that during its pulsation the IJV is distended and hence that the pressure gradient drives the IJV haemodynamics. If this is true, then it will imply the following: (i) the blood velocity in the IJV is a periodic function of the time with period equal to the cardiac period and (ii) the instantaneous blood velocity is given by a time function that can be derived from a flow-dynamics theory that uses the instantaneous pressure gradient as a parameter. The aim of the present study is to confirm the hypothesis that JVP regulates the IJV blood flow and that pressure waves are transmitted from the heart toward the brain through the IJV wall.

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.

Head and Neck Veins of the Mouse. A Magnetic Resonance, Micro Computed Tomography and High Frequency Color Doppler Ultrasound Study

To characterize the anatomy of the venous outflow of the mouse brain using different imaging techniques. Ten C57/black male mice (age range: 7-8 weeks) were imaged with high-frequency Ultrasound, Magnetic Resonance Angiography and ex-vivo Microcomputed tomography of the head and neck. Under general anesthesia, Ultrasound of neck veins was performed with a 20MHz transducer; head and neck Magnetic Resonance Angiography data were collected on 9.4T or 7T scanners, and ex-vivo Microcomputed tomography angiography was obtained by filling the vessels with a radiopaque inert silicone rubber compound. All procedures were approved by the local ethical committee. The dorsal intracranial venous system is quite similar in mice and humans. Instead, the mouse Internal Jugular Veins are tiny vessels receiving the sigmoid sinuses and tributaries from cerebellum, occipital lobe and midbrain, while the majority of the cerebral blood, i.e. from the olfactory bulbs and fronto-parietal lobes, is apparently drained through skull base connections into the External Jugular Vein. Three main intra-extracranial anastomoses, absent in humans, are: 1) the petrosquamous sinus, draining into the posterior facial vein, 2) the veins of the olfactory bulb, draining into the superficial temporal vein through a foramen of the frontal bone 3) the cavernous sinus, draining in the External Jugular Vein through a foramen of the sphenoid bone. The anatomical structure of the mouse cranial venous outflow as depicted by Ultrasound, Microcomputed tomography and Magnetic Resonance Angiography is different from humans, with multiple connections between intra- and extra- cranial veins.

An ultrasonographic technique to assess the jugular venous pulse: a proof of concept

The purpose of the work described here was to investigate the feasibility of assessing the jugular venous pulse (JVP) using ultrasound (US) equipment. Three young healthy subjects underwent a B-mode US scan of the internal jugular vein (IJV) to acquire a sonogram sequence in the transverse plane. On each acquired sonogram, the IJV contour was manually traced, and both the cross-sectional area (CSA) and the perimeter were measured. The CSA data set represents the US jugular diagram (USJD). The arterial distension waveform of the subjects was compared with its USJD. The correlation between the CSA and the perimeter was assessed during the cardiac cycle to verify IJV distension. For each subject, a short sonogram sequence of a few seconds was recorded, and the USJD obtained exhibited periodic behavior. Furthermore, for all subjects, the CSA was found to be correlated with the perimeter (Pearson coefficient, R > 0.9), indicating that the IJV in supine position is distended. We compared 390 manually traced contours of the IJV cross-sectional area with corresponding values semi-automatically calculated by an algorithm developed in-house. For all subjects, the sensitivity, specificity and accuracy were around 95%, 85% and 90% respectively. We found that a diagram reflecting the JVP can be obtained by analyzing a B-mode sonogram sequence of the IJV; such a diagram can result in a new methodology to assess the IJV functionality.

A new hemodynamic model for the study of cerebral venous outflow

We developed a mathematical model of the cerebral venous outflow for the simulation of the average blood flows and pressures in the main drainage vessels of the brain. The main features of the model are that it includes a validated model for the simulation of the intracranial circulation and it accounts for the dependence of the hydraulic properties of the jugular veins with respect to the gravity field, which makes it an useful tool for the study of the correlations between extracranial blood redistributions and changes in the intracranial environment. The model is able to simulate the average pressures and flows in different points of the jugular ducts, taking into account the amount of blood coming from the anastomotic connections; simulate how the blood redistribution due to change of posture affects flows and pressures in specific points of the system; and simulate redistributions due to stenotic patterns. Sensitivity analysis to check the robustness of the model was performed. The model reproduces average physiologic behavior of the jugular, vertebral, and cerebral ducts in terms of pressures and flows. In fact, jugular flow drops from ∼11.7 to ∼1.4 ml/s in the passage from supine to standing. At the same time, vertebral flow increases from 0.8 to 3.4 ml/s, while cerebral blood flow, venous sinuses pressure, and intracranial pressure are constant around the average value of 12.5 ml/s, 6 mmHg, and 10 mmHg, respectively. All these values are in agreement with literature data.