Correlation between intracranial pressure and venous sinus pressures in patients undergoing cerebral venography and manometry

Total brain volume is associated with severity of transverse sinus stenosis in idiopathic intracranial hypertension

BACKGROUND

Idiopathic intracranial hypertension (IIH) is a complex neurological condition characterized by symptoms of increased intracranial pressure of unclear etiology. While transverse sinus stenosis (TSS) is often present in patients with IIH, how and why it occurs remains unclear.

METHODS

IIH patients and a set of age-matched normal controls were identified from our single-center tertiary care institution from 2016 to 2024. Brain MRIs before treatment were computationally segmented and parcellated using FreeSurfer software. Extent of TSS on MR venograms was graded using the Farb scoring system. Relationship between normalized brain volume, normalized brain-to-CSF volume, and TSS was investigated. Multiple linear regression was conducted to investigate the association between continuous variables, accounting for the covariates body mass index, sex, and age.

RESULTS

In total, 84 IIH patients (mean age, 29.8 years; 87% female) and 15 normal controls (mean age, 28.1 years) were included. Overall, increasing/worsening TSS was found to be significantly associated with normalized total brain volume (p=0.018, R=0.179) and brain-to-CSF ratio volume (p=0.026, R=0.184). Additionally, there was a significant difference between controls and IIH patients with mild and severe stenosis regarding normalized total brain volume (ANCOVA, p=0.023) and brain-to-CSF ratio volume (ANCOVA, p=0.034). Likewise, IIH patients with severe TSS had a significantly higher brain-to-CSF volume compared with controls (p=0.038) and compared with IIH patients with mild TSS (p=0.038).

CONCLUSIONS

These findings suggest that total brain volume is associated with extent of TSS, which may reflect extramural venous compression due to enlarged brain and/or venous hypertension with associated cerebral congestion/swelling.

Characterizing a new clinical phenotype: the co-existence of cerebral venous outflow and connective tissue disorders

Background

There is increasing recognition of connective tissue disorders and their influence on disease in the general population. A conserved clinical phenotype involving connective tissue disorders and idiopathic intracranial hypertension (IIH) and associated cerebral venous outflow disorders (CVD) has not been previously described.

Methods

A single-institution retrospective review of a prospectively maintained database of patients with connective tissue disorders and CVD was performed.

Results

A total of 86 patients were identified. The majority of these patients carried a diagnosis of Ehlers-Danlos syndrome (55%) and most were non-obese (mean body mass index 29.7 kg/m2), Caucasian (90%) females (87%). Most prevalent presenting symptoms included pressure headache (98%), dizziness (90%), tinnitus (92%), and cognitive dysfunction (69%). Aside from CVD and IIH, the most common associated conditions were postural orthostatic tachycardia syndrome (POTS; 55.8%), cerebrospinal fluid (CSF) leaks (51.2%), dysautonomia (45.3%), cranio-cervical instability (37.2%), mast cell activation syndrome (25.6%), and tethered cord syndrome (23.3%). Allergies to medications (87.2%) and surgical tape (19.8%) were also frequent. Despite significantly lower opening pressures on lumbar puncture, headache severity and quality of life scores were reported with the same severity of classic IIH patients, suggesting an underlying hypersensitivity to intracranial pressures and cerebral venous congestion.

Conclusion

There is a rare but conserved clinical phenotype that has not been described previously that presents with severe IIH symptoms in predominantly young, non-obese Caucasian women with a high associated incidence of dysautonomia, POTS, craniocervical instability, and CSF leaks, among others.

Factors associated with the initial intracranial hemorrhage occurrence in patients with cerebral venous thrombosis

OBJECTIVES

Studies focusing on intracranial hemorrhage (ICH) in patients with cerebral venous thrombosis (CVT) are limited; thus, we aimed to identify factors associated with the occurrence of ICH in Thai patients with CVT.

METHODS

This retrospective cohort study recruited patients with CVT admitted to a tertiary university-based hospital between 2002 and 2022. The baseline characteristics, clinical presentations, radiographic findings, and etiologies were compared between the ICH and non-ICH groups. The factors with p < 0.2 in the univariate analysis were further analyzed using multivariable logistic regression analysis to identify independent factors associated with ICH in patients with CVT.

RESULTS

Of 228 screenings, 202 patients were eligible. The incidence rate of ICH was 36.63%. The ICH group showed a higher prevalence of focal neurological deficits (63.51% vs. 26.56%, p < 0.001), seizures (68.92% vs. 21.88%, p < 0.001), dependency status at admission (60.81% vs. 39.84%, p = 0.004), superior sagittal sinus thrombosis (71.62% vs. 39.07%, p < 0.001), superficial cortical vein thrombosis (36.49% vs. 10.16%, p < 0.001), and hormonal use (17.57% vs. 7.03%, p = 0.021) than the non-ICH group. In contrast, the ICH group showed a lower prevalence of isolated increased intracranial pressure (10.81% vs. 21.88%, p = 0.048) than the non-ICH group. Seizures (adjusted odds ratio [aOR], 4.537; 95% confidence interval [CI], 2.085-9.874; p < 0.001), focal neurological deficits (aOR, 2.431; 95% CI, 1.057-5.593; p = 0.037), and superior sagittal sinus thrombosis (aOR, 1.922; 95% CI, 1.913-4.045; p = 0.045) were independently associated with ICH in the multivariable logistic regression analysis.

CONCLUSIONS

Seizures, focal neurological deficits, and superior sagittal sinus thrombosis are associated with ICH in patients with CVT.

A descriptive study of venous pressures and gradients while awake and both pre- and post-stent under anesthesia in patients with idiopathic intracranial hypertension

BACKGROUND

This study aims to explore factors that affect venous sinus pressures and associated gradients while awake and under general anesthesia (GA) both before and after venous sinus stenting (VSS) in patients with idiopathic intracranial hypertension (IIH).

METHODS

A retrospective analysis was performed examining pressures and gradients in patients with IIH having undergone awake venography followed by VSS under GA.

RESULTS

174 patients were included. Compared with awake, GA superior sagittal sinus (SSS) pressures were 2.6 mmHg lower (p=0.01) resulting in a total cranial gradient reduction of 2.5 mmHg (p=0.002). The transverse-sigmoid gradient, the most commonly stented segment, did not differ under the two conditions (p=0.30). Regression analyses demonstrated that body mass index, gender, blood pressure, and end-tidal carbon dioxide content significantly affected venous pressures (all p<0.05). After stenting, mean total cranial gradients decreased by 13.2 mmHg while skull base gradients increased by 0.8 mmHg. Stenting resulted in an 84% mean reduction in the target gradient and a mean decrease in SSS pressures by 78% of the target gradient. When cardiopulmonary and anesthetic factors were optimized, GA had a limited effect on the target gradient in most patients (p=0.88).

CONCLUSIONS

This study is the largest series to date to report on cerebral venous pressure measurements and gradients recorded while awake and under GA both before and after VSS for IIH. In a well-controlled cardiorespiratory and anesthetic setting, GA venography may provide information that is not substantially inequivalent to that obtained while awake.

Venous Pathologies and Interventions of the Head

Intracranial venous pathologies are a historically underrecognized group of disorders that can have a devastating impact on patients. Despite advancements in peripheral venous disorders and arterial neurointerventions, intracranial venous pathologies have received comparatively little attention. Understanding the anatomy, physiology, clinical relevance, and treatment options of intracranial venous pathologies is fundamental to evolving therapies and research priorities. This article provides an overview of major intracranial venous pathologies, the respective pathophysiologies, and treatment options.

[Idiopathic intracranial hypertension: From physiopathological mechanisms to therapeutic decision]

Clinical features include visual disturbances, headaches, and pulsatile tinnitus that can be associated with reduced quality of life, and a risk of irreversible visual impairment in some cases. Obese women of childbearing age represent the main at-risk population, and the incidence of the disease is increasing because of rising prevalence of obesity worldwide. In addition, an imbalance in sex hormones is reported as a contributing risk factor. The pathophysiology of idiopathic intracranial hypertension involves a disturbance of the evacuation pathway of intracranial fluids caused by the increase in intracranial venous pressure. Brain imaging is useful for diagnosis with several signs including bilateral stenosis of the transverse sinuses that plays a major role in the pathogenesis of the disease by creating a positive feedback loop that increases intracranial venous hypertension and contributes to clinical manifestations. Treatment aims to relieve symptoms and prevent permanent visual impairment. Drug therapies including acetazolamide and topiramate have moderate effectiveness. Among invasive treatments, transverse sinus stenting seems to be the most interesting option to consider in drug-resistant patients. Weight loss remains essential to achieve a sustainable improvement by reducing central venous pressure. Future randomized trials are expected to reach a consensus on this treatment.

Pearls & Oy-sters: Cerebral Venous Congestion Associated With Cognitive Decline Treated by Jugular Release

Cognitive dysfunction is often multifaceted and can be seen across all age groups in medicine. The combination of cognitive decline and increased intracranial pressure may suggest possible anatomical abnormalities. We present a case report from our academic center that describes a young man with new cognitive fatigue and brain fog in the setting of increased venous pressure that resolved with surgical intervention at a site of jugular vein stenosis. We discuss current hypotheses from basic and clinical research related to pathophysiology underlying venous vascular congestion and associated neurological disorders. Further research is warranted to elucidate underlying mechanisms of venous congestion and cognition to better identify therapies and improve quality of life for patients.

Interactions of brain, blood, and CSF: a novel mathematical model of cerebral edema

Background

Previous models of intracranial pressure (ICP) dynamics have not included flow of cerebral interstitial fluid (ISF) and changes in resistance to its flow when brain swelling occurs. We sought to develop a mathematical model that incorporates resistance to the bulk flow of cerebral ISF to better simulate the physiological changes that occur in pathologies in which brain swelling predominates and to assess the model’s ability to depict changes in cerebral physiology associated with cerebral edema.

Methods

We developed a lumped parameter model which includes a representation of cerebral ISF flow within brain tissue and its interactions with CSF flow and cerebral blood flow (CBF). The model is based on an electrical analog circuit with four intracranial compartments: the (1) subarachnoid space, (2) brain, (3) ventricles, (4) cerebral vasculature and the extracranial spinal thecal sac. We determined changes in pressure and volume within cerebral compartments at steady-state and simulated physiological perturbations including rapid injection of fluid into the intracranial space, hyperventilation, and hypoventilation. We simulated changes in resistance to flow or absorption of CSF and cerebral ISF to model hydrocephalus, cerebral edema, and to simulate disruption of the blood–brain barrier (BBB).

Results

The model accurately replicates well-accepted features of intracranial physiology including the exponential-like pressure–volume curve with rapid fluid injection, increased ICP pulse pressure with rising ICP, hydrocephalus resulting from increased resistance to CSF outflow, and changes associated with hyperventilation and hypoventilation. Importantly, modeling cerebral edema with increased resistance to cerebral ISF flow mimics key features of brain swelling including elevated ICP, increased brain volume, markedly reduced ventricular volume, and a contracted subarachnoid space. Similarly, a decreased resistance to flow of fluid across the BBB leads to an exponential-like rise in ICP and ventricular collapse.

Conclusions

The model accurately depicts the complex interactions that occur between pressure, volume, and resistances to flow in the different intracranial compartments under specific pathophysiological conditions. In modelling resistance to bulk flow of cerebral ISF, it may serve as a platform for improved modelling of cerebral edema and blood–brain barrier disruption that occur following brain injury.

Intracranial Venous Hypertension and Venous Sinus Stenting in the Modern Management of Idiopathic Intracranial Hypertension

Idiopathic intracranial hypertension (IIH) is a debilitating condition that has traditionally been difficult to treat. In recent years, there has been increasing focus on the role of intracranial venous hypertension in the pathophysiology of IIH. Based on increased understanding of this pathophysiology, venous sinus stenting (VSS) has emerged as a safe and reliable treatment for a certain population of patients with IIH. Stratifying patients with IIH based on the status of their venous outflow can provide insight into which patients may enjoy reduction in their symptoms after VSS and provides information regarding why some patients may have symptom recurrence. The traditional view of IIH as a disease due to obesity in young women has been cast into doubt as the understanding of the role of intracranial venous hypertension has improved.