Anatomy of Intracranial Veins

A cross-sectional study on the correlation between internal cerebral vein asymmetry and hemorrhagic transformation following endovascular thrombectomy

Introduction

Hemorrhagic transformation (HT) is a severe complication in patients with acute ischemic stroke due to large vessel occlusion (AIS-LVO) after endovascular treatment (EVT). We hypothesize that asymmetry of the internal cerebral veins (ICVs) on baseline CT angiogram (CTA) may serve as an adjunctive predictor of HT.

Methods

We conducted a study on consecutive AIS-LVO patients from November 2020 to April 2022. These patients had anterior circulation occlusions and were treated with EVT. Asymmetrical ICVs were assessed using CTA and defined as hypodensity (reduced opacification) on the ipsilateral side of occlusion compared to the contralateral side. The primary outcome was HT, defined as hemorrhage within the ischemic territory. This was evaluated using follow-up imaging (CT scan or magnetic resonance imaging) performed 48 h post-EVT. HT was classified into four subtypes based on the European Cooperative Acute Stroke Study-II criteria.

Results

A total of 126 patients were included, with an HT rate of 49.2% (62/126). ICV asymmetry was observed in 54.0% (68/126) of patients. The ICV asymmetry group exhibited a significantly higher risk of parenchymatous hematoma-type HT (33.8% vs. 15.5%, p = 0.019) and symptomatic intracerebral hemorrhage (sICH) (23.5% vs. 5.2%, p = 0.004). In multivariate logistic regression, ICV asymmetry (OR 3.809, 95% CI 1.582-9.171), baseline Alberta Stroke Program Early CT Score (OR 0.771, 95% CI 0.608-0.978), intravenous recombinant tissue plasminogen activator (OR 2.847, 95% CI 1.098-2.7.385), and poor collateral circulation (OR 3.998, 95% CI 1.572-10.169) were identified as independent risk factors of HT.

Conclusion

ICV asymmetry, likely resulting from impaired autoregulation or tissue micro-perfusion hampering cerebral blood flow (CBF), is a novel radiological sign that independently predicts HT. It is associated with a higher risk of sICH in AIS-LVO patients after EVT. Further research is warranted to validate these findings.

[Venous factor in surgical management of skull base meningiomas]

Skull base venous system is a variable anatomical formation in both health and pathology. Damage to venous structures during surgical treatment of craniobasal meningiomas can lead to formidable postoperative complications, such as hemorrhagic infarctions, cerebral edema and persistent neurological deficit. Despite the improvement of microsurgical techniques, methods of morphological and functional angiography, as well as modeling the mechanisms of compensation for venous hemodynamic disorders, the problem of preventing postoperative venous complications remains relevant.

OBJECTIVE

To analyze available literature data on the role of venous system in surgery for skull base meningiomas and prevention of venous outflow disorders.

MATERIAL AND METHODS

The PRISMA algorithm was used to search for publications on venous complications, venous outflow compensation and prevention of vein damage in skull base meningiomas. The PubMed and Google Scholar databases were reviewed.

RESULTS

Thirty-six manuscripts were assessed. Statistics of venous complications in neurosurgery, venous system reorganization in craniobasal meningiomas, modern methods of X-ray diagnosis and minimization of venous complications during tumor resection are described.

CONCLUSION

Peculiarities of venous hemodynamics in skull base meningiomas are important in planning surgical treatment, as evidenced by many studies in recent years. Improvement of microsurgical techniques and highly informative methods of X-ray diagnosis reduce the likelihood of venous complications in neurosurgery. However, persistent risk of vein damage during resection of craniobasal meningiomas necessitates further improvement of diagnostic and treatment algorithms.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Asymmetric deep cerebral venous filling predicts poor outcome of acute basilar artery occlusion after endovascular treatment

OBJECTIVE

To explore the relationship between asymmetric deep cerebral venous (ADCV) filling and poor outcomes after endovascular treatment (EVT) in patients with acute basilar artery occlusion (ABAO).

METHODS

ABAO patients were selected from a prospectively collected data at our center. The DCV filling was evaluated using computed tomography perfusion (CTP)-derived reconstructed 4D-DSA or mean venous map. ADCV filling was defined as the internal cerebral vein (ICV), thalamostriate vein (TSV), or basal vein of Rosenthal (BVR) presence of ipsilateral filling defects or delayed opacification compared to the contralateral side. Poor prognosis was defined as a modified Rankin scale score >3 at the 90-day follow-up.

RESULTS

A total of 90 patients were enrolled in the study, with a median Glasgow Coma Scale of 6, 46 (51.1%) showed ADCV filling, 59 (65.6%) had a poor prognosis, and 27 (30.7%) had malignant cerebellar edema (MCE). Multivariate adjusted analysis revealed significant associations between asymmetric TSV and poor prognosis (odds ratio, 9.091, p = 0.006); asymmetric BVR (OR, 9.232, p = 0.001) and asymmetric ICV (OR, 4.028, p = 0.041) were significantly associated with MCE.

CONCLUSION

Preoperative ADCV filling is an independent influencing factor for the poor outcome after EVT in ABAO patients.