Patterns and Rates of Supplementary Venous Drainage to the Internal Jugular Veins

Risk factors for the development of secondary intracranial hypertension in acute cerebral venous thrombosis

PURPOSE

Intracranial hypertension (IH) can complicate cerebral venous thrombosis (CVT), potentially causing permanent visual loss. Current knowledge on risk factors for the development of IH following CVT is scarce. We applied a compound classifier (CSF opening pressure > 25 cmH₂O, papilledema, or optic disc protrusion on MRI) as a surrogate for IH and studied the predictive value of thrombus location, the number of thrombosed segments, and thrombus volume.

METHODS

We prospectively included 26 patients with acute CVT and complete MRI data. IH was defined by CSF opening pressure > 25 cmH₂O, papilledema, or optic disc protrusion on MRI. Using high-resolution contrast-enhanced venography, we determined the thrombus location, number of thrombosed segments, and thrombus volume. We analyzed their association with IH by logistic regression, their predictive power by the area under the receiver operating characteristic curve, and their association with CSF opening pressure by linear regression.

RESULTS

IH occurred in 46% of CVT patients and was associated with higher thrombus volume (AUC 0.759, p = 0.025) and superior sagittal sinus thrombosis both alone (OR 2.086, p = 0.049) and combined with transverse sinus thrombosis (OR 2.014, p = 0.028). Effects in patients presenting CSF opening pressure > 25 cm H₂O and the compound classifier were consistent. Thrombus volume > 4 ml was the single most important predictor of higher CSF opening pressure (ß = 0.566, p = 0.035), increasing IH risk.

CONCLUSION

Larger thrombus volume, dominant transverse sinus occlusion, and extensive superior sagittal combined with transverse sinus thrombosis were associated with IH. Thrombus volumetry might identify patients at risk for IH and direct further clinical evaluation.

Angiographic Evaluation of Cranial Venous Outflow Patterns in Patients With and Without Idiopathic Intracranial Hypertension

BACKGROUND

Several collateral venous pathways exist to assist in cranial venous drainage in addition to the internal jugular veins. The important extrajugular networks (EJN) are often readily identified on diagnostic cerebral angiography. However, the angiographic pattern of venous drainage through collateral EJN has not been previously compared among patients with and without idiopathic intracranial hypertension (IIH).

OBJECTIVE

To quantify EJN on cerebral angiography among patients both with and without IIH and to determine whether there is a different EJN venous drainage pattern in patients with IIH.

METHODS

Retrospective imaging review of 100 cerebral angiograms (50 IIH and 50 non-IIH patients) and medical records from a single academic medical center was performed by 2 independent experienced neuroendovascular surgeons. Points were assigned to EJN flow from 0 to 6 using an increasing scale (with each patient's dominant internal jugular vein standardized to 5 points to serve as the internal reference). Angiography of each patient included 11 separately graded extrajugular networks for internal carotid and vertebral artery injections.

RESULTS

Patients in the IIH group had statistically significant greater flow in several of the extrajugular networks. Therefore, they preferentially drained through EJN compared with the non-IIH group. Right transverse-sigmoid system was most often dominant in both groups, yet there was a significantly greater prevalence of codominant sinus pattern on posterior circulation angiograms.

CONCLUSION

Patients with IIH have greater utilization of EJN compared with patients without IIH. Whether this is merely an epiphenomenon or possesses actual cause-effect relationships needs to be determined with further studies.

Effect of intracranial venous collaterals on neurological outcomes in cerebral venous thrombosis

This study identifies predictors of favourable intracranial venous collaterals and the effect of intracranial venous collaterals on outcomes and recanalization in patients with cerebral venous thrombosis (CVT). Data of 61 patients with CVT were retrospectively reviewed. Venous collateralization was defined as expanded cortical vein formation through different drainage pathways. Recanalization grades were classified into complete or partial recanalization based on images obtained during hospitalisation and follow-up. Independent predictors of collateral formation and poor prognosis were investigated via univariate and binary logistic regression analyses. The effects of different intracranial venous collaterals on recanalization in patients with CVT were assessed. A risk prediction nomogram for prognosis was constructed. Age ≤ 35 years (odds ratio (OR) = 7.067; 95% confidence interval (CI) = 1.776-28.277; P = 0.006) and male sex (OR = 5.490; 95% CI = 1.205-25.004; P = 0.028) were independent predictors of favourable venous collaterals. Venous collaterals were associated with early recanalization (P = 0.017) and not with long-term recanalization (P = 0.252). Male sex (OR = 0.047; 95% CI = 0.003-0.651; P = 0.023), subacute onset (OR = 0.026; 95% CI = 0.002-0.367; P = 0.007), and good collateral grade (OR = 0.168; 95% CI = 0.029-0.985; P = 0.048) were independent factors of favourable neurological outcomes at discharge. Haemorrhage on computed tomography at admission (OR = 10.868; 95% CI = 2.082-56.733; P = 0.005) was inversely correlated with prognosis. These findings suggested that male patients under 35 years of age are more likely to have favourable venous collaterals and good outcomes. Venous collaterals are significantly associated with early recanalization. These findings highlight the importance of venous collateral evaluation in patients with CVT.