Effect of different surgical positions on the cerebral venous drainage: a pilot study using healthy volunteers.

Excessive neck flexion and rotation in certain surgical positions may cause kinking of the internal jugular vein that obstructs cerebral venous blood flow and results in elevated intracranial pressure. The objective of this study was to measure internal jugular vein flow and identify potential impediments to venous flow in supine, prone, and park bench positions using non-anaesthetised volunteers. Twenty-seven volunteers were recruited. Venous flow rate was derived from ultrasound measurements of the vessel cross-sectional area and flow velocity. Change from supine to prone position produced a significant increase in both jugular vein cross-sectional areas without affecting venous flows. In the right park bench position, the right internal jugular vein cross-sectional area decreased from 1.2 to 0.9 cm(2) (p = 0.027) without substantive changes in mean venous flow rate (p = 0.91) when compared with supine. In summary, the internal jugular vein flow was not compromised by either prone or park bench positions in non-anaesthetised volunteers, and careful positioning may prevent kinking of the jugular vein. Further studies in anaesthetised and ventilated patients are needed to validate these results for clinical practice.

Chronic Influences of Obstructive Sleep Apnea on Cerebral Venous Flow.

OBJECTIVES: Evidence reveals a pathophysiologic link between sleep apnea syndrome and cerebrovascular diseases. It is known that obstructive sleep apnea (OSA) may cause serial hemodynamic changes and structural abnormalities in the cerebral and cardiac arterial systems, but its effect on the cerebral venous system has remained unclear. The purpose of this study was to compare internal jugular vein hemodynamics between patients with OSA and healthy individuals. METHODS: Patients with OSA and age-, body mass index-, and sex-matched healthy control participants were recruited for a jugular venous duplex study and neurologic examination. The luminal area of the internal jugular vein, jugular venous flow volume, time-averaged mean velocity, and presence of jugular venous reflux were recorded. These flow characteristics were obtained at different respiratory statuses, and we analyzed the differences between patients and controls. RESULTS: In the OSA group, there was an increasing flow volume in total internal jugular veins at rest. The frequency of venous reflux in patients compared with controls was significantly decreased (26.7% versus 53.3%, respectively; P < .05). The internal jugular vein drainage dominance was greater on the left side in the OSA group (right versus left: 48.8% versus 51.2%), whereas it was greater on the right side in the control group (right versus left: 61.7% versus 38.3%). CONCLUSIONS: Our data showed peculiar internal jugular vein hemodynamics at baseline and different respiratory statuses in patients with OSA. These characteristics imply that cerebral venous drainage conditions might be involved in the pathophysiologic mechanisms of OSA syndrome.

A Case of Cavernous Sinus Dural Arteriovenous Fistula Draining Solely to the Superior Ophthalmic Vein with Normal Cerebral Venous Flow from the Superficial Middle Cerebral Vein to the Inferior Petrosal Sinus due to a Septum in the Cavernous Sinus.

Objective: We report here an atypical case of cavernous sinus dural arteriovenous fistula (CSDAVF) with a septation that separates the cavernous sinus (CS) into two components, namely, normal cerebral venous drainage and shunted blood drainage into the superior ophthalmic vein (SOV) alone. The CSDAVF was successfully treated by selective transvenous embolization (TVE) through the septum with the trans-inferior petrosal sinus (IPS) approach. Case Presentation: A 74-year-old woman presented with right exophthalmos and tinnitus on the right side. Neuroradiological examination showed CSDAVF mainly supplied by multiple feeders from the bilateral ascending pharyngeal artery and meningohypophyseal trunk with a shunted pouch located medial-dorsally to the right CS. Blood from the CSDAVF drained via the anterior component of the CS to the right SOV only. Normal cerebral venous blood from the right superficial middle cerebral vein drained through the dorsolateral component of the right CS into the right IPS. These findings suggest that a septal barrier exists between the outflow tract of the dural arteriovenous fistula and the normal cerebral venous outflow tract within the CS. The CSDAVF was successfully treated by selective TVE through the septum with the trans-IPS approach after detailed evaluation of 3D rotational angiography (3DRA) and MRA/MR venography (MRV) cross-sectional images. The patient's symptoms improved, and she was discharged uneventfully. Conclusion: Septation within the CS can completely separate the drainage route of the CSDAVF from the normal cerebral drainage route. Successful catheterization to the shunted pouch through the septum with the IPS approach and selective embolization were possible with detailed evaluation of anatomy on MRA/MRV cross-sectional images and 3DRA images.

The manifestation of vortical and secondary flow in the cerebral venous outflow tract: An in vivo MR velocimetry study.

Aberrations in flow in the cerebral venous outflow tract (CVOT) have been implicated as the cause of several pathologic conditions including idiopathic intracranial hypertension (IIH), multiple sclerosis (MS), and pulsatile tinnitus (PT). The advent of 4D flow magnetic resonance imaging (4D-flow MRI) has recently allowed researchers to evaluate blood flow patterns in the arterial structures with great success. We utilized similar imaging techniques and found several distinct flow characteristics in the CVOT of subjects with and without lumenal irregularities. We present the flow patterns of 8 out of 38 subjects who have varying heights of the internal jugular bulb and varying lumenal irregularities including stenosis and diverticulum. In the internal jugular vein (IJV) with an elevated jugular bulb (JB), 4Dflow MRI revealed a characteristic spiral flow that was dependent on the level of JB elevation. Vortical flow was also observed in the diverticula of the venous sinuses and IJV. The diversity of flow complexity in the CVOT illustrates the potential importance of hemodynamic investigations in elucidating venous pathologies.

Early diagnosis and management of cerebral venous flow obstruction secondary to transsinus fracture after traumatic brain injury.

BACKGROUND AND PURPOSE: Cerebral venous flow obstruction (CVFO) is a fatal complication of traumatic brain injury. To compare the outcomes of patients with CVFO secondary to traumatic-brain-injury-induced transsinus fracture who were diagnosed early versus those diagnosed late in the therapeutic course. METHODS: In total, 403 patients with transsinus fracture were reviewed retrospectively. The patients were divided into an early-diagnosis group (n=338) and a delayed-diagnosis group (n=65). The patients submitted to 2D time-of-flight magnetic resonance venography (2D-TOF MRV) and/or CT venography (CTV), depending upon the findings of intracranial pressure monitoring, in order to identify potentially complicated CVFO. These examinations took place within 3 days of the onset of malignant intracranial hypertension symptoms in the early-diagnosis group, and after an average of 7 days in the delayed-diagnosis group. Once diagnosed, patients received intravenous thrombolytic therapy with low-dose urokinase. Patients with massive transsinus epidural hematoma, depressed fracture, or cerebral hernia were treated surgically to relieve the compression and repair any damage to the venous sinuses. RESULTS: Cerebral venous flow obstruction was much more severe in the delayed-diagnosis group than in the early-diagnosis group (p<0.001), and hence patients in the former group were given a higher dose of urokinase (p<0.001) for thrombolytic therapy. They were also significantly more likely to need surgery (48.1% vs. 20.6%, p=0.003) and had a higher mortality rate (37.0% vs. 4.1%, p<0.001). However, patients in both groups experienced a similarly favorable prognosis, not only with regard to functional outcome but also with respect to neuroradiological improvement, as evaluated by 2D-TOF MRV/CTV at the final follow-up (p=0.218). CONCLUSIONS: Delayed diagnosis can result in increased risk of surgery and death in the acute phase. Thrombolytic therapy with low-dose urokinase resulted in promising improvements in both functional and neuroradiological outcomes in all of the patients in this study, regardless of the time to diagnosis.