Cerebral venous anatomy: implications for the neurointerventionalist.

Meaningful contributions to neurointerventional practice may be possible by considering the dynamic aspects of angiography in addition to fixed morphologic information. The functional approach to venous anatomy requires integration of the traditional static anatomic features of the system-deep, superficial, posterior fossa, medullary veins, venous sinuses, and outflow routes into an overall appreciation of how a classic model of drainage is altered, embryologically, or pathologically, depending on patterns of flow-visualization made possible by angiography. In this review, emphasis is placed on balance between alternative venous networks and their redundancy, and the problems which arise when these systems are lacking. The role of veins in major neurovascular diseases, such as dural arteriovenous fistulae, arteriovenous malformations, pulsatile tinnitus, and intracranial hypertension, is highlighted, and deficiencies in knowledge emphasized.

Cerebrovascular Reserve Impairment in the Anterior Cerebral Artery Territory Predicts Deep Temporal Artery Enlargement After Combined Revascularization Surgery in Moyamoya Disease.

OBJECTIVE: A combined surgery of direct and indirect revascularization has been frequently performed in patients with moyamoya disease, though the efficacy of indirect revascularization surgery in adult patients with moyamoya disease has not been established. This study aimed to evaluate superficial temporal artery (STA) and deep temporal artery (DTA) diameters 1 day and 3 months after combined revascularization surgery in patients with moyamoya disease. We also investigated clinical factors related to DTA enlargement after surgery. METHODS: We examined 78 cerebral hemispheres in 57 adult and pediatric patients with moyamoya disease who underwent combined revascularization surgery [STA-MCA bypass and encephalo-duro-myo-synangiosis] in our institution. STA and DTA diameters were measured on axial magnetic resonance angiography images at 1 day and 3 months after surgery. RESULTS: DTA diameter increased in 64 hemispheres (82.1%). DTA diameter increase in association with STA diameter decrease was found in 39 hemispheres (50%). The proportion of hemispheres with a reduction in STA diameter was significantly higher in hemispheres with DTA enlargement than in hemispheres with DTA reduction (P = 0.0088). Among the 64 hemispheres with DTA enlargement, 51 (79.7%) showed cerebrovascular reserve (CVR) impairment in the anterior cerebral artery (ACA) territory before surgery. CVR impairment in the ACA territory was the only clinical factor related to DTA enlargement (P < 0.001). CONCLUSION: The DTA frequently enlarges after combined revascularization surgery, even in adult patients with moyamoya disease. In patients with impaired CVR in the ACA territory, blood supply from the DTA to the ACA territory can be expected after combined revascularization surgery.

[Skull Base Vessel Anatomy].

Knowledge of the arterial and venous anatomy of the skull base is essential to interventional neuroradiologists in assuring a safe procedure. The anatomy of this area is complex and difficult to master in a short period of time. However, knowing some basic rules and starting from basic structures facilitates learning. The author summarized in this article the important vascular structures at the skullbase from the extracranial to intracranial anastomosis and the dural arterial supply. The venous structures involving the cavernous sinus and the structures in the craniocervical junction area are also described. To make this knowledge practical, the final goal is for one to be able to accurately identify these vessels on angiographic images. Anastomoses can be formed when there is a common territory of supply. This fact is important when planning tumor embolization.

Dural venous system: angiographic technique and correlation with ex vivo investigations.

BACKGROUND: The dural vasculature plays a key role in several important conditions, including dural fistulas and subdural collections. While in vivo investigations of intrinsic dural arterial angioarchitecture are rare, no angiographic studies of dural venous drainage exist to our knowledge. OBJECTIVE: To describe methods by which dural venous drainage might be visualized with current angiographic equipment and technique, and to correlate our results with existing ex vivo literature. METHODS: Digital subtraction angiography and 3D angiography (rotational and Dyna CT) of dural neurovasculature were acquired in the context of subdural hematoma embolization and normal dura. Protocols for visualization of dural venous drainage were established, and findings correlated with ex vivo studies. RESULTS: Meningeal arteries supply both the skull and dura. Normal dural enhancement is accentuated by the presence of hypervascular membranes. Intrinsic meningeal veins/sinuses parallel outer layer arteries with well-known tram-tracking appearance. Dura adjacent to main arterial trunks drains via skull base foramina into the pterygopalatine venous plexus, or via emissary veins into the temporalis venous plexus. Dura near the sinuses drains into venous pouches adjacent to the sinus, before emptying into the sinus proper-possibly the same pouches implicated in the angioarchitecture of dural fistulas. Finally, posterior temporoparietal convexity dura, situated in a watershed-like region between middle and posterior meningeal territories, frequently empties into diploic and emissary veins of the skull. Wide variation in balance is expected between these three routes. Drainage patterns appear to correlate with venous embryologic investigations of Padget and ex vivo studies in adults. CONCLUSIONS: Continued attention to dural venous drainage may prove useful in the diagnosis and management of dural-based vascular diseases.

New-generation tyrosine kinase inhibitor-associated asymptomatic cerebrovascular stenosis: two illustrative cases.

New-generation tyrosine kinase inhibitors (TKIs), nilotinib and ponatinib, for chronic myelogenous leukemia (CML) have been reported to cause symptomatic cerebral ischemia. Herein, we report two patients with asymptomatic cerebral artery stenosis associated with these TKIs, as a previously unreported finding. Both patients were in their 40 s and administered new-generation TKIs without vascular risk factors. New-generation TKIs for CML can cause major cerebrovascular stenosis without any symptoms. Examining the neck and intracranial arteries using magnetic resonance angiography and carotid ultrasonography may prevent future cerebral infarctions associated with these TKIs.

Arterial Anatomy of the Parasellar Area.

The arterial anatomy of the parasellar area is complex in that it deals with extracranial-intracranial anastomosis and supply to various cranial nerves in a small area. Pathologies such as hypervascular tumors and shunts are not uncommon and require good knowledge of anatomy in planning the treatment. In this article, the basic anatomy of the arterial supply in this region is discussed, covering the origins, territories, relation to the cranial nerves, and the connections among different systems.

Hemiparesis without Responsible Hematomas in Patients with Subarachnoid Hemorrhage Undergoing Early Aneurysmal Repair.

OBJECTIVE: The presence of hemiparesis on arrival in patients with subarachnoid hemorrhage (SAH) is presumed to affect prognosis; intracranial hematomas with mass effect responsible for hemiparesis are frequently observed in these patients. The aim of this study was to clarify characteristics and outcomes of patients who presented with hemiparesis on arrival with no responsible hematomas (hemiparesis without hematoma) having mass effect demonstrated on computed tomography. METHODS: Consecutive patients with SAH treated with surgery for ruptured cerebral aneurysms within 5 days of onset between 2003 and 2015 were retrospectively reviewed. RESULTS: Hemiparesis without hematoma was present in 25 of 858 surgically treated patients (2.9%). Internal carotid artery aneurysms were significantly more common in patients with hemiparesis without hematoma than in the other patients (P < 0.05). In 19 of 21 surviving patients (90.5%) with hemiparesis without hematoma on arrival, the hemiparesis improved at discharge. Favorable outcomes were achieved in 16 of 25 patients with hemiparesis without hematoma (64%) and in 13 of 59 patients with hemiparesis with hematomas (22.0%); this difference was significant (P < 0.05). CONCLUSIONS: Hemiparesis can be expected to improve in patients with SAH with hemiparesis without hematoma, and such patients appear to have a better prognosis than patients with SAH with hemiparesis and responsible hematomas. A possible major mechanism of hemiparesis without hematoma based on the characteristics identified is a combination of transient ipsilateral hemispheric functional failure caused by the impact of aneurysmal rupture and transient ischemia of the perforators originating from the internal carotid artery.

Preservation of Anterior Choroidal Artery Blood Flow During Trapping of the Internal Carotid Artery for a Ruptured Blood Blister-Like Aneurysm with High-Flow Bypass.

BACKGROUND: The ideal surgery for a blood blister-like aneurysm (BBA) in the internal carotid artery (ICA) involves complete termination of blood flow into the BBA by trapping of the ICA at sites both proximal and distal to the BBA. In the present report, we describe a clipping method with ICA trapping for prevention of anterior choroidal artery ischemia, a major problem in ICA trapping with reconstruction surgery using external carotid artery-middle cerebral artery high-flow bypass (HFB). METHODS: The data from patients with a ruptured BBA treated by the combination of ICA trapping and blood flow reconstruction from 2008 to 2018 were retrospectively evaluated. RESULTS: Fifteen patients had been treated with the combination surgery. Clip placement for ICA trapping depended on the relationship between the distal neck of the BBA and the posterior communicating artery. In the case of the BBA distal neck located at the same level or distal to the posterior communicating artery, oblique placement of a distal clip to the ICA was mandatory to maintain blood flow of the anterior choroidal artery. No patients developed recurrence of the BBA after trapping. The outcomes were assessed using the modified Rankin scale score, with a score of 0 or 1 in 12 of the 15 patients (80%). CONCLUSIONS: A complete shutdown of blood flow to the BBA by ICA trapping is essential for the permanent prevention of BBA recurrence. In cases of a BBA distal neck located distal to the posterior communicating artery, the oblique clipping technique applied to the ICA is useful to prevent ischemic complications of the anterior choroidal artery.

Endovascular treatment of a dural arteriovenous fistula in a patient with Loeys-Dietz syndrome: A case report.

Background Loeys-Dietz syndrome (LDS) is a recently recognized autosomal dominant connective tissue disease. The manifestations of LDS include vascular tortuosity, scoliosis, craniosynostosis, aneurysm and aortic dissections. Clinical presentation A 35-year-old woman treated with Stanford type B aortic dissection and breast cancer was referred to us for Borden type II dural arteriovenous fistula (dAVF) draining to the vein of Galen, involving the midline of tentorium cerebelli. The dAVF was treated successfully by combined transarterial and transvenous embolization. Because of tortuosity of vertebral arteries, a genetic test was conducted confirming LDS type 2. Conclusions To our knowledge, this is the first case report of dAVF associated with LDS. The relationship between LDS and dAVF is unknown but this report shows the possibility that mutation of transforming growth factor ß receptors 2 ( TGFBR2) related to LDS may be related to shunt diseases. Because intervention in LDS seems to be feasible compared to Ehlers Danlos syndrome and Marfan syndrome, it is important to make the correct diagnosis.

Predictors of early vs. late permanent shunt insertion after aneurysmal subarachnoid hemorrhage.

OBJECTIVE: Numerous studies have identified different predictors for secondary hydrocephalus after aneurysmal subarachnoid hemorrhage (SAH), although predictors regarding timing of the shunt operation have never been reported. Predictors for an early shunt, which was defined as a shunt operation performed ≤30 days after SAH onset, and for a late shunt, performed at >40 days, were investigated. METHODS: A total of 735 consecutive SAH patients admitted to our hospital between 2003 and 2014 who underwent surgery for ruptured aneurysms within five days of onset were retrospectively assessed. RESULTS: Secondary hydrocephalus developed in 225 patients, including 70 with an early shunt and 96 with a late shunt. Multivariate analysis showed that predictors for secondary hydrocephalus were age ≥70 years, World Federation of Neurosurgical Society (WFNS) grade IV-V, Fisher grade 3-4, intraventricular hemorrhage, anterior cerebral artery aneurysms, and external drainage for acute hydrocephalus (p < 0.05). In the early and late shunt groups, multivariate analysis indicated that early shunt was significantly associated with coil embolization, and late shunt was correlated with middle cerebral artery aneurysms and cerebral infarction due to vasospasm (p < 0.05). DISCUSSION: The difference in the predictors between the early and late shunts implied that the mechanisms of secondary hydrocephalus differed between the early and late shunt groups. Knowledge of the associated risk factors might help to predict the timing of the shunt operation for early rehabilitation planning in the future.

Developmental Venous Anomaly: Benign or Not Benign.

Developmental venous anomalies (DVAs), previously called venous angiomas, are the most frequently encountered cerebral vascular malformations. However, DVA is considered to be rather an extreme developmental anatomical variation of medullary veins than true malformation. DVAs are composed of dilated medullary veins converging centripetally into a large collecting venous system that drains into the superficial or deep venous system. Their etiology and mechanism are generally accepted that DVAs result from the focal arrest of the normal parenchymal vein development or occlusion of the medullary veins as a compensatory venous system. DVAs per se are benign and asymptomatic except for under certain unusual conditions. The pathomechanisms of symptomatic DVAs are divided into mechanical, flow-related causes, and idiopathic. However, in cases of DVAs associated with hemorrhage, cavernous malformations (CMs) are most often the cause rather than DVAs themselves. The coexistence of CM and DVA is common. There are some possibilities that DVA affects the formation and clinical course of CM because CM related to DVA is generally located within the drainage territory of DVA and is more aggressive than isolated CM in the literature. Brain parenchymal abnormalities surrounding DVA and cerebral varix have also been reported. These phenomena are considered to be the result of venous hypertension associated with DVAs. With the advance of diagnostic imagings, perfusion study supports this hypothesis demonstrating that some DVAs have venous congestion pattern. Although DVAs should be considered benign and clinically silent, they can have potential venous hypertension and can be vulnerable to hemodynamic changes.

Density of the cerebral cortex in computed tomography angiography source images and clinical outcomes in Grade V subarachnoid hemorrhage.

OBJECTIVE: Among patients diagnosed with Grade V subarachnoid hemorrhage (SAH) according to the World Federation of Neurosurgical Societies (WFNS), the identification of those with the possibility of recovery is not feasible, although approximately one-fifth of these patients have favorable outcomes according to a recently published series of surgical papers. We hypothesized that computed tomography angiography (CTA) source images (SIs), which have applied to the detection of acute ischemia, might be useful for selecting Grade V patients with possibilities for favorable outcomes. METHODS: We retrospectively assessed 170 SAH patients who underwent surgery between January 2009 and February 2012 and quantitatively measured their mean cerebral cortical densities from the initial CTA-SIs. RESULTS: The cortical densities of 123 patients of Grades I-IV were strongly affected by the following two CTA-SI findings that were revealed by multivariate analysis: the density of the internal carotid artery (ICA) just proximal to the petrous portion and the ratio of the subarachnoid (SA) space to intracranial volume (P < 0.05). Favorable outcomes were obtained in 9 of the 47 Grade V patients (19.1%), and the predictors of the favorable outcomes according to multivariate analysis were increased cortical densities on the CTA-SIs and female patients (P < 0.05). CONCLUSION: The outcomes of Grade V patients could be partly predicted based on the estimates of cortical density from the CTA-SIs, and this measure might be useful for the selection of Grade V patients for surgery, provided that both ICA density and SA space ratio are confirmed before the evaluation of cortical density.

[Two cases of spontaneous intracranial hypotension associated with chronic subdural hematoma only treated with burr hole irrigation of the hematomas].

We reported two cases of spontaneous intracranial hypotension (SIH) associated with bilateral chronic subdural hematoma (CSDH). The patients presented with severe positional headache, aggravated by sitting or standing. Neither spinal surgery nor lumbar-tap had been performed in these patients. They were diagnosed as SIH with bilateral CSDH. Headache was aggravated and CSDHs volume increased despite conservative therapy. However, after a burr hole irrigation of hematoma, not only CSDHs but also the symptoms with SIH were completely resolved and there was no recurrence. We demonstrated that burr hole irrigation for CSDH associated with SIH might completely resolve the SIH symptom in some cases, as in the present report. The mechanism of this phenomenon was discussed.