Gerasimos Baltsavias

Cranial dural arteriovenous shunts. Part 1. Anatomy and embryology of the bridging and emissary veins

We reviewed the anatomy and embryology of the bridging and emissary veins aiming to elucidate aspects related to the cranial dural arteriovenous fistulae. Data from relevant articles on the anatomy and embryology of the bridging and emissary veins were identified using one electronic database, supplemented by data from selected reference texts. Persisting fetal pial-arachnoidal veins correspond to the adult bridging veins. Relevant embryologic descriptions are based on the classic scheme of five divisions of the brain (telencephalon, diencephalon, mesencephalon, metencephalon, myelencephalon). Variation in their exact position and the number of bridging veins is the rule and certain locations, particularly that of the anterior cranial fossa and lower posterior cranial fossa are often neglected in prior descriptions. The distal segment of a bridging vein is part of the dural system and can be primarily involved in cranial dural arteriovenous lesions by constituting the actual site of the shunt. The veins in the lamina cribriformis exhibit a bridging-emissary vein pattern similar to the spinal configuration. The emissary veins connect the dural venous system with the extracranial venous system and are often involved in dural arteriovenous lesions. Cranial dural shunts may develop in three distinct areas of the cranial venous system: the dural sinuses and their interfaces with bridging veins and emissary veins. The exact site of the lesion may dictate the arterial feeders and original venous drainage pattern.

Cranial dural arteriovenous shunts. Part 3. Classification based on the leptomeningeal venous drainage

The commonly used Borden and Cognard classification systems for the prediction of clinical behavior of cranial dural arteriovenous shunts focus on the venous drainage, particularly the presence of leptomeningeal venous drainage, and on the direction of flow, particularly the presence of retrograde flow. In addition, the latter includes ectasia and spinal drainage as criteria of two distinct grades. However, none of the above classifications (a) differentiates direct from exclusive leptomeningeal venous drainage, (b) considers cortical venous congestion as a factor potentially associated with an aggressive clinical course, and (c) anticipates ectasia in shunts with a mixed dural-cortical venous drainage (type 2). In this study, we analyzed the angiographic images of 107 consecutive patients having a cranial dural arteriovenous fistula with leptomeningeal venous drainage, based on a newly developed scheme. This scheme, symbolized with the acronym “DES,” groups the dural shunts according to three factors: directness and exclusivity of leptomeningeal venous drainage and signs of venous strain. According to the combination of the three factors, eight different groups were distinguished. All analyzed cases could be assigned to one of these groups. Directness of leptomeningeal venous drainage expresses the exact site of the shunt (bridging vein vs sinus wall), whereas exclusivity expresses venous outlet restrictions. All bridging vein shunts had a direct leptomeningeal venous drainage. Almost all bridging vein shunts and all “isolated” sinus shunts had an exclusive leptomeningeal venous drainage. Venous strain, manifested as ectasia and/or congestion, denotes the decompensation of the cerebral venous system due to the shunt reflux. The comparison of the presented concept with the currently used classifications highlighted the advantages of the former and the weaknesses of the latter.

The collateral circulation in pediatric moyamoya disease.

PurposeThe descriptions of collateral circulation in moyamoya have so far been a mixture of topography-based and vessels’ source-based analyses. We aimed to investigate the anatomy and systematize the vascular anastomotic networks in pediatric moyamoya disease.MethodsFrom a series of 25 consecutive complete angiographic studies of newly diagnosed children with moyamoya, 14 children had moyamoya disease and 11 were diagnosed with moyamoya syndrome, i.e., moyamoya angiopathy with some additional concomitant systemic disease. We retrospectively analyzed the arterial branches supplying the moyamoya anastomotic networks, their origin, course, location, and connections with the recipient vessels.ResultsWe describe four types of anastomotic networks in children with moyamoya disease, two superficial-meningeal and two deep-parenchymal. As superficial-meningeal, we defined the leptomeningeal and the durocortical networks. Apart from the previously described leptomeningeal network observed in the convexial watershed zones, we report on the basal temporo-orbitofrontal leptomeningeal network. The second superficial-meningeal network is the durocortical network, which can be basal or calvarian in location. We define as deep-parenchymal networks the nonpreviously described subependymal network and the inner striatal and inner thalamic networks. The subependymal network is fed by the intraventricular branches of the choroidal system and diencephalic perforators, which at the level of the periventricular subependymal zone, anastomose with medullary—cortical arteries as well as with striatal arteries. The inner striatal and thalamic networks are constituted by intrastriatal connections among striatal arteries and intrathalamic connections among thalamic arteries when the disease compromises the origin of one or more sources of their supply.ConclusionThe previously inexplicitly described “moyamoya abnormal network” in pediatric moyamoya disease can be described as a composition of four anastomotic networks with distinct angioarchitecture. A better understanding of the collateralization in moyamoya may help in defining a new staging system of the disease with clinical relevance.

Selective and superselective angiography of pediatric moyamoya disease angioarchitecture in the posterior circulation.

The angioarchitecture of the so-called moyamoya vessels in children has not been explicitly analyzed. We aimed to investigate the precise anatomy of the vascular anastomotic networks in patients with childhood moyamoya disease. Six children diagnosed with moyamoya disease for the first time underwent an angiographic investigation with selective and superselective injections. We recorded the arterial branches feeding the moyamoya anastomotic networks, their connections and the recipient vessels. Depending on the level of the steno-occlusive lesion, the feeding vessels included the medial striate arteries, the perforators of the choroidal segment of the carotid, the uncal artery, the medial and lateral branches of the intraventricular segment of the anterior choroidal artery, perforators of the communicating segment, the superior hypophyseal arteries, the prechiasmal branches of the ophthalmic artery, the ethmoidal arteries and the dural branches of the cavernous carotid. Through connections, which are described, the recipient vessels were the lateral striate arteries and the middle cerebral, the medial striate arteries and the anterior cerebral, medullary arteries around the ventricular system, anterior temporal branches of the middle cerebral, orbitofrontal and frontopolar branches of the anterior cerebral, as well as other cortical branches of the anterior and middle cerebral territories. The use of high quality selective and superselective angiography enabled us to clearly demonstrate for the first time aspects of the microangiographic anatomy of the moyamoya anastomotic network previously only vaguely or incompletely described.

Silicone models as basic training and research aid in endovascular neurointervention-a single-center experience and review of the literature

The rapid development and wider use of neurointerventional procedures have increased the demand for a comprehensive training program for the trainees, in order to safely and efficiently perform these procedures. Artificial vascular models are one of the dynamic ways to train the new generation of neurointerventionists to acquire the basic skills of material handling, tool manipulation through the vasculature, and development of hand-eye coordination. Herein, the authors present their experience regarding a long-established training program and review the available literature on the advantages and disadvantages of vascular silicone model training. Additionally, they present the current research applications of silicone replicas in the neurointerventional arena.

Ventriculoatrial Shunts in Adults, Incidence of Infection, and Significant Risk Factors: A Single-Center Experience

BACKGROUND In recent years, the number of ventriculoatrial (VA) shunt insertions has decreased worldwide, the major cause being the risk of shunt infection. VA shunts remain as an alternative option to ventriculoperitoneal shunts. We describe our 10-year experience with VA shunts by analyzing the incidence of shunt infections and predisposing cofactors. METHODS During a median follow-up of 15.3 months, 259 shunt insertions, performed on 255 patients, were analyzed. The infection rate was calculated and the predisposing cofactors age, gender, cause of the hydrocephalus, previous external ventricle drainage, antibiotic-impregnated catheters, the number of revisions, the educational level of the surgeons, and the duration of the operations were analyzed. Two observation times were stratified. RESULTS We found overall infections in 18 patients (7.1%), 16 deep infections (6.3%) including 1 shunt nephritis (0.4%) and 2 superficial infections (0.8%). Wound dehiscence occurred in 17 patients (6. 6%). Analyzing follow-up time, the infection rate was 3.65% (95% confidence interval, 0.9%-5.9%) at survival time 1, 3.38% (95% confidence interval, 1.1%-6.2%) at survival time 2. In the first 6 months, 95% of patients were free of infection. Only the number of revision procedures was associated with the number of infections (P value < 0.0005). CONCLUSIONS In our patient cohort, the infection rate related to VA shunt insertion is low; the only statistically significant risk factor was the number of revisions. If the VA shunt is applied following a standardized protocol, the infection risk does not represent an argument for reluctance towards the VA draining concept.

Persistent ventral ophthalmic artery associated with supraclinoid internal carotid artery aneurysm: Case report and review of the literature

A persistent ventral ophthalmic artery arising from the A1 segment of the anterior cerebral artery associated with an ipsilateral asymptomatic supraclinoid internal carotid artery (ICA) aneurysm is extremely rare. This variation and association were thoroughly documented by digital substraction angiography (DSA) and 3-dimensional rotational angiography (3DRA) in a 49-year-old female with polycystic kidney disease. A short review of the related literature is also presented.

Intra-arterial administration of papaverine during mechanical thrombectomy for acute ischemic stroke.

BACKGROUND The use of stent retrievers for mechanical thrombectomy in acute ischemic stroke may induce significant vasospasm, which at the early phases of reperfusion may be crucial for rethrombosis of the recanalized vessel. We aimed to study whether the use of intra-arterial papaverine in selected cases of vasospasm was associated with improved cerebral perfusion, arterial reocclusion, or increased hemorrhagic complications. METHODS We retrospectively studied 9 consecutive patients with large artery acute occlusion, treated with stent retriever and intra-arterial papaverine. Onset to administration of intravenous recombinant tissue-plasminogen activator time, baseline National Institute of Health Stroke Scale, time to reperfusion, number of passes of the stent retriever, modified Rankin Scale score at discharge, postprocedural hemorrhage, onset to reperfusion time, papaverine dose, and thrombolysis in cerebral infarction grade were recorded in all patients. RESULTS After papaverine administration, the caliber of the infused arteries and their flow was increased in all cases. In none of the treated cases a reocclusion occurred after papaverine infusion. In one of the studied patients (11%), a parenchymal bleeding occurred 36 hours postoperatively. CONCLUSIONS This small study suggests that intra-arterial infusion of papaverine for the treatment of cerebral vasospasm after mechanical thrombectomy in acute ischemic stroke is effective and safe.

Complications of Sigmoid Sinus Transvenous Occlusion for the Endovascular Treatment of Dural Arteriovenous Shunts with Emphasis on Inner Ear Dysfunction.

OBJECTIVE Embolization of cranial dural sinus arteriovenous fistulae with transvenous occlusion of the involved sinuses is an established strategy when the collateral brain drainage allows it. We aimed to investigate the frequency and types of complications after endovascular occlusion of the sigmoid sinus. METHODS From our database, we detected 52 endovascularly treated consecutive cases of cranial dural arteriovenous shunts involving the sigmoid sinus. The cases treated through the transvenous approach alone or combined with the transarterial one were analyzed retrospectively. Previously reported series and cases were reviewed and critically analyzed. RESULTS In 15 cases, a transvenous approach was used and in 4 combined a transvenous approach with a transarterial approach. Two patients (13.3%) both treated with the transvenous approach alone presented postoperatively with vertigo and hearing loss. In the first case, the sinus occlusion involved the whole sigmoid sinus, whereas in the second case the occlusion was restricted to a parallel channel posteriorly to the proximal segment of the sigmoid sinus. Magnetic resonance imaging and ear, nose, and throat investigations failed to elucidate the cause and pathomechanism of these symptoms. No other complications occurred. CONCLUSIONS Although the transvenous occlusion of the sigmoid sinus generally is a safe therapeutic option for the treatment of dural arteriovenous fistulae, inner ear dysfunction is still a possible complication. The combined analysis of the reported and our cases did not allow a plausible explanation of this complication and its pathomechanism remains obscure.

Missed Anterior Inferior Cerebellar Artery Aneurysm Mimicking Vestibular Neuritis—Clues to Prevent Misdiagnosis

We discuss a case with combined vestibulocochlear and facial neuropathy mimicking a less urgent peripheral vestibular pattern of acute vestibular syndrome (AVS). With initial magnetic resonance imaging read as normal, the patient was treated for vestibular neuropathy until headaches worsened and a diagnosis of subarachnoid hemorrhage was made. On conventional angiography, a ruptured distal right-sided aneurysm of the anterior inferior cerebellar artery was diagnosed and coiled. Whereas acute vestibular loss usually points to a benign peripheral cause of AVS, combined neuropathy of the vestibulocochlear and the facial nerve requires immediate neuroimaging focusing on the cerebellopontine angle. Imaging should be assessed jointly by neuroradiologists and the clinicians in charge to take the clinical context into account.