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Normal Perfusion Pressure Breakthrough Theory
... Experimental models have been used for decades in several brain vascular diseases as stroke and cerebral aneurysms [8] and their contribution has had a tremendous impact in the understanding of the pathophysiology and molecular mechanisms through basic sciences research and therapeutic drug and device development. Since the beginnings of bAVM treatment, physicians began looking for models that could allow development, testing and training in new therapeutic tools and acquiring knowledge to improve the understanding of the disease [9]. Because of their complex structure and physiology, it has been challenging to adequately replicate a bAVM in an in vivo or in vitro model. ...
... The first model developed for bAVM was created by the group of Dr. Robert Spetzler [9] to study and emulate the chronic hemodynamic effects of bAVM in the surrounding tissue. For this purpose, they created a vascular anastomosis between the common carotid artery and the external jugular vein in cats, generating an AV shunt using the circle of Willis (Fig. 3). ...
... Main division of in vivo or in vitro, and the specific models with their publication's total number and frequency (%). [9]. A surgical anastomosis between the common carotid artery and the caudal external jugular vein, creating a right to left shunt using the circle of Willis. ...
Background
Brain arteriovenous malformations (bAVM) are one of the most complex vascular lesions in humans. Their understanding and treatment have been possible through the use of different experimental models. The aim of this scoping review was to systematically map the existing experimental models used for bAVM research and training.
Methods
A scoping review was conducted, and a search process was performed in 8 electronic databases from inception to April 30th, 2020. Study selection included all types of research articles that used any kind of experimental model for AVM study. Selection and data extraction were performed by independent reviewers.
Results
The initial search retrieved 954 articles which were reduced to 177 articles after the whole inclusion / exclusion process. We identified 9 main AVM experimental models, divided in in vivo: transgenic, rete mirabile, carotid-jugular fistula, carotid-jugular plexus fistula, arteriovenous shunt and cornea; or in vitro: 3D cast, computer generated and biological graft. First developed models were dedicated to study the hemodynamic effects and then followed by endovascular testing using the swine rete mirabile. The latest developments have come with transgenic models, allowing the manipulation and creation of AVMs in rodent brains, giving a huge step in the understanding of genetic origin, angiogenic mechanisms or potential therapeutic targets for the future.
Conclusions
There is no unique model that could account for all features of bAVM. We expect a continuous development of more accurate models that could lead to optimize and develop new treatment strategies for increasing the cure rate of this disease.
... In the current trend, total intravenous anesthesia is preferred, due to its pharmacokinetic and pharmacodynamic characteristics, within which cerebral vasomotor tone is preserved, better coupling flowmetabolism, vasoreactivity to carbon dioxide and less vasodilation. 25 It is considered that controlled ventilation in general anesthesia procedures reduces the risk of potential movement of the patient in the critical periods of the procedure, this in turn facilitates visualization of the cerebral vessels and control in the injection of embolic material. In addition to this, controlled hypotension would reduce the flow through the fistula. ...
... Avoiding periods of hypertension is critical to reduce episodes of intraoperative rupture and thus avoid intracerebral edema and hemorrhage. 25,26 As a perioperative objective in these procedures, maintenance of normotension or controlled hypotension is recommended, maintaining between 15-20% below the patient's initial blood pressure, although a high level of evidence has been found, this suggestion is supported by current evidence, 25,27-30 so routine monitoring should be complemented with invasive monitoring of systemic blood pressure. The use of a central venous catheter is considered in case of comorbidities and its placement is justified for the use of vasopressor infusions during the procedure. ...
Arteriovenous fistulas correspond to a rare type of cerebral vascular malformation, consisting of a direct connection between the meningeal arteries and the dural venous sinuses or leptomeningeal veins. They represent between 10-15% of cerebral vascular malformations. The main clinical picture of presentation is incidental, however, the symptoms can vary from mild symptoms such as tinnitus to cerebral hemorrhage. The formation of this systemic entity is attributable to different factors, among which are the release of proangiogenic factors, increased microthrombotic activity, increased expression of fibroblast growth factor and endothelial growth factor. The first-line diagnostic method is computed tomography, the gold standard is digital subtraction angiography.
... The carotid-jugular fistula (CJF) model is one of the first models created to study AVMs [37,38]. Spetzler and colleagues pioneered this model to investigate the Normal Perfusion Pressure Breakthrough (NPPB) theory, a phenomenon linked to swelling and hemorrhage in brain tissue surrounding AVM lesions post-surgery [56]. This model was developed in cats and involved an anastomosis between the common carotid artery (CCA) and the external jugular vein (EJV). ...
... This model was developed in cats and involved an anastomosis between the common carotid artery (CCA) and the external jugular vein (EJV). This anastomosis allowed for non-infarction cerebral hypoperfusion due to retrograde blood flow from the circle of Willis [56]. However, other researchers have found minimal and transient cerebrovascular hemodynamic changes through the CJF formation [57,58], suggesting this model might not fully elucidate NPPB mechanisms. ...
Arteriovenous malformation (AVM) is an anomaly of blood vessel formation. Numerous models have been established to understand the nature of AVM. These models have limitations in terms of the diameter of the vessels used and the impact on the circulatory system. Our goal was to establish an AVM model that does not cause prompt and significant hemodynamic and cardiac alterations but is feasible for follow-up of the AVM’s progression. Sixteen female rats were randomly divided into sham-operated and AVM groups. In the AVM group, the saphenous vein and artery were interconnected using microsurgical techniques. The animals were followed up for 12 weeks. Anastomosis patency and the structural and hemodynamic changes of the heart were monitored. The hearts and vessels were histologically analyzed. During the follow-up period, shunts remained unobstructed. Systolic, diastolic, mean arterial pressure, and heart rate values slightly and non-significantly decreased in the AVM group. Echocardiogram results indicated minor systolic function impact, with slight and insignificant changes in aortic pressure and blood velocity, and minimal left ventricular wall enlargement. The small-caliber saphenous AVM model does not cause acute hemodynamic changes. Moderate but progressive alterations and venous dilatation confirmed AVM-like features. The model seems to be suitable for studying further the progression, enlargement, or destabilization of AVM.
... 5 While treatment efforts have progressed from reliance on surgical resection to endovascular approaches (eg, glue embolization or coiling) and stereotactic radiosurgery, it was only 44 years ago that the pathology was first modeled in the laboratory. 6 Prior to the design of a synthetic anastomosis coupled with vessel ligation by Spetzler et al, were largely based on embolization or study of the normal cerebrovascular anatomy. The animal and early genetic models have been reported on at length and numerous times across the literature, but novel developments spanning the previous decade have ushered in a technological revolution of vascular modeling that warrant discussion and analysis. ...
... [14][15][16] It was only under the direction of Spetzler et al that a functional model of brain AVM was developed. 6 This novel, feline model, was based on an anastomosis between the rostral CCA and either the caudal internal jugular vein or external jugular vein (EJV). The AV shunt formed the basis for numerous future models relying on retrograde flow through a carotid jugular (fistula) anastomosis ( Figure 2A). ...
BACKGROUND
Research of William Hunter's hypothesized (then discovered) arteriovenous varix (now arteriovenous malformation [AVM]) has developed exponentially over the previous quarter‐millennium. Virchow and Luschka's subsequent contributions (nearly 100 years later) by identifying an AVM of the brain and its congenital nature were 2 of the first significant developments made in the field. AVMs present as an erroneous connection (known as a fistula) between an artery and a vein that bypasses the capillary circulation. The arteries and arterioles contributing to the malformation are known as feeders which connect to the draining veins via a plexiform vascular network known as a nidus. Prior to the design of a synthetic anastomosis coupled with vessel ligation by Spetzler et al, animal models were largely based on embolization or study of the normal anatomy. The animal and early genetic models have been reported on at length and numerous times across the literature, but novel developments spanning the previous decade have ushered in a technological revolution of vascular modeling that warrants discussion and analysis.
METHODS
Parameterization of a PubMed query to include all literature including the words “brain,” “arteriovenous malformation,” and “model” yielded 489 articles. After extraction of relevant literature and full‐text screening, 41 articles were chosen for detailed review.
RESULTS
Technological innovations outside of neurosurgery have greatly impacted the development of novel AVM models in the form of 3D flow models printed into silicon models and combined with advanced imaging technology such as 4D flow magnetic resonance imagin. Technological developments in preservation solutions, catheterization tools, and imaging technologies have also allowed for advent of the cerebrovascular placental model for testing of treatments such as radiosurgery, glue embolization, coiling, as well as histological assessment of tissue directly after intervention.
CONCLUSION
We review the breadth of AVM models in the literature over the last almost 5 decades.
... The high-flow arterial blood entering the low-flow venous system can cause venous hypertension, leading to venous dilatation and an increased risk of hemorrhage. Additionally, the lack of a capillary bed within the AVM disrupts the normal oxygen and nutrient exchange between arteries and veins, further contributing to tissue hypoxia and ischemia [5]. Furthermore, AVMs can trigger a phenomenon known as "steal", where the abnormal shunting of blood through the malformation diverts blood flow away from surrounding brain tissue, potentially causing neurological deficits. ...
Arterial spin labeling (ASL) has emerged as a promising noninvasive tool for the evaluation of both pediatric and adult arteriovenous malformations (AVMs). This paper reviews the advantages and challenges associated with the use of ASL in AVM assessment. An assessment of the diagnostic workup of AVMs and their variants in both adult and pediatric populations is proposed. Evaluation after treatments, whether endovascular or microsurgical, was similarly examined. ASL, with its endogenous tracer and favorable safety profile, offers functional assessment and arterial feeder identification. ASL has demonstrated strong performance in identifying feeder arteries and detecting arteriovenous shunting, although some studies report inferior performance compared with digital subtraction angiography (DSA) in delineating venous drainage. Challenges include uncertainties in sensitivity for specific AVM features. Detecting AVMs in challenging locations, such as the apical cranial convexity, is further complicated, demanding careful consideration due to the risk of underestimating total blood flow. Navigating these challenges, ASL provides a noninvasive avenue with undeniable merits, but a balanced approach considering its limitations is crucial. Larger-scale prospective studies are needed to comprehensively evaluate the diagnostic performance of ASL in AVM assessment.
... 12,13,[15][16][17] Rapid enlargement of AVMs has also been shown to lead to ischemic symptoms in patients. 18,19 Based on our patient's negative brain imaging 8 years prior, we suspect the AVM formed de novo and conceivably enlarged rapidly, resulting in a steal syndrome. This central disturbance may have contributed to the patient's autonomic symptoms, which are thought to be related to centrally mediated thermoregulation dysfunction and irregularity of impulses in a motor neuron pool. 2 The precise location of the patient's AVM may explain the motor deficit and pain syndrome observed. ...
BACKGROUND
Complex regional pain syndrome (CRPS) is typically described as a peripheral nerve disorder in which exaggerated allodynia and hyperalgesia follow a minor injury. Some researchers propose a central mechanism, although current evidence is lacking.
OBSERVATIONS
A 14-year-old female presented with classic CRPS symptoms of left upper-extremity weakness and hyperalgesia after a bout of sharp pain in her thumb while shoveling snow. A possible seizure prompted magnetic resonance imaging, revealing a right frontal Spetzler-Martin grade II arteriovenous malformation (AVM) adjacent to the primary motor cortex. Brodmann areas 1, 3a, and 3b, which are responsible for localizing and processing burning and painful sensations, were also involved. The patient underwent transarterial Onyx embolization in two sessions and microsurgical resection, after which her CRPS symptoms completely resolved.
LESSONS
To our knowledge, this is the first reported case of a cerebral AVM presenting as CRPS, which supports a central mechanism. The authors propose that rapid growth of the AVM led to a vascular steal phenomenon of surrounding parenchyma, which disrupted the patient’s normal motor function and nociceptive processing. Further validation in other series is needed.
... Meyer et al. urge caution at the adoption of OHT, as cortical oxygen saturation measured using microspectrophotometry is greatest in brain tissue with angiographic evidence of arterial stagnation following AVM resection [49]. Staged deconstruction of arterial feeders can gradually decrease BAVM flow and decrease the likelihood of complications related to normal perfusion pressure breakthrough [62,63,7]. However, compounded risk for repeat intervention, inaccessibility of deep arterial feeders, and incomplete understanding of BAVM autoregulatory physiology may favor shorter interval for attempted BAVM cure. ...
Recent evidence has demonstrated a close relationship between the cerebral venous and lymphatic systems. Venous congestion has been implicated in a host of neurologic disorders, with relevance for vascular etiologies. Objective: The authors aim to review the literature as it pertains to brain arteriovenous a a (BAVM) a a a a a , a a implications of BAVM treatment. Results: BAVMs offer a unique challenge, with sudden alteration in flow dynamics leading to increased hemorrhage risk and difficult challenges post-treatment. Conclusion: Recent progress in the understanding of CNS fluid dynamics and glymphatic pathways have revealed important implications for BAVM pathology and treatment. As imaging techniques and treatment modalities advance, there is a need to further investigate this relationship as it relates to therapeutic options and post-treatment sequalae.
... La descompresión quirúrgica permite que el flujo sanguíneo cerebral vuelva a los valores normales. Por lo tanto, parece razonable plantear la hipótesis de que la restauración repentina de la presión de perfusión normal en áreas de autorregulación vascular cerebral defectuosa debido a la inflamación subcortical subyacente a la compresión de la superficie, la impedancia focal del drenaje venoso o la pérdida isquémica de la reactividad del CO2, podría a su vez conducir al daño vascular que resultó en hemorragia intraparenquimatosa (15) . Ogasawara, et al. (16) , describió el síndrome de hiperperfusión, después del drenaje del hematoma subdural, que se presenta con delirio temporal y alteraciones del flujo sanguíneo en el PET CT y debe considerarse como parte del riesgo de una hemorragia cerebral remota (16) . ...
Introducción: La hemorragia intracerebral remota es una complicación neuroquirúrgica poco frecuente, ocurre en el 18% de los procedimientos intracraneales y aún menos en la cirugía de columna. Presentación de caso clínico: Un hombre de 89 años con un hematoma subdural derecho, que se sometió a un drenaje por craneotomía, en la tomografía de control presentó un hematoma intraparenquimatoso occipito temporal izquierdo y hemorragia intraventricular. Conclusión: Algunas teorías que han tratado de explicar las causas de la hemorragia intracerebral remota, el síndrome de hiperperfusión, la hipertensión, la angiopatía amiloide, el infarto venoso o el uso de anticoagulantes orales.
... Endovascular embolization, microsurgery, and radiosurgery have been used to prevent hemorrhage [1,3,4], but no comprehensive reports have clarified the treatment for pelvic AVM. Even after embolization, rare hemorrhage has occurred in the cerebrovascular field [4][5][6][7]. However, this has not been reported in pelvic AVM. ...
We treated a 64-year-old man who had an inferior mesenteric arteriovenous malformation with multiple shunts. As multiple varicosities in the draining vein became enlarged, two dilated shunts on the superior rectal and sigmoid colon arteries were coil embolized. Two days after embolization, a varicosity near the shunt (65 mm diameter) ruptured, causing intra-abdominal hemorrhage and surgical hemostasis. There were thrombi in the ruptured varicosity and its draining vein. The likely cause was a pressure increase in the incompletely thrombosed varicosity due to shunt blood flow from the remaining shunts after embolization.
... The blood pressure in the postoperative course can also influence the treatment outcome. For example, postoperative increases in blood pressure can lead to neurological deterioration with cerebral oedema, based on the Normal Perfusion Pressure Breakthrough Theory [36]. This has been investigated and addressed in various publications [15,22,24,27], but was not the aim of our study. ...
Background
Resection of cerebral arteriovenous malformations (AVM) is technically demanding because of size, eloquent location or diffuse nidus. Controlled arterial hypotension (CAH) could facilitate haemostasis. We performed a study to characterize the duration and degree of CAH and to investigate its association with blood loss and outcome.
Methods
We retrospectively analysed intraoperative arterial blood pressure of 56 patients that underwent AVM-resection performed by the same neurosurgeon between 2003 and 2012. Degree of CAH, AVM size, grading and neurological outcome were studied. Patients were divided into two groups, depending on whether CAH was performed (hypotension group) or not (control group).
Results
The hypotension group consisted of 28 patients, which presented with riskier to treat AVMs and a higher Spetzler-Martin grading. CAH was achieved by application of urapidil, increasing anaesthetic depth or a combination thereof. Systolic and mean arterial blood pressure were lowered to 82 ± 7 and 57 ± 7 mmHg, respectively, for a median duration of 58 min [25% percentile: 26 min.; 75% percentile: 107 min]. In the hypotension group, duration of surgery (4.4 ± 1.3 h) was significantly ( p < 0.001) longer, and median blood loss (500 ml) was significantly ( p = 0.002) higher than in the control group (3.3 ± 0.9 h and 200 ml, respectively). No case fatalities occurred. CAH was associated with a higher amount of postoperative neurological deficits.
Conclusions
Whether CAH caused neurological deficits or prevented worse outcomes could be clarified by a prospective randomised study, which is regarded as ethically problematic in the context of bleeding. CAH should only be used after strict indication and should be applied as mild and short as possible.
... More specifically, packing the venous collector of the VGAM with embolic material through a transvenous approach may successfully shut down the arteriovenous connections draining into it but will also impair the flow of the deep veins potentially ending into the venous collector. The deep venous ischemia combined with the local increase in arterial blood pressure taking place after rapid and complete obliteration of the arteriovenous shunts [similar to the normal perfusion breakthrough phenomenon described by Spetzler et al. [83]] can explain the hemorrhagic transformation in these deep venous infarcts [16]. ...
Introduction
Vein of Galen malformations (VOGMs) represent a rare, congenital pathologic entity with often catastrophic natural history. The advances in endovascular treatment in recent years have allowed for a paradigm shift in the treatment and outcome of these high-flow shunts even though their pathogenetic mechanisms of formation and evolution remain in part obscure.
Areas covered
The overall management of VOGMs requires a tailored case-to-case approach, starting with in utero detection and reserving endovascular treatment for indicated cases. . Lately, the advances in translational research with whole-genome sequencing and the coupling with cellular-level hemodynamics attempt to shed more light in the pathogenesis and evolution of these lesions. At the same time the advances in endovascular techniques allow for more safety and tailored technical strategy planning. Furthermore, the advances in MRI techniques allow a better understanding of their vascular anatomy. In view of these recent advances and by performing a PUBMED literature review of the last 15 years, we attempt a review of the evolutions in the imaging, management, endovascular treatment and understanding of underlying mechanisms for VOGMs.
Expert opinion
The progress in the fields detailed in this review appears very promising in better understanding VOGMs and expanding the available therapeutic arsenal.
... -Normal perfusion pressure breakthrough [14,15] -Occlusive hyperemia [16] -Venous engorgement [17][18][19] The Normal perfusion pressure breakthrough theory is a term coined by Spetzler in 1978. He used it to indicate a postoperative hyperemia responsible for hemorrhagic infarction. ...
In AVM surgery perioperative complications can arise and can have serious perioperative consequences. Surgically related complications in AVM treatment, in many cases, can be avoided by paying attention to details:
1. Careful selection of the patient: - addressing a patient with eloquent AVM to Gamma Knife treatment - preoperative treatment with selective embolization of the accessible deep feeders - preoperative gamma knife or embolize those patient with an over-expressed venous pattern
2. Meticulous coagulation of deep medullary feeders: - Using dirty coagulation - Using dry non-stick coagulation - Using micro clips - Using laser - Reaching the choroidal vessel in the ventricle when possible - Avoiding occlusive coagulation with hemostatic agents
3. Check and avoiding any residual of the AVM
4. Keep the patient under pressure control during postoperative period
Fulfilling these steps contributes to reduce complications in this difficult surgery, leading to a safer treatment that compares favorably with natural history of brain arteriovenous malformations.
... The arterial pressure should be kept at 20% below baseline following embolization, as rapid changes in perfusion pressure across vasculature with impaired autoregulatory function can result in hyperemia, swelling, and hemorrhage. "Normal perfusion pressure breakthrough" is used to describe this phenomenon of hyperemia and edema, attributing it to reperfusion of previously chronically ischemic brain parenchyma following nidal embolization, which may be minimized by staging procedures [33]. Steroids may be required to reduce postprocedure peri-nidal edema and are often administered prophylactically. ...
Purpose of Review
This review considers important aspects in the provision of anesthesia for endovascular neurosurgery. Subject literature was reviewed to include important publications which have influenced neuro-interventional practice alongside recent meta-analyses to provide a contemporaneous evidence-based review.
Recent Findings
The scope of endovascular neurosurgery and interventional neuro-radiology continues to expand. The advancement of catheter and imaging technologies, alongside the development of novel techniques, has allowed a minimally invasive endovascular approach to be applied to pathologies previously only treatable by open surgery, and to patients previously considered unsuitable for invasive surgical approaches. This has led to increasing complexity in both the procedures performed and the patients encountered in the neuro-radiology suite.
Summary
An understanding of the technical aspects, physiological requirements, and potential problems relating to each procedure is required to facilitate close cooperation between the anesthesiologist and neuro-interventional team, to provide safe and effective care.
... [14,24] In contrast, some studies revealed a higher bleeding risk when only a partial obliteration was achieved after FSRS. [8,25] However, some studies indicate that the incidence of this event will decrease over time after a transient higher bleeding rate because thickening of the vascular wall following radiation makes the nidi more resistant to fluctuating blood pressures. [26] No rebleeding was observed after the treatment in our study, probably because of the small sample size. ...
Background: The aim of this study was to examine the efficacy and safety of treating large or eloquently located intracranial arteriovenous malformations (AVMs) with fractionated stereotactic radiosurgery (FSRS).
Materials and Methods: Eighteen patients with AVM treated with FSRS between March 2006 and August 2018 were retrospectively evaluated. The nidus obliteration, volume reduction, rate of rebleeding, newly onset neurological deficit, and signal change in magnetic resonance imaging (MRI) were evaluated.
Results: With a median follow-up of 88 months (range: 24–154), 6 of the 18 lesions (33.3%) had a complete obliteration. All obliteration occurred in patients received the total treatment dose of 21 Gy (6 of 9 patients, 66.7%). The median time to complete obliteration was 38 months (range: 12–53). The mean volume reduction after FSRS in the 25 Gy group was 30.2% ± 20.9% and that in the 21 Gy group was 87.7% ± 24.2%. During the follow-up period, 4 of 18 (22.2%) lesions revealed T2 signal change in the MRI. No FSRS-related complication was noted clinically or radiologically.
Conclusion: According to the present results, FSRS could be an effective and safe treatment alternative for complicated AVMs. Delayed toxicity after treatment is not noticed in the current study, but long-term follow-up is required. A higher dose in total and each fraction is likely needed when treating larger lesions.
... La descompresión quirúrgica permite que el flujo sanguíneo cerebral vuelva a los valores normales. Por lo tanto, parece razonable plantear la hipótesis de que la restauración repentina de la presión de perfusión normal en áreas de autorregulación vascular cerebral defectuosa debido a la inflamación subcortical subyacente a la compresión de la superficie, la impedancia focal del drenaje venoso o la pérdida isquémica de la reactividad del CO2, podría a su vez conducir al daño vascular que resultó en hemorragia intraparenquimatosa (15) . Ogasawara, et al. (16) , describió el síndrome de hiperperfusión, después del drenaje del hematoma subdural, que se presenta con delirio temporal y alteraciones del flujo sanguíneo en el PET CT y debe considerarse como parte del riesgo de una hemorragia cerebral remota (16) . ...
Introducción: La hemorragia intracerebral remota es una complicación neuroquirúrgica poco frecuente, ocurre en el 18% de los procedimientos intracraneales y aún menos en la cirugía de columna. Presentación de caso clínico: Un hombre de 89 años con un hematoma subdural derecho, que se sometió a un drenaje por craneotomía, en la tomografía de control presentó un hematoma intraparenquimatoso occipito temporal izquierdo y hemorragia intraventricular. Conclusión: Algunas teorías que han tratado de explicar las causas de la hemorragia intracerebral remota, el síndrome de hiperperfusión, la hipertensión, la angiopatía amiloide, el infarto venoso o el uso de anticoagulantes orales.
... La descompresión quirúrgica permite que el flujo sanguíneo cerebral vuelva a los valores normales. Por lo tanto, parece razonable plantear la hipótesis de que la restauración repentina de la presión de perfusión normal en áreas de autorregulación vascular cerebral defectuosa debido a la inflamación subcortical subyacente a la compresión de la superficie, la impedancia focal del drenaje venoso o la pérdida isquémica de la reactividad del CO2, podría a su vez conducir al daño vascular que resultó en hemorragia intraparenquimatosa (15) . Ogasawara, et al. (16) , describió el síndrome de hiperperfusión, después del drenaje del hematoma subdural, que se presenta con delirio temporal y alteraciones del flujo sanguíneo en el PET CT y debe considerarse como parte del riesgo de una hemorragia cerebral remota (16) . ...
Introduction: Remote intracerebral hemorrhage is an infrequent neurosurgical complication, which occurs in up to 18% of intracranial procedures and even less in spinal surgery. Clinical case: A 89 years old man with a right subdural hematoma, who underwent drainage by craniotomy, but in the control CT scan presented a left intraparenchymal haematoma at occipito-temporal zone, and with intraventricular blood. Conclusion: There are some theories that have tried to explain the causes of remote intracerebral hemorrhage, as is the hyperperfusion syndrome, hypertension, amyloid angiopathy, venous infarctation or other clinical associated conditions such as the use of oral anticoagulants.
Keywords: hyperperfusion syndrome, remote intracerebral hemorrhage, subdural hematoma
Cerebral vascular malformations refer to conditions related to abnormal vascular configurations in the brain. A direct arterial-venous connection without an intervening capillary network characterizes arteriovenous malformations (AVMs). Moyamoya disease is a rare arteriopathy defined by progressive stenosis of the internal carotid arteries and their branches, forming a collateral pathway that appears as a “puff of smoke.” Dural arteriovenous fistulas (DAVF) are abnormal fistulous communications within the dural leaflets that usually occur near dural venous sinuses but can develop anywhere within the intracranial dura mater. Carotid-cavernous fistulas (CCF) are characterized by an aberrant connection between branches of the carotid artery and the cavernous sinus, leading to the shunting of blood from the high-pressure arterial system into the low-pressure venous circulation. There is not enough evidence-based data regarding these patients’ best anesthetic and postoperative management. Induced hypotension to maintain a systolic blood pressure < 120 mmHg during the postoperative period is related to a lower incidence of hemorrhage in the postoperative period of AVMs resections. In Moyamoya disease, hyperventilation and hypotension can lead to vasoconstriction of the diseased vessels, reducing cerebral blood flow and worsening brain ischemia. Therefore, it is crucial to maintain strict control of the blood pressure of these patients intra and postoperatively. The blood pressure should be kept at normal or slightly higher levels, avoiding the use of noradrenaline, which impairs microcirculation. Polycythemia is undesirable as it increases viscosity and also impairs microcirculation. Salicylic acid should be reintroduced early in the postoperative period.
Post-operative cerebral edema and hemorrhage are common after resection of cerebral arteriovenous malformations. This has traditionally been attributed to normal perfusion pressure breakthrough, a phenomenon of pathologic vasoreactivity in the surrounding brain caused by chronic oligemia from the nearby shunt. As endovascular techniques for arteriovenous malformation treatment have advanced, more arteriovenous malformations are being treated without open surgery, even to the point of cure. Here we revisit the concept of normal perfusion pressure breakthrough as applied to the hemodynamic changes after arteriovenous malformation embolization, which we propose is responsible for the persistent rate of hemorrhagic complications seen after these procedures.
Brain arteriovenous malformations (AVMs) are a rare entity of vascular anomalies, characteristic of anatomical shunting where arterial blood directly flows into the venous circulation. The main aim of the active treatment policy of brain AVMs is the prevention of haemorrhage. There are well-established treatment strategies that continually improve in their safety and efficacy, primarily due to the advances in imaging modalities, targeted and novel techniques, the development of alternative treatment approaches, and even better experience with the disease itself. There are interesting imaging novelties that may be prospectively applicable in the decision-making and planning of the most effective treatment approach for individual patients with intracranial AVM. Surgery is often considered the first-line treatment; however, each patient should be evaluated individually, and the risks of the active treatment policy should not overcome the benefits of the spontaneous natural history of the disease. All treatment modalities, i.e., surgery, radiosurgery, endovascular embolization, and observation, are justified but need to be meticulously selected for each individual patient in order to deliver the best treatment outcome. This chapter deals with historical and currently applied dogmas, followed by introductions of advances in each available treatment modality of AVM management.
Ameliyathane Dışı Anestezi Uygulama Alanlarının Organizasyonu Betül AKAYCAN Ameliyathane Dışı Anestezi Uygulamalarında Hasta Değerlendirilmesi Bilge ASLAN, Erdal ÖZCAN Ameliyathane Dışı Anestezide Kullanılan Anestezik ve Sedatif İlaçlar Eda Uysal AYDIN, Levent ÖZTÜRK Ameliyathane Dışı Ventilasyon Yöntemleri- Yüksek Frekanslı Jet Ventilasyon Esra UYAR TÜRKYILMAZ, Handan GÜLEÇ Hedef Kontrollü İnfüzyon Evren Selma EVİRGEN Çocuklarda Ameliyathane Dışındaki Anestezi Uygulamaları Devrim Tanıl KURT, Ezgi ERKILIÇ Geriatrik Hastalarda Ameliyathane Dışı Anestezi Uygulamaları Bilal KATİPOĞLU, Eyüp HORASANLI Gastrointestinal Endoskopik Girişimlerde Anestezi Eda UYSAL AYDIN Oğuz Uğur AYDIN Transluminal Endoskopik Cerrahide ve Tek İnsizyon Laparoskopik Cerrahide Anestezi Meltem ŞİMŞEK, Mehmet ŞAHAP Bronkoskopi Ünitelerinde Anestezi Halide CEYHAN Kalp Kateterizasyon ve Elektrofizyoloji Ünitelerinde Anestezi Aygün GÜLER, Tülin GÜMÜŞ Kardiyoversiyon ve Anestezi Bilge KÜÇÜKÇAY, Kemal Eşref ERDOĞAN Manyetik Rezonans Görüntüleme, Bilgisayarlı Tomografi ve Anestezi Cemile ALTIN Girişimsel Radyolojide Anestezi Fatma Neşe KURTULGU Nöroradyolojik Girişimlerde Anestezi Abdullah YALÇIN Radyasyon Onkolojisinde Anestezi Bilge ASLAN, Erdal ÖZCAN Elektrokonvülzif Tedavide Anestezi Filiz KAYA İn Vitro Fertilizasyon Uygulamalarında Anestezi Yasemin AKÇAALAN Böbrek Taşı Kırma Ünitelerinde Anestezi Fazilet ERBAY Diş Ünitelerinde Anestezi Süleyman SARI Savaş, Doğal Afet ve Pandemi Döneminde Ameliyathane Dışı Anestezi Filiz AKASLAN
Arteriovenous malformations (AVMs) are congenital vascular lesions that may appear throughout the central nervous system. They consist of direct connections between arteries and veins, without an intervening capillary bed. They are believed to be about one-tenth as common as intracranial aneurysms. Spinal AVMs are discussed in Chap. 20. Vein of Galen malformations and pial arteriovenous fistulas are separate entities and are discussed in the Appendix to this chapter.
Intracranial embolization procedures are therapeutic endovascular occlusions of vessels involved in vascular lesions of the cerebral circulation. This chapter focuses on transarterial embolization in the intracranial circulation for six primary indications: brain arteriovenous malformations, pial arteriovenous fistulas, vein of Galen malformations, carotid cavernous fistulas, dural arteriovenous fistulas, brain tumors, and intracranial bleeding, including middle meningeal embolization for chronic subdural hematomas. Basic access concepts are discussed in Chap. 4, specific embolization procedures on intracranial aneurysms in Chap. 5, and transvenous embolization procedures in Chap. 11.
OBJECTIVE: The objective is to explore the correlation between carotid artery calcification score and cerebral hyperperfusion syndrome (CHS) after carotid artery stenting (CAS) in patients with carotid artery stenosis.
METHODS: Consecutive patients treated for carotid artery stenosis from October 2016 to August 2021 from two centers were studied. Carotid artery calcification score was manually segmented on multi-detector row spiral computed tomography angiography scans before CAS. The associations between carotid artery calcification score and the occurrence of CHS during the in-hospital time were assessed.
RESULTS: A total of 175 patients were enrolled in the study. The mean age was 72.12 ± 7.51 years. All patients were undergone CAS treatment successfully. There were 46 cases that occurred CHS (26.29%). Univariate logistic regression analyses showed that for every 1 unit (100-score) increase in carotid artery calcification score, the risk of CHS increased by 1937% (odds ratio [OR] = 20.37, 95% confidence interval [CI]: 7.54–55.03, P < 0.01). In addition, the increasing rate was significantly different between the open-cell group (OR = 261.7, P < 0.01) and the closed-cell group (OR = 11.4, P < 0.01). The area under curve of predictiong model of carotid artery calcification score to CHS was 0.84 (95% CI, 0.75–0.93).
CONCLUSION: Carotid artery calcification score was an independent risk factor for CHS in patients who underwent CAS. The application of carotid artery calcification score as risk factor in clinical screening of carotid artery stenosis patients may have beneficial effects on the management of CAS.
Objectives
One of the risk factors for cerebral hyperperfusion following carotid endarterectomy (CEA) is a chronic reduction in cerebral perfusion pressure due to internal carotid artery (ICA) stenosis, which is clinically detected as increased cerebral blood volume (CBV). The perfusion fraction (f) is one of the intra-voxel incoherent motion (IVIM) parameters obtained using magnetic resonance (MR) imaging that theoretically reflects CBV. The present study aimed to determine whether preoperative IVIM-f on MR imaging predicts development of cerebral hyperperfusion following CEA.
Materials and Methods
Sixty-eight patients with unilateral ICA stenosis (≥ 70%) underwent preoperative diffusion-weighted 3-T MR imaging, and IVIM-f maps were generated from these data. Quantitative brain perfusion single-photon emission computed tomography (SPECT) was performed before and immediately after CEA. Regions-of-interest (ROIs) were automatically placed in the bilateral middle cerebral artery territories in all images using a three-dimensional stereotactic ROI template, and affected-to-contralateral ratios in the ROIs were calculated on IVIM-f maps.
Results
Nine patients (13%) exhibited postoperative hyperperfusion (cerebral blood flow increases of ≥ 100% compared with preoperative values in the ROIs on brain perfusion SPECT). Only high IVIM-f ratios were significantly associated with the occurrence of postoperative hyperperfusion (95% confidence interval, 253.8–6774.2; p = 0.0031) on logistic regression analysis. The sensitivity, specificity, and positive and negative predictive values of the IVIM-f ratio to predict the occurrence of postoperative hyperperfusion were 100%, 81%, 45%, and 100%, respectively.
Conclusions
Preoperative IVIM-f on MR imaging can predict development of cerebral hyperperfusion following CEA.
Most strokes are attributed to atherosclerosis of neck and intracranial arteries, brain embolism from the heart, and penetrating artery disease; these are discussed in detail in many other books. This compendium fills an important niche by providing authoritative discussions on the other, less common causes of stroke, including various forms of angiitis, coagulation disorders, infective, paraneoplastic and metabolic disorders that may be associated with stroke, and a number of rare syndromes such as Eales disease and Fabry's disease. This new edition contains detailed, up-to-date information about the nature, diagnosis, and treatment of those relatively uncommon types of cerebrovascular disease that cause strokes. It is therefore a unique scientific and clinical resource that provides a useful reference to help physicians diagnose and treat stroke patients who do not fit well into the usual clinical categories. New chapters include stroke in patients with Lyme disease, scleroderma, Cogan's syndrome, Chagas' disease, and HIV.
An observational cohort study was performed in patients with diagnosis of brain AVM in a third level medical center in Mexico City, from December 2007 to January 2018. Patients were divided into 3 groups: small (S-M Grade I and II), Transitional (S-M Grade III) and Giant (S-M Grade IV and V). and then these groups subcategorized in bimodal treatment (embolization plus microsurgery) and others (microsurgery, radiosurgery, conservative). Functional outcome was assessed with the modified Rankin Scale (mRS) and compared between the 2 groups before treatment and 24 months follow-up.
97 patients were diagnosed, 22 excluded due to inconsistency in medical records or abandoning the treatment. The final sample analyzed was 75 patients. The overall had a mean age of 22 [14-38] years and the predominant sex was male in 55% (n=41). The clinical presentation was: focal neurological deficit 28% (n=21), seizures 27% (n=20), headache 24% (n=18), and intracranial hemorrhage 21% (n=16). Only seven (9.3%) patients from the total sample developed trans-procedural rupture of brain AVM, After 24 months follow up 24 (31.9%) patients remains with neurological sequel, and four (5.3%) died. In low grade brain AVMs the mean MRS decreased from 2.5±1.2 to 0.7±0.9, in transitional grade brain AVMs from 2.3±1.7 to 0.9±1, and in giant AVMs 2.4±1.1 to 2.3±2.1.
Bimodal or multimodal treatment should be carefully considered in high-grade arteriovenous malformations. The main objective, having embolization as a first step is to reduce the risk of intraoperative bleeding, obliterating feeder arteries that will be difficult to control with microsurgery. Additionally, the risk of trans procedure rupture of the bAVM is directly proportional to the “aggressiveness” which it is treated.
Objective: Normal perfusion pressure breakthrough (NPPB) and occlusive hyperemia (OH) have been reported to cause bleeding and cerebral edema after resection of cerebral arteriovenous malformation (AVM). However, much is unknown regarding the mechanism of these events. Additionally, they do not always coincide with the Spetzler–Martin AVM Grading Scale. In this study, we examined the relationship between the changes in intraoperative angiography (IOA) and single photon emission computed tomography (SPECT) findings, and the risk of developing NPPB and OH.
Materials and methods: From December 2016 to October 2018 in our hospital, 11 patients underwent AVM resection using intraoperative cerebral angiography (IOA). There were six unruptured AVM cases and five ruptured ones, where the average nidus size was 20.8 mm and the average number of draining veins was 1.9. During surgery, complete resection was confirmed using IOA, and postoperative blood pressure was strictly monitored and controlled. If NPPB or OH was suspected on SPECT the day following the surgery, strict blood pressure management was performed.
Results: Unruptured lesions in three cases and ruptured lesions in one case showed significant findings on SPECT. In these cases, stagnation of the contrast agent was observed at the end of the IOA feeders. There were no bleeding complications in patients with suspected NPPB or OH, and cases did not worsen when compared to the preoperative (mRS).
Conclusion: Stagnation of the contrast agent at the end of the IOA feeders is effective basis for assessing the risk of NPPB and OH. This is particularly useful for postoperative management, especially for reducing postoperative complications.
Background
Cerebellar arteriovenous malformations (cAVMs) are rare and challenging lesions with an aggressive natural history. The mechanisms whereby a patient can worsen clinically after a supratentorial AVM resection include an acute alteration in cerebral hemodynamics, which is a known cause of postoperative hyperemia, edema and/or hemorrhage. These phenomena has not been described for cAVMS. Moreover, the underlying pathophysiology of edema and hemorrhage after AVM resection still remains controversial.
Methods
We report a patient that presented an abrupt neurological deterioration after cAVM surgical resection. Emergent external ventricular drainage to treat incipient hydrocephalus only partially reverted the patient's deterioration. Consecutive post-surgery CT images revealed fourth ventricle compression secondary to cerebellar swelling that concurred with a new neurological deterioration. Densitometric analysis was performed in these CT images to reveal the nature of these changes as well as their evolution over time.
Results
Importantly, we demonstrated a dynamic increase in the cerebellum mean density at the interval of Hounsfield values which correspond to hyperemia values. These changes were dynamic, and when hyperemia resolved and cerebellar density returned to basal levels, the fourth ventricle re-expanded and the patient neurologically recovered.
Conclusions
This study demonstrated the utility of quantitative CT image analysis in the context of hemodynamic alterations following cAVM resection. Densitometric CT analysis demonstrated that hyperemic changes, but not ischemic ones, were time-dependent and were responsible for swelling and hemorrhage that conditioned neurological status and patient's evolution.
Objective
Our study aimed to identify predictive factors for malignant post-treatment edema and hemorrhage in patients who underwent microsurgical treatment of arteriovenous malformation (AVM) in our institution.
Methods
The study included 72 patients treated by microsurgery for cerebral symptomatic and/or ruptured AVM between 2010 and 2020. Six patients developed postprocedural malignant edema and hemorrhage (group M); the other 66 patients had no malignant edema and hemorrhage (group NM). In each patient, flow was assessed indirectly by summing the diameters of all feeding arteries to obtain an overall diameter (ODA), and similarly for draining veins (ODV). High-flow was defined as a delay between feeding artery injection and draining vein injection (DAV) < 1 second on dynamic digital subtraction angiography. Univariate analysis was performed.
Results
Mean ODA and ODV were respectively 11 mm (± 8.2) and 11 mm (± 5.3) in group M and 2.9 mm (± 1.4) and 3.7 mm (± 1.3) in group NM (P = 0.001). High-flow AVM was demonstrated in 4 out of 5 patients (85%) in group M and in 14 out of 55 (25%) in group NM (P = 0.02). Associated aneurysm was seen in 5 patients in group M (83%) and in 11 in group NM (17%) (P = 0.001).
Conclusion
High-flow AVM may be associated with higher risk of postoperative edema and hemorrhage. Multidisciplinary discussion is mandatory in these cases, to define a pre-therapeutic plan for progressive staged vascular malformation occlusion.
Over the past 30 years, the treatment of deep and eloquent arteriovenous malformations (AVMs) has moved away from microneurosurgical resection and towards medical management and the so-called minimally invasive techniques, such as endovascular embolization and radiosurgery. The Spetzler-Martin grading system (and subsequent modifications) has done much to aid in risk stratification for surgical intervention; however, the system does not predict the risk of hemorrhage nor risk from other interventions. In more recent years, the ARUBA trial has suggested that unruptured AVMs should be medically managed. In our experience, although these eloquent regions of the brain should be discussed with patients in assessing the risks and benefits of intervention, we believe each AVM should be assessed based on the characteristics of the patient and the angio-architecture of the AVM, in particular venous hypertension, which may guide us to treat even high-grade AVMs when we believe we can (and need to) to benefit the patient. Advances in imaging and intraoperative adjuncts have helped us in decision making, preoperative planning, and ensuring good outcomes for our patients. Here, we present several cases to illustrate our primary points that treating low-grade AVMs can be more difficult than treating high-grade ones, mismanagement of deep and eloquent AVMs at the behest of dogma can harm patients, and the treatment of any AVM should be tailored to the individual patient and that patient's lesion.
Brain arteriovenous malformations (AVMs) are complex vascular lesions characterized by a tangle of vessels with no interposed normal brain tissue. This tangle, the nidus, constitutes a high-flow vascular malformation connecting feeding arteries to draining veins. While relatively rare, AVMs are emphasized because of their potentially devastating effects on otherwise healthy young adults. In fact, AVMs are one of the leading causes of hemorrhagic stroke in young patients. We have seen a significant improvement in the management of AVMs over the past few decades. These classically challenging lesions have benefited from advances in the fields of microsurgery, endovascular surgery, and radiation oncology. Clinical trials have also helped refine our understanding of the natural history of the disease and the best management options. Despite these advances, AVM’s biologic and hemodynamic complexity still requires that each lesion be studied carefully and evaluated with a holistic approach to the patient to determine the best course of action (Bendok et al, Advances and innovations in brain arteriovenous malformation surgery. Neurosurgery 74:S60–S73, 2014).
Hoje em dia a praticidade na transmissão da informação é algo fundamental, pois todos estão cada vez menos dispostos a fazer grandes leituras, com muito pouco conteúdo de aplicabilidade pratica, O livro Manual de Complicações em Cirurgia Vascular é resultado da união de um grupo de colegas, com o objetivo de fornecer uma literatura atualizada e objetiva, sobre as adversidades passíveis de ocorrerem na prática da nossa especialidade, inicialmente, a partir de uma ideia do Dr. Heriberto Brito de Oliveira, que frente às demandas como perito médico e assistente técnico, frequentemente se deparava com essas situações.
Tais adversidades, podem sim ocorrer, independente da técnica ou do cuidado do cirurgião, portanto essa obra tem a finalidade de tornar acessível a todos, o conhecimento dos eventos adversos mais frequentes, nas diversas áreas da cirurgia vascular tais como, nas cirurgias arteriais e venosas, procedimentos endovasculares, trauma vascular, escleroterapia, dentre outras, tendo também um capitulo dedicado a legislação sobre a “fleboestetica”, contemplando desta forma, as áreas de maior abrangência do nosso dia a dia, podendo então ser vista como uma forma de ensino, alerta e ate mesmo como respaldo técnico, para as demandas jurídicas.
Atentando-se para um formato mais pratico, podendo ser acessado on line, este manual é portanto somente no formato digital e está disponível aos profissionais de forma gratuita, com o propósito de disseminar o conhecimento, à todos os cirurgiões, em especial aos mais jovens, de forma ágil, moderna e sem custo.
Esta obra só foi possível graças à disponibilidade dos colegas de todos os cantos do Brasil, em dividirem seu precioso tempo, na confecção de seus capítulos, ficando aqui nosso agradecimento à todos.
Os autores.
Arteriovenous malformations (AVMs) are defined as an abnormal collection of dysplastic blood vessels wherein the arterial blood flows directly into the draining veins without any intervening neural parenchyma or capillary beds. These are usually congenital lesions with a lifelong risk of hemorrhage of about 2–4% per year. These lesions tend to enlarge with age and may progress from low-flow AVMs at birth to medium- or high-flow and high-pressure AVMs in adulthood. Grossly, it appears as a “tangle” of vessels with a well-circumscribed center called nidus. Intracranial AVMs are classified as parenchymal and dural depending, upon the location of AVMs. Intracranial AVMs in pediatric patients might present with congestive heart failure (CHF) in neonates, seizures or hemorrhage, and varying degrees of ischemic symptoms. Anesthetic management in this group of patients is quite challenging as surgical interventions are associated with massive blood loss. The pediatric population has a low cardiopulmonary reserve and poorly tolerates such losses. This chapter describes the anesthetic management of patients with intracranial AVMs posted for various interventions.
"Essentials of Diagnosis, Treatment, and Application of Cardio and Peripheral vascular Diseases" is intended to serve as a clinical resource for healthcare professionals who evaluate and manage patients with cardiovascular and related diseases in various forms and challenges.
The author strives to provide short, focused chapters so that busy practitioners can quickly find the information they need when facing specific symptoms and manifestations of coronary heart disease, hypertension, other heart diseases, abdominal aortic aneurysms and aortic dissecting aneurysm, etc. The content covers specific management issues in various aspects of cardiac and peripheral vascular diseases, including: epicardial coronary artery related diseases, coronary microcirculation disorders, arrhythmia, basic vascular surgery skills, perioperative physical assessment and assessment, diagnosis, treatment of aneurysms, etc. The last part of the book reviews ultrasound and postoperative care, which are also two integral parts of the treatment of cardiac and peripheral vascular diseases. The appendix of each chapter provides the standard reference table of this book. More importantly, this book complements traditional textbooks by providing professional treatments by experienced clinicians from the First Hospital of China Medical University.
Background
Intraparenchymal hemorrhage (IPH), possibly due to reperfusion, after evacuation of a cranial chronic subdural hematoma (cSDH) is a known phenomenon. However it is sparingly reported and not well understood.
Methods
An illustrative case series is presented. A literature review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines to identify all previously reported cases.
Results
A total of 48 cases were analyzed. Males were 85.4% of the population, and the mean age was 67.5 years old. Pre-existing head trauma and hypertension were the most common comorbidities. Headache was a presenting symptom in 60.4% of cases. Midline shift was explicitly stated in 54.2% of cases. Initial burr hole alone was performed 75.0% of the time, while craniotomy alone was done in 16.7% of cases. Any initial craniotomy patients were associated with a modified Rankin Scale (mRS) score of 5 (p=.03). The IPH was located in the cerebral hemisphere 62.5% of cases, and more likely to occur ipsilateral to a unilateral cSDH (p=.02). The IPH occurred on a mean 1.9 days after surgery, and 50.0% occurred within 24 hours of initial intervention. Median mRS at discharge was 2. The mortality rate was 25%. Lastly, a multifactorial reperfusion pathophysiology is proposed.
Conclusion
IPH after cSDH evacuation is associated with significant morbidity and mortality. Prompt recognition, regulating blood pressure, controlling the amount and rate of extra-axial fluid drained, and meticulous surgical technique are critical to optimize the care of patients with cSDH and reduce the rate of post-operative IPH.
Objective:
To evaluate and compare the efficacy of intraoperative neurophysiological monitoring (IONM) and intraoperative transcranial Doppler (TCD) techniques for identification of hypoperfusion during carotid artery (CA) clamp and hyperperfusion after release of occlusion during carotid endarterectomy (CEA).
Methods:
A retrospective, consecutive case series of 152 patients undergoing CEA between June 2018 and March 2020 were reviewed. Monitoring of somatosensory evoked potentials (SEPs), motor evoked potentials (MEPs), electroencephalogram (EEG) and TCD were investigated.
Results:
Three patient cohorts were observed after clamping CA: A, in 132 of the 152 patients (87%), TCD blood flow velocity decreased by less than 50%, and there were no changes in IONM; B, in 5 of 152 (3%) patients, TCD blood flow rate was reduced between 50% and 100% with no changes in IONM; C, in 15 patients (10%), blood flow velocity was reduced by 50% to 100%, and all IONM modalities met warning criteria. With increased blood pressure, IONM and blood flow velocities improved to less than warning criteria in 8/15 patients. In 6 of the 7 remaining patients, IONM modalities recovered to baseline immediately after clamps were removed from CA. The one patient with persistent MEP deterioration experienced a postoperative proximal muscle weakness which recovered 48 hours later. In 22 patients, TCD detected hyperperfusion at the moment of clamp release.
Conclusions:
TCD blood flow velocity is correlated with MEP and SEP amplitude changes after clamping. After declamping, TCD can detect hyperperfusion and help to regulate blood pressure to prevent hyperperfusion.
Der Schlaganfall ist die zweithäufigste Todesursache weltweit. Für die Therapie des ischämischen Schlaganfalls steht derzeit nur eine bewährte Methode zur Verfügung, die Rekanalisation durch Thrombektomie oder Fibrinolyse mit recombinant tissue plasminogen activator. Doch ein enges therapeutisches Zeitfenster und Kontraindikationen führen dazu, dass weniger als 10 % der Patienten davon profitieren können. Die Suche nach alternativen Therapiestrategien ist zwingend erforderlich. Eine vielversprechende Alternative ist Neuroprotektion durch Hypothermie, die sich gut mit Rekanalisationsverfahren kombinieren ließe. Für die Erforschung neuer Therapiestrategien sind präklinische Studien nötig. Da sich Nagetiermodelle nur bedingt für die Erforschung neurointerventioneller Therapien eignen, ist hier der Einsatz von Großtieren unerlässlich. Schafe eignen sich aufgrund einiger Vorteile für Schlaganfallmodelle. Bei Rekanalisationsstudien ist es notwendig, den temporären Verschluss eines Gehirngefäßes nachweisen zu können.
Ziel dieser Arbeit war zum einen die Darstellung der Vor- und Nachteile und des Einsatzes von Großtieren in der neurointerventionellen Forschung. Weitere Ziele dieser Arbeit waren die Evaluierung eines Schaf-Schlaganfallmodells und die Testung eines geeigneten Verfahrens zur zuverlässigen Darstellung eines temporären Gefäßverschlusses (Etablierungsstudie). Darüber hinaus sollte die Testung eines Kühlkathetersystems für eine Kombination von Rekanalisation und Hypothermie erfolgen (Sicherheits- und Machbarkeitsstudie).
Für den Überblick über den Einsatz von Großtieren in der neurointerventionellen Forschung wurde ein systematisches Review angefertigt. Durch die Suche in zwei Datenbanken wurden 5250 Publikationen identifiziert und anhand der Abstracts deren Inhalt überprüft. 540 Arbeiten wurden einer Volltextauswertung unterzogen und 334 Paper letztendlich eingeschlossen. In der Etablierungsstudie zur Evaluierung eines Schlaganfallmodells wurde bei zehn Schafen ein Schlaganfall induziert. Danach wurden eine digitale Subtraktionsangiographie (DAS), eine Magnetresonanztomografie (MRT), eine Magnetresonanzangiographie (MRA), sowie eine Computertomographie (CT) einschließlich -perfusion und -angiographie durchgeführt. In der darauffolgenden Sicherheits- und Machbarkeitsstudie wurde bei 20 Schafen ein Schlaganfall induziert. Primäre Endpunkte waren die Sicherheit und Machbarkeit des neuen Kühlkatheters. Als sekundärer Endpunkt wurde unter anderem die Beurteilung der neurologischen Funktion gewählt.
Das Review zeigt den vielfältigen Einsatz von Großtiermodellen und deren klinische Relevanz. Das Review zeigt auch auf, dass bei Studien mit Großtieren noch die Notwendigkeit für Verbesserungen besteht, allen voran Randomisierung und Verblindung. In der Etablierungsstudie konnte die DSA den Gefäßverschluss nicht zuverlässig nachweisen. Die CT-Perfusion hingegen war gut geeignet, um den Gefäßverschluss über die Hirnminderperfusion zu belegen. Die Time-of-Flight-MRA hat sich zur Darstellung eines permanenten Gefäßverschlusses als zuverlässig erwiesen. Die diffusionsgewichtete Bildgebung im MRT ist geeignet, die endgültige Infarktgröße zu bestimmen. Die Sicherheit und Machbarkeit des Kühlkatheters konnte nachgewiesen werden, da keine Gefäßschäden durch histologische Untersuchungen zu finden waren und eine ausreichend schnelle und tiefe Kühlung des Gehirns erreicht werden konnte. Die klinisch-neurologische Bewertung der Tiere ergab jedoch keinen signifikanten Unterschied zwischen den Gruppen.
Schlussfolgerungen: Insgesamt lässt sich der Schluss ziehen, dass die Erforschung von therapeutischen Alternativen für den Schlaganfall enorm wichtig und der Einsatz von Großtieren unerlässlich ist. Das Schaf eignet sich gut für diesen Einsatz. Der getestete Kühlkatheter ist komplikationsfrei und ohne medizinische Sicherheitsbedenken einsetzbar. Die Wirksamkeit sollte nun in einer verblindeten, randomisierten Studie mit ausreichender Gruppengröße getestet werden.
Blood oxygenation-level dependent cerebrovascular reactivity (BOLD-CVR) has gained attention in recent years as an effective way to investigate CVR, a measure of the hemodynamic state of the brain, with high spatial and temporal resolution. An association between impaired CVR and diverse pathologies has been observed, especially in ischemic cerebrovascular diseases and brain gliomas. The ability to obtain this information intraoperatively is novel and has not been widely tested. We report our first experience with this intraoperative technique in vascular and oncologic neurosurgical patients, discuss the results of its feasibility, and the possible developments of the intraoperative employment of BOLD-CVR.
Background: Eloquent location of a brain arteriovenous malformation (BAVM) is known to increase the surgical risk. Surgical removal of such BAVMs is challenging. Useful indicators for the safe removal of eloquent BAVMs are needed. The aim of this study was to determine the surgical risk factors for these challenging entities.
Methods: The authors retrospectively reviewed 29 motor and/or sensory BAVM patients who underwent surgeries. The risk factors for surgical morbidity were analyzed. As a new risk factor, maximum nidus depth, was evaluated.
Results: Complete obliteration was achieved in 28 patients (96.6%). Postoperative transient and permanent neurological deteriorations were seen in nine patients (31.0%) and five patients (17.2%), respectively. In univariate analysis, maximum nidus depth (p = 0.0204) and asymptomatic onset (p = 0.0229) were significantly correlated with the total morbidity. In multivariate analysis, only maximum nidus depth was significantly correlated with total morbidity (p = 0.0357; odds ratio, 2.78598; 95% confidence interval, 0.8866-8.7535). The cut-off value for the maximum nidus depth was 36 mm for total morbidity (area under the curve [AUC], 0.7428) and 41 mm for permanent morbidity (AUC, 0.8833). The cutoff value of the maximum nidus size was 30 mm for total morbidity (AUC, 0.5785) and 30 mm for permanent morbidity (AUC, 0.7625). AUC was higher for the maximum nidus depth than it was for the maximum nidus size.
Conclusions: Maximum nidus depth was significantly associated with surgical morbidity of eloquent BAVMs. The maximum nidus depth is a novel and a simpler indicator of the risk of surgical morbidity.
Keywords: Arteriovenous malformation; Depth; Microsurgery; Nidus; Size; Spetzler-Martin.
This is an open access proceeding book of 9th European-Japanese Cerebrovascular Congress at Milan 2018. Since many experts from Europe and Japan had very important and fruitful discussion on the management of Cerebrovascular diseases, the proceeding book is very attractive for the physician and scientists of the area.
Cerebrovascular malformations are a major cause of intracranial hemorrhage in young adults and children. They are resource-intensive to manage with invasive treatment modalities, and there is no current medical therapy option available for patients. A better understanding of the genetics and biology of cerebrovascular malformations is needed to elucidate common biologic mechanisms and potential therapeutic targets. Different cerebrovascular malformations have varying genetic etiology but share commonalities in signaling pathways affecting angiogenesis, vascular remodeling, inflammation, and response to injury. Inherited mutations underlie hereditary hemorrhagic telangiectasia (HHT), cerebral cavernous malformations (CCMs), capillary malformation-arteriovenous malformation (CM-AVM), and venous malformations. Somatic mutations have now been identified in most cerebrovascular malformations, including most recently for sporadic brain AVM, further suggesting common pathways affecting downstream ERK signaling as a potential therapeutic target. Additional modifier genes and other factors are emerging as important predictors explaining the variable expressivity of the disease and may shed light on the progression of these related vascular malformations. In this chapter, we focus on the vascular biology and genetics of brain AVMs and CCMs; other cerebrovascular malformations are also discussed briefly.
We describe a case in which intraoperative indocyanine green videoangiography (ICG-VA) enabled the detection of hyperemia in the brain adjacent to the nidus during cerebral arteriovenous malformation (AVM) surgery. A 43-year-old woman presented with paresis and sensory disturbance in her left upper extremity, which revealed a subcortical hematoma in the right parietal lobe due to a small ruptured AVM. Craniotomy was performed. During surgery, despite resection of the nidus, a persistent red draining vein was observed. ICG-VA demonstrated that the reddish blood flow was not from the residual nidus but from the adjacent brain, suggesting hyperemia. The procedure was completed without additional manipulation. The paresis was almost completely reversed, and the patient was discharged 2 weeks after surgery. Interestingly, the observed hyperemia after nidus resection corresponded to an area where the pial venous reflux from the draining vein was observed before the resection, and it is possible that chronic venous hypertension contributed to this post-resection hyperemia. During AVM surgery, ICG-VA may be useful in evaluating changes in blood flow not only in malformation but also in adjacent brain regions.
Background
Cerebellar arteriovenous malformations (cAVMs) are rare and challenging lesions with an aggressive natural history. The mechanisms whereby a patient can worsen clinically after a supratentorial AVM resection include an acute alteration in cerebral hemodynamics, which is a known cause of postoperative hyperemia, edema and/or hemorrhage. These phenomena has not been described for cAVMS. Moreover, the underlying pathophysiology of edema and hemorrhage after AVM resection still remains controversial.
Methods
We report a patient that presented an abrupt neurological deterioration after cAVM surgical resection. Emergent external ventricular drainage to treat incipient hydrocephalus only partially reverted the patient's deterioration. Consecutive post-surgery CT images revealed fourth ventricle compression secondary to cerebellar swelling that concurred with a new neurological deterioration. Densitometric analysis was performed in these CT images to reveal the nature of these changes as well as their evolution over time.
Results
Importantly, we demonstrated a dynamic increase in the cerebellum mean density at the interval of Hounsfield values which correspond to hyperemia values. These changes were dynamic, and when hyperemia resolved and cerebellar density returned to basal levels, the fourth ventricle re-expanded and the patient neurologically recovered.
Conclusions
This study demonstrated the utility of quantitative CT image analysis in the context of hemodynamic alterations following cAVM resection. Densitometric CT analysis demonstrated that hyperemic changes, but not ischemic ones, were time-dependent and were responsible for swelling and hemorrhage that conditioned neurological status and patient's evolution.
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