Natural History and Histopathology of Expanding Cysts and Hematomas After Stereotactic Radiosurgery for Arteriovenous Malformations of the Brain: A Case Series

BACKGROUND

We reviewed the clinical course and histopathologic findings for cases involving the formation of expanding cysts and/or hematomas after gamma knife surgery (GKS) for arteriovenous malformations (AVMs).

METHODS

We report a single-center retrospective review of 18 patients who presented with cyst and/or hematoma expansion after GKS for AVMs between 1993 and 2023. Expanding cysts and hematomas were defined as well-demarcated cavities filled with fluid or well-marginated heterogenous hematomas presenting with expansion proximal to or in the location of the original AVM, respectively. Patient demographics, AVM characteristics, history of interventions and surgeries, and imaging and histopathologic features of expanding cysts and hematomas were collected for analysis.

RESULTS

Among 1072 AVM patients treated using GKS, 18 presented with expanding cysts or hematomas during a total follow-up period of 16,757 patient-years (0.11 case/100 persons/patient-year). The time to cyst or hematoma identification was 4-13 years after initial GKS, with a mean duration of 8.6 years. Among the patients examined, 7 (38.9%) presented mainly with hematoma, 10 (55.6%) presented mainly with cysts, and 1 presented with approximately equal components of both. Among the 18 patients, 13 (72.2%) underwent craniotomy to treat cyst or hematoma expansion. All the specimens had similar histopathologic characteristics, including organizing hematoma with fresh and old hemorrhage, fibrinoid necrosis of the vessels, gliosis of normal brain tissue, infiltration of hemosiderin-laden histiocytes, and extravascular protein leakage.

CONCLUSIONS

Our findings suggest that the formation of these 2 complications can be attributed to a common mechanism involving radiation-induced vascular damage in brain tissue adjacent to the AVM and subsequent chronic inflammation and capillary dilatation.

Frameless versus frame-based stereotactic radiosurgery for intracranial arteriovenous malformations: A propensity-matched analysis

Objective

The frameless linear accelerator (LINAC) based stereotactic radiosurgery (SRS) has been evolving with a reduction in patient discomfort. However, there was limited evidence comparing frame-based and frameless SRS for intracranial arteriovenous malformations (AVM). We aimed to compare the treatment outcomes between frame-based and frameless LINAC SRS.

Materials and Methods

This retrospective cohort compared the outcomes of frame-based LINAC SRS (1998-2009) with frameless LINAC SRS (2010-2020). The primary outcome was the obliteration rate. The other outcomes included the neurological, radiological, and functional outcomes after SRS. A matched cohort was identified by propensity scores for further comparisons.

Results

A total of 65 patients were included with a mean follow-up time of 13.2 years (158.5 months). There were 40 patients in the frame-based group and 25 patients in the frameless group. The overall obliteration rate was comparable (Frame-based 82.5% vs Frameless 80.0%, p = 0.310) and not significantly different over time (log-rank p = 0.536). The crude post-SRS hemorrhage rate was 1.5% and the incidence was 0.3 per 100 person-years. There were 67.7% of patients with AVM obliteration without new persistent neurological deficits at the last visit and 56.9% of patients with AVM obliteration without any deficits (transient or persistent) during the entire follow-up period. Four patients (8.0%) developed late onset persistent adverse radiation effects (more than 96 months after SRS) among 50 patients with more than 8-year surveillance. In the propensity-matched cohort of 42 patients, there was no significant difference in AVM obliteration (Frame-based vs Frameless, log-rank p = 0.984).

Conclusion

Frameless and frame-based LINAC SRS have comparable efficacy in intracranial AVM obliteration. A longer follow-up duration may further characterize the rate of late adverse radiation effects in frameless SRS.

Sphenoidal meningoencephalocele associated with CSF fistula and arteriovenous malformation Spetzler-Martin V: A case report

Cerebral Arteriovenous malformations (AVMs) are presumed congenital anomalies of the blood vessels, which can increase intracranial pressure by uncertain mechanisms. We report the rare case of a 55-year-old male patient who complained about CSF rhinorrhea. Persisting CSF leakage prompted CT, which evidenced a bone defect in the right middle cranial fossa with protruding brain tissue. The diagnosis of a sphenoidal meningoencephalocele was made. Neuroimaging evidenced an AVM Spetzler Martin V. The lesion was targeted via an endonasal approach with resection of the herniated brain tissue and closure of the bony and dural defects. The postoperative course was uneventful without recurrence of the CSF fistula. Documentation of these cases is essential to come up with standardized therapeutical protocols and follow-up. Nevertheless, conservative management of the AVM and surgical repair of the bone defects is an appropriate approach in the first instance, depending on the morphology and characterization of the AVM.

Safety and Effectiveness of First-line Endovascular Management of Low-Grade Brain Arteriovenous Malformations : Single Center Experience in 145 Patients

PURPOSE

Spetzler-Martin grade (SMG) I-II (low-grade) brain arteriovenous malformations (BAVMs) are often considered safe for microsurgical resection; however, the role of endovascular treatment (EVT) remains to be clarified in this indication, especially for unruptured BAVMs. The purpose of our study was to assess the safety and effectiveness of endovascular treatment as the first-line treatment for low-grade BAVMs.

METHODS

From our local database, we retrospectively retrieved patients with low-grade BAVMs, either ruptured or unruptured, treated by embolization as first-line treatment in our department between January 2005 and January 2020. The primary endpoint was the total obliteration rate of BAVMs, and secondary endpoints were hemorrhagic complications and final clinical outcome, assessed through shift of the modified Rankin scale, and mortality rate secondary to BAVM embolization.

RESULTS

A total of 145 patients meeting inclusion criteria and treated by EVT as first-line therapy were included in the study (82 ruptured and 63 unruptured BAVMs). Overall, complete exclusion of BAVMs was achieved in 110 patients (75.9%); 58 patients (70.7%) with ruptured and 52 (82.5%) unruptured BAVMs, including 37.9% BAVMs excluded by EVT alone (35.5% among ruptured and 44.4% among unruptured BAVMs) and 38% by combined treatment (EVT and surgery or EVT and SRS). There was no BAVM volume cut-off predictive for total obliteration by embolization alone. Early minor hemorrhagic complications were reported in 14 patients (9.6%) and early major hemorrhagic complications were reported in 5 patients (3.4%). No late hemorrhagic complications (0%) occurred; mortality rate was 0.7% (1/145 patients). Improved/unchanged mRS was reported in 137 patients (94.5%).

CONCLUSION

Endovascular treatment alone or associated with others exclusion techniques, might be safe and effective for complete exclusion of low-grade brain arteriovenous malformations regardless of the volume.

Comparing hematoma characteristics in primary intracerebral hemorrhage versus intracerebral hemorrhage caused by structural vascular lesions

Intracerebral hemorrhage (ICH) caused by structural vascular lesions is associated with better outcomes than primary ICH, but this relationship is poorly understood. We tested the hypothesis that ICH from a vascular lesion has more benign hematoma characteristics compared to primary ICH. We performed a retrospective study using data from our medical center. The SMASH-U criteria were used to adjudicate the etiology of ICH. The co-primary outcomes were admission parenchymal hematoma volume and hematoma expansion at 24 h. Linear and logistic regression analyses were performed to test associations. A total of 231 patients were included of whom 42 (18%) had a vascular lesion. Compared to primary ICH patients, those with structural vascular lesions were younger (49 vs. 68 years, p < 0.001), less likely to have hypertension (29% vs. 74%, p < 0.001), had lower mean admission systolic blood pressure (140 ± 23 vs. 164 ± 35, p < 0.001), less frequently had IVH (26% vs. 44%, p = 0.03), and had mostly lobar or infratentorial hemorrhages. The median admission hematoma volume was smaller with vascular lesions (5.9 vs. 9.7 mL, p = 0.01). In regression models, ICH from a vascular lesion was associated with smaller admission hematoma volume (beta, -0.67, 95% CI, -1.29 to -0.05, p = 0.03), but no association with hematoma expansion was detected when assessed as a continuous (OR, 0.93; 95% CI, -4.46 to 6.30, p = 0.73) or dichotomous exposure (OR, 1.86; 95% CI, 0.40 to 8.51, p = 0.42). In a single-center cohort, patients with ICH from vascular lesions had smaller hematoma volumes than patients with primary ICH.

Economic analysis of n-butyl cyanoacrylate compared with ethylene vinyl alcohol copolymer liquid embolic embolization of brain arteriovenous malformations (bAVMs) from a US hospital perspective

BACKGROUND

In US hospitals, the liquid embolic systems (LESs) n-butyl cyanoacrylate (n-BCA) and ethylene vinyl alcohol copolymer (EVOH) are used for brain arteriovenous malformation (bAVM) embolization to achieve presurgical devascularization. The aim of this study was to perform an economic analysis comparing four techniques for bAVM embolization based on LES, ancillary device, and angiography suite time costs.

METHODS

An economic model was developed comparing the embolization costs for n-BCA, EVOH with the plug and push technique, EVOH with detachable-tip microcatheters, and EVOH with balloon microcatheters. Per procedure costs were calculated for bAVMs with one to four pedicles. Annual cohort analyses were performed to evaluate the potential impact for low and high-volume centers. Sensitivity analyses were performed to determine cost drivers.

RESULTS

The analyses showed that the n-BCA technique was the least costly of the four techniques. Total per procedure costs for one to four embolized pedicles ranged from $5941 to $10,074 for the n-BCA technique, $8428 to $30,345 for the EVOH balloon microcatheter technique, $12,711 to $47,477 for the EVOH plug and push technique, and $13,900 to $52,233 for the EVOH detachable-tip microcatheter technique. Cohort analyses costs for 52 annual cases ranged from $308,953 to $523,838 with the n-BCA technique and from $722,816 to $2,716,096 with the EVOH detachable-tip microcatheter technique.

CONCLUSIONS

Procedure costs associated with n-BCA are lower than those with each of the three EVOH techniques examined. Future cost analyses should compare the costs of new LES products once available.

Single-center experience with endovascular treatment of cerebral arteriovenous malformations with intent to cure in pediatric patients

PURPOSE

This study aimed to report the incidence of technical complications and immediate complete angiographic occlusion, identify associated factors with failure of complete occlusion and identify predictors of technical complications in a single-center experience of pediatric arteriovenous malformations (AVM) treated with endovascular treatment with intent to cure.

METHODS

Patients between 1 and 18 years of age undergoing endovascular embolization between 2011 and 2020 were included.

RESULTS

A total of 120 embolizations were performed in 69 patients. The most frequent clinical presentation was intracerebral hemorrhage (76.8%). Immediate obliteration of the malformations was achieved in 40 (58%) cases. The technical complication rate was 15%. AVM nidus size between 3 and 6 cm (OR: 3.91; 95% CI 1.1-13.85; p = 0.035) and the presence of multiple feeders (OR: 5.08; 95% CI 1.41-18.28; p = 0.074) were predictive of failure of immediate complete occlusion. The location of the temporal lobe (OR: 7.83; p = 0.048), deep venous drainage (OR: 4.67; p = 0.112), and the presence of an intranidal aneurysm (OR: 3.58; p = 0.134) were predictors of technical complications.

CONCLUSIONS

Embolization of pediatric AVMs with intent to cure shows a high rate of technical complications and acceptable immediate occlusion rates. Nidus size and the presence of multiple feeders were predictive of failure of complete occlusion, while temporal lobe location, deep venous drainage, and the presence of an intranidal aneurysm were predictors of technical complications. Further studies are needed to determine the best therapeutic approach in the pediatric population.

Three-Dimensional Printing Assisted Preoperative Surgical Planning for Cerebral Arteriovenous Malformation

Objective

The aim of this study to investigate the benefits of patient-based 3-dimensional (3D) cerebral arteriovenous malformation (AVM) models for preoperative surgical planning and education.

Methods

Fifteen patients were operated on for AVMs between 2015 and 2019 with patient-based 3D models. Ten patients’ preoperative cranial angiogram screenings were evaluated preoperatively or perioperatively via patient-based 3D models. Two patients needed emergent surgical intervention; their models were solely designed based on their AVMs and used during the operation. However, the other patients who underwent elective surgery had the modeling starting from the skull base. These models were used both preoperatively and perioperatively. The benefits of patients arising from treatment with these models were evaluated via patient files and radiological data.

Results

Fifteen patients (10 males and five females) between 16 and 66 years underwent surgery. The mean age of the patients was 40.0±14.72. The most frequent symptom patients observed were headaches. Four patients had intracranial bleeding; the symptom of admission was a loss of consciousness. Two patients (13.3%) belonged to Spetzler-Martin (SM) grade I, four (26.7%) belonged to SM grade II, eight (53.3%) belonged to SM grade III, and one (6.7%) belonged to SM grade IV. The mean operation duration was 3.44±0.47 hours. Three patients (20%) developed transient neurologic deficits postoperatively, whereas three other patients died (20%).

Conclusion

Several technological innovations have emerged in recent years to reduce undesired outcomes and support the surgical team. For example, 3D models have been employed in various surgical procedures in the last decade. The routine usage of patient-based 3D models will not only support better surgical planning and practice, but it will also be useful in educating assistants and explaining the situation to the patient as well.

Comparison of management approaches in deep-seated intracranial arteriovenous malformations: Does treatment improve outcome?

Deep-seated intracranial arteriovenous malformations (AVMs) represent a subset of AVMs characterized by variably reported outcomes regarding the risk of hemorrhage, microsurgical complications, and response to stereotactic radiosurgery (SRS). We aimed to compare outcomes of microsurgery, SRS, endovascular therapy, and conservative follow-up in deep-seated AVMs. A prospectively maintained database of AVM patients (1990-2017) was queried to identify patients with ruptured and unruptured deep-seated AVMs (extension into thalamus, basal ganglia, or brainstem). Comparisons of hemorrhage-free survival and poor functional outcome (modified Rankin scale [mRS] > 2) were performed between conservative management, microsurgery (±pre-procedural embolization), SRS (±pre-procedural embolization), and embolization utilizing multivariable Cox and logistic regression analyses controlling for univariable factors with p < 0.05. Of 789 AVM patients, 102 had deep-seated AVMs (conservative: 34; microsurgery: 6; SRS: 54; embolization: 8). Mean follow-up time was 6.1 years and did not differ significantly between management groups (p = 0.393). Complete obliteration was achieved in 49% of SRS patients. Upon multivariable analysis controlling for baseline rupture with conservative management as a reference group, embolization was associated with an increased hazard of hemorrhage (HR = 6.2, 95%CI [1.1-40.0], p = 0.037), while microsurgery (p = 0.118) and SRS (p = 0.167) provided no significant protection from hemorrhage. Controlling for baseline mRS, microsurgery was associated with an increased risk of poor outcome (OR = 9.2[1.2-68.3], p = 0.030), while SRS (p = 0.557) and embolization (p = 0.541) did not differ significantly from conservative management. Deep AVMs harbor a high risk of hemorrhage, but the benefit from intervention Remains uncertain. SRS may be a relatively more effective approach if interventional therapy is indicated.

Fulminant Guillain-Barré syndrome developed after surgical treatment of intracranial hemorrhage due to arteriovenous malformation: a case report

Guillain-Barré syndrome (GBS) is a rare autoimmune disorder. GBS after surgical treatment of intracranial hemorrhage due to arteriovenous malformation (AVM) is even rarer. We present a 62-year-old man diagnosed with intracranial AVM and cerebral hemorrhage. He developed GBS after the operation for AVM and cerebral hemorrhage. Following surgical excision of AVM and cerebral hematoma, the patient developed generalized weakness, with subsequent quadriplegia and life-threatening dyspnea. The diagnosis was confirmed to be the acute motor-sensory axonal neuropathy subtype of GBS after cerebrospinal fluid analysis and antibody tests. The patient responded poorly to immunoglobulin and steroid therapy. His family abandoned further management and signed out of the hospital against medical advice. Despite being rare, GBS can occur after intracranial hemorrhage and surgery. Clinicians should rule out GBS when patients show no improvement or develop new neurologic.

The CTSC-RAB38 Fusion Transcript Is Associated With the Risk of Hemorrhage in Brain Arteriovenous Malformations

Brain arteriovenous malformations (bAVMs) are congenital anomalies of blood vessels that cause intracranial hemorrhage in children and young adults. Chromosomal rearrangements and fusion genes play an important role in tumor pathogenesis, though the role of fusion genes in bAVM pathophysiological processes is unclear. The aim of this study was to identify fusion transcripts in bAVMs and analyze their effects. To identify fusion transcripts associated with bAVM, RNA sequencing was performed on 73 samples, including 66 bAVM and 7 normal cerebrovascular samples, followed by STAR-Fusion analysis. Reverse transcription polymerase chain reaction and Sanger sequencing were applied to verify fusion transcripts. Functional pathway analysis was performed to identify potential effects of different fusion types. A total of 21 fusion transcripts were detected. Cathepsin C (CTSC)-Ras-Related Protein Rab-38 (RAB38) was the most common fusion and was detected in 10 of 66 (15%) bAVM samples. In CTSC-RAB38 fusion-positive samples, CTSC and RAB38 expression was significantly increased and activated immune/inflammatory signaling. Clinically, CTSC-RAB38 fusion bAVM cases had a higher hemorrhage rate than non-CTSC-RAB38 bAVM cases (p < 0.05). Our study identified recurrent CTSC-RAB38 fusion transcripts in bAVMs, which may be associated with bAVM hemorrhage by promoting immune/inflammatory signaling.

Sylvian fissure arteriovenous malformations: case series and systematic review of the literature

BACKGROUND

Sylvian fissure arteriovenous malformations are rare but important vascular lesions, whose importance lies in both haemorrhage and seizure risk. Although surgery has been recommended as a treatment, the overall estimation of success has not been reported to render outcomes easier to understand in comparison to other treatment modalities.

OBJECTIVES

This systematic review of the literature and two cases aims to illustrate the results of surgery as a contemporary treatment option and present a novel anatomical classification system for Sylvian fissure arteriovenous malformations.

MATERIALS AND METHODS

A systematic review was performed by searching MEDLINE (PubMed), EMBASE and Cochrane electronic bibliographic databases from conception to 2018. The following keywords were used: 'Sylvian fissure' AND 'AVM' OR 'arteriovenous malformation' OR 'intracranial arteriovenous malformation' OR 'cerebral arteriovenous malformation' OR 'brain arteriovenous malformation'. The search strategy was not limited by study design but only included keywords in the English language. In addition, two local institution Sylvian fissure arteriovenous malformations are presented and incorporated.

RESULTS

A total of nine full-text articles were included in the analysis. The results of reported cases and the literature review emphasise the role of surgery in the treatment of Sylvian fissure arteriovenous malformations, with an acceptable result in carefully selected patients. We propose a classification system which may inform the choice of surgical approach for these lesions.

CONCLUSIONS

Surgery remains the cornerstone of Sylvian fissure arteriovenous malformation treatment, which may apply to high-grade lesions in this special anatomical location.

Hemorrhage Following Complete Arteriovenous Malformation Resection With No Detectable Recurrence: Insights From a 27-Year Registry

BACKGROUND

Although recurrence and de novo formation of arteriovenous malformations (AVMs) have been reported following complete resection, the occurrence of hemorrhage in the same location of an AVM with no detectable lesion (lesion-negative hemorrhage) has not been described after microsurgery.

OBJECTIVE

To characterize the incidence and properties of lesion-negative hemorrhage following complete microsurgical resection.

METHODS

A prospectively maintained registry of AVM patients seen at our institution between 1990 and 2017 was used. Microsurgically treated patients were selected, and the incidence of a lesion-negative hemorrhage was calculated and described with a Kaplan-Meier curve. Baseline characteristics as well as functional outcome at last follow-up were compared between patients with and without a lesion-negative hemorrhage.

RESULTS

From a total of 789 AVM patients, 619 (79%) were treated, and 210 out of 619 patients (34%) underwent microsurgery with or without preoperative embolization or radiosurgery. The microsurgically treated cohort was followed up for a mean of 6.1 ± 3.0 yr after surgery with 5 (2.4%) patients experiencing postresection lesion-negative hemorrhage (3.9 per 1000 person-years) at an average of 8.6 ± 9.0 yr following surgery. Follow-up angiograms after hemorrhage (up to 2 mo posthemorrhage) confirmed the absence of a recurrent or de novo AVM in all cases. All patients with a lesion-negative hemorrhage initially presented with rupture before resection (Fisher P = .066; log-rank P = .057). The occurrence of a lesion-negative hemorrhage was significantly associated with worse modified Rankin scale scores at last follow-up (P = .031).

CONCLUSION

A lesion-negative hemorrhage can occur following complete microsurgical resection in up to 2.4% of patients. Exploration of possible underlying causes is warranted.

Endovascular Treatment of an Arteriovenous Malformation Associated with a Double Origin of the Posterior Inferior Cerebellar Artery

INTRODUCTION

A double origin of the posterior inferior cerebellar artery (DOPICA) is a rare anatomical variant. Posterior fossa arteriovenous malformations (AVMs), especially cerebellar AVMs, are also not common. Consequently, the association of a DOPICA with a cerebellar AVM is even rare.

CASE PRESENTATION

We present a rare case of a pediatric cerebellar AVM supplied by a branch of a DOPICA which was treated endovascularly with NBCA. Total obliteration was achieved in the immediate controls and at 1-year follow-up.

CONCLUSION

Navigation through tortuous and long branches from a DOPICA is technically feasible. Although NBCA cure rates are relatively low, when the microcatheter can no longer navigate through the feeding artery, a correct dilution of NBCA with lipiodol can provide adequate penetration of this embolic agent, to obliterate the AVM nidus completely.

Perioperative Treatment of Brain Arteriovenous Malformations Between 2006 and 2014: The Helsinki Protocol

Objective

We reviewed retrospectively the perioperative treatment of microsurgically resected brain arteriovenous malformations (bAVMs) at the neurosurgical department of Helsinki University Hospital between the years 2006 and 2014. We examined the performance of the treatment protocol and the incidence of delayed postoperative hemorrhage (DPH).

Methods

The Helsinki protocol for postoperative treatment of bAVMs was used for the whole patient cohort of 121. The patients who had subsequent DPH were reviewed in more detail.

Results

Five out of 121 (4.1%) patients had DPH. These patients had a higher Spetzler–Martin grade (SMG) (p = 0.043) and a more complex venous drainage pattern (p = 0.003) as compared to those who had no postoperative bleed. Patients with DPH had 43% larger intravenous fluid intake in the neurosurgical intensive care unit (p = 0.052); they were all male (p = 0.040) and had longer stay in the intensive care unit (p = 0.022).

Conclusions

The Helsinki protocol for postoperative treatment of bAVMs was found to produce comparable results to a more complex treatment algorithm. DPH was associated with high SMG, complex venous drainage pattern, male gender and high intravenous fluid intake. Our findings support the use of SMG in defining patient’s postoperative treatment as the DPHs in our study occurred in patients with grade 2–5.

Dural Arteriovenous Fistula Associated with Dental Implant

BACKGROUND

Dural arteriovenous fistulas (DAVFs) are characterized by pathologic shunts between meningeal arteries and venous sinuses, without nidus. Although many lesions are considered idiopathic, there may be an association with inflammatory processes, including sinus thrombosis, venous hypertension, craniotomy, trauma, and infections.

CASE DESCRIPTION

A 50-year-old woman with an infectious complication of a dental implant evolved with an occipital DAVF. To our knowledge, this is the first case of a dental implant-related DAVF reported in the medical literature.

CONCLUSIONS

Physicians should be aware of the possibility of DAVF formation after craniofacial infections. Better understanding of the etiopathogenesis of this type of lesion is required to avoid and treat potential complications.

Cerebellar mutism after embolization of vermian arteriovenous malformation

BACKGROUND

Cerebellar mutism is usually associated with posterior fossa tumor surgery.

CASE REPORT

We report a case of a 17-year-old female, presented with headache and tremor after hemorrhage from a vermian arteriovenous malformation. She was successfully treated by embolization; however, on immediate postoperative, she developed persistent mutism. To the best authors' knowledge, this is the first case of cerebellar mutism after endovascular treatment reported in the medical literature.

CONCLUSION

The endovascular approach may have the same potential of complication of conventional surgery; therefore, more study is necessary to clarify the role and limits of this technique to treat cerebellar arteriovenous malformation.

A coil in the hair-a case report of percutaneous coil migration

Coil migration following cerebral aneurysm treatment has been described and may result in stroke, recurrent aneurysm, or local mass effect. Cerebral coil embolization is also applied in arteriovenous malformations and arteriovenous fistulas, but these pathologies are relatively rare and coil migration is not as well described. Furthermore, these cases are more commonly treated with combinations of multiple modalities to achieve cure. Embolization, surgery, and radiation each have risks and benefits and combinations may have synergistic risks and benefits not seen in monotherapy. We report a case of extravascular and extra-corporeal coil migration after embolization and craniectomy to treat a patient with hemorrhage from an arteriovenous fistula.

[Intracranial vascular malformations]

Intracranial vascular malformations range from incidental asymptomatic vascular alterations up to life-threatening vascular disorders. Arteriovenous malformations and dural arteriovenous fistulas are cerebral vascular malformations with arteriovenous shunting of blood. In the majority of cases they are accompanied by an elevated risk of intracerebral hemorrhage and can cause severe symptoms. They can be treated conservatively or interventionally via microneurosurgery, endovascular embolization and radiation therapy. Cavernous malformations, developmental venous anomalies (DVA) and capillary telangiectasia are cerebral vascular malformations without arteriovenous shunting. Cavernous malformations are rarely symptomatic in the form of cerebral hemorrhage, headache or seizures and in such cases an operative treatment can be indicated. The DVA and capillary telangiectasia are usually asymptomatic and do not require treatment.

Reimagining ARUBA: Theoretical Optimization of the Treatment of Unruptured Brain Arteriovenous Malformations

BACKGROUND AND PURPOSE

The results of the A Randomized Trial of Unruptured Brain Arteriovenous (ARUBA) study, indicating that conservative medical management of unruptured brain arteriovenous malformations (UBAVM) is superior to interventional therapy, have generated debates that have hampered their application into clinical practice. Irrespectively of study conclusions, it seems reasonable to explore how much better interventional therapy would have to be to become competitive with conservative medical management.

METHODS

We conducted an exploratory analysis to replicate the original data from ARUBA. The functional form of the replicated ARUBA data, according to their Weibull distribution, allowed estimation of parameters. We carried out Monte Carlo simulations while introducing theoretical reductions of interventional risk, and the results were used to construct theoretical and example Kaplan-Meier curves from simulations.

RESULTS

The "ARUBA Replication" analysis showed results nearly identical to those published in the study, with an estimated hazard ratio of 0.27 (95% CI: 0.14-0.55). At 50% interventional risk reduction, the simulations showed an estimated event rate of 14.9%, and the protective effect of conservative medical management was no longer statistically significant. Greater risk reductions hastened the time to benefit for interventional therapy, and an 80% risk reduction demonstrated superiority of interventional therapy at just over 2 years Hazard Ratio (HR: 1.44, 95% CI: 0.55-4.92).

CONCLUSIONS

Reduction in risk of interventional therapy by 50%-80% results in more competitive clinical outcomes, equating or surpassing the benefit of conservative medical management of UBAVM. This conjecture should be taken into consideration in the design of future studies of this patient population, particularly because it is supported by recent observational studies.

Surgical Treatment of Arteriovenous Malformations: Role of Preoperative Staged Embolization

Preoperative embolization is complementary to surgery for large brain arteriovenous malformations (AVMs). From January 2005 to December 2015, 69 patients harboring an AVM were managed in our department by the same surgeon (RG). Forty one were ruptured and 65 were supratentorial. Thirty nine smaller AVMs were treated with surgery stand-alone, whereas, for 30 larger malformations, surgery was combined with adjuvant treatment involving preoperative staged embolization and/or, less frequently, radiosurgery. In all patients treated with surgery alone, complete resection of AVM was achieved. A successful preoperative partial endovascular obliteration of AVM was obtained in 24 out of 27 more complex cases, with a zero mortality rate and a very low morbidity. Here, embolization was of a certain utility in the handling of deeper feeders and nidus excision, also facilitating intraoperative hemostasis. In three cases of residuals, radiosurgery was performed. In those patient treated with a combined approach, a good overall outcome, 0-2 modified Rankin Scale (mRS), was achieved in 25 cases. Preoperative embolization proved to be a reasonable option complementary to high-grade AVMs surgery, reducing the frequency of breakthrough hemorrhages, aiding the elimination of deep feeders, and making the nidus dissection easier.

Developmental Venous Anomaly Serving as a Draining Vein of Brain Arteriovenous Malformation

Developmental venous anomalies are cerebral vascular malformations that present normal venous drainage of cerebral tissue. With increased and accessible usage of modern diagnostic tools, they are now one of the most commonly diagnosed cerebral vascular malformations. Although developmental venous anomalies are considered to be benign lesions, association with arteriovenous malformation renders malignant potential to this combined pathology. In the case presented, these malformations were clinically silent and diagnosed accidentally, so they were not treated either with surgery, endovascular surgery or radiosurgery, considering the possible complications such as venous infarction of the brain, and because there was no obvious neurologic deficit related to this pathology. The patient presents for regular neurosurgical follow up examinations and has been free from symptoms that were present on admission.

Extending the indications for transvenous approach embolization for superficial brain arteriovenous malformations

INTRODUCTION

Transarterial embolization is the standard endovascular treatment strategy for intracranial arteriovenous malformations (AVMs). The transvenous approach has been indicated for the embolization of deep AVMs meeting a set of strict eligibility criteria. The present study aims to assess the safety and efficacy of the transvenous approach for superficial AVMs.

METHODS

A retrospective series of 12 patients presenting with cortical AVMs were treated by endovascular embolization using a transvenous approach with a curative intent.

RESULTS

Nine patients (75%) had ruptured AVMs at admission. The mean nidus size was 1.9 cm, six patients (50%) had a nidus in eloquent areas and the median Spetzler-Martin grade was 2. The rate of immediate angiographic occlusion of the AVMs was 91.6% (11/12). One patient in whom immediate angiographic occlusion was not achieved showed spontaneous occlusion at the 6-month follow-up. No procedural or clinical complications were observed. The mean and median modified Rankin scale (mRS) scores at discharge were 1.7 and 2 (range 0-3, SD=0.96), and the mean and median mRS scores at 6 months were 1.6 and 2 (0-3, 1.16). Nine patients (75%) were independent (mRS ≤2) at discharge and 11 patients (91.6%) were independent (mRS ≤2) at the 6-month follow-up.

CONCLUSIONS

The curative transvenous embolization of superficial intracranial AVMs is feasible and appears safe and effective when strict anatomical selection is respected. This technique extends the current indications for transvenous embolization of intracranial AVMs and may improve cure rates while reducing embolization-related complications.

Volume-staged stereotactic radiosurgery for large intracranial arteriovenous malformations

Stereotactic radiosurgery (SRS) is an effective treatment option for intracranial arteriovenous malformations (AVM). However, the treatment of large AVMs (nidus volume ≥12cm³) with single-session SRS alone yields generally poor outcomes. Volume-staged SRS (VS-SRS) is a therapeutic strategy for large AVMs which seeks to avoid the disadvantages of single-session SRS, but reports regarding its efficacy remain limited. The aim of this retrospective cohort study is to assess the outcomes of VS-SRS for large AVMs. We identified all AVM patients who underwent VS-SRS at our institution from 2000 to 2015 with ≥12months follow-up. Baseline and outcomes data were analyzed. A total of 12 patients were selected for the study cohort, with a median age of 30years. The median maximum AVM diameter and nidus volume were 4.3cm and 13.6cm³, respectively. The Spetzler-Martin grade was III and IV each in six AVMs (50%). All patients underwent VS-SRS in two stages, and the median margin dose was 17Gy for both VS-SRS procedures. The median time interval between the two procedures was three months. After a median radiologic follow-up duration of 39months, the median degree of AVM volume reduction (evaluable in nine patients) was 87% (range 12-99%). The rates of radiologically evident, symptomatic, and permanent radiation-induced changes were 58%, 25%, and 8%, respectively. There were no cases of post-SRS hemorrhage. VS-SRS substantially reduces the size of large AVMs. A potential role for VS-SRS may be to facilitate subsequent definitive intervention to obliterate a shrunken, residual nidus.

[Clinical useness of multimodal techniques in microsurgical resection of cerebral arteriovenous malformation]

Objective: To explore the clinical useness of intraoperative functional neuronavigation and fluorescent indocyanine green(ICG) angiography as well as electrophysiological evaluation during microsurgical resection of cerebral arteriovenous malformations (AVM). Methods: A series of 42 consecutive cases with AVM underwent microsurgery by intraoperative functional neuronavigation at Department of Neurosurgery of People's Liberation Army General Hospital from January 2009 to February 2015 were retrospectively analyzed. Of the 42 patients, 29 were males and 13 were females aging from 4 to 62 years (mean age 32.6 years). Preoperative assessment included functional magnetic resonance imaging and diffusion tensor imaging to identify the relationship between lesions and eloquent areas. The results of images were integrated into three-dimensional datasets to achieve intraoperative microscopic-based functional neuronavigation during AVM resection. Operations involved in motor areas and corticospinal tract were performed under continuous electrophysiological monitoring. ICG angiography was performed at pre-dissection, post-clipping of the feeders, and post-resection of the nidus. FLOW 800 software presented a color map and ICG intensity-time curve to demostrate the vascular architecture. Postoperative digital subtraction angiography was re-examined routinely to evaluate the extent of resection. Clinical outcomes were evaluated with the modified Rankin Scale. Results: All patients underwent surgery under intraoperative navigation. Of the 42 patients, total resection was achieved in 36 cases (85.7%, 36/42) including 14 cases of AVM in eloquent areas. A total of 40 ICG angiographies were successfully performed among 11 patients. Average number of ICG injections per operation was 3.6 (ranging from 3 to 6). Feeders were visualized in 10 patients and drainers were visualized in 9 cases. The post-surgical follow-up period varied from 3 months to 70 months (mean 22.5 months). 83.8% of the patients returned to normal work and life during the followed-up period. Conclusion: Combining intraoperative neuronavigation and electrophysiological monitoring, as well as fluorescent ICG angiography contribute to microsurgical resection of cerebral AVM effectively in selecting suitable patients, further avoiding neurologic compromise as well.

[Interventional radiology in the head and neck region]

In interventional neuroradiology, endovascular embolization represents an important and helpful tool in the treatment of multiple head and neck diseases. These interventional procedures may be performed with curative intent, to reduce the surgical risk within a multimodal treatment concept, or to improve or at least maintain a good quality of life within a palliative therapy concept. In addition to a good understanding of disease pathology, knowledge of vascular anatomy, including collateral vessels and dangerous extracranial-intracranial anastomoses, is essential for successful treatment, as is implementation of an established technique using appropriate material. Indications for endovascular embolization are i. otherwise unmanageable bleeding (caused by e. g., trauma, vascular malformation, or tumor), ii. reduction of perioperative bleeding by preoperative embolization in case of a hypervascularized tumor, iii. selective induction of tumor necrosis by palliative embolization to enhance local tumor control. Major complications such as stroke, loss of vision, and cranial nerve palsy are mostly due to a lack of preinterventional evaluation. Regarding neurological deficits, interventions within the supply region of the external carotid artery have a complication rate below 1%.

Cortical plasticity in patients with cerebral arteriovenous malformations

The aim of this review is to ascertain the evidence for cortical plasticity in arteriovenous malformation (AVM) patients. Chronic hypoperfusion due to vascular steal from cerebral AVM can result in a translocation of eloquent neurological functions to other brain areas, a phenomenon known as cortical plasticity. We performed a systematic literature review of the studies that have evaluated cortical plasticity in AVM patients. A total of 22 studies from 1996 to 2014 were included for the analyses. The evaluation of cortical plasticity was performed prior to AVM intervention in 109 patients, and during or after AVM intervention in 18. The most commonly assessed neurological functions were motor in 85% and language in 11% of the former cohort, and motor in 78% and language, cognition, and memory each in 39% of the latter cohort. Functional MRI was the most frequently used method for evaluating cortical plasticity, and was performed in 63% of the former and 56% of the latter cohort. In conclusion, cortical plasticity appears to be influenced by both AVM pathogenesis and intervention. Given the limited evidence that is currently available for cortical plasticity in AVM patients, further studies are warranted to determine its incidence and impact on long term clinical outcomes.

Visual Field Defect after Transfrontal Sinus Approach of Ethmoidal Dural Arteriovenous Fistulas (eDAVFs) : Experience and Complication of Transfrontal Sinus Approach

The approach to ethmoidal dural arteriovenous fistulas (eDAVFs) is usually via a pterional or a frontal craniotomy. However, the transfrontal sinus is a more direct route to the fistula. The aim of this report is to describe our experience and associated complications occurring as a result of flow diversion in the transfrontal sinus approach for eDAVFs. In this report, we discuss visual field defects occurring after a transfrontal sinus operation. This approach is most direct for surgical treatment of an eDAVF, enabling preservation of neural structures with minimal to no negative effects on the brain. Although the surgery was uneventful, the patient presented with a left side visual field defect. An ophthalmologic exam detected an arterial filling delay in the choroidal membrane and ischemic optic neuropathy was highly suspected. The patient is currently recovering under close observation with no special treatment. The transfrontal sinus approach provides the most direct and shortest route for eDAVFs, while minimizing intraoperative bleeding. However, complications, such as visual field defects may result from a sudden flow diversion or eyeball compression due to scalp traction.

Angiographic factors associated with haemorrhagic presentation of brain arteriovenous malformation in a Chinese paediatric population

OBJECTIVE

To identify specific angiographic factors associated with haemorrhagic presentation of brain arteriovenous malformation in Chinese paediatric patients.

DESIGN

Retrospective cross-sectional observational study.

SETTING

Four locoregional tertiary neurosurgical centres in Hong Kong: Queen Elizabeth Hospital, Tuen Mun Hospital, Kwong Wah Hospital, and Pamela Youde Nethersole Eastern Hospital.

PATIENTS

Patients aged 18 years or younger who underwent pretreatment digital subtraction angiography for brain arteriovenous malformation between 1 January 2005 and 31 July 2013 were included. Patients were divided into haemorrhagic and non-haemorrhagic groups based on the initial presentation. Pretreatment digital subtraction angiographies were independently reviewed by two experienced neuroradiologists.

MAIN OUTCOME MEASURES

The following parameters were evaluated for their association with haemorrhagic presentation by univariate and multivariate analyses: nidus location, nidus size, nidus morphology (diffuse or compact); origin and number of arterial feeders; venous drainage; number of draining veins; presence of aneurysms, venous varices, and venous stenosis.

RESULTS

A total of 67 children and adolescents (28 male, 39 female) with a mean age of 12 years were included. Of them, 52 (78%) presented with haemorrhage. Arteriovenous malformation size (P=0.004) and morphology (P=0.05) were found to be associated with haemorrhagic presentation by univariate analysis. Small arteriovenous malformation nidus size and diffuse nidal morphology were identified as independent risk factors for haemorrhage by multivariate analysis.

CONCLUSION

Smaller arteriovenous malformation size and diffuse nidal morphology are angiographic factors independently associated with haemorrhagic presentation. Bleeding risk is important in determining the therapeutic approach (aggressive vs conservative) and timeframe, particularly in paediatric patients.

Embolization of cerebral arteriovenous malformations with silk suture particles prior to stereotactic radiosurgery

We aimed to determine the long term durability of silk suture and polyvinyl alcohol (PVA) particle embolization (SPE) of arteriovenous malformations (AVM), and to evaluate the outcomes following multimodality management of AVM with combined SPE and stereotactic radiosurgery (SRS). A general supposition among neurointerventionalists is that embolization of cerebral AVM with silk sutures and PVA particles does not yield a durable occlusion. We performed a retrospective review of all AVM patients treated at our institution with combined SPE and SRS. After extracting the baseline, embolization and SRS data for each patient, the durability of SPE was determined by evaluating the postembolization recanalization between the last procedural angiogram and the most recent neuroimaging. Four AVM patients who underwent a total of nine SPE procedures through 21 arterial pedicles were included for the analyses. The nidus volumes were 5.8-75 cm(3) and the Spetzler-Martin grades were II and V in one patient and III in two patients. The median degree of devascularization per procedure was <25%. There were no procedural complications, with all patients maintaining functional independence after embolization (modified Rankin scale score 0-2). After a median follow-up duration of 27 months (range: 23-36), there were no patients with recanalization. SRS (marginal dose 13-18 Gy) resulted in 40 to >95% volume reduction. Following SRS, one patient remained asymptomatic, two patients improved, and one patient deteriorated due to a latency period AVM hemorrhage. In conclusion, SPE can safely provide durable AVM devascularization, therefore, appropriately selected nidi can be effectively treated with combined SPE and SRS.

CT and MR imaging of non-cavernous cranial dural arteriovenous fistulas: Findings associated with cortical venous reflux

PURPOSE

To compare the conventional CT and MR findings of DAVFs in relation to the venous drainage pattern on digital subtraction angiography (DSA).

MATERIALS AND METHODS

Cross-sectional imaging findings (CT and/or MR) in 92 patients were compared to the presence of cortical venous reflux (CVR) on DSA.

RESULTS

Imaging features significantly more prevalent in patients with CVR included: abnormally dilated and tortuous leptomeningeal vessels (92% vs. 4%, p<0.001) or medullary vessels (69% vs. 0%, p<0.001), venous ectasias (45% vs. 0%, p<0.001) and focal vasogenic edema (38% vs. 0%, p<0.001). The following findings trended towards association but did not reach the p value established following Bonferroni correction: dilated external carotid artery branches (71% vs. 38%, p=0.005), cluster of vessels surrounding dural venous sinus (50% vs. 19%, p=0.009), presence of hemorrhage (33 vs. 12%, p=0.040), and parenchymal enhancement (21% vs. 0%, p=0.030).

CONCLUSION

In the appropriate clinical setting, recognition of ancillary signs presumably related to venous arterialization and congestion as well as arterial feeder hypertrophy should prompt DSA confirmation to identify DAVFs associated with CVR.

Predictive Capability of the Spetzler-Martin versus Supplementary Grading Scale for Microsurgical Outcomes of Cerebellar Arteriovenous Malformations

The recently described supplementary grading scale may be superior to the widely used Spetzler-Martin grading scale in the prediction of microsurgical outcomes for cerebellar arteriovenous malformations (AVM). We report two cases of ruptured cerebellar AVMs with the same Spetzler-Martin grade but different supplementary grades treated with microsurgical resection. Both patients had symptomatic brainstem compression from cerebellar hematomas and subsequently underwent uncomplicated surgeries; however, their outcomes were significantly different. It has previously been proposed that AVMs distort cerebellar anatomy in a different manner than supratentorial cerebral anatomy thereby potentially resulting in misrepresentation when utilizing the Spetzler-Martin grading scale. However, the components of the supplementary grading scale are independent of cerebellar anatomy, which may explain why it has been shown to be better than the Spetzler-Martin grading scale for prediction of surgical outcomes. In addition, due to the smaller volume of the posterior fossa compared to the supratentorial compartment, rupture of cerebellar AVMs may result in rapid and catastrophic neurological compromise. Therefore, the role of microsurgery may be more critical for AVMs of the cerebellar than for those located elsewhere. Simple and effective grading systems are invaluable tools for clinical and surgical decision-making, although the decisions rendered should always be made in conjunction with the patient's presentation and the physician's experience.