A proposed grading system for arteriovenous malformations

Dilemmas in managing coexisting arteriovenous and cavernous malformations: Case report

Coexisting arteriovenous malformations (AVMs) and cavernous malformations (CMs) are rare. Here, we present our dilemmas in managing a patient with a cerebral AVM and a pontine CM. A 47-year-old patient suffered from headaches, vomiting, and transient swallowing difficulties. The cerebral computed tomography showed a pontine hyperintense lesion, while the axial magnetic resonance imaging of the head disclosed a frontal interhemispheric AVM and a CM located in the rostral and ventral aspect of the pons. Despite a pontine hemorrhage, the patient underwent microsurgical excision of the frontal lesion in the first place, due to the increased bleeding risk, followed by stereotactic radiosurgery of the pontine CM. On the 6 months follow-up, the patient's clinical status was stable. A reasonable treatment strategy based on risk stratification is paramount in managing patients with coexisting AVMs and CMs. The optimal outcome frequently requires a staged multidisciplinary approach.

Effects of Preoperative Embolization on Spetzler-Martin Grade I and II Arteriovenous Malformations: A Propensity-Adjusted Analysis

BACKGROUND

Cerebral arteriovenous malformations (AVMs) with low Spetzler-Martin grades (I and II) are associated with good neurological outcomes after microsurgical resection; however, the use of preoperative embolization for these lesions is controversial.

OBJECTIVE

To compare the neurological outcomes of preoperative embolization with no embolization in patients with low-grade AVMs.

METHODS

Patients with a Spetzler-Martin grade I or II AVM who underwent microsurgical resection during January 1, 1997, through December 31, 2019, were analyzed. Patients undergoing preoperative embolization were compared with patients not undergoing embolization. A propensity score was constructed from baseline characteristics and used to match intervention (embolization) and control (nonembolization) groups in a 1:1 ratio. The primary outcome was poor neurological status on last follow-up examination, defined as a modified Rankin Scale score >2 and a modified Rankin Scale score worse at follow-up than at the preoperative examination.

RESULTS

Of the 603 patients analyzed, 310 (51.4%) underwent preoperative embolization and 293 (48.6%) did not. Patients in the embolization cohort compared with those in the nonembolization cohort had a higher percentage of Spetzler-Martin grade II AVMs (71.6% vs 52.6%, P < .001) and a lower percentage of hemorrhage (41% vs 55%, P = .001). After propensity score matching, no differences were found between paired cohorts (each N = 203) for baseline characteristics with a significant reduction in absolute standardized mean differences. No significant differences were found in primary outcomes between treatment groups in the matched or unmatched cohorts.

CONCLUSION

Preoperative embolization of low-grade Spetzler-Martin AVMs is not associated with improved neurological outcomes after microsurgical resection.

Correlation between angioarchitectural characteristics of brain arteriovenous malformations and clinical presentation of 183 patients

BACKGROUND

The correlation between angioarchitecture and clinical presentation of brain arteriovenous malformation (bAVM) remains a subject of debate.

OBJECTIVE

The main purpose of the present study was to assess the correlation between angioarchitectural characteristics of bAVM and clinical presentation.

METHODS

A retrospective review of all consecutive patients presenting a bAVM who underwent a cerebral angiography at Beneficencia Portuguesa Hospital in São Paulo between January 2006 and October 2016 was carried out. Patients were divided in five groups: group 1 - hemorrhage; group 2 - seizure; group 3 - headache; group 4 - progressive neurological deficits (PND); group 5 - incidental).

RESULTS

A total of 183 patients were included, with group 1 comprising 56 cases, group 2 49 cases, group 3 41 cases, group 4 28 cases, and group 5 9 cases. Regarding hemorrhage presentation, a statistical correlation was observed with female gender (P < 0.02), Spetzler-Martin 3B (P < .0015), and lesions with low flow (P < 0.04). A positive association was found between group 2 and age less than 36 years (P < 0.001), male sex (P < 0.018), presence of superficial lesions not classified as SM 3B (P < 0.002), presence of venous ectasia (p <0.03), and arterial steal phenomenon (P < 0.03). Group 4 was associated with older age (P < 0.01).

CONCLUSIONS

Angioarchitectural characteristics can be correlated with some clinical presentations as well as with some clinical data, making it possible to create predictive models to differentiate clinical presentations.

Magnetic resonance imaging detected radiation-induced changes in patients with proton radiation-treated arteriovenous malformations

Background

Treatment of intracranial arteriovenous malformations (AVMs) includes surgery, radiation therapy, endovascular occlusion, or a combination. Proton radiation therapy enables very focused radiation, minimizing dose to the surrounding brain.

Purpose

To evaluate the presence of radiation-induced changes on post-treatment MRI in patients with AVMs treated with proton radiation and to compare these with development of symptoms and nidus obliteration.

Material and Methods

Retrospective review of pre- and post-treatment digital subtraction angiography and MRI and medical records in 30 patients with AVMs treated with proton radiation. Patients were treated with two or five fractions; total radiation dose was 20–35 physical Gy. Vasogenic edema (minimal, perinidal, or severe), contrast enhancement (minimal or annular), cavitation and nidus obliteration (total, partial, or none) were assessed.

Results

26 of 30 patients (87%) developed MRI changes. Vasogenic edema was seen in 25 of 30 (83%), abnormal contrast enhancement in 18 of 26 (69%) and cavitation in 5 of 30 (17%). Time from treatment to appearance of MRI changes varied between 5 and 25 months (median 7, mean 10). Seven patients developed new or deteriorating symptoms that required treatment with corticosteroids; all these patients had extensive MRI changes (severe vasogenic edema and annular contrast enhancement). Not all patients with extensive MRI changes developed symptoms. We found no relation between MRI changes and nidus obliteration.

Conclusion

Radiation-induced MRI changes are seen in a majority of patients after proton radiation treatment of AVMs. Extensive MRI changes are associated with new or deteriorating symptoms.

Venous tortuosity as a novel biomarker of rupture risk in arteriovenous malformations: ARI score

BACKGROUND

Risk of rupture in arteriovenous malformations (AVMs) varies considerably among series. Hemodynamic factors, especially within the venous side of the circuit, seem to be responsible but are not yet well defined. We analyzed tortuosity in the draining vein as a potential new marker of rupture in AVMs, and propose a simple index to predict AVM bleeding.

METHODS

A retrospective analysis of the venous angioarchitecture of brain AVMs was carried out at our center from 2013 to 2021, with special attention to venous tortuosity. After univariate analysis, the features of interest were combined to construct several predictive models using multivariate logistic regression. The best model proposed was the new AVM rupture index (ARI), which was then validated in an independent cohort.

RESULTS

68 AVMs were included in the first step and 32 in the validation cohort. Venous tortuosity, expressed as at least one curve >180°, was a significant predictor of rupture (p=0.023). The proposed bleeding index consisted of: venous tortuosity (any curve of >180°), single draining vein, and paraventricular/infratentorial location. It seems to be a robust evaluation tool, with an area under the receiver operating characteristic (AUROC) curve of 0.806 (95% CI 0.714 to 0.899), consistently replicated in the independent sample (AUROC 0.759 (95% CI 0.607 to 0.911)), and with an inter-rater kappa coefficient of 0.81 .

CONCLUSIONS

Venous tortuosity may serve as a predictor of bleeding in AVMs that warrants further investigation. This likely new marker was one of the three elements of the proposed ARI. ARI outperformed the predictive accuracy of previous scores, and remained consistent in an independent cohort.

Microsurgical resection versus stereotactic radiosurgery for low-grade intracranial arteriovenous malformations: A 27-year institutional experience

The role of microsurgery and radiosurgery in the management of low-grade (Spetzler-Martin grade 1 and 2) arteriovenous malformations (AVMs) remains controversial. We aimed to compare outcomes of low-grade AVMs following microsurgery and radiosurgery using a database of AVM patients presenting between 1990 and 2017. Procedure-related complications, obliteration, and functional status at last follow-up were compared between groups. Hemorrhage-free survival was compared using Kaplan-Meier analysis with subgroup analyses by rupture status on presentation. The study involved 233 patients, of which 113 and 120 were treated with microsurgery and radiosurgery, respectively. The complication rates were statistically comparable between both treatment modalities. Mean follow-up time was 5.1 ± 5.2 years. In the complete cohort, there was no significant difference in hemorrhage-free survival between microsurgery and radiosurgery (log-rank p = 0.676, Breslow p = 0.493). When excluding procedure-related hemorrhage and partial resection, hemorrhage-free survival was significantly higher in the surgically treated cohort (log-rank = 0.094, Breslow p = 0.034). The obliteration rate was significantly higher in the surgical cohort (96% vs. 57%, p < 0.001), while functional status was similar. Microsurgery may offer superior hemorrhage-free survival in the early post-treatment period and demonstrates equivalent long-term hemorrhage control and functional outcome at 5 years compared to radiosurgery with nearly complete obliteration rates. Persistent neurologic deficits following microsurgery and symptomatic cerebral edema represent important treatment risks despite low SM grading. Appropriate patient selection even when dealing with low-grade AVMs is advised, as judicious patient selection and emphasis on technical success can minimize procedure-related hemorrhage and the incidence of subtotal resection.

Review of treatment and therapeutic targets in brain arteriovenous malformation

Brain arteriovenous malformations (bAVM) are an important cause of intracranial hemorrhage (ICH), especially in younger patients. The pathogenesis of bAVM are largely unknown. Current understanding of bAVM etiology is based on studying genetic syndromes, animal models, and surgically resected specimens from patients. The identification of activating somatic mutations in the Kirsten rat sarcoma viral oncogene homologue (KRAS) gene and other mitogen-activated protein kinase (MAPK) pathway genes has opened up new avenues for bAVM study, leading to a paradigm shift to search for somatic, de novo mutations in sporadic bAVMs instead of focusing on inherited genetic mutations. Through the development of new models and understanding of pathways involved in maintaining normal vascular structure and functions, promising therapeutic targets have been identified and safety and efficacy studies are underway in animal models and in patients. The goal of this paper is to provide a thorough review or current diagnostic and treatment tools, known genes and key pathways involved in bAVM pathogenesis to summarize current treatment options and potential therapeutic targets uncovered by recent discoveries.

The safety profile and angioarchitectural changes after acute targeted embolization of ruptured arteriovenous malformations

OBJECTIVE

The aim of this study was to 1) compare the safety and efficacy of acute targeted embolization of angiographic weak points in ruptured brain arteriovenous malformations (bAVMs) versus delayed treatment, and 2) explore the angioarchitectural changes that follow this intervention.

METHODS

The authors conducted a retrospective analysis of a prospectively acquired database of ruptured bAVMs. Three hundred sixteen patients with ruptured bAVMs who presented to the hospital within 48 hours of ictus were included in the analysis. The first analysis compared clinical and functional outcomes of acutely embolized patients to those with delayed management paradigms. The second analysis compared these outcomes of patients with acute embolization to those with angiographic targets who did not undergo acute embolization. Finally, a subset of 20 patients with immediate postembolization angiograms and follow-up angiograms within 6 weeks of treatment were studied to determine the angioarchitectural changes after acute targeted embolization. Kaplan-Meier curves for survival between the groups were devised. Multivariate logistical regression analysis was conducted.

RESULTS

There were three deaths (0.9%) and an overall rerupture rate of 4.8% per year. There was no statistical difference in demographic variables, mortality, and rerupture rate between patients with acute embolization and those with delayed management. Patients with acute embolization were more likely to present functionally worse (46.9% vs 69.8%, modified Rankin Scale score 0-2, p = 0.018) and to require an adjuvant therapy (71.9% vs 26.4%, p < 0.001). When comparing acutely embolized patients to those nonacutely embolized angiographic targets, there was a significant protective effect of acute targeted therapy on rerupture rate (annual risk 1.2% vs 4.3%, p = 0.025) and no difference in treatment complications. Differences in the survival curves for rerupture were statistically significant. Multivariate analyses significantly predicted lower rerupture in acute targeted treatment and higher rerupture in those with associated aneurysms, deep venous anatomy, and higher Spetzler-Martin grade. All patients with acute embolization experienced complete obliteration of the angiographic weak point with various degrees of resolution of the nidus; however, some had spontaneous recurrence of their bAVM, while others had spontaneous resolution over time. No patients developed new angiographic weak points.

CONCLUSIONS

This study demonstrates that acute targeted embolization of angiographic weak points, particularly aneurysms, is technically safe and protective in the early phase of recovery from ruptured bAVMs. Serial follow-up imaging is necessary to monitor the evolution of the nidus after targeted and definitive treatments. Larger prospective studies are needed to validate these findings.

Preoperative Embolization With Fused CT Angiography and Tractography Facilitates Safe Resection of a Spetzler-Martin Grade IV Arteriovenous Malformation

Brain arteriovenous malformations (BAVMs) are high-flow vascular lesions that have a propensity to rupture resulting in high rates of morbidity and mortality. Microsurgical resection of BAVMs is the standard of care for high-risk, resectable lesions. Multiple imaging modalities aid in the surgical planning and resection of high-grade BAVMs, but all have hidden variables that would prove useful if available. We present a 20-year-old male with a ruptured BAVM with concern for the involvement of the corticospinal tract (CST) and basal ganglia. We describe the melding of computed tomography angiography (CTA) and diffusion tensor imaging (DTI) in addition to preoperative embolization to aid in the planning and resection of a lesion close to eloquent structures. Post-operative CTA and DTI showed a total resection of the lesion with retained CST white matter tracts, and the patient retained the functional ability of the contralateral limbs. The combination of CTA, brain DTI, and preoperative embolization provides a framework to improve the safety of resection of BAVMs that occur near eloquent brain networks.

Benefits from Exclusion Treatment of Unruptured Brain Arteriovenous Malformations on Epilepsy in Adults

PURPOSE

In approximately 30% of the patients, brain arteriovenous malformations (bAVMs) are revealed by seizures, which may alter the patients' quality of life. Our objective was to evaluate the benefits of exclusion treatment (radiosurgery, embolization and/or surgery) on posttherapeutic epilepsy in bAVM patients without intracranial hemorrhage prior to treatment.

METHODS

Our retrospective observational single-center study included all consecutive adult patients with an unruptured bAVM and epilepsy, treated at our institution from 1995 to 2019 and who were followed for at least 1 year. Data on angioarchitectural characteristics of bAVMs, on epilepsy and posttreatment modified Rankin Scale (mRS) were collected. The primary endpoint was a seizure-free status (defined as Engel class IA) after exclusion treatment versus conservative management.

RESULTS

In this study one hundred and one consecutive adult patients with bAVMs, epilepsy and without bAVM rupture before any treatment were included; 21 (21%) in the conservative management group vs. 80 (79%) in the exclusion treatment group. After exclusion treatment, 55% of the patients from the group were Engel IA after treatment vs. 10% of the conservative management group (odds ratio [OR] 11.37, 95% confidence interval [CI] 2.48-107.24, p < 0.001).

CONCLUSION

Our results suggest that exclusion treatment in unruptured bAVMs with epilepsy is associated with a higher seizure-free rate in comparison with conservative management. Data from randomized controlled studies are necessary to confirm these findings.

Endovascular treatment of brain arteriovenous malformations involving the anterior cerebral artery

To date, at least to the best of our knowledge, there are only limited studies available on the endovascular treatment (EVT) of brain arteriovenous malformations (BAVMs) involving the anterior cerebral artery (ACA), thus termed ACA-BAVMs. The present study retrospectively examined 60 patients with ACA-BAVMs treated with EVT. The patients were aged between 10 and 72 years (mean age, 35.4±7.0 years) and included 28 females (46.7%, 28/60). The ACA-BAVMs were divided into three types: Type I BAVMs were those located below and in front of the corpus callosum genu, type II BAVMs were those located at the upper area of the corpus callosum from the genu to the anterior portion of corpus callosum body, and type III BAVMs were those located from the anterior portion of corpus callosum body to the splenium of the corpus callosum. There were 9 (15%, 9/60), 15 (25%, 15/60) and 36 (60%, 36/60) patients with type I, II and III ACA-BAVMs, respectively. Statistical analysis revealed that the posterior cerebral artery (PCA) tended to be involved in type II and III BAVMs. All patients were treated using EVT. During EVT, there were 3 cases of intraoperative bleeding (5%, 3/60), which tended to occur in type I and II ACA-BAVMs. The other 57 cases (95%, 57/60) had no complications and new neurological deficits. At the time of discharge, 48 (80%, 48/60) patients had a Glasgow Outcome Scale score of 5. During the clinical follow-up period, 47 patients were classified according to the modified Rankin Scale (mRS) score; 39 (83%, 39/47) patients presented with an mRS score of 0. On the whole, the present study demonstrated that EVT may be a safe treatment for ACA-BAVMs.

Stereotactic Radiosurgery With vs. Without Prior Embolization for Brain Arteriovenous Malformations: A Propensity Score Matching Analysis

Objective: Whether partial embolization could facilitate the post-stereotactic radiosurgery (SRS) obliteration for brain arteriovenous malformations (bAVMs) remains controversial. We performed this study to compare the outcomes of SRS with and without prior embolization for bAVMs.

Methods: We retrospectively reviewed the Beijing Tiantan AVMs prospective registration research database from September 2011 to October 2014. Patients were categorized into two groups, combined upfront embolization and SRS (Em+SRS group) and SRS alone (SRS group), and we performed a propensity score matching analysis based on pre-embolization baseline characteristics; the matched groups each comprised 76 patients.

Results: The obliteration rate was similar between SRS and Em+SRS (44.7 vs. 31.6%; OR, 1.754; 95% CI, 0.905–3.401; p = 0.096). However, the SRS group was superior to the Em+SRS group in terms of cumulative obliteration rate at a follow-up of 5 years (HR,1.778; 95% CI, 1.017–3.110; p = 0.033). The secondary outcomes, including functional state, post-SRS hemorrhage, all-cause mortality, and edema or cyst formation were similar between the matched cohorts. In the ruptured subgroup, the SRS group could achieve higher obliteration rate than Em+SRS group (56.5 vs. 31.9%; OR, 2.773; 95% CI, 1.190–6.464; p = 0.018). The cumulative obliteration rate at 5 years was also higher in the SRS group (64.5 vs. 41.3%; HR, 2.012; 95% CI, 1.037–3.903; p = 0.038), and the secondary outcomes were also similar between the matched cohorts.

Conclusion: Although there was no significant difference in the overall obliteration rate between the two strategies, this study suggested that pre-SRS embolization may have a negative effect on post-SRS obliteration. Furthermore, the obliteration rates of the SRS only strategy was significantly higher than that of the Em+SRS strategy in the ruptured cohort, while no such phenomenon was found in the unruptured cohort.

The BSCM score: a guideline for surgical decision-making for brainstem cavernous malformations

Microsurgical resection of brainstem cavernous malformations (BSCMs) can be performed today with acceptable morbidity and mortality. However, in this highly eloquent location, the indication for surgery remains challenging. We aimed to elaborate a score system that may help clinicians with their choice of treatment in patients with BSCMs in this study. A single-center series of 88 consecutive BSCMs patients with 272 follow-up visits were included in this study. Univariable and multivariable generalized estimating equations (GEE) were constructed to identify the association of variables with treatment decisions. A score scale assigned points for variables that significantly contributed to surgical decision-making. Surgical treatment was recommended in 37 instances, while conservative treatment was proposed in 235 instances. The mean follow-up duration was 50.4 months, and the mean age at decision-making was 45.9 years. The mean BSCMs size was 14.3 ml. In the multivariable GEE model, patient age, lesion size, hemorrhagic event(s), mRS, and axial location were identified as significant factors for determining treatment options. With this proposed score scale (grades 0–XII), non-surgery was the first option at grades 0–III. The crossover point between surgery and non-surgery recommendations lay between grades V and VI while surgical treatment was found in favor at grades VII–X. In conclusion, the proposed BSCM operating score is a clinician-friendly tool, which may help neurosurgeons decide on the treatment for patients with BSCMs.

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.

Treatment-Associated Stroke in Patients Undergoing Endovascular Therapy in the ARUBA Trial

Background and Purpose

Since the publication of ARUBA trial (A Randomized Trial of Unruptured Brain Arteriovenous Malformations), outcomes in treated and untreated patients with unruptured arteriovenous malformation have been thoroughly compared. However, no prior analysis of ARUBA patients has sought to identify risk factors for perioperative stroke. Improved understanding of risks within the ARUBA cohort will help clinicians apply the study’s findings in a broader context.

Methods

The National Institute of Neurological Disorders and Stroke database was queried for all data relating to ARUBA patients, including demographics, interventions undertaken, and timing of stroke. Retrospective cohort analysis was performed with the primary outcome of perioperative stroke in patients who underwent endovascular intervention, and stroke risk was modeled with multivariate analysis.

Results

A total of 64 ARUBA patients were included in the analysis. One hundred and fifty-ninth interventions were performed, and 26 (16%) procedures resulted in stroke within 48 hours of treatment. Posterior cerebral artery supply (adjusted odds ratio, 4.42 [95% CI, 1.23–15.9], P=0.02) and Spetzler-Martin grades 2 and 3 arteriovenous malformation (adjusted odds ratio, 7.76 [95% CI, 1.20–50.3], P=0.03; 9.64 [95% CI, 1.36–68.4], P=0.04, respectively) were associated with increased perioperative stroke risk in patients who underwent endovascular intervention. Patients treated in the United States or Germany had a significantly lower stroke risk than patients treated in other countries (adjusted odds ratio, 0.18 [95% CI, 0.04–0.82], P=0.02).

Conclusions

Knowing patient and lesion characteristics that increase risk during endovascular treatment can better guide clinicians managing unruptured brain arteriovenous malformation. Our analysis suggests risk of perioperative stroke is dependent on Spetzler-Martin grade and posterior-circulation arterial supply. Differences in regional treatment paradigms may also affect stroke risk.

Hemodynamic Analysis of Cerebral AVMs with 3D Phase-Contrast MR Imaging

BACKGROUND AND PURPOSE

The hemodynamics associated with cerebral AVMs have a significant impact on their clinical presentation. This study aimed to evaluate the hemodynamic features of AVMs using 3D phase-contrast MR imaging with dual velocity-encodings.

MATERIALS AND METHODS

Thirty-two patients with supratentorial AVMs who had not received any previous treatment and had undergone 3D phase-contrast MR imaging were included in this study. The nidus diameter and volume were measured for classification of AVMs (small, medium, or large). Flow parameters measured included apparent AVM inflow, AVM inflow index, apparent AVM outflow, AVM outflow index, and the apparent AVM inflow-to-outflow ratio. Correlation coefficients between the nidus volume and each flow were calculated. The flow parameters between small and other AVMs as well as between nonhemorrhagic and hemorrhagic AVMs were compared.

RESULTS

Patients were divided into hemorrhagic (n = 8) and nonhemorrhagic (n = 24) groups. The correlation coefficient between the nidus volume and the apparent AVM inflow and outflow was .83. The apparent AVM inflow and outflow in small AVMs were significantly smaller than in medium AVMs (P < .001 for both groups). The apparent AVM inflow-to-outflow ratio was significantly larger in the hemorrhagic AVMs than in the nonhemorrhagic AVMs (P = .02).

CONCLUSIONS

The apparent AVM inflow-to-outflow ratio was the only significant parameter that differed between nonhemorrhagic and hemorrhagic AVMs, suggesting that a poor drainage system may increase AVM pressure, potentially causing cerebral hemorrhage.

Current and Future Challenges of Functional MRI and Diffusion Tractography in the Surgical Setting: From Eloquent Brain Mapping to Neural Plasticity

Decades ago, Spetzler (1986) and Sawaya (1998) provided a rough brain segmentation of the eloquent areas of the brain, aimed to help surgical decisions in cases of vascular malformations and tumors, respectively. Currently in clinical use, their criteria are in need of revision. Defining functions (eg, sensorimotor, language and visual) that should be preserved during surgery seems a straightforward task. In practice, locating the specific areas that could cause a permanent vs transient deficit is not an easy task. This is particularly true for the associative cortex and cognitive domains such as language. The old model, with Broca's and Wernicke's areas at the forefront, has been superseded by a dual-stream model of parallel language processing; named ventral and dorsal pathways. This complicated network of cortical hubs and subcortical white matter pathways needing preservation during surgery is a work in progress. Preserving not only cortical regions but most importantly preserving the connections, or white matter fiber bundles, of core regions in the brain is the new paradigm. For instance, the arcuate fascicululs and inferior fronto-occipital fasciculus are key components of the dorsal and ventral language pathways, respectively; and their damage result in permanent language deficits. Interestedly, the damage of the temporal portions of these bundles -where there is a crossroad with other multiple bundles-, appears to be more important (permanent) than the damage of the frontal portions - where plasticity and contralateral activation could help. Although intraoperative direct cortical and subcortical stimulation have contributed largely, advanced MR techniques such as functional MRI (fMRI) and diffusion tractography (DT), are at the epi-center of our current understanding. Nevertheless, these techniques posse important challenges: such as neurovascular uncoupling or venous bias on fMRI; and appropriate anatomical validation or accurate representation of crossing fibers on DT. These limitations should be well understood and taken into account in clinical practice. Unifying multidisciplinary research and clinical efforts is desirable, so these techniques could contribute more efficiently not only to locate eloquent areas but to improve outcomes and our understanding of neural plasticity. Finally, although there are constant anatomical and functional regions at the individual level, there is a known variability at the inter-individual level. This concept should strengthen the importance of a personalized approach when evaluating these regions on fMRI and DT. It should strengthen the importance of personalized treatments as well, aimed to meet tailored needs and expectations.

Multimodality Management in bAVM Surgery - Recent Experience from International Cerebrovascular Fellowship

Background:

Arteriovenous malformation (bAVM) presents maldevelopment of the brain’s vessels with a direct connection between cerebral arteries and veins. By current data, patients from Spetzler Ponce A (SP) are found to benefit from the treatment. Considering the outcome, most of SP C and some of the SP B are the most debatable.

Objective:

Arteriovenous malformation presents maldevelopment of the brain’s vessels with a consequent direct connection between cerebral arteries and veins. The annual risk of hemorrhage in adults is reported for 2-3 %. They usually present with unilateral headaches seizures and intracranial hemorrhage. By current data, patients from Spetzler Ponce A (SP) are found to benefit from the treatment. Considering the outcome, most of SP C and some of the SP B are the most debatable.

Methods:

The study included a cohort of bAVM patients referred to Fujita Health University Bantane Hotokukai Hospital, Nagoya, Aichi, Japan where the main author (AA) has completed an international cerebrovascular fellowship under the mentorship of Professor Yoko Kato. Japanese Stroke Guidelines (JSG) were used for the treatment decision. Patients were graded according to the Spetzler Ponce (SP) system. Considering American Heart Association criteria (AHA), embolization was used as a part of multimodal treatment. Intraoperative microscopic video tools included Indocyanine green ICG, FLOW 800 and dual image video angiography DIVA. Clinical outcomes were measured using Modified Ranking Score (mRs).

Results:

A total of eleven patients with brain bAVM were studied with a median age of 32 years [IQR = 22-52]. There were ten patients presented with supratentorial and a single patient with infratentorial AVM. Patients were graded according to the Spetzler Ponce (SP) system. There were eight patients in SP A (72,7%), one in group B (9 %) while the rest of them were in C (18 %). Two patients had associated aneurysms that required treatment. The median size of the AVM nidus was 3,50 cm [IQR= 2-5]. Deep venous drainage was found in six patients while three were located in eloquent zones. Clinical outcomes were considered good by mRs <2 in eight patients, seven from the surgically treated group (72,7 % respectively). Surgery median length time was 427, 5 minutes; [IQR =320 - 463] with complete AVM resection in all patients and no mortality recorded in this cohort with the median follow up of 39,5 months [IQR = 19-59].

Conclusion:

Ideal management of bAVM is still controversial. Those complex vascular lesions require multimodal treatment in a majority of cases in highly specialized centers. In SP A patients, surgery provides the best results with a positive outcome and a small number of complications. With the improvement of endovascular feeder occlusion SP B patients become prone to a more positive outcome. Nowadays, intraoperative microscopic tools such as FLOW 800, ICG and DIVA are irreplaceable while improving safety to deal with bAVM. For SP C patients, a combination of endovascular and stereotactic radiosurgery was found to be a good option in the present time.

Reducing the Cognitive Footprint of Brain Tumor Surgery

The surgical management of brain tumors is based on the principle that the extent of resection improves patient outcomes. Traditionally, neurosurgeons have considered that lesions in “non-eloquent” cerebrum can be more aggressively surgically managed compared to lesions in “eloquent” regions with more known functional relevance. Furthermore, advancements in multimodal imaging technologies have improved our ability to extend the rate of resection while minimizing the risk of inducing new neurologic deficits, together referred to as the “onco-functional balance.” However, despite the common utilization of invasive techniques such as cortical mapping to identify eloquent tissue responsible for language and motor functions, glioma patients continue to present post-operatively with poor cognitive morbidity in higher-order functions. Such observations are likely related to the difficulty in interpreting the highly-dimensional information these technologies present to us regarding cognition in addition to our classically poor understanding of the functional and structural neuroanatomy underlying complex higher-order cognitive functions. Furthermore, reduction of the brain into isolated cortical regions without consideration of the complex, interacting brain networks which these regions function within to subserve higher-order cognition inherently prevents our successful navigation of true eloquent and non-eloquent cerebrum. Fortunately, recent large-scale movements in the neuroscience community, such as the Human Connectome Project (HCP), have provided updated neural data detailing the many intricate macroscopic connections between cortical regions which integrate and process the information underlying complex human behavior within a brain “connectome.” Connectomic data can provide us better maps on how to understand convoluted cortical and subcortical relationships between tumor and human cerebrum such that neurosurgeons can begin to make more informed decisions during surgery to maximize the onco-functional balance. However, connectome-based neurosurgery and related applications for neurorehabilitation are relatively nascent and require further work moving forward to optimize our ability to add highly valuable connectomic data to our surgical armamentarium. In this manuscript, we review four concepts with detailed examples which will help us better understand post-operative cognitive outcomes and provide a guide for how to utilize connectomics to reduce cognitive morbidity following cerebral surgery.

Controlled arterial hypotension during resection of cerebral arteriovenous malformations

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.

Outcomes of stereotactic radiosurgery for hemorrhagic arteriovenous malformations with or without prior resection or embolization

OBJECTIVE

The major concern about ruptured arteriovenous malformations (rAVMs) is recurrent hemorrhage, which tends to preclude stereotactic radiosurgery (SRS) as a therapeutic modality for these brain malformations. In this study, the authors aimed to clarify the role of SRS for rAVM as a stand-alone modality and an adjunct for a remnant nidus after surgery or embolization.

METHODS

Data on 410 consecutive patients with rAVMs treated with SRS were analyzed. The patients were classified into groups, according to prior interventions: SRS-alone, surgery and SRS (Surg-SRS), and embolization and SRS (Embol-SRS) groups. The outcomes of the SRS-alone group were analyzed in comparison with those of the other two groups.

RESULTS

The obliteration rate was higher in the Surg-SRS group than in the SRS-alone group (5-year cumulative rate 97% vs 79%, p < 0.001), whereas no significant difference was observed between the Embol-SRS and SRS-alone groups. Prior resection (HR 1.78, 95% CI 1.30-2.43, p < 0.001), a maximum AVM diameter ≤ 20 mm (HR 1.81, 95% CI 1.43-2.30, p < 0.001), and a prescription dose ≥ 20 Gy (HR 2.04, 95% CI 1.28-3.27, p = 0.003) were associated with a better obliteration rate, as demonstrated by multivariate Cox proportional hazards analyses. In the SRS-alone group, the annual post-SRS hemorrhage rates were 1.5% within 5 years and 0.2% thereafter and the 10-year significant neurological event-free rate was 95%; no intergroup difference was observed in either outcome. The exclusive performance of SRS (SRS alone) was not a risk for post-SRS hemorrhage or for significant neurological events based on multivariate analyses. These results were also confirmed with propensity score-matched analyses.

CONCLUSIONS

The treatment strategy for rAVMs should be tailored with due consideration of multiple factors associated with the patients. Stand-alone SRS is effective for hemorrhagic AVMs, and the risk of post-SRS hemorrhage was low. SRS can also be favorably used for residual AVMs after initial interventions, especially after failed resection.

Stereotactic radiosurgery with versus without prior Onyx embolization for brain arteriovenous malformations

OBJECTIVE

Investigations of the combined effects of neoadjuvant Onyx embolization and stereotactic radiosurgery (SRS) on brain arteriovenous malformations (AVMs) have not accounted for initial angioarchitectural features prior to neuroendovascular intervention. The aim of this retrospective, multicenter matched cohort study is to compare the outcomes of SRS with versus without upfront Onyx embolization for AVMs using de novo characteristics of the preembolized nidus.

METHODS

The International Radiosurgery Research Foundation AVM databases from 1987 to 2018 were retrospectively reviewed. Patients were categorized based on AVM treatment approach into Onyx embolization (OE) and SRS (OE+SRS) or SRS alone (SRS-only) cohorts and then propensity score matched in a 1:1 ratio. The primary outcome was AVM obliteration. Secondary outcomes were post-SRS hemorrhage, all-cause mortality, radiological and symptomatic radiation-induced changes (RICs), and cyst formation. Comparisons were analyzed using crude rates and cumulative probabilities adjusted for competing risk of death.

RESULTS

The matched OE+SRS and SRS-only cohorts each comprised 53 patients. Crude rates (37.7% vs 47.2% for the OE+SRS vs SRS-only cohorts, respectively; OR 0.679, p = 0.327) and cumulative probabilities at 3, 4, 5, and 6 years (33.7%, 44.1%, 57.5%, and 65.7% for the OE+SRS cohort vs 34.8%, 45.5%, 59.0%, and 67.1% for the SRS-only cohort, respectively; subhazard ratio 0.961, p = 0.896) of AVM obliteration were similar between the matched cohorts. The secondary outcomes of the matched cohorts were also similar. Asymptomatic and symptomatic embolization-related complication rates in the matched OE+SRS cohort were 18.9% and 9.4%, respectively.

CONCLUSIONS

Pre-SRS AVM embolization with Onyx does not appear to negatively influence outcomes after SRS. These analyses, based on de novo nidal characteristics, thereby refute previous studies that found detrimental effects of Onyx embolization on SRS-induced AVM obliteration. However, given the risks incurred by nidal embolization using Onyx, this neoadjuvant intervention should be used judiciously in multimodal treatment strategies involving SRS for appropriately selected large-volume or angioarchitecturally high-risk AVMs.

A novel score for evaluating cerebral aneurysms treated with flow diversion: 4F-flow diversion predictive score

Background and purpose

Although grading scales for angiography outcomes following cerebral aneurysm treatment with flow diversion have been published, physicians have not widely adopted these scales in practice. The aim of this study is to propose and validate a novel Flow diversion Predictive Score (4F-FPS) grading scale based on previously established scales that is simple and reliable.

Methods

We retrospectively analyzed consecutive patients who underwent endovascular treatment for cerebral aneurysms with flow diversion between January 2014 and September 2019. The included patients were randomly divided into the derivation and validation group in a 70/30 ratio, respectively. Aneurysms were classified as incomplete or complete occlusion based on final angiography outcomes. 4F-FPS was derived to predict aneurysm occlusion from multivariate logistic regression analyses in the derivation group and validated with previously published grading scales in the validation group.

Results

Overall, 662 patients [mean age, 53.8 years; 72.5% (480/662) female] with 662 aneurysms treated with the Pipeline^TM flow diverter were included [69.9% (463/662) derivation group, 30.1% (199/662) validation group]. The incidence of aneurysm occlusion was 82.7%. 4F-FPS demonstrated significant discrimination in 10-fold cross validation [mean receiver operating characteristic (ROC) area, 0.862 ± 0.055] and calibration (Cox & Snell R ², 0.251; Nagelkerke R ², 0.413) in the derivation group. The ROC area of 4F-FPS score in both the derivation and validation groups is the largest compared with previously published grading scales/scores (p < 0.05), which shows better sensitivity and specificity. The 4F-FPS score showed excellent prediction, discrimination, and calibration properties.

Conclusion

The 4F-FPS score is a simple and reliable tool to predict angiography outcome after flow diversion treatment. If widely adopted, it may provide a common language to be used in future reporting of flow diversion results for clinical trials and daily practice.

Clinical trial registration

http://www.clinicaltrials.gov. Unique identifier: NCT03831672.

Adverse radiation effects in volume-staged radiosurgery for large arteriovenous malformations: a multiinstitutional study

OBJECTIVE

The optimal treatment paradigm for large arteriovenous malformations (AVMs) is controversial. One approach is volume-staged stereotactic radiosurgery (VS-SRS). The authors previously reported efficacy of VS-SRS for large AVMs in a multiinstitutional cohort; here they focus on risk of symptomatic adverse radiation effects (AREs).

METHODS

This is a multicentered retrospective review of patients treated with a planned prospective volume staging approach to stereotactically treat the entire nidus of an AVM, with volume stages separated by intervals of 3-6 months. A total of 9 radiosurgical centers treated 257 patients with VS-SRS between 1991 and 2016. The authors evaluated permanent, transient, and total ARE events that were symptomatic.

RESULTS

Patients received 2-4 total volume stages. The median age was 33 years at the time of the first SRS volume stage, and the median follow-up was 5.7 years after VS-SRS. The median total AVM nidus volume was 23.25 cm3 (range 7.7-94.4 cm3), with a median margin dose per stage of 17 Gy (range 12-20 Gy). A total of 64 patients (25%) experienced an ARE, of which 19 were permanent. Rather than volume, maximal linear dimension in the Z (craniocaudal) dimension was associated with toxicity; a threshold length of 3.28 cm was associated with an ARE, with a 72.5% sensitivity and a 58.3% specificity. In addition, parietal lobe involvement for superficial lesions and temporal lobe involvement for deep lesions were associated with an ARE.

CONCLUSIONS

Size remains the dominant predictor of toxicity following SRS, but overall rates of AREs were lower than anticipated based on baseline features, suggesting that dose and size were relatively dissociated through volume staging. Further techniques need to be assessed to optimize outcomes.

Spontaneous disappearance of brain arteriovenous malformation: A case series

OBJECTIVE

Brain arteriovenous malformation (BAVM) is defined as abnormal communication between cerebral of arteries and veins, without capillaries. Clinically, it may involve intracranial hemorrhage or seizures. Complete spontaneous resolution, known as BAVM disappearance, has been reported in rare cases.

METHODS

We retrospectively collated all cases of BAVM in Lille University Hospital, from 2005 to 2018, and identified all cases of spontaneous BAVM disappearance on angiography (nidus and early venous drainage).

RESULTS

There were 4 cases of spontaneous BAVM disappearance, in 3573 patients: i.e., prevalence of 0.1%. Sex ratio was 2:2; ages ranged from 14 to 46 years; nidus size was generally small (<20mm); 3 of the 4 patients had superficial venous drainage. Revelation of BAVM was by hemorrhage in 3 cases and by seizure in 1. There were no cases of recanalization at 1 year's follow-up.

CONCLUSION

Spontaneous BAVM disappearance is rare. Associated factors may include small nidus, superficial venous drainage and hemorrhage.

Arteriovenous malformations in the optic apparatus: systematic literature review and report of four cases

OBJECTIVE

Rare arteriovenous malformations (AVMs) of the optic apparatus account for < 1% of all AVMs. The authors conducted a systematic review of the literature for cases of optic apparatus AVMs and present 4 cases from their institution. The literature is summarized to describe preoperative characteristics, surgical technique, and treatment outcomes for these lesions.

METHODS

A comprehensive search of the English-language literature was performed in accordance with established Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to identify all published cases of AVM in the optic apparatus in the PubMed, Web of Science, and Cochrane databases. The authors also searched their prospective institutional database of vascular malformations for such cases. Data regarding the clinical and radiological presentation, visual acuity, visual fields, extent of resection, and postoperative outcomes were gathered.

RESULTS

Nine patients in the literature and 4 patients in the authors' single-surgeon series who fit the inclusion criteria were identified. The median age at presentation was 29 years (range 8-39 years). Among these patients, 11 presented with visual disturbance, 9 with headache, and 1 with multiple prior subarachnoid hemorrhages; the AVM in 1 case was found incidentally. Four patients described prior symptoms of headache or visual disturbance consistent with sentinel events. Visual acuity was decreased from baseline in 10 patients, and 11 patients had visual field defects on formal visual field testing. The most common visual field defect was temporal hemianopia, found in one or both eyes in 7 patients. The optic chiasm was affected in 10 patients, the hypothalamus in 2 patients, the optic nerve (unilaterally) in 8 patients, and the optic tract in 2 patients. Six patients underwent gross-total resection; 6 patients underwent subtotal resection; and 1 patient underwent craniotomy, but no resection was attempted. Postoperatively, 9 of the patients had improved visual function, 1 had no change, and 3 had worse visual acuity. Eight patients demonstrated improved visual fields, 1 had no change, and 4 had narrowed fields.

CONCLUSIONS

AVMs of the optic apparatus are rare lesions. Although they reside in a highly eloquent region, surgical outcomes are generally good; the majority of patients will see improvement in their visual function postoperatively. Microsurgical technique is critical to the successful removal of these lesions, and preservation of function sometimes requires subtotal resection of the lesion.

A tribute to the late Professor Donald Simpson, Australian neurosurgeon and namesake of the Simpson grading system for meningioma extent of resection

Donald Simpson (1927-2018) was a neurosurgeon from Adelaide, Australia, who is often cited for the 1957 publication he wrote as a trainee on the relationship between extent of resection and outcomes for meningiomas. That paper summarized a series of over 300 patients operated on in England by well-known neurosurgeons Sir Hugh Cairns and Joseph Buford Pennybacker. Simpson was also known later in his career, when he was at the University of Adelaide in South Australia, for his contributions to the areas of hydrocephalus, spina bifida, craniofacial anomalies, head injury, brain abscesses, and neurosurgical history, and he published extensively on these topics. In addition to his work in clinical neurosurgery, Simpson made humanitarian contributions studying kuru in New Guinea and aiding refugees during the Vietnam War. Simpson was an active member and leader of many Australian surgical organizations and was an officer of the Order of Australia. Donald Simpson's legacy as an adult and pediatric neurosurgeon, an academician, a leader, and a humanitarian is extensive and will prove long lasting. Professor Simpson's life serves as an example from which all neurosurgeons may learn.

Effect of Prior Embolization on Outcomes After Stereotactic Radiosurgery for Pediatric Brain Arteriovenous Malformations: An International Multicenter Study

BACKGROUND

Pediatric brain arteriovenous malformations (AVMs) are a significant cause of morbidity but the role of multimodal therapy in the treatment of these lesions is not well understood.

OBJECTIVE

To compare the outcomes of stereotactic radiosurgery (SRS) with and without prior embolization for pediatric AVMs.

METHODS

We retrospectively evaluated the International Radiosurgery Research Foundation pediatric AVM database. AVMs were categorized, based on use of pre-embolization (E + SRS) or lack thereof (SRS-only). Outcomes were compared in unadjusted and inverse probability weight (IPW)-adjusted models. Favorable outcome was defined as obliteration without post-SRS hemorrhage or permanent radiation-induced changes (RIC).

RESULTS

The E + SRS and SRS-only cohorts comprised 91 and 448 patients, respectively. In unadjusted models, the SRS-only cohort had higher rates of obliteration (68.5% vs 43.3%,  < .001) and favorable outcome (61.2% vs 36.3%, P < .001) but a lower rate of symptomatic RIC (9.0% vs 16.7%, P = .031). The IPW-adjusted rates of every outcome were similar between the 2 cohorts. However, cumulative obliteration rates at 3, 5, 8, and 10 yr remained higher in the absence of prior embolization (46.3%, 64.6%, 72.6%, and 77.4% for SRS-only vs 24.4%, 37.2%, 44.1%, and 48.7% for E + SRS cohorts, respectively; SHR = 0.449 [0.238-0.846], P = .013).

CONCLUSION

Embolization appears to decrease cumulative obliteration rates after SRS for pediatric AVMs without affecting the risk of post-treatment hemorrhage or adverse radiation effects arguing against the routine use of pre-SRS embolization. While endovascular therapy can be considered for occlusion of high-risk angioarchitectural features prior to SRS, future studies are necessary to clarify its role.

Chronic encapsulated expanding hematomas after stereotactic radiosurgery for intracranial arteriovenous malformations

OBJECTIVE

Cerebral arteriovenous malformations (AVMs) are rare cerebral vascular lesions that are associated with high morbidity and mortality from hemorrhage; however, stereotactic radiosurgery (SRS) is a well-validated treatment modality. Few reports have delineated a subgroup of patients who develop delayed chronic encapsulated expanding hematomas (CEEHs) despite angiographic evidence of AVM obliteration following radiosurgery. In this report, the authors performed a retrospective review of more than 1000 radiosurgically treated intracranial AVM cases to delineate the incidence and management of this rare entity.

METHODS

Between 1988 and 2019, 1010 patients with intracranial AVM underwent Gamma Knife SRS at the University of Pittsburgh Medical Center. In addition to a review of a prospective institutional database, the authors performed a retrospective chart review of the departmental AVM database to specifically identify patients with CEEH. Pertinent clinical and radiological characteristics as well as patient outcomes were recorded and analyzed.

RESULTS

Nine hundred fifty patients with intracranial AVM (94%) had sufficient clinical follow-up for analysis. Of these, 6 patients with CEEH underwent delayed resection (incidence rate of 0.0045 event per person-year). These patients included 4 males and 2 females with a mean age of 45.3 ± 13.8 years at the time of initial SRS. Four patients had smaller AVM volumes (4.9-10 cm3), and 3 of them were treated with a single SRS procedure. Two patients had larger-volume AVMs (55 and 56 cm3), and both underwent multimodal management that included staged SRS and embolization. Time to initial recognition of the CEEH after initial SRS ranged between 66 and 243 months. The time between CEEH recognition and resection ranged from 2 to 9 months. Resection was required because of progressive neurological symptoms that correlated with imaging evidence of gradual hematoma expansion. All 6 patients had angiographically confirmed obliteration of their AVM. Pathology revealed a mixed chronicity hematoma with areas of fibrosed blood vessels and rare areas of neovascularization with immature blood vessels but no evidence of a persistent AVM. All 6 patients reported persistent clinical improvement after hematoma resection.

CONCLUSIONS

CEEH after SRS for AVM is a rare complication with an incidence rate of 0.0045 event per person-year over the authors' 30-year experience. When clinical symptoms progress and imaging reveals progressive enlargement over time, complete resection of a CEEH results in significant clinical recovery. Knowledge of this rare entity facilitates timely detection and eventual surgical intervention to achieve optimal outcomes.

Spetzler-Martin Grade III Arteriovenous Malformations: A Comparison of Modified and Supplemented Spetzler-Martin Grading Systems

BACKGROUND

The modified Spetzler-Martin (SM) grading system proposes that grade III arteriovenous malformation (AVM) subtypes are associated with variable microsurgical risks, with small AVMs (III-) having lower risk and medium/eloquent AVMs (III+) having higher risk. Adding patient age and AVM bleeding status and compactness to the SM grade produces a score - the supplemented SM (Supp-SM) grade - to more accurately assess preoperative risk.

OBJECTIVE

To compare the predictive power of the modified SM and Supp-SM grades for risk assessment in patients with grade III AVMs.

METHODS

Patients with SM grade III AVMs treated between 2011 and 2018 were retrospectively reviewed. Good outcomes were defined as modified Rankin Scale (mRS) scores ≤ 2 or unchanged/improved mRS scores (pre- vs postsurgery).

RESULTS

Of 102 patients with SM grade III AVMs, 59% had grade III- and 24% had grade III+ AVMs. Supp SM grade 6 and grade 7 AVMs accounted for 44% and 24%, respectively. Overall, 33% of patients worsened but outcomes did not significantly differ by SM III subtype. Neurological outcomes were associated with Supp-SM grade, with proportions of patients with worsening increasing from 0% with Supp-SM grade 4 AVMs to 54% with Supp-SM grade 7 AVMs. Analyses of factors associated with neurological worsening identified age > 60 yr and Supp-SM grade 7 as significant.

CONCLUSION

Supp-SM grades were more predictive of microsurgical outcomes than modified SM grades for grade III AVMs, with a hard cutoff for acceptable surgical risk at Supp-SM grade 6. Supp-SM grading is a better decision-making tool than subtyping with the modified SM scale.

Hemorrhagic transformation of ischemic cerebral proliferative angiopathy: A case report

BACKGROUND

Cerebral proliferative angiopathy (CPA) is a rare vascular disease characterized by the presence of diffuse vascular proliferation, progressive vascular hyperflow and vasodilation of multiple vessels in the normal brain parenchyma. Unlike cerebral arteriovenous malformations, CPA has a mixed appearance between that of lesions with cell proliferation and endothelial proliferation. To date, the pathogenesis of CPA is unclear, in which changes induced by cortical ischemia in the elastic layer of the blood supply artery and smooth muscle cells may be involved.

CASE SUMMARY

In this article, we retrospectively analyzed a case of hemorrhagic transformation of ischemic CPA diagnosed by digital subtraction angiography and reviewed the related literature for further exploration of its pathogenesis, diagnosis and treatment.

CONCLUSION

The information in the present case report may facilitate further clinical research on this cerebrovascular disease.

Clinical and Angioarchitectural Features of Hemorrhagic Brain Arterio-Venous Malformations in Adults and Children: Contrasts and Implications on Outcome

BACKGROUND

Hemorrhage from brain arteriovenous malformations (bAVMs) is estimated at 3% per annum. Features influencing risk of hemorrhage include perforator/posterior circulation supply, associated aneurysms, and deep drainage. Children are more likely to present with bAVM bleeds.

OBJECTIVE

To analyze differences in bAVM angioarchitecture between children and adults and describe predictors of poor outcome.

METHODS

Data were collected from adult and pediatric tertiary referral hospitals. Demographic data, bleed location, treatment, and follow-up modified Rankin Scale (mRS) were collected. Angioarchitectural assessment included aneurysm presence, nidus morphology, perinidal angiogenesis, intranidal shunting, steal phenomenon, venous ectasia, venous stenosis, venous reflux, and pseudophlebitic pattern. Regression analyses conducted to determine predictors of mRS > 2.

RESULTS

A total of 270 adult and 135 pediatric ruptured bAVMs were assessed. Median age was 42 (adults) and 10.9 (children) yr. Intranidal aneurysms were more frequent in children (P = .012), whereas prenidal aneurysms were more common in adults (P < .01). Children demonstrated more perinidal angiogenesis (P = .04), whereas steal phenomenon was commoner in adults (P < .01). Venous ectasia (P < .01), reflux (P < .01), and pseudophlebitic pattern (P = .012) were more frequent in adults. Children had better outcome (mRS score ≤ 2) (P < .01). Older age (odds ratio [OR] = 1.02), eloquent location (OR = 2.5), multicompartmental hemorrhage (OR = 1.98), venous reflux (OR = 2.5), diffuse nidus (OR = 1.83), pseudophlebitic pattern (OR = 1.96), intranidal shunts (OR = 2), and no treatment (OR = 3.68) were significant predictors of mRS > 2.

CONCLUSION

Children are more likely to have intranidal aneurysms and perinidal angiogenesis, whereas adults have more prenidal aneurysms, venous ectasia, corticovenous reflux, and pseudophlebitic pattern. Eloquent location, diffuse nidus, intranidal shunts, venous reflux, and pseudophlebitic pattern predict poorer outcome.

Spetzler-Martin Grade III Arteriovenous Malformations: A Multicenter Propensity-Adjusted Analysis of the Effects of Preoperative Embolization

BACKGROUND

Spetzler-Martin (SM) grade III arteriovenous malformations (AVMs) are at the boundary of safe operability, and preoperative embolization may reduce surgical risks.

OBJECTIVE

To evaluate the benefits of preoperative AVM embolization by comparing neurological outcomes in patients with grade III AVMs treated with or without preoperative embolization.

METHODS

All microsurgically treated grade III AVMs were identified from 2011 to 2018 at 2 medical centers. Neurological outcomes, measured as final modified Rankin Scale scores (mRS) and changes in mRS from preoperative baseline to last follow-up evaluation, were compared in patients with and without preoperative embolization.

RESULTS

Of the 102 patients with grade III AVMs who were treated microsurgically, 57 (56%) underwent preoperative embolization. Significant differences were found between the patients with and without embolization in AVM eloquence (74% vs 93%, P = .02), size ≥ 3 cm (47% vs 73%, P = .01), diffuseness (7% vs 22%, P = .04), and mean final mRS (1.1 vs 2.0, P = .005). Poor outcomes were more frequent in patients without embolization (38%) than with embolization (7%) (final mRS > 2; P < .001). Propensity-adjusted analysis revealed AVM resection without embolization was a risk factor for poor outcome (mRS score > 2; odds ratio, 4.2; 95% CI, 1.1-16; P = .03).

CONCLUSION

Nonembolization of SM grade III AVMs is associated with an increased risk of poor neurological outcomes after microsurgical resection. Preoperative embolization of intermediate-grade AVMs selected because of large AVM size, surgical inaccessibility of feeding arteries, and high flow should be employed more often than anticipated, even in the context of increasing microsurgical experience with AVMs.

Creation of a comprehensive training and career development approach to increase the number of neurosurgeons supported by National Institutes of Health funding

OBJECTIVE

To increase the number of independent National Institutes of Health (NIH)-funded neurosurgeons and to enhance neurosurgery research, the National Institute of Neurological Disorders and Stroke (NINDS) developed two national comprehensive programs (R25 [established 2009] for residents/fellows and K12 [2013] for early-career neurosurgical faculty) in consultation with neurosurgical leaders and academic departments to support in-training and early-career neurosurgeons. The authors assessed the effectiveness of these NINDS-initiated programs to increase the number of independent NIH-funded neurosurgeon-scientists and grow NIH neurosurgery research funding.

METHODS

NIH funding data for faculty and clinical department funding were derived from the NIH, academic departments, and Blue Ridge Institute of Medical Research databases from 2006 to 2019.

RESULTS

Between 2009 and 2019, the NINDS R25 funded 87 neurosurgical residents. Fifty-three (61%) have completed the award and training, and 39 (74%) are in academic practice. Compared to neurosurgeons who did not receive R25 funding, R25 awardees were twice as successful (64% vs 31%) in obtaining K-series awards and received the K-series award in a significantly shorter period of time after training (25.2 ± 10.1 months vs 53.9 ± 23.0 months; p < 0.004). Between 2013 and 2019, the NINDS K12 has supported 19 neurosurgeons. Thirteen (68%) have finished their K12 support and all (100%) have applied for federal funding. Eleven (85%) have obtained major individual NIH grant support. Since the establishment of these two programs, the number of unique neurosurgeons supported by either individual (R01 or DP-series) or collaborative (U- or P-series) NIH grants increased from 36 to 82 (a 2.3-fold increase). Overall, NIH funding to clinical neurological surgery departments between 2006 and 2019 increased from $66.9 million to $157.3 million (a 2.2-fold increase).

CONCLUSIONS

Targeted research education and career development programs initiated by the NINDS led to a rapid and dramatic increase in the number of NIH-funded neurosurgeon-scientists and total NIH neurosurgery department funding.

Intracerebral and subarachnoid hemorrhage in pregnancy

Maternal stroke occurs in around 34 out of every 100,000 deliveries and is responsible for around 5%-12% of all maternal deaths. It is most commonly hemorrhagic, and women are at highest risk for developing pregnancy-related hemorrhage during the early postpartum period through 6 weeks following the delivery. The most common causes of hemorrhagic stroke in pregnant patients are arteriovenous malformations and cerebral aneurysms. Management is similar to that for acute hemorrhagic stroke in the nonpregnant population with standard use of computed tomography and judicious utilization of intracranial vessel imaging and contrast. The optimal delivery method is evaluated on a case-by-case basis, and cesarean delivery is not always required. As most current studies are limited by retrospective design, relatively small sample sizes, and heterogeneous study term definitions, strong and comprehensive evidence-based guidelines on the management of acute hemorrhagic stroke in pregnant patients are still lacking. In the future, multicenter registries and prospective studies with uniform definitions will help improve management strategies in this complex patient population.

Intermediate-grade brain arteriovenous malformations and the boundary of operability using the supplemented Spetzler-Martin grading system

OBJECTIVE

Supplemented Spetzler-Martin grading (Supp-SM), which is the combination of Spetzler-Martin and Lawton-Young grades, was validated as being more accurate than stand-alone Spetzler-Martin grading, but an operability cutoff was not established. In this study, the authors surgically treated intermediate-grade AVMs to provide prognostic factors for neurological outcomes and to define AVMs at the boundary of operability.

METHODS

Surgically treated Supp-SM intermediate-grade (5, 6, and 7) AVMs were analyzed from 2011 to 2018 at two medical centers. Worsened neurological outcomes were defined as increased modified Rankin Scale (mRS) scores on postoperative examinations. A second analysis of 2000-2011 data for Supp-SM grade 6 and 7 AVMs was performed to determine the subtypes with improved or unchanged outcomes. Patients were separated into three groups based on nidus size (S1: < 3 cm, S2: 3-6 cm, S3: > 6 cm) and age (A1: < 20 years, A2: 20-40 years, A3: > 40 years), followed by any combination of the combined supplemented grade: low risk (S1A1, S1A2, S2A1), intermediate risk (S2A2, S1A3, S3A1, or high risk (S3A3, S3A2, S2A3).

RESULTS

Two hundred forty-six patients had intermediate Supp-SM grade AVMs. Of these patients, 102 had Supp-SM grade 5 (41.5%), 99 had Supp-SM grade 6 (40.2%), and 45 had Supp-SM grade 7 (18.3%). Significant differences in the proportions of patients with worse mRS scores at follow-up were found between the groups, with 24.5% (25/102) of patients in Supp-SM grade 5, 29.3% (29/99) in Supp-SM grade 6, and 57.8% (26/45) in Supp-SM grade 7 (p < 0.001). Patients with Supp-SM grade 7 AVMs had significantly increased odds of worse postoperative mRS scores (p < 0.001; OR 3.7, 95% CI 1.9-7.3). In the expanded cohort of 349 Supp-SM grade 6 AVM patients, a significantly higher proportion of older patients with larger Supp-SM grade 6 AVMs (grade 6+, 38.6%) had neurological deterioration than the others with Supp-SM grade 6 AVMs (22.9%, p = 0.02). Conversely, in an expanded cohort of 197 Supp-SM grade 7 AVM patients, a significantly lower proportion of younger patients with smaller Supp-SM grade 7 AVMs (grade 7-, 19%) had neurological deterioration than the others with Supp-SM grade 7 AVMs (44.9%, p = 0.01).

CONCLUSIONS

Patients with Supp-SM grade 7 AVMs are at increased risk of worse postoperative neurological outcomes, making Supp-SM grade 6 an appropriate operability cutoff. However, young patients with small niduses in the low-risk Supp-SM grade 7 group (grade 7-) have favorable postoperative outcomes. Outcomes in Supp-SM grade 7 patients did not improve with surgeon experience, indicating that the operability boundary is a hard limit reflecting the complexity of high-grade AVMs.

Long-term outcome and quality of life after CNS cavernoma resection: eloquent vs. non-eloquent areas

The aim of this study is to analyze the long-term quality of life after surgery of cavernoma. A monocentric retrospective study was conducted on 69 patients with cavernoma treated microsurgically between 2000 and 2016. The eloquence was adopted from Spetzler-Martin definition. A most recent follow-up was elicited between 2017 and 2019, in which the quality of life (QoL) was evaluated with the Short Form-12 questionnaire (SF12). Forty-one lesions were in eloquent group (EG), 22 in non-eloquent group (NEG), 3 in orbit, and 3 in the spinal cord. Postoperative worsening of the modified Rankin scale (mRS) occurred in 19.5% of cases in EG versus 4.5% in NEG. After a mean follow-up of 6.5 years (SD 4.6), the neurological status was better or unchanged compared to baseline in 85.4% of EG and 100% of NEG. Regarding QoL assessment of 44 patients (EG n = 27, NEG n = 14) attended the last follow-up. Patients after eloquent cavernoma resection reported a non-inferior QoL in most SF12 domains (except for physical role) compared to NEG. However, they reported general health perception inferior to norms, which was affected by the limited physical and emotional roles. At a late follow-up, the surgical morbidity was transient in the NEG and mostly recovered in the EG. The QoL comparison between eloquent and non-eloquent cavernomas created interesting and new data after prolonged follow-up. These results add value for decision-making as well as patient counseling for future encountered cases. Preoperative evaluation of QoL is recommended for future studies to assess QoL dynamics.

Chinese Cerebrovascular Neurosurgery Society and Chinese Interventional & Hybrid Operation Society, of Chinese Stroke Association Clinical Practice Guidelines for Management of Brain Arteriovenous Malformations in Eloquent Areas

Aim: The aim of this guideline is to present current and comprehensive recommendations for the management of brain arteriovenous malformations (bAVMs) located in eloquent areas. Methods: An extended literature search on MEDLINE was performed between Jan 1970 and May 2020. Eloquence-related literature was further screened and interpreted in different subcategories of this guideline. The writing group discussed narrative text and recommendations through group meetings and online video conferences. Recommendations followed the Applying Classification of Recommendations and Level of Evidence proposed by the American Heart Association/American Stroke Association. Prerelease review of the draft guideline was performed by four expert peer reviewers and by the members of Chinese Stroke Association. Results: In total, 809 out of 2,493 publications were identified to be related to eloquent structure or neurological functions of bAVMs. Three-hundred and forty-one publications were comprehensively interpreted and cited by this guideline. Evidence-based guidelines were presented for the clinical evaluation and treatment of bAVMs with eloquence involved. Topics focused on neuroanatomy of activated eloquent structure, functional neuroimaging, neurological assessment, indication, and recommendations of different therapeutic managements. Fifty-nine recommendations were summarized, including 20 in Class I, 30 in Class IIa, 9 in Class IIb, and 2 in Class III. Conclusions: The management of eloquent bAVMs remains challenging. With the evolutionary understanding of eloquent areas, the guideline highlights the assessment of eloquent bAVMs, and a strategy for decision-making in the management of eloquent bAVMs.

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.

Perioperative Dynamics of Intracranial B-waves of Blood Flow Velocity in the Basal Cerebral Arteries in Patients with Brain Arteriovenous Malformation

Intracranial B-waves (8-30 mHz) of blood flow velocity (BFV) in the cerebral arteries are observed in various pathologies of the brain. Changes in B-waves of BFV in pathological arteriovenous shunting and "steal" syndrome remain poorly understood. The aim of this study was to evaluate the dynamics of the B-wave amplitude of BFV (BWA) in patients with an arteriovenous malformation (AVM) in the brain. In 38 such patients, cerebral autoregulation (CA) was assessed using a cuff test and transfer function analysis of the mean blood pressure (BP) and BFV in the basal cerebral arteries within the range of Mayer waves (80-120 mHz). BWA was calculated with spectral analysis. Reliable CA impairment was denoted on the AVM side as compared with the contralateral side prior to intervention. BWA was greater on the AVM side (4.5 ± 2.7 cm/s) than on the contralateral side (2.2 ± 1.4 cm/s, p < 0.05). After embolization, there was a reliable improvement (p < 0.05) in CA and a decrease in BWA on the AVM side (2.7 ± 1.8 cm/s). Thus, a considerable increase in BWA on the AVM side that is not induced by BP fluctuations may indicate additional compensation for blood flow under conditions of reduced perfusion pressure. This assumption is supported by a reduction in BWA after AVM embolization.

Biologically effective dose and prediction of obliteration of unruptured arteriovenous malformations treated by upfront Gamma Knife radiosurgery: a series of 149 consecutive cases

OBJECTIVE

Arteriovenous malformations (AVMs) present no pathologic tissue, and radiation dose is confined in a clear targeted volume. The authors retrospectively evaluated the role of the biologically effective dose (BED) after Gamma Knife radiosurgery (GKRS) for brain AVMs.

METHODS

A total of 149 consecutive cases of unruptured AVMs treated by upfront GKRS in Lille University Hospital, France, were included. The mean length of follow-up was 52.9 months (median 48, range 12-154 months). The primary outcome was obliteration, and the secondary outcome was complication appearance. The marginal dose was 24 Gy in a vast majority of cases (n = 115, 77.2%; range 18-25 Gy). The mean BED was 220.1 Gy2.47 (median 229.9, range 106.7-246.8 Gy2.47). The mean beam-on time was 32.3 minutes (median 30.8, range 9-138.7 minutes). In the present series, the mean radiation dose rate was 2.259 Gy/min (median 2.176, range 1.313-3.665 Gy/min). The Virginia score was 0 in 29 (19.5%), 1 in 61 (40.9%), 2 in 41 (27.5%), 3 in 18 (12.1%), and 4 in 0 (0%) patients, respectively. The mean Pollock-Flickinger score was 1.11 (median 1.52, range 0.4-2.9). Univariate (for obliteration and complication appearance) and multivariate (for obliteration only) analyses were performed.

RESULTS

A total of 104 AVMs (69.8%) were obliterated at the last follow-up. The strongest predictor for obliteration was BED (p = 0.03). A radiosurgical obliteration score is proposed, derived from a fitted multivariable model: (0.018 × BED) + (1.58 × V12) + (-0.013689 × beam-on time) + (0.021 × age) - 4.38. The area under the receiver operating characteristic curve was 0.7438; after internal validation using bootstrap methods, it was 0.7088. No statistically significant relationship between radiation dose rate and obliteration was found (p = 0.29). Twenty-eight (18.8%) patients developed complications after GKRS; 20 (13.4%) of these patients had transient adverse radiological effects (perilesional edema developed). Predictors for complication appearance were higher prescription isodose volume (p = 0.005) and 12-Gy isodose line volume (V12; p = 0.001), higher Pollock-Flickinger (p = 0.02) and Virginia scores (p = 0.003), and lower beam-on time (p = 0.03).

CONCLUSIONS

The BED was the strongest predictor of obliteration of unruptured AVMs after upfront GKRS. A radiosurgical score comprising the BED is proposed. The V12 appears as a predictor for both efficacy and toxicity. Beam-on time was illustrated as statistically significant for both obliteration and complication appearance. The radiation dose rate did not influence obliteration in the current analysis. The exact BED threshold remains to be established by further studies.

Vascular anomalies of the head and neck: diagnosis and treatment

Vascular malformations and vascular tumors comprise the two specific subsets of vascular anomalies that arise as a result of disorganized angiogenesis and neoplasm, respectively. Malformations are separate entities from vascular tumors (e.g., hemangiomas) and are recognized by the International Society for the Study of Vascular Anomalies (ISSVA) as such. Vascular malformations are classified into four main groups: simple, combined, anomalies of major vessels, and those associated with other vascular anomalies. Vascular tumors are neoplastic growths of blood vessels and are morphologically and molecularly distinct from malformations but can arise in the head and neck and have syndromic association. Head and neck vascular anomalies are not uncommon in the pediatric population and require special care in the workup, diagnostic imaging and clinical care. The purpose of this manuscript is to discuss the diagnosis and management of the most common intracranial and extracranial vascular malformations and tumors in the head and neck in children and adolescents.

Development and external validation of a clinical prediction model for functional impairment after intracranial tumor surgery

OBJECTIVE

Decision-making for intracranial tumor surgery requires balancing the oncological benefit against the risk for resection-related impairment. Risk estimates are commonly based on subjective experience and generalized numbers from the literature, but even experienced surgeons overestimate functional outcome after surgery. Today, there is no reliable and objective way to preoperatively predict an individual patient's risk of experiencing any functional impairment.

METHODS

The authors developed a prediction model for functional impairment at 3 to 6 months after microsurgical resection, defined as a decrease in Karnofsky Performance Status of ≥ 10 points. Two prospective registries in Switzerland and Italy were used for development. External validation was performed in 7 cohorts from Sweden, Norway, Germany, Austria, and the Netherlands. Age, sex, prior surgery, tumor histology and maximum diameter, expected major brain vessel or cranial nerve manipulation, resection in eloquent areas and the posterior fossa, and surgical approach were recorded. Discrimination and calibration metrics were evaluated.

RESULTS

In the development (2437 patients, 48.2% male; mean age ± SD: 55 ± 15 years) and external validation (2427 patients, 42.4% male; mean age ± SD: 58 ± 13 years) cohorts, functional impairment rates were 21.5% and 28.5%, respectively. In the development cohort, area under the curve (AUC) values of 0.72 (95% CI 0.69-0.74) were observed. In the pooled external validation cohort, the AUC was 0.72 (95% CI 0.69-0.74), confirming generalizability. Calibration plots indicated fair calibration in both cohorts. The tool has been incorporated into a web-based application available at https://neurosurgery.shinyapps.io/impairment/.

CONCLUSIONS

Functional impairment after intracranial tumor surgery remains extraordinarily difficult to predict, although machine learning can help quantify risk. This externally validated prediction tool can serve as the basis for case-by-case discussions and risk-to-benefit estimation of surgical treatment in the individual patient.

Retrospective Study and Outcome Predictor after Microsurgical Resection of Cerebral Arteriovenous Malformations in Nepal

Objective:

The purpose of this study is to assess demographic, clinical, and morphological characteristics of patients with brain arteriovenous malformations (bAVMs). The relation of outcome using modified Ranklin Scale (mRS) at time of discharge, early and last follow ups with respect to various factors.

Materials and Methods:

Demographic data, arteriovenous malformation characteristics, and treatment outcomes were evaluated in 43 bAVMs treated with microsurgery between 2009 and 2019. For this series, 43 patients were retrospectively reviewed. A subgroup analysis for Spetzler-Martin grades (SMG) I/II, III, IV/V and III–V were performed. The mRS was used to assess functional outcomes.

Results:

Overall, mean age at diagnosis was 33 years (standard deviation = 19). Transient deficit, mRS deterioration and impaired functional outcome occurred less frequently in SMG I–II patients compared with Grade III–V patients combined (29% vs. 32% respectively, P = 0.00). All patients with SMG Grade I, Supplemented SMG Grade 2, 3, 4 and 6 had a mRS score of 2 or less at the last follow-up. Age was the only significant predictor of overall outcome after bAVM surgery on Chi-square test (P = 0.046), i.e: all patients <20 years had mRS score of 2 or less on last follow-up. Unfavorable outcome (mRS score of 3 or more than 3) level increased with higher grades in SMG on long term follow-up.

Conclusion:

The results of our case series of bAVM with SMG Grade I and Suplemented Grade 2, 3, 4 and even higher grade i.e., 6 can have excellent overall outcome after microsurgical resection. Association of factors which increases the grading system of bAVM like eloquence, deep venous drainage and increasing sizes did not correlate with the predicted unfavorable outcomes, whereas age of patients was a predictor of overall outcome. Although the small sample size of this study is a limitation, age of patient plays important role on the overall outcome.