Significance of factors contributing to surgical complications and to late outcome after elective surgery of cerebral arteriovenous malformations

Feasibility of awake craniotomy for brain arteriovenous malformations: A scoping review

Background

Brain Arteriovenous Malformations (AVMs) located in proximity to eloquent brain regions are associated with poor surgical outcomes, which may be due to higher rates of postoperative neurological deterioration. Current treatment protocols include stereotactic radiosurgery, transarterial embolization, and surgical resection under general anesthesia. Awake Craniotomy (AC) allows intraoperative mapping of eloquent areas to improve post-operative neurologic outcomes.

Objectives

We reviewed the current literature reporting surgical outcomes and assessed the feasibility of AC for AVM resection.

Methods

The PRISMA guidelines were utilized as a template for the review. Three databases including PubMed, Scopus, and Cochrane Library were searched using a predefined search strategy. After removing duplicates and screening, full texts were analyzed. Outcomes including the extent of resection, intra-operative and post-operative complications, and long-term neurologic outcomes were assessed.

Results

12 studies were included with a total of 122 AVM cases. Spetzler-Martin grading was used for the classification of the AVMs. The asleep-awake-asleep protocol was most commonly used for AC. Complete resection was achieved in all cases except 5. Intraoperative complications included seizures (n = 2) and bleeding (n = 4). Short-term post-operative complications included hemorrhage (n = 3), neurologic dysfunctions including paresis (n = 3), hemiplegia (n = 10), dysphasia/aphasia (n = 6), cranial nerve dysfunction (n = 3), and pulmonary embolism (n = 1). Almost all neurological deficits after surgery gradually improved on subsequent follow-ups.

Conclusion

AVMs may shift the anatomical location of eloquent brain areas which may be mapped during AC. All studies recommended AC for the resection of AVMs in close proximity to eloquent areas as mapping during AC identifies the eloquent cortex thus promoting careful tissue handling which may preserve neurologic function and/or predict the postoperative functional status of the patients We, therefore, conclude that AC is a viable modality for AVMs resection near eloquent language and motor areas.

Microsurgical Treatment of Arteriovenous Malformations: A Single-Center Study Experience

OBJECTIVE

The purpose of the study was to assess the functional outcomes after microsurgical resection of arteriovenous malformations (AVMs) and to compare the results between patients eligible for A Randomized Trial of Unruptured Brain Arteriovenous Malformations in this surgical series to the results reported and the ARUBA study.

METHODS

We reviewed the records of 169 patients who underwent microsurgical treatment of arteriovenous malformation (AVMs) in our institution between January 2016 and December 2021. These patients' functional status was assessed using modified Rankin Scale (mRS) scores at the last follow-up and before treatment. The mRS scores at the latest follow-up were classified into good outcomes (mRS < 3) and poor outcomes (mRS ≥ 3). Clinical presentation, patients' demographics, AVM characteristics, follow-up time, and obliteration rate were analyzed. Subgroup analyses were performed on the whole cohort, comparing Spetzler-Martin Grade I and Grade II, and ARUBA-eligible AVMs.

RESULTS

The initial hemorrhagic presentation occurred in 71 (42%) out of 169 patients. The majority of the patients presented with headaches (73%). The AVMs were completely obliterated in 166 (98.2%) patients. The series included 65 Spetzler-Martin Grade I (38.5%), 46 Grade II (27.2%), 32 Grade III (18.9%), 22 Grade IV (13%), and 4 Grade V (2.4%) AVMs. There were 98 unruptured and 79 ARUBA-eligible cases. Also, optimal functional outcome was achieved in 145 (85.8%) patients. The overall mortality rate was 5.3% (9/169). The multivariate analysis illustrated that a poor outcome was significantly associated with presurgical mRS ≥3 (p < 0.013; OR, 0.206; 95% CI 0.059-0.713), increasing age (p < 0.045; odds ratio [OR], 1.022; 95% CI 1.000-0.045), and female gender (p < 0.009; OR, 2.991; 95% CI 1.309-6.832).

CONCLUSIONS

Our study suggests that better outcomes can be obtained using microsurgical resection in the majority of patients with AVMs. Independent predictors of poor outcomes after surgical resection of AVMs include increasing age at the time of surgery, poor presurgical functional status, and female gender. Supposing that patients are more suitable for microsurgery after presurgical examination, outcomes are normally better in that case than those achieved by multimodal interventions (such as conservative treatment or ARUBA treatment arm). Therefore, we recommend early surgical removal on all surgically accessible AVMs to prevent successive hemorrhages and the consequences of poor neurological outcomes.

Surgical Outcomes of Awake Craniotomy for Treatment of Arteriovenous Malformations in Eloquent Cortex: A Systematic Review

OBJECTIVE

Arteriovenous malformations (AVMs) located in eloquent brain regions are historically associated with a poor prognosis. Awake craniotomy (AC) with the adjunct of brain mapping has the potential of identifying non-eloquent gyri to maximize resection, thereby theoretically decreasing the risk of neurologic deficits. With limited evidence regarding the efficacy of AC in treatment of eloquent AVMs, this review aims to investigate its surgical outcomes.

METHODS

A systematic search in the PubMed database was performed to identify all relevant studies up to February 2022.

RESULTS

A total of 13 studies were extracted for quantitative analysis, yielding a total of 46 patients. The mean age was 34.1 years, and most patients were female (54.8%). Seizures were the most frequently reported presenting symptom (41%, 19 of 46 cases). Spetzler-Martin Grade III was the most prevalent (45.9%, 17 cases) with a mean nidus size of 32.6 mm. Seventy-four percent of AVMs were located on the left side, with the frontal lobe being the most common location (30%, 14 of 46 cases). The most common eloquent regions were language (47.8%, 22 of 46 cases), motor (17.4%, 8 of 46 cases), and language + motor cortices (13.1%, 6 of 46 cases). Complete resection of AVM was achieved in 41 patients (89%). Intraoperative complications occurred in 14 of 46 cases (30.4%) with transient postoperative neurologic deficits in 14 patients (30.4%).

CONCLUSIONS

AC may enable precise microsurgical excision of eloquent AVMs with preservation of critical brain functions. Risk factors for poor outcomes include eloquent AVMs located in the language + motor regions and the occurrence of intraoperative complications such as seizures/hemorrhage.

Application of diffusion tensor-based tractography in treatment of brain arteriovenous malformations: a systematic review

There is no systematic review investigating the utility of Diffusion tensor-based tractography findings for treating brain arteriovenous malformations (bAVMs). This systematic review aims to investigate the outcomes following bAVM treatment when tractography data is incorporated into treatment planning. PubMed/MEDLINE, Scopus, and Cochrane Library, were searched for published studies. Prospective or retrospective studies involving at least one patient with confirmed bAVM and available data on tractography and clinical outcomes were included. A total of 16 studies were eligible for this review, consisting of 298 patients. 48.2% of patients were female. The mean age of the patients was 27.5 years (range: 5-77). Stereotactic radiosurgery (SRS) and microsurgical resection each were the treatment of choice in eight studies, respectively. Two-hundred forty-eight patients underwent SRS as the primary treatment, while microsurgery was used to resect the bAVMs in 50 patients. The corticospinal tract, optic pathway, and arcuate fasciculus were the most widely investigated white matter tracts. Tractography disruption and failure frequencies were 19.1% and 1.8%, respectively. The pooled proportions (95% CI) of obliteration rates were 88.78% (73.51-95.76) for microsurgery and 51.45% (13-17-88.10) following SRS. Treatment-related non-hemorrhagic complications rates occurred in 24.2% and 9.9% of patients who underwent microsurgical resection and SRS, respectively. Tractography findings can contribute to providing a more accurate dosimetry analysis of functional white matter tracts at risk prior to SRS and minimizing the surgical morbidity following microsurgical resection.

Clinical features and outcome in pediatric arteriovenous malformation: institutional multimodality treatment

PURPOSE

Intracranial arteriovenous-malformation (AVM) is a relatively rare condition in pediatrics, yet is a major cause of spontaneous intracranial hemorrhage with a risk of fatal hemorrhage reported to be between 4 and 29%. Little is known about vessel morphology and optimum treatment modalities including multimodality combination therapy and prognosis in children.

METHODS

A retrospective review of all children presenting to our institution from 2006 to 2020 that had an AVM was undertaken.

RESULTS

A total of 50 children were identified with median age of 11 (range 1-16) years. The mean follow-up was 7.6 years. Forty-one children presented as an emergency and of those, 40 had hemorrhage identified on initial brain imaging. The average nidus size was 25 mm, drainage was superficial in 51% of cases, and located in eloquent cortex in 56%. The supplemental Spetzler-Martin grading indicated 78% (39/50) were grade 4 and above (moderate to high risk). Primary treatment modalities included embolization in 50% (25) or SRS in 30% (15) and surgery in 20% (10).The AVM was obliterated on follow-up DSA in 66% children. Three children had post-treatment hemorrhage, two related to embolization and one the day following SRS, giving a re-bleed rate of 6%. The GOSE was available for 32 children at long term follow and 94% had a good outcome (GOSE 5-8). Two children died due to acute hemorrhage (4%).

CONCLUSION

The majority of children with AVM present with hemorrhage. The rebleed rate during definitive treatment is low at 6% over the study period. The selective use of the 3 modalities of treatment has significantly reduced mortality and severe disability.

Selective arterial temporary flow arrest with balloons during transvenous embolization for the treatment of brain arteriovenous malformations: a feasibility study with MRI-monitored adverse events

BACKGROUND

The technique of endovascular transvenous embolization for brain arteriovenous malformations (AVMs) has emerged in the last 8 years as a very promising therapeutic alternative for otherwise incurable cases. Selective temporary flow arrest during transvenous endovascular embolization (TFATVE) is a novel adaptation of our previously described transvenous approach, which employs hyper-compliant balloons intra-arterially for the selective occlusion of arterial feeders during ethylene vinyl copolymer (EVOH) injection, in order to reduce intra-nidal pressure and increase nidi occlusion rates.

METHODS

We performed a feasibility study of the TFATVE technique between January 2016 and April 2020. Consecutive patients were included. All patients had at least one axial brain MRI or CT in the first 48 hours following intervention, and at least one brain MRI scan within the first postoperative month, in order to detect both silent and clinically evident adverse events. Patients' demographics, angio-architectural characteristics, total injection and procedure times, angiographic and clinical outcomes were analyzed.

RESULTS

22 patients underwent TFATVE during transvenous endovascular treatment of brain AVMs. Among them, 86.4% were high Spetzler-Martin's grade. Good clinical outcome (modified Rankin Scale <2) was achieved in 95.5% of the cases, with 0% of procedure-related mortality and 4.5% of clinically significant, procedure-related morbidity. Total occlusion of the nidus was achieved in >90% of the cases at the end of the procedure and angiographic stability was achieved in all cases; 100% of the cases had angiographic cure at follow-up.

CONCLUSIONS

TFATVE seems a safe and effective technique when conducted in carefully selected patients in highly specialized centers.

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.

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.

Selection of Patients for Treatment of Brain Arteriovenous Malformations by the Transvenous Approach: Relationship with Venous Anatomy and Risk of Hemorrhagic Complications

BACKGROUND AND PURPOSE

Intracranial hemorrhage represents a severe complication of brain arteriovenous malformation treatment. The aim of this cohort was to report the rate of hemorrhagic complications after transvenous endovascular embolization and analyze the potential angioarchitectural risk factors as well as clinical outcomes.

MATERIALS AND METHODS

During an 11-year period, 57 patients underwent transvenous endovascular embolization. All cases of hemorrhagic complications were identified. We analyzed the following variables: sex, age, hemorrhagic presentation, Spetzler-Martin grade, size of the AVM before the transvenous treatment, number of venous collectors, pattern of drainage, presence of dilated veins, and technical aspects. Univariate and multivariate multiple regression analyses were performed to evaluate the potential risk factors for procedure-related hemorrhagic complications.

RESULTS

Hemorrhagic complications (either intraprocedural or periprocedural) unrelated to a perforation due to micronavigation occurred in 8 (14.0%) procedures. Significant (mRS > 2) and persistent neurologic deficits were present in 2 (3.5%) patients at 6-month control. Larger nidi, especially >3 cm (P = .03), and a larger number of venous collectors have shown a statistically significant correlation with hemorrhagic complications. Only the number of venous collectors was identified as an independent predictor of hemorrhagic complications in the multivariate analysis (OR, 8.7; 95% confidence interval, 2.2-58.2) (P = .006).

CONCLUSIONS

Larger nidus sizes and an increased number of venous collectors may increase the risk of hemorrhagic complications when implementing transvenous endovascular treatment of AVMs. The technique is effective and promising, especially with small nidi and single venous collectors.

Anesthetic Management of Awake Craniotomy for Resection of the Language and Motor Cortex Vascular Malformations

BACKGROUND

Although the safety and feasibility of awake craniotomy are well established for epilepsy and brain tumor surgery, its application for resection of vascular lesions, including arteriovenous malformations (AVMs) and cavernomas, is still limited. Apart from the usual challenges of awake craniotomy, vascular lesions pose several additional problems. Our goal is to determine the safety and practicality of awake craniotomy in patients with cerebral vascular malformations located near the eloquent areas, using a refined anesthetic protocol.

METHODS

A retrospective case series was performed on 7 patients who underwent awake craniotomy for resection of AVMs or cavernomas located in the eloquent language and motor areas. Our protocol consisted of achieving deep sedation, without a definitive airway, using a combination of propofol, dexmedetomidine, and remifentanil/fentanyl during scalp block placement and surgical exposure, then transitioning to a wakeful state during the resection.

RESULTS

Six patients had intracranial AVMs, and 1 patient had a cavernoma. Six patients had complete resection; however, 1 patient underwent repeat awake craniotomy for residual AVM nidus. The patients tolerated the resection under continuous awake neurologic and neurophysiologic testing without significant perioperative complications or the need to convert to general anesthesia with a definitive airway.

CONCLUSIONS

Awake craniotomy for excision of intracranial vascular malformations located near the eloquent areas, in carefully selected patients, can facilitate resection by allowing close neuromonitoring and direct functional assessment. A balanced combination of sedative and analgesic medications can provide both adequate sedation and rapid wakeup, facilitating the necessary patient interaction and tolerance of the procedure.

A novel proposed grading system for cerebellar arteriovenous malformations

OBJECTIVE

The objective of this study was to evaluate the existing Spetzler-Martin (SM), Spetzler-Ponce (SP), and Lawton-Young (LY) grading systems for cerebellar arteriovenous malformations (AVMs) and to propose a new grading system to estimate the risks associated with these lesions.

METHODS

Data for patients with cerebellar AVMs treated microsurgically in two tertiary medical centers were retrospectively reviewed. Data from patients at institution 1 were collected from September 1999 to February 2013, and at institution 2 from October 2008 to October 2015. Patient outcomes were classified as favorable (modified Rankin Scale [mRS] score 0-2) or poor (mRS score 3-6) at the time of discharge. Using chi-square and logistic regression analysis, variables associated with poor outcomes were assigned risk points to design the proposed grading system. The proposed system included neurological status prior to treatment (poor, +2 points), emergency surgery (+1 point), age > 60 years (+1 point), and deep venous drainage (deep, +1 point). Risk point totals of 0-1 comprised grade 1, 2-3 grade 2, and 4-5 grade 3.

RESULTS

A total of 125 cerebellar AVMs of 1328 brain AVMs were reviewed in 125 patients, 120 of which were treated microsurgically and included in the study. With our proposed grading system, we found poor outcomes differed significantly between each grade (p < 0.001), while with the SM, SP, and LY grading systems they did not (p = 0.22, p = 0.25, and p = 1, respectively). Logistic regression revealed grade 2 had 3.3 times the risk of experiencing a poor outcome (p = 0.008), while grade 3 had 9.9 times the risk (p < 0.001). The proposed grading system demonstrated a superior level of predictive accuracy (area under the receiver operating characteristic curve [AUROC] of 0.72) compared with the SM, SP, and LY grading systems (AUROC of 0.61, 0.57, and 0.51, respectively).

CONCLUSIONS

The authors propose a novel grading system for cerebellar AVMs based on emergency surgery, venous drainage, preoperative neurological status, and age that provides a superior prognostication power than the formerly proposed SM, SP, and LY grading systems. This grading system is clinically predictive of patient outcomes and can be used to better guide vascular neurosurgeons in clinical decision-making.

Microsurgery Versus Stereotactic Radiosurgery for Brain Arteriovenous Malformations: A Matched Cohort Study

BACKGROUND

Microsurgery (MS) and stereotactic radiosurgery (SRS) remain the preferred interventions for the curative treatment of brain arteriovenous malformations (AVM), but their relative efficacy remains incompletely defined.

OBJECTIVE

To compare the outcomes of MS to SRS for AVMs through a retrospective, matched cohort study.

METHODS

We evaluated institutional databases of AVM patients who underwent MS and SRS. MS-treated patients were matched, in a 1:1 ratio based on patient and AVM characteristics, to SRS-treated patients. Statistical analyses were performed to compare outcomes data between the 2 cohorts. The primary outcome was defined as AVM obliteration without a new permanent neurological deficit.

RESULTS

The matched MS and SRS cohorts were each comprised of 59 patients. Both radiological (85 vs 11 mo; P < .001) and clinical (92 vs 12 mo; P < .001) follow-up were significantly longer for the SRS cohort. The primary outcome was achieved in 69% of each cohort. The MS cohort had a significantly higher obliteration rate (98% vs 72%; P = .001), but also had a significantly higher rate of new permanent deficit (31% vs 10%; P = .011). The posttreatment hemorrhage rate was significantly higher for the SRS cohort (10% for SRS vs 0% for MS; P = .027). In subgroup analyses of ruptured and unruptured AVMs, no significant differences between the primary outcomes were observed.

CONCLUSION

For patients with comparable AVMs, MS and SRS afford similar rates of deficit-free obliteration. Nidal obliteration is more frequently achieved with MS, but this intervention also incurs a greater risk of new permanent neurological deficit.

Benign Intracranial Lesions - Radiotherapy: An Overview of Treatment Options, Indications and Therapeutic Results

BACKGROUND

Radiation Therapy (RT) is an established treatment option for benign intracranial lesions. The aim of this study is to display an update on the role of RT concerning the most frequent benign brain lesions and tumors.

METHODS

Published articles about RT and meningiomas, Vestibular Schwannomas (VSs), Pituitary Adenomas (PAs), Arteriovenous Malformations (AVMs) and craniopharyngiomas were reviewed and extracted data were used.

RESULTS

In meningiomas RT is applied as an adjuvant therapy, in case of patientrefusing surgery or in unresectable tumors. The available techniques are External Beam RT (EBRT) and stereotactic ones such as Stereotactic Radiosurgery (SRS), Fractionated Stereotactic RT (FSRT), Intensity Modulated RT (IMRT) and proton-beam therapy. The same indications are considered in PAs, in which SRS and FSRT achieve excellent tumor control rate (92-100%), acceptable hormone remission rates (>50%) and decreased Adverse Radiation Effects (AREs). Upon tumor growth or neurological deterioration, RT emerges as alone or adjuvant treatment against VSs, with SRS, FSRT, EBRT or protonbeam therapy presenting excellent tumor control growth (>90%), facial nerve (84-100%), trigeminal nerve (74-99%) and hearing (>50%) preservation. SRS poses an effective treatment modality of certain AVMs, demonstrating a 3-year obliteration rate of 80%. Lastly, a combination of microsurgery and RT presents equal local control and 5-year survival rate (>90%) but improved toxicity profile compared to total resection in case of craniopharyngiomas.

CONCLUSION

RT comprises an effective treatment modality of benign brain and intracranial lesions. By minimizing its AREs with optimal use, RT projects as a potent tool against such diseases.

Curative treatment for low-grade arteriovenous malformations

Background

Spetzler-Martin (SM) grade I-II (low-grade) arteriovenous malformations (AVMs) are often considered safe for microsurgery or radiosurgery. The adjunctive use of preoperative embolization to reduce surgical risk in these AVMs remains controversial.

Objective

To assess the safety of combined treatment of grade I-II AVMs with preoperative embolization followed by surgical resection or radiosurgery, and determine the long-term functional outcomes.

Methods

With institutional review board approval, a retrospective analysis was carried out on patients with ruptured and unruptured SM I-II AVMs between 2002 and 2017. Details of the endovascular procedures, including number of arteries supplying the AVM, number of branches embolized, embolic agent(s) used, and complications were studied. Baseline clinical and imaging characteristics were compared. Functional status using the modified Rankin Scale (mRS) before and after endovascular and microsurgical treatments was compared.

Results

258 SM I-II AVMs (36% SM I, 64% SM II) were identified in patients with a mean age of 38 ± 17 years. 48% presented with hemorrhage, 21% with seizure, 16% with headache, 10% with no symptoms, and 5% with clinical deficits. 90 patients (68%) in the unruptured group and 74 patients (59%) in the ruptured group underwent presurgical embolization (p = 0.0013). The mean number of arteries supplying the AVM was 1.44 and 1.41 in the unruptured and ruptured groups, respectively (p = 0.75). The mean number of arteries embolized was 2.51 in the unruptured group and 1.82 in the ruptured group (p = 0.003). n-Butyl cyanoacrylate and Onyx were the two most commonly used embolic agents. Four complications were seen in four patients (4/164 patients embolized): two peri-/postprocedural hemorrhage, one dissection, and one infarct. All patients undergoing surgery had a complete cure on postoperative angiography. Patients were followed up for a mean of 55 months. Good long-term outcomes (mRS score ≤ 2) were seen in 92.5% of patients with unruptured AVMs and 88.0% of those with ruptured AVMs. Permanent neurological morbidity occurred in 1.2%.

Conclusions

Curative treatment of SM I-II AVMs can be performed using endovascular embolization with microsurgical resection or radiosurgery in selected cases, with very low morbidity and high cure rates. Compared with other published series, these outcomes suggest that preoperative embolization is a safe and effective adjunct to definitive surgical treatment. Long-term follow-up showed that patients with low-grade AVMs undergoing surgical resection or radiosurgery have good functional outcomes.

Delayed hemorrhagic complication after complete embolization of a brain arteriovenous malformation

Endovascular embolization is an essential therapeutic approach in the multidisciplinary management of cerebral arteriovenous malformations (AVM). However, it rarely occludes the AVM in its entirety. It is often combined with surgery or stereotactic radiosurgery. The aim of embolization is to reduce the size of the nidus and the intra-nidal flow in order to facilitate the microsurgical or the radiosurgical procedure. We report the case of a 61-year-old patient with a right frontal hemorrhagic AVM treated with complete embolization in a single session. Initially, a surgical procedure for excision of the AVM was scheduled 24hours post-embolization. This surgery was canceled due to a good angiographic result of the embolization. Eight days post-embolization, there was a massive re-bleed of the AVM which justified emergency surgical management. This case illustrates a delayed post-embolization hemorrhagic complication of an occluded AVM and prompts a review of the therapeutic strategy of the cerebral AVM to select the most effective and least morbid procedure or combination of procedures.

Comparison of the Long-term Efficacy and Safety of Gamma Knife Radiosurgery for Arteriovenous Malformations in Pediatric and Adult Patients

It is debated whether the efficacy and long-term safety of gamma knife radiosurgery (GKRS) for arteriovenous malformations (AVMs) differs between adult and pediatric patients. We aimed to clarify the long-term outcomes of GKRS in pediatric patients and how they compare to those in adult patients. We collected data for 736 consecutive patients with AVMs treated with GKRS between 1990 and 2014 and divided the patients into pediatric (age < 20 years, n = 144) and adult (age ≥ 20 years, n = 592) cohorts. The mean follow-up period in the pediatric cohort was 130 months. Compared to the adult patients, the pediatric patients were significantly more likely to have a history of hemorrhage (P < 0.001). The actuarial rates of post-GKRS nidus obliteration in the pediatric cohort were 36%, 60%, and 87% at 2, 3, and 6 years, respectively. Nidus obliteration occurred earlier in the pediatric cohort than in the adult cohort (P = 0.015). The actuarial rates of post-GKRS hemorrhage in the pediatric cohort were 0.7%, 2.5%, and 2.5% at 1, 5, and 10 years, respectively. Post-GKRS hemorrhage was marginally less common in the pediatric cohort than in the adult cohort (P = 0.056). Cyst formation/encapsulated hematoma were detected in seven pediatric patients (4.9%) at a median post-GKRS timepoint of 111 months, which was not significantly different from the rate in the adult cohort. Compared to adult patients, pediatric patients experience earlier therapeutic effects from GKRS for AVMs, and this improves long-term outcomes.

Differences in Functional Outcome Across Subtypes with Spetzler-Martin Grade II Arteriovenous Malformations

BACKGROUND

The Spetzler-Martin grading system for brain arteriovenous malformations (AVMs) is based on size (S), eloquence (E), and deep venous drainage (V). However, variation exists due to subgroup heterogeneity. While previous studies have demonstrated variations in outcomes within grade III AVMs, no studies have focused on grade II AVM subtypes.

OBJECTIVE

We aim to delineate how functional outcomes differ among patients with subtypes of grade II AVMs.

METHODS

We retrospectively reviewed patients with AVMs evaluated at our institution from 1990 to 2013. Grade II AVMs were divided into 3 subtypes: group 1 (S2V0E0), group 2 (S1V0E1), and group 3 (S1V1E0). Baseline characteristics were compared, and functional status was assessed using the modified Rankin Scale (mRS) at pretreatment and last follow-up. Differences in mRS between the 2 time points were compared.

RESULTS

A total of 208 grade II patients (34.0%) were retrieved from 611 graded patients. After accounting for missing data, our cohort consisted of 137 patients. Mean age of all patients was 37.2 years, with 74 females (54.0%). No significant difference was observed across subgroups for pretreatment mRS ( P = .096), treatment modalities ( P = .943), follow-up durations ( P = .125), and mRS at last follow-up ( P = .716). In a subgroup analysis between group 1 and group 3, more patients with worsened mRS were observed in group 3 ( P = .039). This distinction was further confirmed in surgically treated patients ( P = .049), but not in patients treated with radiosurgery ( P = .863).

CONCLUSION

Subtypes of grade II AVMs portend different posttreatment gains in functional outcome. Group 1 (S2V0E0) patients had the best functional outcome gain from treatment, while group 3 (S1V1E0) patients fared less well, particularly with surgical treatment.

Clinical Experience and Results of Microsurgical Resection of Arterioveonous Malformation in the Presence of Space-Occupying Intracerebral Hematoma

BACKGROUND: Management of ruptured arteriovenous malformations (AVMs) with a mass-producing intracerebral hematoma (ICH) represents a surgical dilemma.

OBJECTIVE: To evaluate the clinical outcome and obliteration rates of microsurgical resection of AVM when performed concomitantly with evacuation of an associated space-occupying ICH.

METHODS: Data of patients with AVM were collected prospectively. Cases were identified in which an AVM was resected and an associated space-occupying ICH was evacuated at the same time, and divided into “group 1,” in which the surgery was performed acutely within 48 h of presentation (secondary to elevated intracranial pressure); and “group 2,” in which selected patients were operated upon in the presence of a liquefying ICH in the “subacute” stage. Clinical outcomes were assessed using the modified Rankin Scale, with a score of 0 to 2 considered a good outcome. Obliteration rates were assessed using postoperative angiography.

RESULTS: From 2001 to 2015, 131 patients underwent microsurgical resection of an AVM, of which 65 cases were included. In “group 1” (n = 21; Spetzler-Ponce class A = 13, class B = 5, and class C = 3), 11 of 21 (52%) had a good outcome and in 18 of 19 (95%) of those who had a postoperative angiogram the AVMs were completely obliterated. In “group 2” (n = 44; Spetzler-Ponce class A = 33, class B = 9, and class C = 2), 31 of 44 (93%) had a good outcome and 42 of 44 (95%) were obliterated with a single procedure. For supratentorial AVMs, the ICH cavity was utilized to provide an operative trajectory to a deep AVM in 11 cases, and in 26 cases the ICH cavity was deep to the AVM and hence facilitated the deep dissection of the nidus.

CONCLUSION: In selected patients the presence of a liquefying ICH cavity may facilitate the resection of AVMs when performed in the subacute stage resulting in a good neurological outcome and high obliteration rate.

Multimodal Treatment Strategy for Spetzler-Martin Grade III Arteriovenous Malformations of the Brain

The Spetzler–Martin (S–M) grading scale was developed to assess the risk of postoperative neurological complications after the surgical treatment of arteriovenous malformations (AVMs) of the brain. Treatment-associated morbidity and poor outcomes are particularly relevant to Grade III AVMs and improving the safety while attaining acceptable cure rates still poses a challenge. A multimodal treatment strategy combining surgery, embolization, and radiosurgery is recommended for S–M Grade III AVMs because of the surgical risk. Grade III AVMs are the heterogeneous group that has been further divided into subgroups according to the size, the location in eloquent cortex, and the presence of deep venous drainage. The risks associated with different treatment modalities vary depending on the subgroup, and the rating scales have been further refined to predict the risk more accurately and help determine the most appropriate treatment choice. Previous results for the treatment of S–M Grade III AVMs vary widely among studies, and the treatment modalities are also different in each study. Being familiar with previous treatment results is essential for improving treatment outcomes.

Microsurgical Outcome of Unruptured Brain Arteriovenous Malformations: A Single-Center Experience

OBJECTIVE

We describe our single-center experience treating unruptured brain arteriovenous malformations (uBAVMs) with microsurgical treatment.

METHODS

During a 7-year period, 282 patients with uBAVMs were surgically treated at our institution. Patient clinical features, postsurgical complications, arteriovenous malformation obliteration rate, seizure control, and functional outcome were collected and analyzed. Seizure control was evaluated with the Engel classification system. Patient functional outcome was assessed with modified Rankin Scale score.

RESULTS

Complete obliteration was achieved in 98.2% of cases. Surgical mortality rate was zero, and overall mortality rate was 1.1%. Good functional outcome (modified Rankin Scale score 0-1) was achieved in 86.9% of all patients, including 92.5% of patients with Spetzler-Martin (S-M) grade I and II uBAVMs, 80.6% of patients with S-M grade III uBAVMs, and 62.5% of patients with S-M grade IV and V uBAVMs. Poor outcome was significantly associated with arteriovenous malformation size ≥6 cm, deep venous drainage, eloquent location, and poor seizure control (all P < 0.05). For 177 patients with presurgical seizures, good seizure outcome (Engel class I) was achieved in 124 (70.1%) patients after microsurgical treatment. A short history of seizure occurrence, fewer presurgical seizures, and generalized tonic-clonic seizure type may be predictors of good seizure outcome (all P < 0.05).

CONCLUSIONS

Good functional outcome can be achieved by microsurgical resection in S-M grade I and II and selected grade III uBAVMs. Surgical resection for high-grade (grade IV and V) uBAVMs is challenging. A high seizure-free rate can be achieved in patients with initial seizure presentation.

Comparative surgical outcome associated with the management of brain arteriovenous malformation in a regional neurosurgical centre

OBJECTIVES

Microsurgical resection of brain arteriovenous malformation (AVMs) is challenging, however, expert surgical series from large volume centres, have reported over 95% occlusion rates with 2 to 8% risk of morbidity & mortality. Data from a regional neurosurgical unit was analysed and compared with published series for the purposes of quality control. We also compared our surgical result with other treatment modalities from the whole AVM cohort managed over the same study period.

DESIGN

Retrospective analysis of a locally held AVM database.

SUBJECTS

Of the 141 AVM patients, 54 (35M, 19F, age range 9-68 years) underwent microsurgical removal of AVM by the senior author, from 2006 to 2012. 27 (19%), 18 (13%), 20 (14%), 22 (16%) had endovascular therapy only, radiosurgery only, combination therapy (endovascular and radiosurgery) and conservative management, respectively.

METHODS

Case notes were reviewed to determine clinical and radiological outcomes. Statistical analysis performed using SPSS with p < 0.05 defined as statistical significance.

RESULTS

In the surgical series, the Spetzler-Martin (SM) grade distribution was as follows: 17 grade I (32%), 31 grade II (57%), and 6 grade III (11%). 31 patients (57%) presented with intracranial haemorrhage, 12 patients (22%) with seizures. Of the 54 patients, 51 (94%) had angiographically confirmed obliteration of their AVM. Median follow-up for the entire cohort was 7 years. 83% of surgical patients have mRS 0-1, compared to 78%, 67%, 45%, 18% of patients managed by endovascular therapy, radiosurgery, combination therapy, conservative surveillance, respectively (p < 0.0001). However, the groups were not comparable in terms of SM grade or clinical presentation and the numbers in each group were relatively small. Seizure presentations were encountered in 23% (32/141) of the overall patients, and all the surviving patients were on anticonvulsants, except in the surgical arm, 7/12 (58%) patients were off their antiepileptic medications at last follow-up.

CONCLUSIONS

The results demonstrate a 94% surgical obliteration rate and 11% long-term neurological deficits for brain AVM patients managed surgically and were comparable to expert series. Achieving acceptable results is possible in lower volume settings, however, patient selection is important and the role of an experienced neurovascular team cannot be overstated.

Microsurgery for cerebral arteriovenous malformations: subgroup outcomes in a consecutive series of 288 cases

OBJECTIVE The objective of this study was to review the outcomes after microsurgical resection of cerebral arteriovenous malformations (AVMs) from a consecutive single-surgeon series. Clinical and imaging data were analyzed to address the following questions concerning AVM treatment in the post-ARUBA (A Randomized Trial of Unruptured Brain Arteriovenous Malformations) era. 1) Are the patients who present with unruptured or ruptured AVMs doing better at long-term follow-up? 2) Is the differentiation between Ponce Class A (Spetzler-Martin Grade I and II) patients versus Ponce Class B and C patients (Spetzler-Martin Grade III and IV) meaningful and applicable to surgical practice? 3) How did the ARUBA-eligible patients of this surgical series compare with the results reported in ARUBA? METHODS Two hundred eighty-eight patients with cerebral AVMs underwent microsurgical resection between 1983 and 2012 performed by the same surgeon (J.S.). This is a prospective case collection study that represents a consecutive series. The results are based on prospectively collected, early-outcome data that were supplemented by retrospectively collected, follow-up data for 94% of those cases. The analyzed data included the initial presentation, Spetzler-Martin grade, obliteration rates, surgical and neurological complications, and frequency of pretreatment with embolization or radiosurgery. The total cohort was compared using "small-AVM," Spetzler-Martin Grade I and II, and ARUBA-eligible AVM subgroups. RESULTS The initial presentation was hemorrhage in 50.0% and seizures in 43.1% of patients. The series included 53 Spetzler-Martin Grade I (18.4%), 114 Spetzler-Martin Grade II (39.6%), 90 Spetzler-Martin Grade III (31.3%), 28 Spetzler-Martin Grade IV (9.7%), and 3 Spetzler-Martin Grade V (1.0%) AVMs. There were 144 unruptured and 104 ARUBA-eligible cases. Preembolization was used in 39 cases (13.5%). The occlusion rates for the total series and small AVM subgroup were 99% and 98.7%, respectively. The mean follow-up duration was 64 months. Early neurological deterioration was seen in 39.2% of patients, of which 12.2% had permanent and 5.6% had permanent significant deficits, and the mortality rate was 1.7% (n = 5). Outcome was better for patients with AVMs smaller than 3 cm (permanent deficit in 7.8% and permanent significant deficit in 3.2% of patients) and Ponce Class A status (permanent deficit in 7.8% and significant deficit in 3.2% of patients). Unruptured AVMs showed slightly higher new deficit rates (but 0 instances of mortality) among all cases, and in the small AVM and Ponce Class A subgroups. Unruptured Spetzler-Martin Grade I and II lesions had the best outcome (1.8% permanent significant deficit), and ARUBA-eligible Spetzler-Martin Grade I and II lesions had a slightly higher rate of permanent significant deficits (3.2%). CONCLUSIONS Microsurgery has a very high cure rate. Focusing microsurgical AVM resection on unruptured lesions smaller than 3 cm or on Spetzler-Martin Grade I and II lesions is a good strategy for minimizing long-term morbidity. Well-selected microsurgical cases lead to better outcomes than with multimodal interventions, as in the ARUBA treatment arm, or conservative treatment alone. Long-term prospective data collection is valuable.

Outcome of microsurgical excision of unruptured brain arteriovenous malformations in ARUBA-eligible patients

OBJECTIVES

To determine the outcome of microsurgical excision of selected unruptured brain arteriovenous malformations (AVMs), and to compare the results with those of the ARUBA trial.

METHODS

Prospective data collection for all patients undergoing microsurgical excision of unruptured brain AVMs by two neurovascular surgeons. Outcome measures similar to those assessed in the ARUBA trial (death and stroke) as well as modified Rankin scores (mRS) at 6 months were assessed.

RESULTS

Between September 2004 and September 2014, 45 patients with unruptured brain AVMs underwent microsurgical excision. 11 patients (eight children and three with mRS >2 at presentation) were excluded to match ARUBA eligibility criteria. 34 patients were included in this study. AVM characteristics closely matched those in the ARUBA trial with 70.5% Spetzler-Martin (SM) grade I or II AVMs, 68% AVM size <3 cm. However, compared to ARUBA, a larger proportion of our patients presented with seizures, and a lower proportion with headaches. 8(23%) had preoperative embolization. There were no deaths and no strokes (as defined in ARUBA). 5 (14.7%) had permanent neurological deficit related to surgery within/near eloquent cortex. At 6 months follow-up, 32 (94%) had mRS score of 0-1. Two (6%) had mRS 2 and none had mRS> 2. Postoperative digital DSA confirmed complete AVM excision in all cases. None of the patients have suffered intracranial hemorrhage during the follow-up period of 6-126 (median 69) months.

CONCLUSIONS

Microsurgical excision of unruptured brain AVMs can be performed with low morbidity in selected cases. Our study has limitations particularly the small number of patients with selected AVMs for microsurgical excision. However, our results suggest that ARUBA results may not be applicable to microsurgical excision when cases are appropriately selected for this treatment modality.

Radiosurgery for temporal lobe arteriovenous malformations: effect of temporal location on seizure outcomes

OBJECT

The temporal lobe is particularly susceptible to epileptogenesis. However, the routine use of anticonvulsant therapy is not implemented in temporal lobe AVM patients without seizures at presentation. The goals of this case-control study were to determine the radiosurgical outcomes for temporal lobe AVMs and to define the effect of temporal lobe location on postradiosurgery AVM seizure outcomes.

METHODS

From a database of approximately 1400 patients, the authors generated a case cohort from patients with temporal lobe AVMs with at least 2 years follow-up or obliteration. A control cohort with similar baseline AVM characteristics was generated, blinded to outcome, from patients with non-temporal, cortical AVMs. They evaluated the rates and predictors of seizure freedom or decreased seizure frequency in patients with seizures or de novo seizures in those without seizures.

RESULTS

A total of 175 temporal lobe AVMs were identified based on the inclusion criteria. Seizure was the presenting symptom in 38% of patients. The median AVM volume was 3.3 cm3, and the Spetzler-Martin grade was III or higher in 39% of cases. The median radiosurgical prescription dose was 22 Gy. At a median clinical follow-up of 73 months, the rates of seizure control and de novo seizures were 62% and 2%, respectively. Prior embolization (p = 0.023) and lower radiosurgical dose (p = 0.027) were significant predictors of seizure control. Neither temporal lobe location (p = 0.187) nor obliteration (p = 0.522) affected seizure outcomes. The cumulative obliteration rate was 63%, which was significantly higher in patients without seizures at presentation (p = 0.046). The rates of symptomatic and permanent radiation-induced changes were 3% and 1%, respectively. The annual risk of postradiosurgery hemorrhage was 1.3%.

CONCLUSIONS

Radiosurgery is an effective treatment for temporal lobe AVMs. Furthermore, radiosurgery is protective against seizure progression in patients with temporal lobe AVM–associated seizures. Temporal lobe location does not affect radiosurgery-induced seizure control. The low risk of new-onset seizures in patients with temporal or extratemporal AVMs does not seem to warrant prophylactic use of anticonvulsants.

Brain arteriovenous malformations

An arteriovenous malformation is a tangle of dysplastic vessels (nidus) fed by arteries and drained by veins without intervening capillaries, forming a high-flow, low-resistance shunt between the arterial and venous systems. Arteriovenous malformations in the brain have a low estimated prevalence but are an important cause of intracerebral haemorrhage in young adults. For previously unruptured malformations, bleeding rates are approximately 1% per year. Once ruptured, the subsequent risk increases fivefold, depending on associated aneurysms, deep locations, deep drainage and increasing age. Recent findings from novel animal models and genetic studies suggest that arteriovenous malformations, which were long considered congenital, arise from aberrant vasculogenesis, genetic mutations and/or angiogenesis after injury. The phenotypical characteristics of arteriovenous malformations differ among age groups, with fistulous lesions in children and nidal lesions in adults. Diagnosis mainly involves imaging techniques, including CT, MRI and angiography. Management includes observation, microsurgical resection, endovascular embolization and stereotactic radiosurgery, alone or in any combination. There is little consensus on how to manage patients with unruptured malformations; recent studies have shown that patients managed medically fared better than those with intervention at short-term follow-up. By contrast, interventional treatment is preferred following a ruptured malformation to prevent rehaemorrhage. Management continues to evolve as new mechanistic discoveries and reliable animal models raise the possibility of developing drugs that might prevent the formation of arteriovenous malformations, induce obliteration and/or stabilize vessels to reduce rupture risk. For an illustrated summary of this Primer, visit: http://go.nature.com/TMoAdn.

Endovascular transvenous cure for ruptured brain arteriovenous malformations in complex cases with high Spetzler-Martin grades

OBJECT

Ruptured cerebral arteriovenous malformations (AVMs) with deep localization and high Spetzler-Martin grades are associated with considerable challenges regarding nidus eradication treatment. The authors report their experience with curative endovascular transvenous embolization in a series of patients harboring “untreatable” lesions.

METHODS

Between January 2008 and June 2013, a transvenous endovascular embolization protocol was implemented at the authors' institution for consecutive patients with ruptured brain AVMs that were considered incurable by classic endovascular and surgical techniques. Therapeutic decision making was based on Spetzler-Martin grades, AVM location, type of venous drainage, and angioarchitectural evaluation. Complete exclusion of the nidus was the objective of treatment.

RESULTS

Twenty patients (10 male and 10 female, mean age 36.7 ± 17.7 years) were included. Initial Spetzler-Martin grades were III–V for 90.0% of the patients. The lesions were deeply seated in 80% and in eloquent locations in 90% of cases. The preprocedural modified Rankin Scale score was 0–2 for 12 of the 20 patients (60.0%), 3 for 2 patients (10.0%), and 4 for 6 patients (30.0%). The postprocedural clinical status was unchanged for all patients. The procedure was technically feasible in all cases. Procedure-related mortality was 0%. Ninety percent of the patients were independent in their everyday lives (modified Rankin Scale Scores 0–2) at the 6-month follow-up. In all cases but one (95%) the embolization was curative, confirmed by selective DSA at 6 months and 18 months postintervention.

CONCLUSIONS

Single-session endovascular transvenous embolization seems to be a safe and effective curative treatment for patients harboring complex brain AVMs with high Spetzler-Martin grade.

Current surgical results with low-grade brain arteriovenous malformations

OBJECT

Resection is an appealing therapy for brain arteriovenous malformations (AVMs) because of its high cure rate, low complication rate, and immediacy, and has become the first-line therapy for many AVMs. To clarify safety, efficacy, and outcomes associated with AVM resection in the aftermath of A Randomized Trial of Unruptured Brain AVMs (ARUBA), the authors reviewed their experience with low-grade AVMs-the most favorable AVMs for surgery and the ones most likely to have been selected for treatment outside of ARUBA's randomization process.

METHODS

A prospective AVM registry was searched to identify patients with Spetzler-Martin Grade I and II AVMs treated using resection during a 16-year period.

RESULTS

Of the 232 surgical patients included, 120 (52%) presented with hemorrhage, 33% had Spetzler-Martin Grade I, and 67% had Grade II AVMs. Overall, 99 patients (43%) underwent preoperative embolization, with unruptured AVMs embolized more often than ruptured AVMs. AVM resection was accomplished in all patients and confirmed angiographically in 218 patients (94%). There were no deaths among patients with unruptured AVMs. Good outcomes (modified Rankin Scale [mRS] score 0-1) were found in 78% of patients, with 97% improved or unchanged from their preoperative mRS scores. Patients with unruptured AVMs had better functional outcomes (91% good outcome vs 65% in the ruptured group, p = 0.0008), while relative outcomes were equivalent (98% improved/unchanged in patients with ruptured AVMs vs 96% in patients with unruptured AVMs).

CONCLUSIONS

Surgery should be regarded as the "gold standard" therapy for the majority of low-grade AVMs, utilizing conservative embolization as a preoperative adjunct. High surgical cure rates and excellent functional outcomes in patients with both ruptured and unruptured AVMs support a dominant surgical posture for low-grade AVMS, with radiosurgery reserved for risky AVMs in deep, inaccessible, and highly eloquent locations. Despite the technological advances in endovascular and radiosurgical therapy, surgery still offers the best cure rate, lowest risk profile, and greatest protection against hemorrhage for low-grade AVMs. ARUBA results are influenced by a low randomization rate, bias toward nonsurgical therapies, a shortage of surgical expertise, a lower rate of complete AVM obliteration, a higher rate of delayed hemorrhage, and short study duration. Another randomized trial is needed to reestablish the role of surgery in unruptured AVM management.

Clinical aspects, management and outcome of brain arteriovenous malformations – results with microsurgery first policy

We performed a retrospective study, including patients operated for brain AVMs between 1999 and 2014, in the Clinic of Neurosurgery, Emergency Clinical Hospital Bagdasar-Arseni, Bucharest. 277 patients underwent surgery for brain AVMs. Mean age was 29.82 years. 195 patients (70.40%) presented with hemorrhage and 86 cases (31.05%) were admitted with seizures. We performed total resection of AVMs in 228 cases (82.31%) and subtotal resection in 49 cases (17.69%). Regarding patients with residual nidus, 16 of them underwent second surgery, 27 stereotactic radiosurgery Gamma Knife, 3 embolization and 3 refused further treatment. Modified Rankin Scale (mRS) improved following surgery (Z = -9.248, p = 0.000). Early complications (0-30 days) were encountered in 84 patients (30.32%). We found the following risk factors for postoperative complications occurrence: motor deficit (p = 0.006), co-morbidities (p = 0.023), higher mRS (p = 0.005), lower Karnofsky score (p = 0.003), lower GCS (p = 0.016), profound nidus (p = 0.001), eloquent aria (p = 0.000), large nidus (p = 0.000), multiple arterial territory (p = 0.000), deep feeding arteries (p = 0.000), higher number of feeding arteries (p = 0.000), deep venous drainage (p = 0.000), multiple draining veins (p = 0.000), higher Spetzler- Martin grade (p = 0.006), high flow (p = 0.000), vascular steel (p = 0.000), associated aneurysms (p = 0.010) and decompressive craniectomy (p = 0.019). Mortality was 6.1%. Microsurgery is the treatment of choice for brain AVMs. Surgical results are excellent, with low morbidity and mortality. Patients with poor surgical results belonged to the group admitted with severe altered general state, state of consciousness, massive hematomas and acute brainstem dysfunction. If part of the nidus cannot be safely surgical resected, stereotactic radiosurgery can provide definitive cure of the lesion.

Functional MRI-guided microsurgery of intracranial arteriovenous malformations: study protocol for a randomised controlled trial

INTRODUCTION

Intracranial arteriovenous malformations (AVMs) are associated with high morbidity and mortality. Modern microsurgery has improved the results of surgical treatment of AVMs; however, the treatment of AVMs, particularly eloquently located AVMs, still carries a high risk. Functional MRI (fMRI) has been reported to be used for the preoperative evaluation of AVMs in small case series. The purpose is to identify the utility and efficacy of fMRI-guided microsurgery of AVMs in a large randomised controlled trial.

METHODS AND ANALYSIS

The study is a prospective, randomised controlled clinical trial. This study will enrol a total of 600 eligible patients. These eligible patients will be randomised to the standard microsurgery group and the fMRI-guided microsurgery group in a 1:1 ratio. Patient baseline characteristics and AVM architecture and characteristics will be described. In the fMRI-guided group, fMRI mapping of an eloquent cortex in all AVMs will be identified. Surgical complications and outcomes at pretreatment, post-treatment, at discharge and at 1-month, 3-month and 6-month follow-up intervals will be analysed using the modified Rankin Scale (mRS). This trial will determine whether fMRI-guided microsurgery could improve outcomes in patients with AVMs and also identify the safety and efficacy of fMRI-guided microsurgery.

ETHICS AND DISSEMINATION

The study protocol and written informed consent were reviewed and approved by the Institutional Review Board of Beijing Tiantan Hospital Affiliated to Capital Medical University (ky2012-016-02). Study findings will be disseminated in the printed media.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov NCT01758211.

Surgery for unruptured arteriovenous malformations of the brain is better than conservative management for selected cases: a prospective cohort study

Object

The aim of this study was to identify patients who are likely to benefit from surgery for unruptured brain arteriovenous malformations (ubAVMs).

Methods

The authors' database was interrogated for the risk and outcome of hemorrhage after referral and the outcome from surgery. Furthermore, the outcome from surgery incorporated those cases excluded from surgery because of perceived greater risk (sensitivity analysis). Finally, a comparison was made for the authors' patients between the natural history and surgery. Data were collected for 427 consecutively enrolled patients with ubAVMs in a database that included patients who were conservatively managed. Kaplan-Meier analysis was performed on patients observed for more than 1 day to determine the risk of hemorrhage. Variables that may influence the risk of first hemorrhage were assessed using Cox proportional hazard regression models and Kaplan-Meier life table analyses from referral until the first occurrence of the following: hemorrhage, treatment, or last review. The outcome from surgery (leading to a new permanent neurological deficit with last review modified Rankin Scale [mRS] score > 1) was determined. Further sensitivity analysis was made to predict risk from surgery for the total ubAVM cohort by incorporating outcomes of surgical cases as well as cases excluded from surgery because of perceived risk, and assuming an adverse outcome for these excluded cases.

Results

A total of 377 patients with a ubAVM were included in the analysis of the risk of hemorrhage. The 5-year risk of hemorrhage for ubAVM was 11.5%. Hemorrhage resulted in an mRS score > 1 in 14 cases (88% [95% CI 63%–98%]). Patients with Spetzler-Ponce Class A ubAVMs treated by surgery (n = 190) had a risk from surgery of 1.6% (95% CI 0.3%–4.8%) for a permanent neurological deficit leading to an mRS score > 1 and 0.5% (95% CI < 0.1%–3.2%) for a permanent neurological deficit leading to an mRS score > 2. Patients with Spetzler-Ponce Class B ubAVMs treated by surgery (n = 107) had a risk from surgery of 14.0% (95% CI 8.6%–22.0%) for a permanent neurological deficit leading to an mRS score > 1. Sensitivity analysis of Spetzler-Ponce Class B ubAVMs, including those in patients excluded from surgery, showed that the true risk for surgically eligible patients may have been as high as 15.6% (95% CI 9.9%–23.7%) for mRS score > 1, had all patients who were perceived to have a greater risk experienced an adverse outcome. Patients with Spetzler-Ponce Class C ubAVMs treated by surgery (n = 44) had a risk from surgery of 38.6% (95% CI 25.7%–53.4%) for a permanent neurological deficit leading to an mRS score > 1. Sensitivity analysis of Class C ubAVMs, including those harbored by patients excluded from surgery, showed that the true risk for surgically eligible patients may have been as high as 60.9% (95% CI 49.2%–71.5%) for mRS score > 1, had all patients who were perceived to have a greater risk experienced an adverse outcome.

Conclusions

Surgical outcomes for Spetzler-Ponce Class A ubAVMs are better than those for conservative management.

Radiosurgery for primary motor and sensory cortex arteriovenous malformations: outcomes and the effect of eloquent location

BACKGROUND

Eloquent intracranial arteriovenous malformations (AVMs) located in the primary motor or somatosensory cortex (PMSC) carry a high risk of microsurgical morbidity.

OBJECTIVE

To evaluate the outcomes of radiosurgery on PMSC AVMs and compare them with radiosurgery outcomes in a matched cohort of noneloquent lobar AVMs.

METHODS

Between 1989 and 2009, 134 patients with PMSC AVMs underwent Gamma Knife radiosurgery with a median radiographic and clinical follow-up of 64 and 80 months, respectively. Seizure (40.3%) and hemorrhage (28.4%) were the most common presenting symptoms. Pre-radiosurgery embolization was performed in 33.6% of AVMs. Median AVM volume was 4.1 mL (range, 0.1-22.6 mL), and prescription dose was 20 Gy (range, 7-30 Gy). Cox regression analysis was performed to identify factors associated with obliteration.

RESULTS

The overall obliteration rate, including magnetic resonance imaging and angiography, after radiosurgery was 63%. Obliteration was achieved in 80% of AVMs with a volume less than 3 mL compared with 55% for AVMs larger than 3 mL. No previous embolization (P = .002) and a single draining vein (P = .001) were independent predictors of obliteration on multivariate analysis. The annual post-radiosurgery hemorrhage risk was 2.5%. Radiosurgery-related morbidity was temporary and permanent in 14% and 6% of patients, respectively. Comparing PMSC AVMs with matched noneloquent lobar AVMs, the obliteration rates and clinical outcomes after radiosurgery were not statistically different.

CONCLUSION

For patients harboring PMSC AVMs, radiosurgery offers a reasonable chance of obliteration with a relatively low complication rate. Eloquent location does not appear to confer the same negative prognostic value for radiosurgery that it does for microsurgery.

Multimodality treatment of cerebral arteriovenous malformations

BACKGROUND

Many arteriovenous malformations (AVMs) can be treated with one modality, but with increasing complexity a combination of techniques, including surgical excision, embolization, and radiosurgery, may be beneficial. The 2 senior authors' experience in the multimodal management of AVMs from 1980-2008 is reported, including the results in all patients with rehemorrhage while awaiting treatment or after partial initial treatment has begun. The series contains a disproportionately high number of Spetzler-Martin grade IV and V lesions, owing to the nature of the referral practice.

METHODS

Data were collected prospectively. Only patients who were managed until treatment options were exhausted were included; this entailed either treatment to the point of AVM obliteration or inability to treat further using any or all modalities. Patients who presented with intracranial hemorrhage (ICH) in extremis in whom the AVM was excised during the first operation were also included.

RESULTS

Of the 290 patients, 265 underwent treatment, and 25 were managed conservatively. An unruptured AVM was present in 48% of patients. Cure was achieved in 233 (88%) of treated patients. Cure was achieved in 25 of 37 patients undergoing radiosurgery only, 56 of 57 undergoing surgery, 100 of 101 undergoing embolization and microsurgical excision, 20 of 34 undergoing embolization alone, 12 of 17 undergoing embolization and radiosurgery, 5 of 5 undergoing surgery and radiosurgery, and 14 of 14 patients undergoing all 3 modalities. Spetzler-Martin grade was found to correlate negatively with cure (P < 0.001). There was a good outcome in 210 patients (72%), moderate disability in 40 patients (14%), severe disability in 22 patients (8%), vegetative state in 1 patient, and 17 patients (6%) died. There was a favorable outcome (no or only moderate deficits) in 93% of patients with Spetzler-Martin grade I-III lesions. The outcome was favorable in 13 of 25 patients (52%) having no treatment, 32 of 37 (86%) having radiosurgery only, 30 of 34 (88%) having embolization only, 54 of 57 (95%) having surgery only, 87 of 101 (86%) having embolization and surgery, 16 of 17 (94%) having embolization and radiosurgery, 5 of 5 (100%) having surgery and radiosurgery, and 13 of 14 (93%) having all 3 modalities. These outcomes included morbidity from initial presenting symptoms, from treatment, and from rehemorrhage. Good recovery was more likely in patients who were treated with surgery as one of the treatments (P = .025). Considering only new deficits related to treatment, 9 patients (3%) incurred severe neurologic deficits, 11 patents died after treatment, 2 patients died of postoperative hematomas, and 6 died of rehemorrhage from residual AVM. Increasing age, Spetzler-Martin grade, and rehemorrhage were correlated with a poorer Glasgow Outcome Scale score (P < 0.05).

CONCLUSIONS

These data suggest a higher risk of hemorrhage after partial obliteration of AVM. One should ascertain an acceptably high likelihood of complete obliteration before embarking on treatment. Using a multimodality approach, the authors were able to cure 92% of treated Spetzler-Martin grade I-IV lesions but only 53% of treated Spetzler-Martin grade V lesions. A major neurologic deficit, disabling to the patient, was incurred in 3% of cases, and 11 patients died.

Treatment for brain arteriovenous malformation in the 1998-2011 period and review of the literature

PURPOSE

The results of the treatment of pial AVM provided at our neurosurgical centre are presented. Based on these results and on an overview of literary data on the efficacy and complications of each therapeutic modality, the algorithm of indications, as used at our institution, is presented. COHORT OF PATIENTS: The series comprises 195 patients, aged 9 to 87 years and treated in the years 1998-2011. The surgical group consists of 76 patients; of these, 49 patients solely received endovascular treatment, 25 were consulted and referred directly to the radiosurgical unit, and the remaining 45 were recommended to abide by the strategy of "watch and wait".

RESULTS

In the surgical group, serious complications were 3.9 %, at a 96.1 % therapeutic efficacy. As for AVM treated with purely endovascular methods, serious procedural complications were seen in 4.1 % of patients, with efficacy totalling 32.7 %. One observed patient suffered bleeding, resulting in death. For comparison with literary data for each modality, a survival analysis without haemorrhage following monotherapy for AVM with each particular modality was carried out.

CONCLUSIONS

Based on our analysis, we have devised the following algorithm of treatment: 1. We regard surgical treatment as the treatment of choice for AVM of Spetzler-Martin (S-M) grades I and II, and only for those grade III cases that are surgically accessible. 2. Endovascular intervention should mainly be used for preoperative embolisation, as a curative procedure for lower-grade AVM in patients with comorbidities, and as palliation only for higher-grade cases. 3. Stereotactic irradiation with Leksell Gamma Knife (LGK) is advisable, mainly for poorly accessible, deep-seated grade-III AV malformations. In the case of lower grades, the final decision is left to the properly informed patient. 4. Observation should be used as the method of choice in AVM of grades IV and V, where active therapy carries greater risk than the natural course of the disease.

Surgical treatment of cranial arteriovenous malformations and dural arteriovenous fistulas

Microsurgical resection remains the treatment of choice for more than half of all patients with arteriovenous malformations (AVMs). It reduces the treatment window to a span of a few weeks and is curative. Careful patient selection, meticulous surgical planning, and painstaking technical execution of surgery are typically rewarded with excellent outcomes. For dural arteriovenous fistulas (DAVFs), microsurgical obliteration is often reserved for cases in which endovascular therapy either cannot be pursued or fails. When performed, however, microsurgical obliteration of DAVFs is associated with excellent outcomes as well. This article reviews the current state of microsurgical treatment of AVMs and DAVFs.

Bleeding source identification and treatment in brain arteriovenous malformations

Arteriovenous malformation (AVM) patients who initially present with intracerebral haemorrhage may have an identifiable source of bleeding on angiogram, which can be a treatment target. Previous work suggests that the re-bleed rate may be lowered if a weak area is eliminated.A retrospective cohort study was conducted on patients who presented over a six-year period with a bled AVM. Cases were reviewed looking for the source of the hemorrhage by correlating haematoma location on CT or MRI and any angio-architectural weakness seen on digital subtraction angiography (DSA). Neuroendovascular notes were reviewed to identify the treatment targets. One hundred patients presented with a brain AVM with a 1.7:1 male: female ratio, 41 patients had an initial presentation of hemorrhage. The source of hemorrhage was identified in 18 subjects with 11 intranidal false aneurysms, five flow-related aneurysms, two associated aneurysms and one venous pouch. The location of haemorrhage on the presenting scan significantly correlated with the identified bleeding source using Chi-square analysis (P-value 0.039). Partial targeted embolization was used successfully in 90% with a 9% related technical complication rate not resulting in long-term morbidity or mortality. The mean follow-up period was 34 months with an annual hemorrhage rate of 0.7%. In just under half the patients with AVM bleeding a source of haemorrhage can be identified on DSA and in most cases this will be an intranidal false aneurysm. Flow-related and associated aneurysms in patients with brain AVM can cause haemorrhage and these patients are more likely to have SAH than intracerebral haemorrhage.These weak points are a good target for partial endovascular treatment, are usually accessible and may reduce the higher haemorrhage rate expected over the next two years.

Language and motor mapping during resection of brain arteriovenous malformations: indications, feasibility, and utility

BACKGROUND

Microsurgical resection of arteriovenous malformations (AVMs) located in the language and motor cortex is associated with the risk of neurological deterioration, yet electrocortical stimulation mapping has not been widely used.

OBJECTIVE

To demonstrate the usefulness of intraoperative mapping with language/motor AVMs.

METHODS

During an 11-year period, mapping was used in 12 of 431 patients (2.8%) undergoing AVM resection (5 patients with language and 7 patients with motor AVMs). Language mapping was performed under awake anesthesia and motor mapping under general anesthesia.

RESULTS

Identification of a functional cortex enabled its preservation in 11 patients (92%), guided dissection through overlying sulci down to the nidus in 3 patients (25%), and influenced the extent of resection in 4 patients (33%). Eight patients (67%) had complete resections. Four patients (33%) had incomplete resections, with circumferentially dissected and subtotally disconnected AVMs left in situ, attached to areas of eloquence and with preserved venous drainage. All were subsequently treated with radiosurgery. At follow-up, 6 patients recovered completely, 3 patients were neurologically improved, and 3 patients had new neurological deficits.

CONCLUSION

Indications for intraoperative mapping include preoperative functional imaging that identifies the language/motor cortex adjacent to the AVM; larger AVMs with higher Spetzler-Martin grades; and patients presenting with unruptured AVMs without deficits. Mapping identified the functional cortex, promoted careful tissue handling, and preserved function. Mapping may guide dissection to AVMs beneath the cortical surface, and it may impact the decision to resect the AVM completely. More conservative, subtotal circumdissections followed by radiosurgery may be an alternative to observation or radiosurgery alone in patients with larger language/motor cortex AVMs.

A 3-tier classification of cerebral arteriovenous malformations

Object

The authors propose a 3-tier classification for cerebral arteriovenous malformations (AVMs). The classification is based on the original 5-tier Spetzler-Martin grading system, and reflects the treatment paradigm for these lesions. The implications of this modification in the literature are explored.

Methods

Class A combines Grades I and II AVMs, Class B are Grade III AVMs, and Class C combines Grades IV and V AVMs. Recommended management is surgery for Class A AVMs, multimodality treatment for Class B, and observation for Class C, with exceptions to the latter including recurrent hemorrhages and progressive neurological deficits. To evaluate whether combining grades is warranted from the perspective of surgical outcomes, the 3-tier system was applied to 1476 patients from 7 surgical series in which results were stratified according to Spetzler-Martin grades.

Results

Pairwise comparisons of individual Spetzler-Martin grades in the series analyzed showed the fewest significant differences (p < 0.05) in outcomes between Grades I and II AVMs and between Grades IV and V AVMs. In the pooled data analysis, significant differences in outcomes were found between all grades except IV and V (p = 0.38), and the lowest relative risks were found between Grades I and II (1.066) and between Grades IV and V (1.095). Using the pooled data, the predictive accuracies for surgical outcomes of the 5-tier and 3-tier systems were equivalent (receiver operating characteristic curve area 0.711 and 0.713, respectively).

Conclusions

Combining Grades I and II AVMs and combining Grades IV and V AVMs is justified in part because the differences in surgical results between these respective pairs are small. The proposed 3-tier classification of AVMs offers simplification of the Spetzler-Martin system, provides a guide to treatment, and is predictive of outcome. The revised classification not only simplifies treatment recommendations; by placing patients into 3 as opposed to 5 groups, statistical power is markedly increased for series comparisons.

[Unruptured brain arteriovenous malformations]

Cerebral arteriovenous malformations (AVMs) often become symptomatic in young adults with a variety of neurological symptoms such as epileptic seizures, recurrent headaches, progressive neurological deficits or sudden intracranial hemorrhage. However, recent epidemiological data suggest a large number of AVMs are found without signs of hemorrhage and a relatively low rupture risk of less than 1% per year. Continuous technical progress has led to several specific treatment options for brain AVMs including endovascular embolization, microneurosurgery, and stereotactic radiotherapy, either alone or in any combination. Depending on AVM topography and vascular anatomy, interventional treatment strategies have shown successful occlusion rates ranging between 50 and 100% and a relatively low average procedural morbidity of 10% overall. For unruptured brain AVMs, however, the clinical benefit of invasive treatment remains as yet to be determined. To address this issue, A randomized trial of unruptured brain AVMs (ARUBA) is currently underway evaluating long-term outcome of best possible standard interventional therapy as compared to the natural history risk in a prospective multidisciplinary international study (www.arubastudy.org).

Surgical options in ICH including decompressive craniectomy

Intracerebral haemorrhage (ICH) accounts for 15 to 20% of strokes. The condition carries a higher morbidity and mortality than occlusive stroke. Despite considerable research effort, no therapeutic modality either medical or surgical has emerged with clear evidence of benefit other than in rare aneurysmal cases. Intracerebral haemorrhages can be divided into those that arise from pre-existing macroscopic vascular lesions - so called "ictohaemorrhagic lesions", and those that do not; the latter being the commoner. Most of the research that has been done on the benefits of surgery has been in this latter group. Trial data available to date precludes a major benefit from surgical evacuation in a large proportion of cases however there are hypotheses of benefit still under investigation, specifically superficial lobar ICH treated by open surgical evacuation, deeper ICH treated with minimally invasive surgical techniques, and decompressive craniectomy. When an ICH arises from an ictohaemorrhagic lesion, therapy has two goals: to treat the effects of the acute haemorrhage and to prevent a recurrence. Three modalities are available for treating lesions to prevent recurrence: stereotactic radiosurgery, endovascular embolisation, and open surgical resection. As with ICH without an underlying lesion there is no evidence to support surgical removal of the haemorrhage in most cases. An important exception is ICHs arising from intracranial aneurysms where there is good evidence to support evacuation of the haematoma as well as repair of the aneurysm.

Endovascular treatment of intracranial arteriovenous malformations with onyx: technical aspects

BACKGROUND AND PURPOSE

We report our experiences in the treatment of intracranial arteriovenous malformations (AVMs) with Onyx embolization before neuro- or radiosurgery, focusing on the embolization technique with Onyx.

METHODS

Ninety-three patients (40 women and 53 men, mean age 38 years) with 94 intracranial AVMs with a mean volume of 9.2 mL were embolized with Onyx. The following features of all AVMs were evaluated before the treatment: type of nidus and shunt, draining veins, and feeding arteries.

RESULTS

Complete obliteration rates were 20% at the end of all embolization steps and 53% after embolization and surgery. In 21% of patients the final control angiography is not yet available (after surgery 9%, after radiosurgery 12%). In 4% of patients, radiosurgery was planned due to a persistent arteriovenous shunt. The injection of Onyx resulted in high occlusion rates (volume reduction >90%) when the AVM was in a supratentorial and cortical location, the nidus was compact and plexiform, and when there was a small number of supplying (direct) feeders and one superficial draining vein. Access device-related complications (stuck catheter, vessel perforation) occurred during the embolization of 220 feeding arteries in 6% of patients, with all such instances having had no clinical consequences.

CONCLUSION

With knowledge of the morphologic characteristics of AVMs that are suitable for a treatment with Onyx, high occlusion rates and low complication rates in treating a small number of feeders are feasible. Superselective intranidal or perinidal catheter positions and slow, controlled injections that protect the draining veins make the therapy safe even in complex AVMs and critical locations.

Neurologie des malformations artérioveineuses cérébrales

INTRODUCTION

Brain arteriovenous malformations (AVMs) constitute a neurovascular disorder that comes to clinical attention mainly in young adults in their mid thirties. Associated symptoms often require neurological treatment for symptomatic seizures (focal or generalized), headaches (episodic or chronic), progressive neurological deficits, or spontaneous AVM rupture leading to intracerebral, intraventricular, and/or subarachnoid hemorrhage.

STATE OF ART

Little data exist in the medical literature regarding the natural history risk of the disease and no controlled studies are available on the risk of invasive AVM treatment (endovascular, neurosurgery, radiotherapy).

PERSPECTIVES

This review focuses on all aspects of neurological brain AVM management and discusses possible predictors of the natural history risk as well as the benefit and risk of invasive treatment.

CONCLUSIONS

AVM patient management is ideally based on a trans-disciplinary approach via a neurovascular team of neurologists, neuroradiologists, neurosurgeons, and radiotherapists. A newly diagnosed AVM does not necessarily represent an a priori indication for interventional treatment. The decision in favor or against therapy mainly depends on clinical criteria (ruptured versus unruptured AVM, neurological exam, patient age and co-morbidity, etc.) and the angioarchitecture of the malformation. The ARUBA study is going to be the first randomized clinical trial comparing the risk of invasive treatment versus non-invasive management.