Grade Arteriovenous Malformations Research Articles

IV and V grade arteriovenous Malformations: A multicenter surgical experience. Use of multiple grading system to predict surgical risk

ObjectiveThe aim of our study is to report a multicenter experience in the treatment of IV and V grade arteriovenous malformations (AVMs) and to apply commonly used grading scales for surgical risk assessment for these vascular high-grade lesions. MethodsBetween January 2015 and December 2019, a retrospective study was conducted to identify patients undergoing microsurgical intervention for cAVMs at two Italian centers specialized in the treatment of vascular pathologies. Data on patients with Spetzler-Martin IV and V and with a score equal or more than 7 according to Lawton-Young classification were collected. Ruptured AVMs at admission were subsequently classified according to the new proposed AVICH classification. ResultsA total of 20 patients with high grade (IV and V) cAVMs were enrolled in the study and the average follow-up was 36.45 months. The outcome based on mRS was favorable in 65 % of cases. The pre-operative mRS was a factor influencing clinical outcome, as well as the number of bleedings preceding the treatment, age, and nidus characteristics. S-M IV, L-Y 3 and S-M supp 7 scores were associated with good outcome. Based on the AVICH classification, for ruptured cAVMs, having a score of 9 ore less was correlated to a postoperative mRS fewer or equal than 2. ConclusionsSurgical management for high-grade AVMs should be considered in highly selected patients with repeated bleeding or disabling symptoms. Classification systems provide an aid in selecting patients for surgery, also in grade IV and V. It is essential to establish common registers for the management of these complex vascular malformations.

Intermediate Grade Arteriovenous Malformations

Catapano, Joshua MD; Frisoli, Fabio MD; Nguyen, Candice BS, RN; Labib, Mohamed MD; Cole, Tyler S MD; Baranoski, Jacob F MD, BS; Whiting, Alex MD; Farber, Samuel H MD; Fredrickson, Vance; Lang, Michael J MD; Kim, Helen MPH, PhD; Spetzler, Robert F MD; Lawton, Michael T MD Author Information

Abstract TMP118: Clinical Outcomes of Surgical Resection After Stereotactic Radiosurgery Among Patients With Cerebral Arteriovenous Malformations

Introduction: Surgical treatment of arteriovenous malformations (AVMs), particularly higher grade lesions, can be aided by staged treatment consisting of stereotactic radiosurgery (SRS) followed by surgical resection in a delayed fashion. This strategy can be used to downgrade the AVM S-M grade, reduce blood flow through the AVM and often results in histopathological changes making AVMs more amenable to microsurgical resection. We present our 28-year clinical experience in managing AVMs with pre-operative SRS as a surgical adjunct. Methods: We retrospectively reviewed and analyzed records of all patients treated for cerebral AVMs between February 1991 and July 2019 at our institution. All patients that underwent SRS, with and without embolization, followed by microsurgery were included in the study. Of the 1245 cerebral AVM patients treated at our institution, 62 patients met eligibility criteria. Univariate and multivariate regression analysis was performed where appropriate to examine relationships between key variables and outcomes. Results: The majority of lesions (50%) were high grade (SM 4-5), 28.6% were intermediate (SM 3), while 21.4% were low grade (SM 1-2). Hemorrhage was the presenting sign among 22.6% of patients. Complete resection was achieved among 64.5%, 79% and 82% of patients after first, second and third surgical stages respectively; 16.1% of patients had partial resection requiring further treatment. Radiographic cure was achieved among 53 patients (85.5%), while 8 (12.9%) patients had residual AVM at last follow up. Six of 8 patients without radiographic cure received post-operative SRS. Thirty-seven patients (63.8%) had improved (26, 44.8%) or stable mRS scores (11, 19%), while 21 (36.2%) had a decline in mRS at final follow up compared to mRS at presentation; this includes 4 (6.9%) deaths due to hemorrhage, outside of the perioperative period, but occurring during follow up prior to AVM obliteration. Conclusion: SRS is a useful adjunct in the surgical management of cerebral AVMs. Multimodal therapy allowed for high obliteration rates with acceptable morbidity in this series of patients with predominantly high grade AVMs.

Combined (microsurgical and endovascular) treatment of cerebral arteriovenous malformations

Objective – to analyze the results of combined microsurgical and endovascular treatment of brain arteriovenous malformations (AVM).Materials and methods. Radiological and clinical data of 19 patients who underwent preoperative endovascular embolization and resection of the AVM at the SO «Scientific-practical Center of endovascular neuroradiology NAMS of Ukraine» in 2014–2019 were analyzed. Among patients were 11 (57.9 %) women and 8 (42.1 %) men. The average age of patient was 28.4 year (from 15 to 54 years). All AVMs were I–III grade according to the Spetzler–Martin scale.Results. The average AVM size in its maximum dimension was 3.2 cm (range 3.1–6.8 cm). 14 (73.7 %) AVMs were supratentorial and 5 (26.3 %) – subtentorial, in 9 (47.4 %) cases AVMs were located in eloquent areas of the brain, in 1 (5.3 %) – in the motor area. Cerebral or subarachnoid hemorrhage were observed in 12 (63.2 %) cases, seizures – in 4 (21.1 %), headache not associated with bleeding – in 2 (10.5 %) and neurological deficiency not related to the bleeding – in 1 (3.7 %). In 16 (84.2 %) patients total AVM resection was achieved, 3 (15.8 %) patients underwent subtotal resection. Fourteen (73.7 %) patients had good results at discharge (10 (52.6 %) patients had 0 or 1 according to modified Rankin score, and 4 (21.1%) patients had 2), 5 (26.3 %) – 3 and 4. There were no mortality cases after combined endovascular and microsurgical treatment. Onset of new neurological deficits occurred in 5 (26.3 %) patients, and in 3 (15.8 %) cases it regress at discharge and in 2 (10.5 %) cases was permanent.Conclusions. Combined treatment (endovascular embolization and microsurgical resection) of AVMs of the low grade AVM (I–III grade of the Spetzler–Martin scale) allows achieving good treatment results. The use of preoperative endovascular embolization reduces blood flow through the AVM and prevents postoperative hemodynamic overload, intraoperative and/or postoperative bleeding.

Basic research and surgical techniques for brain arteriovenous malformations.

Arteriovenous malformations (AVMs) are hemorrhagic vascular diseases in which arteries and veins are directly connected with no capillary bed between the two. We herein introduce the results of basic research of this disease and surgical techniques based on our data and experiences. The results obtained from our research show that cell death- and inflammation-related molecules changed or became activated compared with control specimens. These findings indicate that chronic inflammation occurs in and around the nidus of AVMs. Various molecules are involved in the mechanisms of cell death and angiogenesis during this process. Confirmation of blood flow in the nidus is very important to avoid hemorrhagic complications during surgical removal of the nidus. The risk of hemorrhage increases when the blood flow in the nidus is not reduced. We reported the advantages of serial indocyanine green videoangiography, which is used to assess the blood flow during AVM nidus removal. Since publication of the ARUBA trial and Scottish Audit, treatments with high morbidity have not been allowed. It is especially important for neurosurgeons to treat low Spetzler-Martin grade AVMs with low morbidity. J. Med. Invest. 67 : 222-228, August, 2020.

Long-Term Outcomes for Pediatric Patients with Brain Arteriovenous Malformations Treated with Gamma Knife Radiosurgery, Part 1: Analysis of Nidus Obliteration Rates and Related Factors

Little is known about long-term outcomes for pediatric brain arteriovenous malformations (AVMs) treated with Gamma Knife radiosurgery (GKRS). This study investigated annual hemorrhage rates and nidus obliteration rates, and the factors affecting them, in pediatric AVMs treated with GKRS. We examined 189 pediatric AVM patients (age ≤15 years) who underwent GKRS and had at least 12 months of follow-up. The Spetzler-Martin (S-M) grade was I in 29 patients (15%), II in 57 (30%), III in 82 (43%), IV in 16 (9%), and V in 5 (3%). The median treatment volume was 2.2 cm3, and the median marginal dose was 20 Gy. The mean follow-up period was 136 months. During a cumulative latency period to nidus obliteration of 813 years, 23 hemorrhages occurred, resulting in an annual post-GKRS hemorrhage rate of 2.8%. The cumulative hemorrhage rates after GKRS were 3.3%, 8.5%, and 11.9% at 3, 5, and 10 years, respectively. Higher S-M grade was significantly associated with intracranial hemorrhages during the latency period (P < 0.001). The actuarial nidus obliteration rates with repeated GKRS were 64% and 81% at 5 and 10 years, respectively. Absence of pre-GKRS embolization (P= 0.023) and higher marginal dose (P= 0.029) were significant factors predicting nidus obliteration. GKRS is a reasonable treatment option in pediatric AVMs to prevent future hemorrhages. Because higher S-M grade AVMs are more likely to hemorrhage during the latency period, a combined therapy with endovascular embolization should be considered to prevent AVM rupture.

Safety and outcome of combined endovascular and surgical management of low grade cerebral arteriovenous malformations in children compared to surgery alone

PurposeTo evaluate the outcomes of combined preoperative embolization and microsurgical resection in comparison with microsurgical resection alone as the current standard of care for low-grade cerebral arteriovenous malformations (AVM) in the pediatric population. Materials & methodsWe performed a single-center retrospective study of pediatric patients presenting with Spetzler-Martin (SM) grade I and II cerebral AVMs at a high-volume tertiary pediatric hospital between January 2005 and September 2016. Low grade AVM patients were divided into two groups: pre-operative embolization with subsequent microsurgical resection or microsurgical resection alone. Patient demographics, clinical and imaging presentations, AVM morphological characteristics, post-operative complications, and mid to long-term clinical outcomes were studied. Post-embolization and post-surgical outcomes were assessed prior to and after treatment, at 3 months and at final follow-up using the modified Rankin Scale (mRS) to compare both final independent (mRS 0–2) and favorable (no change or improved mRS) clinical outcomes for comparison between study groups. Statistical associations of patient demographics, AVM characteristics/SM grading, and treatment modality group with post-operative complications were performed using univariate logistic regression analysis. ResultsThirty-four patients with low grade cerebral AVMs met the study inclusion criteria (mean age 10.6 ± 3.4 years; range 3–16 years, 22M:12 F). Twenty patients (59%) presented with ruptured AVMs. Twenty-five patients (73.5%) underwent combined treatment with embolization and microsurgical resection, while 9/34 (26.5%) underwent microsurgical resection alone. A total of 35 embolization procedures performed in 25 patients (Mode, 1; Range, 1–7) were associated with two minor post-embolization and 7 subsequent post-surgical (28%) complications, resulting in clinical deterioration in a single patient. Microsurgical resection alone was associated with 3 post-surgical complications (33%), resulting in permanent neurological disability in a single patient. There was no significance association of post-operative complications with either treatment modality group, combined treatment versus surgical resection alone [OR:1.13; 95% CI:0.23–5.62; p-value 0.88]. SM Grade II and eloquent locations were found to be significantly associated with post-surgical complications of low grade pediatric cerebral AVMs [OR 13.2 and OR 8 respectively, p-value 0.004 and 0.005). On mean follow-up time of 35.7 months, final clinical outcome was favorable in the majority of both treatment arms with no dependent (mRS>2) patients in the combined endovascular and surgical cohort. Two patients in the surgical cohort failed to achieve independent functional status, primarily due to a pre-operative morbid status (p-value 0.015). However, there was no significant difference in favorable outcomes between the treatment groups [p-value 0.14]. ConclusionOur study suggests equivalent safety and favorable clinical outcomes related to combined endovascular embolization and microsurgical resection of low grade pediatric cerebral AVMs in comparison to microsurgical resection alone. On long term clinical follow-up, the vast majority of patients achieved an independent and favorable functional status irrespective of pre-operative embolization.

Grades of brain arteriovenous malformations and risk of hemorrhage and death.

ObjectiveTo assess the relationship of the grade of unruptured and untreated Brain Arteriovenous Malformations (AVMs), with the risk of subsequent stroke and death during follow‐up.MethodsThis prospective study was drawn from a cohort of adult patients with unruptured AVMs, who participated in the conservative treatment arm (medical management only for headache or seizures) of the randomized clinical trial of unruptured brain AVMs (ARUBA study). The grade of AVMs (Spetzler–Martin scale) was dichotomized into categories: AVMs of grades I and II were considered low grade; AVMs of grades III and IV were considered high grade. There were no grade V AVM patients in ARUBA. The primary outcome was symptomatic stroke (hemorrhagic or ischemic – documented by imaging) or death.ResultsThe conservative treatment group had 123 patients (“as treated” analysis). 71 (57.7%) had lesions characterized for this analysis as low‐grade lesions and 52 (42.2%) as high grade. From the total of 10 (8.13%) primary outcomes, three occurred (4.22%) in low‐grade AVMs and seven (13.46%) in high‐grade AVMs (P = 0.0942).InterpretationStatistical analysis of the cohort of patients with unruptured and untreated AVMs from ARUBA study showed that the graduation categories (Spetzler–Martin grades) were not associated with the outcome of subsequent stroke or death.

Transvenous Curative Embolization of Cerebral Arteriovenous Malformations: A Prospective Cohort Study.

Curative transvenous embolization is an emerging strategy for treatment of cerebral arteriovenous malformations (AVMs). To assess contemporary outcomes of transvenous embolization as a stand-alone therapy for cerebral AVMs. We prospectively followed 40 patients with 41 AVMs who underwent transvenous endovascular therapy between January 2008 and January 2015. Patient demographics, AVM characteristics, endovascular techniques used, angiographic results, clinical outcomes, and complications were assessed independently. Thirty-eight of 41 (92.6%) AVMs were anatomically cured. The mean patient age was 37.7 yr (range, 18-69 yr) and 55% were female. Twenty-seven (67.5%) patients presented with hemorrhage. The mean size of the AVM nidus was 2.8±1.2 cm, and low Spetzler-Martin grade AVMs comprised 41.5% of lesions. The majority of patients were treated in 1 session (56%; n=23). The mean follow-up period was 28.4 (range, 6-106 mo). There was 1 (2.5%) hemorrhagic complication related to microcatheter navigation and 1 (2.5%) venous infarction was observed without clinical consequences. At 6-mo follow-up, 1 (2.5%) patient had significant disability. There were no recurrences during the follow-up period. Overall mortality was 2.5% and procedure-related mortality was 0%. This prospective contemporary series demonstrates a high rate of complete AVM obliteration and excellent functional outcomes in patients with both ruptured and unruptured AVMs treated with transvenous embolization. This approach is promising and warrants further investigation as a treatment for select AVMs.

104 Stereotactic Radiosurgery for Spetzler-Martin Grade IV and V Arteriovenous Malformations

Abstract INTRODUCTION Due to the complexity of Spetzler-Martin (SM) grade IV-V arteriovenous malformations (AVM), the management of these lesions remains controversial. The aims of this multicenter, retrospective study are to evaluate outcomes after single-session stereotactic radiosurgery (SRS) for SM grade IV-V AVMs and determine predictive factors. METHODS We pooled data from 233 patients (mean age 33 years) with SM grade IV (94.4%) or V AVMs (5.6%) treated with single-session SRS at eight participating centers in the International Gamma Knife Research Foundation. Pre-SRS embolization was performed in 71 AVMs (30.5%). The mean nidus volume, SRS margin dose, and follow-up duration were 9.7 cc, 17.3 Gy, and 84.5 months, respectively. RESULTS &gt;At a mean follow-up interval of 84.5 months, favorable outcome was defined as AVM obliteration, no post-SRS hemorrhage, and no permanently symptomatic radiation-induced changes (RIC) and was achieved in 26.2% of patients. The actuarial obliteration rates at 3, 7, 10, and 12 years were 15%, 34%, 37% and 42%, respectively. The annual post-SRS hemorrhage rate was 3.0%. Symptomatic and permanent RIC occurred in 10.7% and 4% of the patients, respectively. Only larger AVM diameter (P = 0.04) found to be an independent predictor of unfavorable outcome in the multivariate logistic regression analysis. The rate of favorable outcome was significantly lower for unruptured SM grade IV-V AVMs compared to ruptured ones (P = 0.042). Prior embolization was a negative independent predictor of AVM obliteration (P = 0.024) and radiologically evident RIC (P = 0.05) in multivariate analyses. CONCLUSION In this multi-institutional study, single session SRS had limited efficacy in the management of SM grade IV-V AVMs Favorable outcome was only achieved in a minority of unruptured SM grade IV-V AVMs, which supports less frequent utilization of SRS for the management of these lesions. A volume staged SRS approach for large AVMs represents an alternative approach for high grade AVM’s, but it requires further investigation.

Impact on cognitive functions following gamma knife radiosurgery for cerebral arteriovenous malformations.

Background:Radiosurgery is an alternative to surgical resection of arteriovenous malformation (AVM). Very few studies have addressed the concern of radiation injury to the brain and its attendant adverse effects on cognitive function.Materials and Methods:This prospective study included all patients who underwent gamma knife radiosurgery (GKRS) at our institute for cerebral AVM between 2006 and December 2008 (n = 34). All patients underwent neuropsychological evaluation before the procedure. Neuropsychological evaluation was repeated in eighteen patients 2 years following GKRS. Clinical outcome, AVM obliteration, and factors influencing outcome were analyzed in these eighteen patients.Results:Before GKRS, more than 50% had significant impairment of neuropsychological functions compared to normal population norms. 66.6% achieved the excellent radiosurgical outcome. At 2 years follow-up, patients showed varied improvement in neuropsychological function in various categories. Pretherapeutic median value for percentage perseverative responses was 26.5 and at follow-up, it reduced to 18.2 (P = 0.039). Set shifting improved in 11 patients (61.1%), remained same in 5 patients (27.7%), and deteriorated in two patients (11.1%). Patients with a higher Spetzler-Martin grade AVM demonstrated a significantly more favorable shift in follow-up test values for set shifting function (P = 0.021). Patients with postradiation imaging changes had lesser tendency to improve in neuropsychological performance at follow-up.Conclusions:GKRS has no clinically harmful effect on cognitive and neuropsychological functioning in patients with brain AVM. On the contrary, there is an improvement in majority of patients at 2 years following radiosurgery when nidus is obliterated.

Long-Term Follow-Up of Adaptive Multistage Stereotactic Radiosurgery for Treatment of High-Grade Arteriovenous Malformations

The optimal management of high-grade arteriovenous malformations (AVM) remains unclear. There is a paucity of literature addressing the efficacy and safety of radiosurgery for high risk patients. Our institution has adopted a multi-staged stereotactic radiosurgery (SRS) approach with treatment of the entire nidus using a lower dose per stage to achieve AVM obliteration with decreased complications. Retrospective review of patients with high grade Spetzler-Martin (S-M) III-V AVMs with at least two multi-stage SRS treatments between 1989 and 2013. Clinical outcomes of obliteration rate, adverse events and treatment data were collected. Patients with less than 12 months of follow-up after second multi-stage SRS treatment were excluded. Forty-two patients met inclusion criteria (n = 26, S-M III; n = 13, S-M IV; n = 3, S-M V). Median follow-up was 113.6 months after first SRS. Median number of staged SRS treatments was 2 and median interval between SRS treatment stages was 41.9 months. Median dose was 1400 cGy per stage and cumulative median dose at last follow-up or obliteration was 3350 cGy. 22 patients had prior embolization and 2 patients had subtotal resection before SRS. Complete AVM obliteration rate was 38.1%. AVMs that underwent pre-SRS embolization had a significantly lower rate of obliteration (23% vs 55%, p = 0.03). Median volume reduction for non-obliterated AVMs was 69.4%. A lower complete AVM obliteration rate was significantly associated with a higher S-M grade (p = 0.03). Additionally, AVM volume less than 10 cm3 (p = 0.22), first-stage SRS dose greater than 1400 cGy (p = 0.43) and cumulative SRS dose greater than 3200 cGy (p = 0.57) did not significantly influence the rate of obliteration. In total, 21 post-SRS adverse events occurred in 18 patients. Adverse events were defined as persistent headache (n = 3), new/persistent seizure activity (n = 8), symptomatic radiation necrosis (n = 1), post-SRS intracranial hemorrhage +/- neurologic deficits (n = 8, 4 with residual deficits), and neurologic deficits without antecedent intracranial bleed (n = 1). The post-SRS adverse event rate was 5.1% per year (21 events over 409.9 cumulative patient yrs) after initial SRS. A retrospective review of our experience treating high grade AVMs with adaptive multi-stage SRS to the entire nidus demonstrates that this may be an appropriate option as it results in AVM obliteration in a meaningful proportion of patients with an acceptable adverse event rate. Lower AVM obliteration rates were significantly associated with higher S-M grade and pre-SRS embolization. We continue to investigate whether this strategy may be improved with treatment at shorter intervals or additional treatment sessions over time. In spite of an acceptable toxicity profile, treatment of high grade AVMs should be considered with caution since partial obliteration does not protect from bleeding.

Commentary

Commentary

Microsurgery of Spetzler-Martin Grades III, IV and V Arteriovenous Malformations

Introduction: Brain arteriovenous malformations (AVMs) are congenital complex network of dysplastic vessels and represent challenging neurosurgical pathology. There are many controversies in the literature regarding which is the best treatment for Spetzler-Martin high grade AVMs. Therefore, the authors present their operative experience in thirty-three grade III, IV and V brain AVMs and underline the fundamental role of microsurgery in the treatment of these high-grade AVMs. Material and Method: We retrospectively reviewed medical records of patients with brain AVMs operated from 2009 to 2013 by the same senior neurosurgeon, in “Bagdasar-Arseni” Emergency Clinical Hospital. Results: Fifty patients with brain AVMs underwent surgery. Mean age was 37.58 years, varying from 17 to 73 years. Five patients (10%) had AVMs Spetzler-Martin grade I, 12 patients (24%) grade II, 21 patients (42%) grade III, 7 patients (14%) grade IV and 5 patients (10%) grade V. Forty-three patients (86%) had supratentorial and seven patients (14%) had infratentorial lesions. We included in our study thirty-three grade III, IV and V operated in the Fourth Department of Neurosurgery, Emergency Clinical Hospital Bagdasar-Arseni. The medium age of the patients was 33,6 years. There were 16 men and 17 women. Twenty-four (72,8%) patients presented with ruptured AVM, with various types of intracranial hemorrhage, like: intraparenchymatous hematoma, intraventricular hemorrhage and subarachnoid hemorrhage. There is worth to mention that all posterior fossa arteriovenous malformation presented with hemorrhage at admittance. The rest of the cases, nine cases (27,2%), presented with seizure. The preoperative neurological status of the patients presented with ruptured AVM were worse (medium modified Rankin Score 3,8) compared with patients with unruptured AVM (medium modified Rankin Score 1,6). We performed total resection of AVMs in 29 cases (87,8%). Four patients (12,2%) with arteriovenous malformation located in the eloquent areas of the brain had residual nidus. Patients with residual nidus were referred to stereotactic radiosurgery with good outcome. Twenty-one patients (63,6%) presented increased modified Rankin Score (mRS) following surgery, in 8 cases (24,3%) mRS remained unchanged and 3 patients (9,1%) presented decreased mRS. There was one case of death (3%), a 24 year-old female with a Spetzler-Martin grade V ruptured right temporo-parietal arteriovenous malformation, who presented in emergency with a giant right hemispheric intraparenchimatous hematoma. In that case, the Glasgow Coma Scale at admittance was 5 points and neurological exam revealed acute brainstem dysfunction. Long term follow-up (one year postoperative) showed complete recovery of neurological deficits in all patients with excellent quality of life in 22 patients (66,6%) and good quality of life in 10 cases (30,4%). The seizures remitted completed in 6 patients, while 3 patients required only minimum doses of antiepileptic drugs. The patients who presented with ruptured AVM required after operation only preventive anticonvulsivant therapy for maximum three months.

Long-term Results of Gamma Knife Surgery for Partially Embolized Arteriovenous Malformations

The effectiveness and risk of gamma knife surgery (GKS) in the management of partially embolized cerebral arteriovenous malformations (AVMs) remain to be elucidated. To evaluate the long-term imaging and clinical outcomes of GKS in AVM patients who had undergone previous partial embolization and compare the results with patients treated with GKS alone. A total of 215 embolized AVMs were analyzed. The mean patient age was 32.9 years. The mean volume of the nidus was 4.6 mL (range, 0.1-29.4 mL), and the mean prescription dose was 19.6 Gy (range, 4-28 Gy). This group was compared with 729 nonembolized AVMs. After embolization and GKS, angiographically confirmed total obliteration of the AVMs was significantly lower (33%) compared with patients in whom GKS was used alone (60.9%; P < .001). However, the mean nidus size was larger and the Spetzler-Martin grade was higher for the embolized AVMs compared with the nonembolized AVMs. Radiation-induced changes occurred more often in the embolized (43.4%) than the nonembolized (33.4%) AVMs (P = .028). Permanent neurological deficits associated with radiation-induced changes occurred in 2.7% of the embolized compared with 1.3% of the nonembolized patients (P = .14). In our retrospective and historical series, the long-term results suggest that the obliteration rate is significantly lower in embolized AVMs compared with nonembolized AVMs, also because of the fact that the combined treatment is applied to higher grade AVMs; the percentage of grade III-V AVMs was 58.6% and 48.8% for nonembolized AVMs.

Ｈｉｇｈ ｇｒａｄｅ ＡＶＭの治療―われわれの反省と新たな試み―

Stereotactic radiosurgery (SRS) is widely accepted as the optimum treatment strategy for small arteriovenous malformations (AVMs) of less than 3 cm diameter. However, the treatment of large and high grade AVMs classified as Grades III, IV, and V by the Spetzler-Martin system remains controversial, partly because SRS is not so effective, so many technologies have been developed to assist surgical removal of the nidus. Furthermore, the treatment may be influenced by individual variations caused by the complexity of the drainer-nidus-drainer system and the effects on the natural history of pedicle aneurysms, and deep or superficial, and eloquent or non-eloquent location. We have employed 2 different treatment strategies: intravascular embolization with liquid material to decrease AVM size followed by SRS during 1998-2000; and intravascular embolization to control feeders followed by nidus resection since 2001. Here we analyze the outcomes for patients treated by these protocols. Seven patients were treated by intravascular embolization: 2 patients received only intravascular embolization and 5 patients received intravascular embolization followed by CyberKnife irradiation in 4 patients and gamma knife followed by CyberKnife irradiation because of the poor initial response in 1 patient. One of the 2 patients treated by intravascular embolization had modified Rankin Scale (mRS) of 5, and the other patient died of bleeding from the AVM. Only 2 of the 5 patients treated by intravascular embolization followed by irradiation had complete obliteration of the nidus. Furthermore, the patient who received SRS twice later suffered from radiation necrosis. Nine patients were treated by intravascular embolization followed by surgery. The feeders far from the operative field were also embolized to decrease arteriovenous shunting and intraoperative bleeding, and to shorten the operative time, and the nidus was removed within 1 week to avoid newly formed fragile feeders. The hematoma wall adjacent to the nidus was fully utilized as a part of the dissection plane in patients with bleeding episodes. At the end of the operation, intraoperative angiography was performed to confirm complete resection of the nidus. Pre- and post-operative CBF studies were essential to predict NPPB, and this complication was never experienced in this series. The nidus of all 9 patients was completely removed, but 1 patient developed postoperative cerebellar ataxia. Embolic complication caused by intravascular embolization was observed in only one of the 16 patients in the entire study period. The present study suggests that large and high grade AVMs should not be treated by intravascular embolization to decrease the AVM size followed by SRS. Recently, recanalization of embolized nidus that was located out of the SRS irradiation field has been reported. Therefore, the low obliteration rate of our first strategy may have resulted from the presence of viable but angiographically occult nidus. In contrast, the second strategy achieved a high success rate. This study is limited by the small number of patients and large bias introduced by referral and the fact the patients with bleeding, but the findings indicate that intravascular embolization followed by surgery may be the optimum treatment for large and high grade AVMs. A new grading system for AVMs is needed to assess surgical feasibility based on the character of feeders, history of bleeding, and AVM location.

Surgical Excision of Cerebral Arteriovenous Malformations: Late Results

Abstract A follow-up study of 153 consecutive patients who underwent complete excision of an angiographically visualized intracerebral arteriovenous malformation was conducted. The follow-up period ranged from 0.5 to 10.6 years, with a mean of 3.8 years. The presenting clinical event was hemorrhage in about one-half of the patients and seizure in about one-third. There was a marked tendency for postoperative neurological deficits to improve with time, so that whereas the immediate postoperative rate of serious morbidity was 24.2%, only 7.8% of the patients were found to have serious morbidity at follow-up. An additional 3 patients had died. one of an unrelated carcinoma, making the mortality related to arteriovenous malformation 1.3%. The classification of Spetzler and Martin (43) was used retrospectively; the percentages of Grade I (easiest) through Grade V (most difficult) lesions were 7.8%, 22.9%, 28.8%, 26.8%, and 13.8%, respectively. The early result was well correlated to grade, with good or excellent results in 100%, 94.3%, 88.6%, 61%, and 28.6% of the patients in Grades I through V, respectively. At follow-up, 98.7% of the patients with arteriovenous malformations of Grades I, II, and III were in good or excellent condition. The late morbidity and mortality rates for the patients in Grades IV and V were 12.2% and 38.4%, respectively. Of the patients who did not have seizures before surgery, 8.2% had only one or two seizures during the immediate postoperative period, and 7.1% had late seizures that were well controlled with medication in all. Of the patients who had seizures before surgery, over half were either cured or greatly improved with respect to the seizures. In 32.7% there was no change in the frequency of the seizures, and in 12.7% the seizures were more frequent after surgery. There was no history of either proven or suspected intracranial hemorrhage in any of the patients during the entire follow-up period, which in the aggregate totalled 556.3 years.

Surgical excision of cerebral arteriovenous malformations

A follow-up study of 153 consecutive patients who underwent complete excision of an angiographically visualized intracerebral arteriovenous malformation was conducted. The follow-up period ranged from 0.5 to 10.6 years, with a mean of 3.8 years. The presenting clinical event was hemorrhage in about one-half of the patients and seizure in about one-third. There was a marked tendency for postoperative neurological deficits to improve with time, so that whereas the immediate postoperative rate of serious morbidity was 24.2%, only 7.8% of the patients were found to have serious morbidity at follow-up. An additional 3 patients had died, one of an unrelated carcinoma, making the mortality related to arteriovenous malformation 1.3%. The classification of Spetzler and Martin (43) was used retrospectively; the percentages of Grade I (easiest) through Grade V (most difficult) lesions were 7.8%, 22.9%, 28.8%, 26.8%, and 13.8%, respectively. The early result was well correlated to grade, with good or excellent results in 100%, 94.3%, 88.6%, 61%, and 28.6% of the patients in Grades I through V, respectively. At follow-up, 98.7% of the patients with arteriovenous malformations of Grades I, II, and III were in good or excellent condition. The late morbidity and mortality rates for the patients in Grades IV and V were 12.2% and 38.4%, respectively. Of the patients who did not have seizures before surgery, 8.2% had only one or two seizures during the immediate postoperative period, and 7.1% had late seizures that were well controlled with medication in all. Of the patients who had seizures before surgery, over half were either cured or greatly improved with respect to the seizures.(ABSTRACT TRUNCATED AT 250 WORDS)