Advances in the radiosurgical treatment of large inoperable arteriovenous malformations

2007 ◽  
Vol 23 (6) ◽  
pp. E6 ◽  
Author(s):  
Jesse Jones ◽  
Sunyoung Jang ◽  
Christopher C. Getch ◽  
Alan G. Kepka ◽  
Maryanne H. Marymont
Keyword(s):  
Arteriovenous Malformations ◽  
Latency Period ◽  
Peripheral Dose ◽  
Target Delineation ◽  
Dose Volume ◽  
Dose Planning ◽  
Target Volumes ◽  
Risk Of Hemorrhage ◽  
Higher Doses

✓ Radiosurgery has proven useful in the treatment of small arteriovenous malformations (AVMs) of the brain. However, the volume of healthy tissue irradiated around large lesions is rather significant, necessitating reduced radiation doses to avoid complications. As a consequence, this can produce poorer obliteration rates. Several strategies have been developed in the past decade to circumvent dose–volume problems with large AVMs, including repeated treatments as well as dose, and volume fractionation schemes. Although success on par with that achieved in lesions smaller than 3 ml remains elusive, improvements over the obliteration rate, the complication rate or both have been reported after conventional single-dose stereotactic radiosurgery (SRS). Radiosurgery with a marginal dose or peripheral dose < 15 Gy rarely obliterates AVMs, yet most lesions diminish in size posttreatment. Higher doses may then be reapplied to any residual nidi after an appropriate follow-up period. Volume fractionation divides AVMs into smaller segments to be treated on separate occasions. Doses > 15 Gy irradiate target volumes of only 5–15 ml, thereby minimizing the radiation delivered to the surrounding brain tissue. Fewer adverse radiological effects with the use of fractionated radiosurgery over standard radiosurgery have been reported. Advances in AVM localization, dose delivery, and dosimetry have revived interest in hypofractionated SRS. Investigators dispensing ≥ 7 Gy per fraction minimum doses have achieved occlusion with an acceptable number of complications in 53–70% of patients. The extended latency period between treatment and occlusion, about 5 years for emerging techniques (such as salvage, staged volume, and hypofractionated radiotherapy), exposes the patient to the risk of hemorrhage during that period. Nevertheless, improvements in dose planning and target delineation will continue to improve the prognosis in patients harboring inoperable AVMs.

Radiosurgical treatment for rolandic arteriovenous malformations

2006 ◽  
Vol 105 (5) ◽  
pp. 689-697 ◽  
Author(s):  
Yuri M. Andrade-Souza ◽  
Meera Ramani ◽  
Daryl Scora ◽  
May N. Tsao ◽  
Karel terBrugge ◽  
...  
Keyword(s):  
Arteriovenous Malformations ◽  
Latency Period ◽  
Obliteration Rate ◽  
University Of Toronto ◽  
First Choice ◽  
Study Population ◽  
Radiation Induced ◽  
Risk Of Hemorrhage ◽  
The University

Object The authors reviewed the radiosurgical outcomes in patients with arteriovenous malformations (AVMs) located in the rolandic area, including the primary motor and sensory gyri. Methods The study population consisted of 38 patients with rolandic-area AVMs who underwent linear accelerator radiosurgery at the University of Toronto between 1989 and 2000. Obliteration rate, risk of hemorrhage during the latency period, radiation-induced complications, seizure control, and functional status were evaluated. Patients were also divided into two subgroups according to AVM volume (< 3 cm3 and ≥ 3 cm3). Patients were followed up for a median of 42.4 months (range 30–103 months), and the median age of the patients was 40 years (range 12–67 years). The median AVM volume was 8.1 cm3 (range 0.32–21, mean 8.32 cm3), and the median dose at the tumor margin was 15 Gy (range 15–22, mean 16.8 Gy). The risk of hemorrhage after radiosurgery was 5.3% for the 1st year, 2.6% for the 2nd, and 0% for the 3rd. Two patients (5.3%) sustained adverse effects related to radiation for more than 6 months. Complete nidus obliteration after a single radiosurgical treatment was achieved in 23 patients (60.5%). The obliteration rate for AVMs smaller than 3 cm3 was 83.3% (10 of 12) and that for AVMs larger than or equal to 3 cm3 was 50% (13 of 26). Among the patients who had seizures as the initial presentation, 51.8% were free of seizures after radiosurgery and the seizure pattern improved in 40.7% during the 3rd and last year of follow up. Overall, excellent results (obliteration and no new or worsening neurological deficit) can be achieved in approximately 60% of patients. This percentage varies according to the AVM size and can reach 83% in patients with AVMs smaller than 3 cm3. Conclusions Radiosurgery is a safe and effective treatment for people with rolandic AVMs. The low rate of morbidity associated with radiosurgery, compared with other treatments, indicates that this method may be the first choice for patients with AVMs located in this area.

Subtotal obliteration of cerebral arteriovenous malformations after Gamma Knife surgery

2007 ◽  
Vol 106 (3) ◽  
pp. 361-369 ◽  
Author(s):  
Chun Po Yen ◽  
Peter Varady ◽  
Jason Sheehan ◽  
Melita Steiner ◽  
Ladislau Steiner
Keyword(s):  
Gamma Knife ◽  
Arteriovenous Malformations ◽  
Gamma Knife Surgery ◽  
Cerebral Arteriovenous Malformations ◽  
Peripheral Dose ◽  
Risk Of Bleeding ◽  
The Mean ◽  
Risk Of Hemorrhage ◽  
Early Filling

Object Subtotal obliteration of cerebral arteriovenous malformations (AVMs) after Gamma Knife surgery (GKS) implies a complete angiographic disappearance of the AVM nidus but persistence of an early filling draining vein, indicating that residual shunting is still present; hence, per definition there is still a patent AVM and the risk of bleeding is not eliminated. The aim of this study was to determine the risk of hemorrhage for patients with subtotal obliteration of AVMs. Methods After GKS for cerebral AVMs, follow-up angiography demonstrated a subtotally obliterated lesion in 159 patients. Of these, in 16 patients a subtotally obliterated AVM developed after a second GKS was performed for the partially obliterated lesion. The mean age of these patients was 35.2 years at the time of the diagnosis of subtotally obliterated AVMs. The lesion volumes at the time of initial GKS treatment ranged from 0.1 to 11.5 cm3 (mean 2.5 cm3). The mean peripheral dose used in the 175 GKS treatments was 22.5 Gy (median 23 Gy, range 15–31 Gy). To achieve total obliteration of the AVM, 23 patients underwent a new GKS targeting the proximal end of the early filling vein. The mean peripheral dose given in these cases was 23 Gy (median 24, range 18–25 Gy). The incidence of subtotally obliterated AVMs was 7.6% from a total of 2093 AVMs treated and in which follow-up imaging was available. The diagnosis of subtotally obliterated AVMs was made a mean of 29.4 months (range 4–178 months) after GKS. The number of patient-years at risk (from the time of the diagnosis of subtotally obliterated AVMs until either the confirmation of a total obliteration of the lesion on angiography or the time of the latest follow-up angio-graphic study that still visualized the early filling vein) was a mean of 3.9 years, ranging from 0.5 to 13.5 years, and a total of 601 patient-years. There was no case of bleeding after the diagnosis of subtotally obliterated AVMs. Of 90 patients who did not undergo further treatment and in whom follow-up angiography studies were available, the same early filling veins still filled in 24 (26.7%), and the subtotally obliterated AVMs were subsequently obliterated in 66 patients (73.3%). In 19 patients who underwent repeated GKS for subtotally obliterated AVMs and in whom follow-up angiography studies were available, the AVMs were obliterated in 15 (78.9%) and remained patent in four (21.1%). Conclusions The fact that none of the patients with subtotally obliterated AVMs suffered a rupture is not compatible with the assumption of an unchanged risk of hemorrhage for these lesions, and implies that the protection from re-bleeding in patients with subtotal obliteration is significant. Subtotal obliteration does not necessarily seem to be a stage of an ongoing obliteration. At least in some cases it represents an end point of this process, with no subsequent obliteration occurring. This observation requires further confirmation by open-ended follow-up imaging.

scholarly journals The long-term outcomes of radiosurgery for arteriovenous malformations in pediatric and adolescent populations

2015 ◽  
Vol 16 (2) ◽  
pp. 222-231 ◽  
Author(s):  
Shunya Hanakita ◽  
Tomoyuki Koga ◽  
Masahiro Shin ◽  
Hiroshi Igaki ◽  
Nobuhito Saito
Keyword(s):  
Adverse Events ◽  
Arteriovenous Malformations ◽  
Therapeutic Option ◽  
Long Term Outcomes ◽  
Bleeding Rate ◽  
Study Institute ◽  
Delayed Complications ◽  
Risk Of Hemorrhage

OBJECT Although stereotactic radiosurgery (SRS) has been accepted as a therapeutic option for arteriovenous malformations (AVMs) in children and adolescents, substantial data are still lacking regarding the outcomes of SRS for AVMs in this age group, especially long-term complications. This study aimed to clarify the long-term outcomes of SRS for the treatment of AVM in pediatric patients aged ≤ 18 years. METHODS Outcomes of 116 patients who were aged 4–18 years when they underwent SRS between 1990 and 2009 at the study institute were analyzed retrospectively. RESULTS The median follow-up period after SRS was 100 months, with 6 patients followed up for more than 20 years. Actuarial obliteration rates at 3 and 5 years after SRS were 68% and 88%, respectively. Five hemorrhages occurred in 851 patient-years of follow-up. The annual bleeding rate after SRS before obliteration was calculated as 1.3%, which decreased to 0.2% after obliteration. Shorter maximum nidus diameter (p = 0.02) and higher margin dose (p = 0.03) were associated with a higher obliteration rate. Ten patients experienced adverse events after SRS. Of them, 4 patients presented with delayed complications years after SRS (range 9–20 years after SRS). CONCLUSIONS SRS can reduce the risk of hemorrhage in pediatric and adolescent AVMs, with an acceptable risk of complications in the long term. However, adverse events such as expanding hematoma and radiation necrosis that can occur after substantial follow-up should be taken into account at the time that treatment decisions are made and informed consent is obtained.

scholarly journals Gamma Knife surgery for incidental cerebral arteriovenous malformations

2014 ◽  
Vol 121 (5) ◽  
pp. 1015-1021 ◽  
Author(s):  
Chun-Po Yen ◽  
Dale Ding ◽  
Ching-Hsiao Cheng ◽  
Robert M. Starke ◽  
Mark Shaffrey ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Arteriovenous Malformations ◽  
Latency Period ◽  
Invasive Procedure ◽  
Gamma Knife Surgery ◽  
Neurological Deficits ◽  
Cerebral Arteriovenous Malformations ◽  
Long Term Follow Up

Object A relatively benign natural course of unruptured cerebral arteriovenous malformations (AVMs) has recently been recognized, and the decision to treat incidentally found AVMs has been questioned. This study aims to evaluate the long-term imaging and clinical outcomes of patients with asymptomatic, incidentally discovered AVMs treated with Gamma Knife surgery (GKS). Methods Thirty-one patients, each with an incidentally diagnosed AVM, underwent GKS between 1989 and 2009. The nidus volumes ranged from 0.3 to 11.1 cm3 (median 3.2 cm3). A margin dose between 15 and 26 Gy (median 20 Gy) was used to treat the AVMs. Four patients underwent repeat GKS for still-patent AVM residuals after the initial GKS procedure. Clinical follow-up ranged from 24 to 196 months, with a mean of 78 months (median 51 months) after the initial GKS. Results Following GKS, 19 patients (61.3%) had a total AVM obliteration on angiography. In 7 patients (22.6%), no flow voids were observed on MRI but angiographic confirmation was not available. In 5 patients (16.1%), the AVMs remained patent. A small nidus volume was significantly associated with increased AVM obliteration rate. Thirteen patients (41.9%) developed radiation-induced imaging changes: 11 were asymptomatic (35.5%), 1 had only headache (3.2%), and 1 developed seizure and neurological deficits (3.2%). Two patients each had 1 hemorrhage during the latency period (116.5 risk years), yielding an annual hemorrhage rate of 1.7% before AVM obliteration. Conclusions The decision to treat asymptomatic AVMs, and if so, which treatment approach to use, remain the subject of debate. GKS as a minimally invasive procedure appears to achieve a reasonable outcome with low procedure-related morbidity. In those patients with incidental AVMs, the benefits as well as the risks of radiosurgical intervention will only be fully defined with long-term follow-up.

Brain arteriovenous malformations

Neurology ◽  
2020 ◽  
Vol 95 (20) ◽  
pp. 917-927 ◽  
Author(s):  
Ching-Jen Chen ◽  
Dale Ding ◽  
Colin P. Derdeyn ◽  
Giuseppe Lanzino ◽  
Robert M. Friedlander ◽  
...  
Keyword(s):  
Natural History ◽  
Minimally Invasive ◽  
Arteriovenous Malformations ◽  
Cerebral Arteries ◽  
Treatment Strategies ◽  
Latency Period ◽  
Management Options ◽  
Brain Arteriovenous Malformations ◽  
Risk Of Hemorrhage ◽  
Brain Avms

Brain arteriovenous malformations (AVMs) are anomalous direct shunts between cerebral arteries and veins that convalesce into a vascular nidus. The treatment strategies for AVMs are challenging and variable. Intracranial hemorrhage and seizures comprise the most common presentations of AVMs. However, incidental AVMs are being diagnosed with increasing frequency due to widespread use of noninvasive neuroimaging. The balance between the estimated cumulative lifetime hemorrhage risk vs the risk of intervention is often the major determinant for treatment. Current management options include surgical resection, embolization, stereotactic radiosurgery (SRS), and observation. Complete nidal obliteration is the goal of AVM intervention. The risks and benefits of interventions vary and can be used in a combinatorial fashion. Resection of the AVM nidus affords high rates of immediate obliteration, but it is invasive and carries a moderate risk of neurologic morbidity. AVM embolization is minimally invasive, but cure can only be achieved in a minority of lesions. SRS is also minimally invasive and has little immediate morbidity, but AVM obliteration occurs in a delayed fashion, so the patient remains at risk of hemorrhage during the latency period. Whether obliteration can be achieved in unruptured AVMs with a lower risk of stroke or death compared with the natural history of AVMs remains controversial. Over the past 5 years, multicenter prospective and retrospective studies describing AVM natural history and treatment outcomes have been published. This review provides a contemporary and comprehensive discussion of the natural history, pathobiology, and interventions for brain AVMs.

Multimodality treatment of posterior fossa arteriovenous malformations

2008 ◽  
Vol 108 (6) ◽  
pp. 1152-1161 ◽  
Author(s):  
Michael E. Kelly ◽  
Raphael Guzman ◽  
John Sinclair ◽  
Teresa E. Bell-Stephens ◽  
Regina Bower ◽  
...  
Keyword(s):  
Posterior Fossa ◽  
Arteriovenous Malformations ◽  
Multimodality Treatment ◽  
Neurological Complications ◽  
Cure Rate ◽  
Complete Obliteration ◽  
The Mean ◽  
Risk Of Hemorrhage ◽  
Negative Predictor

Object Posterior fossa arteriovenous malformations (AVMs) are relatively uncommon and often difficult to treat. The authors present their experience with multimodality treatment of 76 posterior fossa AVMs, with an emphasis on Spetzler–Martin Grades III–V AVMs. Methods Seventy-six patients with posterior fossa AVMs treated with radiosurgery, surgery, and endovascular techniques were analyzed. Results Between 1982 and 2006, 36 patients with cerebellar AVMs, 33 with brainstem AVMs, and 7 with combined cerebellar–brainstem AVMs were treated. Natural history data were calculated for all 76 patients. The risk of hemorrhage from presentation until initial treatment was 8.4% per year, and it was 9.6% per year after treatment and before obliteration. Forty-eight patients had Grades III–V AVMs with a mean follow-up of 4.8 years (range 0.1–18.4 years, median 3.1 years). Fifty-two percent of patients with Grades III–V AVMs had complete obliteration at the last follow-up visit. Three (21.4%) of 14 patients were cured with a single radiosurgery treatment, and 4 (28.6%) of 14 with 1 or 2 radiosurgery treatments. Twenty-one (61.8%) of 34 patients were cured with multimodality treatment. The mean Glasgow Outcome Scale (GOS) score after treatment was 3.8. Multivariate analysis performed in the 48 patients with Grades III–V AVMs showed radiosurgery alone to be a negative predictor of cure (p = 0.0047). Radiosurgery treatment alone was not a positive predictor of excellent clinical outcome (GOS Score 5; p > 0.05). Nine (18.8%) of 48 patients had major neurological complications related to treatment. Conclusions Single-treatment radiosurgery has a low cure rate for posterior fossa Spetzler–Martin Grades III–V AVMs. Multimodality therapy nearly tripled this cure rate, with an acceptable risk of complications and excellent or good clinical outcomes in 81% of patients. Radiosurgery alone should be used for intrinsic brainstem AVMs, and multimodality treatment should be considered for all other posterior fossa AVMs.

RADIOSURGERY TO REDUCE THE RISK OF FIRST HEMORRHAGE FROM BRAIN ARTERIOVENOUS MALFORMATIONS

Neurosurgery ◽  
2007 ◽  
Vol 60 (3) ◽  
pp. 453-459 ◽  
Author(s):  
Keisuke Maruyama ◽  
Masahiro Shin ◽  
Masao Tago ◽  
Junji Kishimoto ◽  
Akio Morita ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Stereotactic Radiosurgery ◽  
Arteriovenous Malformations ◽  
Gamma Knife Radiosurgery ◽  
Latency Period ◽  
Hazard Ratio ◽  
Cox Proportional Hazards Model ◽  
Brain Arteriovenous Malformations ◽  
Risk Of Hemorrhage ◽  
Observation Period

Abstract OBJECTIVE It remains unclear whether or not and to what extent stereotactic radiosurgery can reduce the risk of first intracranial hemorrhage from brain arteriovenous malformations. METHODS We performed a retrospective observational investigation of 500 patients with arteriovenous malformations who were treated with gamma knife radiosurgery. The risk of first hemorrhage was analyzed using the Cox proportional-hazards model with age at radiosurgery and angiographic obliteration included as time-dependent covariates. Three periods were defined: from birth to radiosurgery (before radiosurgery); from radiosurgery to angiographic obliteration (latency period); and from angiographic obliteration to end of the follow-up period (after obliteration). RESULTS Hemorrhage was documented before radiosurgery in 318 patients (median observation period, 30.0 yr), during the latency period in 11 patients (median observation period, 2.2 yr), and after obliteration in two patients (median observation period, 5.5 yr). Compared with the period before radiosurgery, the risk of hemorrhage decreased by 86% after obliteration (hazard ratio, 0.14; 95% confidence interval, 0.03–0.55; P = 0.005), whereas the reduction observed during the latency period was not statistically significant (hazard ratio, 0.56; 95% confidence interval, 0.31–1.04; P = 0.07). Irrespective of obliteration, the risk of hemorrhage decreased by 62% after radiosurgery (hazard ratio, 0.38; 95% confidence interval, 0.22–0.67; P = 0.001). Similar results were observed when the 33 patients who had undergone previous therapy were excluded from the analysis. CONCLUSION Stereotactic radiosurgery significantly reduces the risk of first hemorrhage from brain arteriovenous malformations. The extent of the decrease might be greater if angiography indicates the evidence of obliteration.

Associated Aneurysms in Pediatric Arteriovenous Malformations and the Implications for Treatment

Neurosurgery ◽  
2011 ◽  
Vol 69 (2) ◽  
pp. 315-322 ◽  
Author(s):  
Caitlin Hoffman ◽  
Howard A. Riina ◽  
Philip Stieg ◽  
Baxter Allen ◽  
Y. Pierre Gobin ◽  
...  
Keyword(s):  
Early Diagnosis ◽  
Clinical Outcome ◽  
Current Literature ◽  
Treatment Strategy ◽  
Arteriovenous Malformations ◽  
Treatment Method ◽  
Time To Treatment ◽  
Risk Of Hemorrhage ◽  
Over Time

Abstract BACKGROUND: Arteriovenous malformations (AVM) with associated aneurysms (AA) increase the risk of hemorrhage in adults. Associated aneurysms are thought to develop over time, and the incidence in children, therefore, has been thought to be minimal, although this has not yet been studied. OBJECTIVE: To define the incidence and morbidity of AA in children and to assess the results of our treatment strategy. METHODS: Patients younger than 18 years of age with pial AVM seen from 2000 to 2009 were reviewed. Demographics, presentation, hemorrhage, AAs, treatment method, and outcome were analyzed. RESULTS: Of 144 patients with AVM, 30 were younger than 18 years of age. AA was identified in 5 of 30 children (16.7%) and 33 of 114 adults (28.9%; P = .25). Mean age at presentation in children was 11.67 years (range, 6 months to 17 years), and mean follow-up was 28.8 months (range, 1-75 months). Hemorrhage at presentation was seen in 80% of patients with AA and 72% with AVM alone. Emergent therapy was required in 60% of patients with AA and 40% with AVM alone (P = .63). Time to treatment was 4.3 days with AA and 27.3 days without (P = .42). There was no difference in outcome between patients with AA and those with AVM alone. CONCLUSION: The incidence of pediatric AA was higher in our series than projected in the current literature. Time to treatment was shorter in children with AA compared with those with AVM alone, although there was no difference in clinical outcome. Although hemorrhage rates were similar, emergent therapy was required more often in patients with AA. Our findings support the need for early diagnosis and treatment of associated aneurysms in children.

scholarly journals Cyst formation after stereotactic radiosurgery for brain arteriovenous malformations: a systematic review

2018 ◽  
Vol 128 (5) ◽  
pp. 1354-1363 ◽  
Author(s):  
Adeel Ilyas ◽  
Ching-Jen Chen ◽  
Dale Ding ◽  
Panagiotis Mastorakos ◽  
Davis G. Taylor ◽  
...  
Keyword(s):  
Systematic Review ◽  
Stereotactic Radiosurgery ◽  
Arteriovenous Malformations ◽  
Time Course ◽  
Surgical Intervention ◽  
Latency Period ◽  
Cyst Formation ◽  
Brain Arteriovenous Malformations ◽  
The Mean

OBJECTIVECyst formation can occasionally occur after stereotactic radiosurgery (SRS) for brain arteriovenous malformations (AVMs). Given the limited data regarding post-SRS cyst formation in patients with AVM, the time course, natural history, and management of this delayed complication are poorly defined. The aim of this systematic review was to determine the incidence, time course, and optimal management of cyst formation after SRS for AVMs.METHODSA literature review was performed using PubMed to identify studies reporting cyst formation in AVM patients treated with SRS. Baseline and outcomes data, including the incidence and management of post-SRS cysts, were extracted from each study that reported follow-up duration. The mean time to cyst formation was calculated from the subset of studies that reported individual patient data.RESULTSBased on pooled data from 22 studies comprising the incidence analysis, the overall rate of post-SRS cyst formation was 3.0% (78/2619 patients). Among the 26 post-SRS cyst patients with available AVM obliteration data, nidal obliteration was achieved in 20 (76.9%). Of the 64 cyst patients with available symptomatology and management data, 21 (32.8%) were symptomatic; 21 cysts (32.8%) were treated with surgical intervention, whereas the remaining 43 (67.2%) were managed conservatively. Based on a subset of 19 studies reporting individual time-to-cyst-formation data from 63 patients, the mean latency period to post-SRS cyst formation was 78 months (6.5 years).CONCLUSIONSCyst formation is an uncommon complication after SRS for AVMs, with a relatively long latency period. The majority of post-SRS cysts are asymptomatic and can be managed conservatively, although enlarging or symptomatic cysts may require surgical intervention. Long-term follow-up of AVM patients is crucial to the appropriate diagnosis and management of post-SRS cysts.

Novalis Shaped Beam Radiosurgery of arteriovenous malformations

2004 ◽  
pp. 425-434
Author(s):  
Alessandra G. Pedroso ◽  
Antonio A. F. De Salles ◽  
Katayoun Tajik ◽  
Raymond Golish ◽  
Zachary Smith ◽  
...  
Keyword(s):  
Arteriovenous Malformations ◽  
Peripheral Dose ◽  
Content Type ◽  
Obliteration Rate ◽  
Shaped Beam ◽  
Martin Grade ◽  
The Mean ◽  
Per Se ◽  
Fine Print

Object. The authors studied outcomes and complications in patients who harbored arteriovenous malformations (AVMs) and underwent stereotactic radiosurgery involving the Novalis shaped beam unit. Methods. Between January 1998 and January 2002, 83 patients were treated with radiosurgery at University of California, Los Angeles. The mean patient age was 37.8 years. Forty-four patients completed follow up. There were 24 women. Sixteen patients underwent repeated radiosurgery. Embolization was performed in 13 patients and radiosurgery alone in 31. The mean follow-up period after embolization was 54.4 ± 21.9 months and 37.4 ± 14.6 months for radiosurgery alone. The mean peripheral dose was 15 Gy (range 12–18 Gy). The mean preradiosurgery lesion volume was 9.7 ± 11.9 ml for radiosurgery alone and 16.2 ± 11.3 ml for embolization. The AVMs in 13 patients (29.8%) were Spetzler—Martin Grade II, 12 (27.5%) were Grade III, eight (18.2%) Grade IV, and five (11.3%) were Grade V and VI each. Spetzler—Martin grade, volume, and peripheral dose were analyzed in consideration to outcome. A positive trend (p = 0.086) was observed between Spetzler—Martin grade and obliteration rate. Volume per se did not predict obliteration (p = 0.48). A peripheral dose of 18 Gy was shown to be the most important predictor for occlusion (p = 0.007). The overall obliteration rate was 52.5%. A transient complication was noticed in one case (2.3%) and but no permanent deficits due to radiosurgery have been detected so far. Three patients (6.8%) bled after radiosurgery. Conclusions. The range of the prescribed peripheral dose was narrow. An association between the mean peripheral dose of 15 Gy, high conformality, and homogeneous dose distribution permitted no permanent complications. Volume per se did not correlate with outcome. The next step will be to increase the peripheral dose shaping the beam and to achieve higher obliteration rates without increasing complications.

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