Stereotactic radiosurgery for Spetzler-Martin Grade III arteriovenous malformations

2014 ◽  
Vol 120 (4) ◽  
pp. 973-981 ◽  
Author(s):  
Hideyuki Kano ◽  
John C. Flickinger ◽  
Huai-che Yang ◽  
Thomas J. Flannery ◽  
Daniel Tonetti ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Arteriovenous Malformations ◽  
Radiation Effects ◽  
Target Volume ◽  
Safe Management ◽  
Cumulative Rate ◽  
Hemorrhage Risk ◽  
Martin Grade ◽  
Latency Interval ◽  
Grade Iii

Object The purpose of this study was to define the outcomes and risks of stereotactic radiosurgery (SRS) for Spetzler-Martin (SM) Grade III arteriovenous malformations (AVMs). Methods Between 1987 and 2009, SRS was performed in 474 patients with SM Grade III AVMs. The AVMs were categorized by scoring the size (S), drainage (D), and location (L): IIIa was a small AVM (S1D1L1, N = 282); IIIb was a medium/deep AVM (S2D1L0, N = 44); and IIIc was a medium/eloquent AVM (S2D0L1, N = 148). The median target volume was 3.8 ml (range 0.1–26.3 ml) and the margin dose was 20 Gy (range 13–25 Gy). Eighty-one patients (17%) underwent prior embolization, and 58 (12%) underwent prior resection. Results At a mean follow-up of 89 months, the total obliteration rates documented by angiography or MRI for all SM Grade III AVMs increased from 48% at 3 years to 69% at 4 years, 72% at 5 years, and 77% at 10 years. The SM Grade IIIa AVMs were more likely to obliterate than other subgroups. The cumulative rate of hemorrhage was 2.3% at 1 year, 4.4% at 2 years, 5.5% at 3 years, 6.4% at 5 years, and 9% at 10 years. The SM Grade IIIb AVMs had a significantly higher cumulative rate of hemorrhage. Symptomatic adverse radiation effects were detected in 6%. Conclusions Treatment with SRS was an effective and relatively safe management option for SM Grade III AVMs. Although patients with residual AVMs remained at risk for hemorrhage during the latency interval, the cumulative 10-year 9% hemorrhage risk in this series may represent a significant reduction compared with the expected natural history.

Stereotactic radiosurgery for arteriovenous malformations, Part 1: management of Spetzler-Martin Grade I and II arteriovenous malformations

2012 ◽  
Vol 116 (1) ◽  
pp. 11-20 ◽  
Author(s):  
Hideyuki Kano ◽  
L. Dade Lunsford ◽  
John C. Flickinger ◽  
Huai-che Yang ◽  
Thomas J. Flannery ◽  
...  
Keyword(s):  
Mr Imaging ◽  
Stereotactic Radiosurgery ◽  
Arteriovenous Malformations ◽  
Radiation Effects ◽  
Bleeding Event ◽  
Latency Period ◽  
Bleeding Risk ◽  
Target Volume ◽  
Maximum Diameter ◽  
Martin Grade

Object The aim of this paper was to define the outcomes and risks of stereotactic radiosurgery (SRS) for Spetzler-Martin Grade I and II arteriovenous malformations (AVMs). Methods Between 1987 and 2006, the authors performed Gamma Knife surgery in 996 patients with brain AVMs, including 217 patients with AVMs classified as Spetzler-Martin Grade I or II. The median maximum diameter and target volumes were 1.9 cm (range 0.5–3.8 cm) and 2.3 cm3 (range 0.1–14.1 cm3), respectively. The median margin dose was 22 Gy (range 15–27 Gy). Results Arteriovenous malformation obliteration was confirmed by MR imaging in 148 patients and by angiography in 100 patients with a median follow-up of 64 months (range 6–247 months). The actuarial rates of total obliteration determined by angiography or MR imaging after 1 SRS procedure were 58%, 87%, 90%, and 93% at 3, 4, 5, and 10 years, respectively. The median time to complete MR imaging–determined obliteration was 30 months. Factors associated with higher AVM obliteration rates were smaller AVM target volume, smaller maximum diameter, and greater marginal dose. Thirteen patients (6%) suffered hemorrhages during the latency period, and 6 patients died. Cumulative rates of AVM hemorrhage 1, 2, 3, 5, and 10 years after SRS were 3.7%, 4.2%, 4.2%, 5.0%, and 6.1%, respectively. This corresponded to rates of annual bleeding risk of 3.7%, 0.3%, and 0.2% for Years 0–1, 1–5, and 5–10, respectively, after SRS. The presence of a coexisting aneurysm proximal to the AVM correlated with a significantly higher hemorrhage risk. Temporary symptomatic adverse radiation effects developed in 5 patients (2.3%) after SRS, and 2 patients (1%) developed delayed cysts. Conclusions Stereotactic radiosurgery is a gradually effective and relatively safe option for patients with smaller volume Spetzler-Martin Grade I or II AVMs who decline initial resection. Hemorrhage after obliteration did not occur in this series. Patients remain at risk for a bleeding event during the latency interval until obliteration occurs. Patients with aneurysms and an AVM warrant more aggressive surgical or endovascular treatment to reduce the risk of a hemorrhage in the latency period after SRS.

Stereotactic radiosurgery for arteriovenous malformations of the cerebellum

2014 ◽  
Vol 120 (3) ◽  
pp. 583-590 ◽  
Author(s):  
Greg Bowden ◽  
Hideyuki Kano ◽  
Daniel Tonetti ◽  
Ajay Niranjan ◽  
John Flickinger ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Posterior Fossa ◽  
Arteriovenous Malformations ◽  
Radiation Effects ◽  
Latency Period ◽  
Target Volume ◽  
Outcome Data ◽  
Cerebellar Malformations ◽  
Latency Interval ◽  
Permanent Neurological Deficit

Object Arteriovenous malformations (AVMs) of the posterior fossa have an aggressive natural history and propensity for hemorrhage. Although the cerebellum accounts for the majority of the posterior fossa volume, there is a paucity of stereotactic radiosurgery (SRS) outcome data for AVMs of this region. The authors sought to evaluate the long-term outcomes and risks of cerebellar AVM radiosurgery. Methods This single-institution retrospective analysis reviewed the authors' experience with Gamma Knife surgery during the period 1987–2007. During this time 64 patients (median age 47 years, range 8–75 years) underwent SRS for a cerebellar AVM. Forty-seven patients (73%) presented with an intracranial hemorrhage. The median target volume was 3.85 cm3 (range 0.2–12.5 cm3), and the median marginal dose was 21 Gy (range 15–25 Gy). Results Arteriovenous malformation obliteration was confirmed by MRI or angiography in 40 patients at a median follow-up of 73 months (range 4–255 months). The actuarial rates of total obliteration were 53% at 3 years, 69% at 4 years, and 76% at 5 and 10 years. Elevated obliteration rates were statistically higher in patients who underwent AVM SRS without prior embolization (p = 0.005). A smaller AVM volume was also associated with a higher rate of obliteration (p = 0.03). Four patients (6%) sustained a hemorrhage during the latency period and 3 died. The cumulative rates of AVM hemorrhage after SRS were 6% at 1, 5, and 10 years. This correlated with an overall annual hemorrhage rate of 2.0% during the latency interval. One patient experienced a hemorrhage 9 years after confirmed MRI and angiographic obliteration. A permanent neurological deficit due to adverse radiation effects developed in 1 patient (1.6%) and temporary complications were seen in 2 additional patients (3.1%). Conclusions Stereotactic radiosurgery proved to be most effective for patients with smaller and previously nonembolized cerebellar malformations. Hemorrhage during the latency period occurred at a rate of 2.0% per year until obliteration occurred.

Stereotactic radiosurgery for arteriovenous malformations, Part 5: management of brainstem arteriovenous malformations

2012 ◽  
Vol 116 (1) ◽  
pp. 44-53 ◽  
Author(s):  
Hideyuki Kano ◽  
Douglas Kondziolka ◽  
John C. Flickinger ◽  
Huai-che Yang ◽  
Thomas J. Flannery ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Arteriovenous Malformations ◽  
Radiation Effects ◽  
Latency Period ◽  
Target Volume ◽  
Neurological Deficits ◽  
Latency Interval ◽  
Brain Avms

Object In this paper, the authors' goal was to define the long-term outcomes and risks of stereotactic radiosurgery (SRS) for arteriovenous malformations (AVMs) of the medulla, pons, and midbrain. Methods Between 1987 and 2006, the authors performed Gamma Knife surgery in 996 patients with brain AVMs; 67 patients had AVMs in the brainstem. In this series, 51 patients (76%) had a prior hemorrhage. The median target volume was 1.4 cm3 (range 0.1–13.4 cm3). The median margin dose was 20 Gy (range 14–25.6 Gy). Results Obliteration of the AVMs was eventually documented in 35 patients at a median follow-up of 73 months (range 6–269 months). The actuarial rates of documentation of total obliteration were 41%, 70%, 70%, and 76% at 3, 4, 5, and 10 years, respectively. Higher rates of AVM obliteration were associated only with a higher margin dose. Four patients (6%) suffered a hemorrhage during the latency period, and 2 patients died. The rate of AVM hemorrhage after SRS was 3.0%, 3.0%, and 5.8% at 1, 5, and 10 years, respectively. The overall annual hemorrhage rate was 1.9%. Permanent neurological deficits due to adverse radiation effects (AREs) developed in 7 patients (10%) after SRS, and a delayed cyst developed in 2 patients (3%). One patient died at an outside institution with symptoms of AREs and unrecognized hydrocephalus. Higher 12-Gy volumes and higher Spetzler-Martin grades were associated with a higher risk of symptomatic AREs. Ten of 22 patients who had ocular dysfunction before SRS had improvement, 9 were unchanged, and 3 were worse due to AREs. Eight of 14 patients who had hemiparesis before SRS improved, 5 were unchanged, and 1 was worse. Conclusions Although hemorrhage after obliteration did not occur in this series, patients remained at risk during the latency interval until obliteration occurred. Thirty-eight percent of the patients who had neurological deficits due to prior hemorrhage improved. Higher dose delivery in association with conformal and highly selective SRS is required for safe and effective radiosurgery.

Stereotactic radiosurgery for arteriovenous malformations, Part 2: management of pediatric patients

2012 ◽  
Vol 9 (1) ◽  
pp. 1-10 ◽  
Author(s):  
Hideyuki Kano ◽  
Douglas Kondziolka ◽  
John C. Flickinger ◽  
Huai-che Yang ◽  
Thomas J. Flannery ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Arteriovenous Malformations ◽  
Radiation Effects ◽  
Pediatric Patients ◽  
Cyst Formation ◽  
Target Volume ◽  
Brain Regions ◽  
Neurological Deficits ◽  
Maximum Diameter ◽  
Latency Interval

Object The authors conducted a study to define the long-term outcomes and risks of stereotactic radiosurgery (SRS) for pediatric arteriovenous malformations (AVMs). Methods Between 1987 and 2006, the authors performed Gamma Knife surgery in 996 patients with brain AVMs; 135 patients were younger than 18 years of age. The median maximum diameter and target volumes were 2.0 cm (range 0.6–5.2 cm) and 2.5 cm3 (range 0.1–17.5 cm3), respectively. The median margin dose was 20 Gy (range 15–25 Gy). Results The actuarial rates of total obliteration documented by angiography or MR imaging at 71.3 months (range 6–264 months) were 45%, 64%, 67%, and 72% at 3, 4, 5, and 10 years, respectively. The median time to complete angiographically documented obliteration was 48.9 months. Of 81 patients with 4 or more years of follow-up, 57 patients (70%) had total obliteration documented by angiography. Factors associated with a higher rate of documented AVM obliteration were smaller AVM target volume, smaller maximum diameter, and larger margin dose. In 8 patients (6%) a hemorrhage occurred during the latency interval, and 1 patient died. The rates of AVM hemorrhage after SRS were 0%, 1.6%, 2.4%, 5.5%, and 10.0% at 1, 2, 3, 5, and 10 years, respectively. The overall annual hemorrhage rate was 1.8%. Larger volume AVMs were associated with a significantly higher risk of hemorrhage after SRS. Permanent neurological deficits due to adverse radiation effects developed in 2 patients (1.5%) after SRS, and in 1 patient (0.7%) delayed cyst formation occurred. Conclusions Stereotactic radiosurgery is a gradually effective and relatively safe management option for pediatric patients in whom surgery is considered to pose excessive risks. Although hemorrhage after AVM obliteration did not occur in the present series, patients remain at risk during the latency interval until obliteration is complete. The best candidates for SRS are pediatric patients with smaller volume AVMs located in critical brain regions.

Stereotactic radiosurgery for arteriovenous malformations, Part 6: multistaged volumetric management of large arteriovenous malformations

2012 ◽  
Vol 116 (1) ◽  
pp. 54-65 ◽  
Author(s):  
Hideyuki Kano ◽  
Douglas Kondziolka ◽  
John C. Flickinger ◽  
Kyung-Jae Park ◽  
Phillip V. Parry ◽  
...  
Keyword(s):  
Stereotactic Radiosurgery ◽  
Arteriovenous Malformations ◽  
Radiation Effects ◽  
Cyst Formation ◽  
Target Volume ◽  
Second Stage ◽  
Kaplan Meier ◽  
Minimum Margin ◽  
Risk Of Hemorrhage ◽  
Median Interval

Object The object of this study was to define the long-term outcomes and risks of arteriovenous malformation (AVM) management using 2 or more stages of stereotactic radiosurgery (SRS) for symptomatic large-volume lesions unsuitable for surgery. Methods In 1992, the authors prospectively began to stage the treatment of anatomical components to deliver higher single doses to AVMs with a volume of more than 10 cm3. Forty-seven patients with such AVMs underwent volume-staged SRS. In this series, 18 patients (38%) had a prior hemorrhage and 21 patients (45%) underwent prior embolization. The median interval between the first-stage SRS and the second-stage SRS was 4.9 months (range 2.8–13.8 months). The median target volume was 11.5 cm3 (range 4.0–26 cm3) in the first-stage SRS and 9.5 cm3 in the second-stage SRS. The median margin dose was 16 Gy (range 13–18 Gy) for both stages. Results In 17 patients, AVM obliteration was confirmed after 2–4 SRS procedures at a median follow-up of 87 months (range 0.4–209 months). Five patients had near-total obliteration (volume reduction > 75% but residual AVM). The actuarial rates of total obliteration after 2-stage SRS were 7%, 20%, 28%, and 36% at 3, 4, 5, and 10 years, respectively. The 5-year total obliteration rate after the initial staged volumetric SRS with a margin dose of 17 Gy or more was 62% (p = 0.001). Sixteen patients underwent additional SRS at a median interval of 61 months (range 33–113 months) after the initial 2-stage SRS. The overall rates of total obliteration after staged and repeat SRS were 18%, 45%, and 56% at 5, 7, and 10 years, respectively. Ten patients sustained hemorrhage after staged SRS, and 5 of these patients died. Three of 16 patients who underwent repeat SRS sustained hemorrhage after the procedure and died. Based on Kaplan-Meier analysis (excluding the second hemorrhage in the patient who had 2 hemorrhages), the cumulative rates of AVM hemorrhage after SRS were 4.3%, 8.6%, 13.5%, and 36.0% at 1, 2, 5, and 10 years, respectively. This corresponded to annual hemorrhage risks of 4.3%, 2.3%, and 5.6% for Years 0–1, 1–5, and 5–10 after SRS. Multiple hemorrhages before SRS correlated with a significantly higher risk of hemorrhage after SRS. Symptomatic adverse radiation effects were detected in 13% of patients, but no patient died as a result of an adverse radiation effect. Delayed cyst formation did not occur in any patient after SRS. Conclusions Prospective volume-staged SRS for large AVMs unsuitable for surgery has potential benefit but often requires more than 2 procedures to complete the obliteration process. To have a reasonable chance of benefit, the minimum margin dose should be 17 Gy or greater, depending on the AVM location. In the future, prospective volume-staged SRS followed by embolization (to reduce flow, obliterate fistulas, and occlude associated aneurysms) may improve obliteration results and further reduce the risk of hemorrhage after SRS.

Stereotactic radiosurgery for arteriovenous malformations, Part 3: outcome predictors and risks after repeat radiosurgery

2012 ◽  
Vol 116 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Hideyuki Kano ◽  
Douglas Kondziolka ◽  
John C. Flickinger ◽  
Huai-che Yang ◽  
Thomas J. Flannery ◽  
...  
Keyword(s):  
Mr Imaging ◽  
Stereotactic Radiosurgery ◽  
Arteriovenous Malformations ◽  
Radiation Effects ◽  
Cyst Formation ◽  
Target Volume ◽  
Volume Reduction ◽  
Factors Associated ◽  
Initial Procedure ◽  
Second Procedure

Object The object of this study was to evaluate the outcomes and risks of repeat stereotactic radiosurgery (SRS) for incompletely obliterated cerebral arteriovenous malformations (AVMs). Methods Between 1987 and 2006, Gamma Knife surgery was performed in 996 patients with AVMs. During this period, repeat SRS was performed in 105 patients who had incompletely obliterated AVMs at a median of 40.9 months after initial SRS (range 27.5–139 months). The median AVM target volume was 6.4 cm3 (range 0.2–26.3 cm3) at initial SRS but was reduced to 2.3 cm3 (range 0.1–18.2 cm3) at the time of the second procedure. The median margin dose at both initial SRS and repeat SRS was 18 Gy. Results The actuarial rate of total obliteration by angiography or MR imaging after repeat SRS was 35%, 68%, 77%, and 80% at 3, 4, 5, and 10 years, respectively. The median time to complete angiographic or MR imaging obliteration after repeat SRS was 39 months. Factors associated with a higher rate of AVM obliteration were smaller residual AVM target volume (p = 0.038) and a volume reduction of 50% or more after the initial procedure (p = 0.014). Seven patients (7%) had a hemorrhage in the interval between initial SRS and repeat SRS. Seventeen patients (16%) had hemorrhage after repeat SRS and 6 patients died. The cumulative actuarial rates of new AVM hemorrhage after repeat SRS were 1.9%, 8.1%, 10.1%, 10.1%, and 22.4% at 1, 2, 3, 5, and 10 years, respectively, which translate to annual hemorrhage rates of 4.05% and 1.79% of patients developing new post–repeat-SRS hemorrhages per year for Years 0–2 and 2–10 following repeat SRS. Factors associated with a higher risk of hemorrhage after repeat SRS were a greater number of prior hemorrhages (p = 0.008), larger AVM target volume at initial SRS (p = 0.010), larger target volume at repeat SRS (p = 0.002), initial AVM volume reduction less than 50% (p = 0.019), and a higher Pollock-Flickinger score (p = 0.010). Symptomatic adverse radiation effects developed in 5 patients (4.8%) after initial SRS and in 10 patients (9.5%) after repeat SRS. Prior embolization (p = 0.022) and a higher Spetzler-Martin grade (p = 0.004) were significantly associated with higher rates of adverse radiation effects after repeat SRS. Delayed cyst formation occurred in 5 patients (4.8%) at a median of 108 months after repeat SRS (range 47–184 months). Conclusions Repeat SRS for incompletely obliterated AVMs increases the eventual obliteration rate. Hemorrhage after obliteration did not occur in this series. The best results for patients with incompletely obliterated AVMs were seen in patients with a smaller residual nidus volume and no prior hemorrhages.

Gamma Knife surgery for arteriovenous malformations within or adjacent to the ventricles

2014 ◽  
Vol 121 (6) ◽  
pp. 1416-1423 ◽  
Author(s):  
Greg Bowden ◽  
Hideyuki Kano ◽  
Huai-che Yang ◽  
Ajay Niranjan ◽  
John Flickinger ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Arteriovenous Malformations ◽  
Radiation Effects ◽  
Target Volume ◽  
Gamma Knife Surgery ◽  
Neurological Deficits ◽  
University Of Pittsburgh ◽  
Complete Obliteration ◽  
Latency Interval ◽  
The University

Object The outcomes of stereotactic radiosurgery for arteriovenous malformations (AVMs) within or adjacent to the ventricular system are largely unknown. This study assessed the long-term outcomes and hemorrhage risks for patients with AVMs within this region who underwent Gamma Knife surgery (GKS) at the University of Pittsburgh. Methods The authors retrospectively identified 188 patients with ventricular-region AVMs who underwent a single-stage GKS procedure during a 22-year interval. The median patient age was 32 years (range 3–80 years), the median target volume was 4.6 cm3 (range 0.1–22 cm3), and the median marginal dose was 20 Gy (range 13–27 Gy). Results Arteriovenous malformation obliteration was confirmed by MRI or angiography in 89 patients during a median follow-up of 65 months (range 2–265 months). The actuarial rates of total obliteration were 32% at 3 years, 55% at 4 years, 60% at 5 years, and 64% at 10 years. Higher rates of AVM obliteration were obtained in the 26 patients with intraventricular AVMs. Twenty-five patients (13%) sustained a hemorrhage during the initial latency interval after GKS, indicating an annual hemorrhage rate of 3.4% prior to AVM obliteration. No patient experienced a hemorrhage after AVM obliteration was confirmed by imaging. Permanent neurological deficits due to adverse radiation effects developed in 7 patients (4%). Conclusions Although patients in this study demonstrated an elevated hemorrhage risk that remained until complete obliteration, GKS still proved to be a generally safe and effective treatment for patients with these high-risk intraventricular and periventriclar AVMs.

scholarly journals Stereotactic radiosurgery for arteriovenous malformations of the postgeniculate visual pathway

2015 ◽  
Vol 122 (2) ◽  
pp. 433-440 ◽  
Author(s):  
Greg Bowden ◽  
Hideyuki Kano ◽  
Ellen Caparosa ◽  
Daniel Tonetti ◽  
Ajay Niranjan ◽  
...  
Keyword(s):  
Visual Field ◽  
Stereotactic Radiosurgery ◽  
Arteriovenous Malformations ◽  
Latency Period ◽  
Visual Pathway ◽  
Target Volume ◽  
Visual Deficit ◽  
Study Interval ◽  
Actuarial Risk ◽  
Latency Interval

OBJECT A visual field deficit resulting from the management of an arteriovenous malformation (AVM) significantly impacts a patient's quality of life. The present study was designed to investigate the clinical and radiological outcomes of stereotactic radiosurgery (SRS) performed for AVMs involving the postgeniculate visual pathway. METHODS In this retrospective single-institution analysis, the authors reviewed their experience with Gamma Knife surgery for postgeniculate visual pathway AVMs performed during the period between 1987 and 2009. RESULTS During the study interval, 171 patients underwent SRS for AVMs in this region. Forty-one patients (24%) had a visual deficit prior to SRS. The median target volume was 6.0 cm3 (range 0.4–22 cm3), and 19 Gy (range 14–25 Gy) was the median margin dose. Obliteration of the AVM was confirmed in 80 patients after a single SRS procedure at a median follow-up of 74 months (range 5–297 months). The actuarial rate of total obliteration was 67% at 4 years. Arteriovenous malformations with a volume < 5 cm3 had obliteration rates of 60% at 3 years and 79% at 4 years. The delivered margin dose proved significant given that 82% of patients receiving ≥ 22 Gy had complete obliteration. The AVM was completely obliterated in an additional 18 patients after they underwent repeat SRS. At a median of 25 months (range 11–107 months) after SRS, 9 patients developed new or worsened visual field deficits. One patient developed a complete homonymous hemianopia, and 8 patients developed quadrantanopias. The actuarial risk of sustaining a new visual deficit was 3% at 3 years, 5% at 5 years, and 8% at 10 years. Fifteen patients had hemorrhage during the latency period, resulting in death in 9 of the patients. The annual hemorrhage rate during the latency interval was 2%, and no hemorrhages occurred after confirmed obliteration. CONCLUSIONS Despite an overall treatment mortality of 5%, related to latency interval hemorrhage, SRS was associated with only a 5.6% risk of new visual deficit and a final obliteration rate close to 80% in patients with AVMs of the postgeniculate visual pathway.

Stereotactic radiosurgery for arteriovenous malformations, Part 4: management of basal ganglia and thalamus arteriovenous malformations

2012 ◽  
Vol 116 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Hideyuki Kano ◽  
Douglas Kondziolka ◽  
John C. Flickinger ◽  
Huai-che Yang ◽  
Thomas J. Flannery ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Stereotactic Radiosurgery ◽  
Arteriovenous Malformations ◽  
Radiation Effects ◽  
Latency Period ◽  
Target Volume ◽  
Neurological Deficits ◽  
Maximum Diameter ◽  
Lower Margin ◽  
Factors Associated

Object The authors conducted a study to define the long-term outcomes and risks of stereotactic radiosurgery (SRS) for arteriovenous malformations (AVMs) of the basal ganglia and thalamus. Methods Between 1987 and 2006, the authors performed Gamma Knife surgery in 996 patients with brain AVMs; 56 patients had AVMs of the basal ganglia and 77 had AVMs of the thalamus. In this series, 113 (85%) of 133 patients had a prior hemorrhage. The median target volume was 2.7 cm3 (range 0.1–20.7 cm3) and the median margin dose was 20 Gy (range 15–25 Gy). Results Obliteration of the AVM eventually was documented on MR imaging in 78 patients and on angiography in 63 patients in a median follow-up period of 61 months (range 2–265 months). The actuarial rates documenting total obliteration after radiosurgery were 57%, 70%, 72%, and 72% at 3, 4, 5, and 10 years, respectively. Factors associated with a higher rate of AVM obliteration included AVMs located in the basal ganglia, a smaller target volume, a smaller maximum diameter, and a higher margin dose. Fifteen (11%) of 133 patients suffered a hemorrhage during the latency period and 7 patients died. The rate of post-SRS AVM hemorrhage was 4.5%, 6.2%, 9.0%, 11.2%, and 15.4% at 1, 2, 3, 5, and 10 years, respectively. The overall annual hemorrhage rate was 4.7%. When 5 patients with 7 hemorrhages occurring earlier than 6 months after SRS were removed from this analysis, the annual hemorrhage rate decreased to 2.7%. Larger volume AVMs had a higher risk of hemorrhage after SRS. Permanent neurological deficits due to adverse radiation effects (AREs) developed in 6 patients (4.5%), and in 1 patient a delayed cyst developed 56 months after SRS. No patient died of AREs. Factors associated with a higher risk of symptomatic AREs were larger target volume, larger maximum diameter, lower margin dose, and a higher Pollock-Flickinger score. Conclusions Stereotactic radiosurgery is a gradually effective and relatively safe management option for deep-seated AVMs in the basal ganglia and thalamus. Although hemorrhage after obliteration did not occur in the present series, patients remain at risk during the latency interval between SRS and obliteration. The best candidates for SRS are patients with smaller volume AVMs located in the basal ganglia.

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