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Ohadi MAD, Iranmehr A, Chavoshi M, Fatollahi MA, Aleyasin MS, Hadjipanayis CG. Stereotactic radiosurgery outcome for deep-seated cerebral arteriovenous malformations in the brainstem and thalamus/basal ganglia: systematic review and meta-analysis. Neurosurg Rev 2023; 46:148. [PMID: 37358733 DOI: 10.1007/s10143-023-02059-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 06/03/2023] [Accepted: 06/19/2023] [Indexed: 06/27/2023]
Abstract
Deep-seated unruptured AVMs located in the thalamus, basal ganglia, or brainstem have a higher risk of hemorrhage compared to superficial AVMs and surgical resection is more challenging. Our systematic review and meta-analysis provide a comprehensive summary of the stereotactic radiosurgery (SRS) outcomes for deep-seated AVMs. This study follows the guidelines set forth by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) Statement. We conducted a systematic search in December 2022 for all reports of deep-seated arteriovenous malformations treated with SRS. Thirty-four studies (2508 patients) were included. The mean obliteration rate in brainstem AVM was 67% (95% CI: 0.60-0.73), with significant inter-study heterogeneity (tau2 = 0.0113, I2 = 67%, chi2 = 55.33, df = 16, p-value < 0.01). The mean obliteration rate in basal ganglia/thalamus AVM was 65% (95% CI: 0.58-0.72) with significant inter-study heterogeneity (tau2 = 0.0150, I2 = 78%, chi2 = 81.79, df = 15, p-value < 0.01). The presence of deep draining veins (p-value: 0.02) and marginal radiation dose (p-value: 0.04) were positively correlated with obliteration rate in brainstem AVMs. The mean incidence of hemorrhage after treatment was 7% for the brainstem and 9% for basal ganglia/thalamus AVMs (95% CI: 0.05-0.09 and 95% CI: 0.05-0.12, respectively). The meta-regression analysis demonstrated a significant positive correlation (p-value < 0.001) between post-operative hemorrhagic events and several factors, including ruptured lesion, previous surgery, and Ponce C classification in basal ganglia/thalamus AVMs. The present study found that radiosurgery appears to be a safe and effective modality in treating brainstem, thalamus, and basal ganglia AVMs, as evidenced by satisfactory rates of lesion obliteration and post-surgical hemorrhage.
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Affiliation(s)
- Mohammad Amin Dabbagh Ohadi
- Departments of Pediatric Neurosurgery Children's Medical Center Hospital, Tehran University of Medical Sciences, Tehran, Iran
- Interdisciplinary Neuroscience Research Program, Tehran University of Medical Sciences, Tehran, Iran
| | - Arad Iranmehr
- Department of Neurosurgery, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran.
- Gammakinfe Radiosurgery Centre Hospital, Tehran University of Medical Sciences, Tehran, Iran.
| | - Mohammadreza Chavoshi
- Department of Radiology, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Amin Fatollahi
- Interdisciplinary Neuroscience Research Program, Tehran University of Medical Sciences, Tehran, Iran
| | - Mir Sajjad Aleyasin
- Interdisciplinary Neuroscience Research Program, Tehran University of Medical Sciences, Tehran, Iran
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Wang L. Letter: Stereotactic Radiosurgery Provides Long-Term Safety for Patients With Arteriovenous Malformations in the Diencephalon and Brainstem: The Optimal Dose Selection and Long-Term Outcomes. Neurosurgery 2023; 92:e41. [PMID: 36637287 DOI: 10.1227/neu.0000000000002278] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 10/06/2022] [Indexed: 01/14/2023] Open
Affiliation(s)
- Lesheng Wang
- Department of Neurosurgery, Zhongnan Hospital of Wuhan University, Wuhan, China
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Abstract
The treatment of arteriovenous malformations (AVMs) has evolved over the last 10 years. It is now possible to see that obliteration continues for up to 10 years and that the final obliteration rate may be between 85% and 90%. Improved imaging has made the treatment more efficient and has reduced the complications. It is possible to treat larger AVMs in a single session than was previously thought possible without increases in the complication rates. In addition, treatments of larger lesions can be staged. The use of 3D rotating angiography produces remarkable images which can be imported into GammaPlan. On the other hand efforts are ongoing to avoid the need for digital subtraction angiography, which would make the treatment a lot more comfortable.
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Affiliation(s)
- Jeremy C Ganz
- Department of Neurosurgery, Haukeland University Hospital, Bergen, Norway.
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Ai X, Xu J. The predictors of clinical outcomes in brainstem arteriovenous malformations after stereotactic radiosurgery. Medicine (Baltimore) 2021; 100:e26203. [PMID: 34087891 PMCID: PMC8183693 DOI: 10.1097/md.0000000000026203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 05/11/2021] [Indexed: 02/05/2023] Open
Abstract
The brainstem arteriovenous malformations (BS-AVMs) have a high morbidity and mortality and stereotactic radiosurgery (SRS) has been widely used to treat BS-AVMs. However, no consensus is reached in the explicit predictors of obliteration for BS-AVMs after SRS.To identify the predictors of clinical outcomes for BS-AVMs treated by SRS, we performed a retrospective observational study of BS-AVMs patients treated by SRS at our institution from 2006 to 2016. The primary outcomes were obliteration of nidus and favorable outcomes (AVM nidus obliteration with mRS score ≤2). For getting the outcomes more accurate, we also pooled the results of previous studies as well as our study by meta-analysis.A total of 26 patients diagnosed with BS-AVMs, with mean volume of 2.6 ml, were treated with SRS. Hemorrhage presentation accounted for 69% of these patients. Overall obliteration rate was 42% with mean follow-up of more than five years and two patients (8%) had a post-SRS hemorrhage. Favorable outcomes were observed in 8 patients (31%). Higher margin dose (>15Gy) was associated with higher obliteration (P = .042) and small volume of nidus was associated with favorable outcomes (P = .036). After pooling the results of 7 studies and present study, non-prior embolization (P = .049) and higher margin dose (P = .04) were associated with higher obliteration rate, in addition, the lower Virginia Radiosurgery AVM Scale (VRAS) was associated with favorable outcomes (P = .02) of BS-AVMs after SRS.In the BS-AVMs patients treated by SRS, higher margin dose (19-24Gy) and non-prior embolization were the independent predictors of higher obliteration rate. In addition, smaller volume of nidus and lower VRAS were the potential predictors of long-term favorable outcomes for these patients.
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Affiliation(s)
| | - Jianguo Xu
- Department of Neurosurgery, West China Hospital of Sichuan University, Chengdu, Sichuan, China
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Zaki Ghali MG, Kan P, Britz GW. Curative Embolization of Arteriovenous Malformations. World Neurosurg 2019; 129:467-486. [DOI: 10.1016/j.wneu.2019.01.166] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 01/15/2019] [Accepted: 01/17/2019] [Indexed: 10/27/2022]
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Sorenson TJ, Lanzino G, Flemming KD, Nasr DM, Chiu SY, Pollock BE, Brinjikji W. Clinical outcome of brainstem arteriovenous malformations after incomplete nidus obliteration. J Clin Neurosci 2019; 65:66-70. [PMID: 30885595 DOI: 10.1016/j.jocn.2019.03.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 03/08/2019] [Indexed: 11/18/2022]
Abstract
PURPOSE Brainstem arteriovenous malformations (AVMs) present a formidable therapeutic challenge, and a variety of surgical and non-surgical treatment strategies can be used to obliterate the AVM nidus, eliminating its risk of hemorrhage. However, complete obliteration of brainstem AVMs is often not possible. We aimed to investigate the natural history of brainstem AVMs with incomplete nidus obliteration after initial treatment. METHODS Data from consecutive patients who presented to our institution during the study period with a brainstem AVM and residual nidus after treatment were retrospectively reviewed. We evaluated patients for the incidence of AVM rupture and calculated the risk of rupture after treatment resulted in incomplete nidus obliteration. RESULTS A total of 14 patients were included, five of whom suffered rupture after incomplete nidus obliteration (36%). Annual risk of rupture was 4.9% (95% CI: 1.60-11.5) per patient over a median follow-up of 72 months. The most common treatment modality of these patients was SRS-alone (n = 6), and two (33%) patients who underwent this treatment later ruptured after 103 and 130 months. Of the five patients who ruptured after treatment, 80% had already ruptured once, and 80% had an intranidal and/or feeding artery aneurysm. CONCLUSIONS Brainstem AVMs with incomplete nidus obliteration are at high risk of future rupture. Patients with brainstem AVMs who have a residual nidus after treatment should be counselled about the risk of AVM rupture and be recommended to undergo close follow-up imaging studies to monitor the nidus.
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Affiliation(s)
- Thomas J Sorenson
- School of Medicine, University of Minnesota, Minneapolis, MN, USA; Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Giuseppe Lanzino
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA; Department of Radiology, Mayo Clinic, Rochester, MN, USA
| | | | - Deena M Nasr
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Shannon Y Chiu
- Department of Neurology, Mayo Clinic, Rochester, MN, USA
| | - Bruce E Pollock
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA
| | - Waleed Brinjikji
- Department of Neurologic Surgery, Mayo Clinic, Rochester, MN, USA; Department of Radiology, Mayo Clinic, Rochester, MN, USA.
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Endovascular Therapy for Brainstem Arteriovenous Malformations. World Neurosurg 2018; 125:481-488. [PMID: 30149173 DOI: 10.1016/j.wneu.2018.08.099] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 08/11/2018] [Accepted: 08/13/2018] [Indexed: 11/21/2022]
Abstract
Brainstem arteriovenous malformations (AVMs) represent ∼5% of all intracranial AVMs and carry a higher risk of hemorrhage than their supratentorial counterparts. There is a high and near-uniform mortality with initial and recurrent episodes of hemorrhage. Brainstem AVMs may also present symptomatically with focal neurologic deficits or hydrocephalus. Treatment is indicated for ruptured and symptomatic brainstem AVMs, as well as those possessing high-risk angioarchitectural features. Microsurgical resection and stereotactic radiosurgery are ideal therapeutic options when feasible. Embolization is most commonly used as adjunctive treatment before surgery or stereotactic radiosurgical irradiation. Preoperative embolization facilitates microsurgical resection and reduces intraoperative and postoperative hemorrhage rates. Use of embolization preradiosurgically helps to reduce nidal size, transforming a large lesion to a size amenable to radiosurgical intervention, increasing the probability of obliteration, decreasing procedural hemorrhage risk, stabilizing the lesion until radiotherapeutic effect achieves obliteration, and providing interval symptomatic resolution. Embolization may also be used effectively as stand-alone monotherapy for small lesions with 1 or 2 arterial feeders not supplying eloquent parenchyma. Although an extensive evidence base exists for clinical usefulness of stereotactic radiosurgery as monotherapy or in combination with other therapeutic modalities, only a few studies have reported specifically on obliteration and complication rates with monotherapeutic embolization in the treatment of brainstem AVMs. The potential role of embolization as monotherapy for brainstem AVMs is reviewed and discussed.
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Jin H, Liu Z, Chang Q, Chen C, Ge H, Lv X, Li Y. A challenging entity of endovascular embolization with ONYX for brainstem arteriovenous malformation: Experience from 13 cases. Interv Neuroradiol 2017; 23:497-503. [PMID: 28614989 PMCID: PMC5624407 DOI: 10.1177/1591019917711679] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Objective Brainstem arteriovenous malformations (AVMs) are rare lesions with a high risk of intracranial hemorrhage and are challenging to treat. We present our experience of endovascular embolization with Onyx in these aggressive lesions. Materials and methods Between 2007 and 2016, 13 patients with brainstem AVMs were embolized with Onyx at our center. Twelve patients presented with intracranial hemorrhage and one with headache. Retrospective examinations of patient demographics, clinical presentation, angiographic features, treatment modalities, postoperative complications and outcomes were carried out. Results The AVMs were in the midbrain in 10 patients (one anterior and nine posterior or dorsal), in the posterior pons in two and pontomedullary in one. Complete occlusion was achieved in three patients. Gamma knife radiosurgery was performed in six patients who were near-completely or partially embolized. Postoperative complications, including five cases of ischemia and one case of hemorrhage, resulted in four cases of neurological deterioration and two deaths. Clinical follow-up was obtained in 10 patients at a mean period of 45.2 months (range 3 to 93 months). During the follow-up, good clinical outcomes were observed in seven patients with posterior or dorsal midbrain AVMs, and one patient with a posterior pons AVM that was partially occluded died of intracranial hemorrhage. Conclusion Endovascular embolization for brainstem AVM with Onyx is a technical challenge and the reflux of Onyx may cause severe complications. Individualized treatment is needed based on the specific subtype of brainstem AVM.
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Affiliation(s)
- Hengwei Jin
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, China
- Beijing Engineering Research Center for Interventional Neuroradiology, China
| | - Zhan Liu
- Department of Neurosurgery, Traditional Chinese Medicine Hospital of Laiwu City, China
| | - Qing Chang
- Department of Neurosurgery, Weifang Yidu Hospital, Qingzhou, China
| | - Chang Chen
- Department of Neurosurgery, Xintai Hospital of Traditional Chinese Medicine, China
| | - Huijian Ge
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, China
- Beijing Engineering Research Center for Interventional Neuroradiology, China
| | - Xianli Lv
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, China
- Beijing Engineering Research Center for Interventional Neuroradiology, China
| | - Youxiang Li
- Department of Interventional Neuroradiology, Beijing Neurosurgical Institute and Beijing Tiantan Hospital, Capital Medical University, China
- Beijing Engineering Research Center for Interventional Neuroradiology, China
- Youxiang Li, Beijing Neurosurgical Institute, Beijing Tiantan Hospital, Capital Medical University, No. 6, Tiantan Xili, Dongcheng, Beijing, 100050, P.R. China.
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Abstract
OBJECTIVE To describe a unique case of an asymptomatic arteriovenous lesion of the internal auditory canal (IAC) and present the associated imaging findings. METHODS Retrospective case report and review of the literature. RESULTS A 55-year-old man presented for further evaluation of a left-sided sudden sensorineural hearing loss that occurred 8 years earlier. Careful review of outside serial magnetic resonance (MR) imaging revealed a contralateral, ill-defined right-sided IAC mass with low T2 signal and subtle peripheral enhancement on postcontrast T1-weighted sequencing. The patient had no history of right-sided otologic symptoms.Subsequent dedicated IAC MR imaging confirmed the presence of a space-occupying lesion adjacent to a complexity of vasculature. The presence of prominent flow voids, paucity of avid enhancement on previous studies, and marked signal within the lesion on time-of-flight MR angiography and MR venography was consistent with the diagnosis of a solitary arteriovenous lesion of the IAC. There was no radiological evidence of recent or remote parenchymal or subarachnoid hemorrhage or stroke. CONCLUSION We report a novel case of an occult asymptomatic IAC arteriovenous lesion. Vascular anomalies confined to the IAC are rare. To date, there have been only four reports in the literature of IAC arteriovenous lesions and our case is the first to present asymptomatically. A high index of suspicion and dedicated imaging is required to identify and accurately diagnose these lesions to guide appropriate counseling and potential intervention.
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Braileanu M, Yang W, Caplan JM, Lin LM, Radvany MG, Tamargo RJ, Huang J. Interobserver Agreement on Arteriovenous Malformation Diffuseness Using Digital Subtraction Angiography. World Neurosurg 2016; 95:535-541.e3. [PMID: 27565471 DOI: 10.1016/j.wneu.2016.08.051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 08/11/2016] [Accepted: 08/12/2016] [Indexed: 01/23/2023]
Abstract
BACKGROUND Arteriovenous malformation (AVM) diffuseness has been shown to be prognostic of treatment outcomes. We assessed interobserver agreement of AVM diffuseness among physicians of different specialty and training backgrounds using digital subtraction angiography (DSA). METHODS All research protocols were approved by the institutional review board for this retrospective chart review. In a single-blinded setting, 2 attending neurosurgeons, 1 attending interventional neuroradiologist, and 1 senior neurosurgical resident rated 80 DSA views of 36 AVMs as either compact or diffuse. Individual interobserver agreement and subgroup agreement were analyzed using κ agreement and intraclass correlation coefficient. RESULTS Disagreement regarding AVM diffuseness occurred in 43.8% of all DSA views (n = 80). Interobserver κ agreement on AVM diffuseness using DSA views among 4 physicians ranged from fair (κ = 0.40 [95% confidence interval (CI) = 0.22-0.58]) to substantial (κ = 0.65 [95% CI = 0.48-0.81]), whereas total intraclass correlation coefficient was 0.81 (95% CI = 0.73-0.87). For the 36 AVMs, κ agreement ranged from fair (κ = 0.36 [95% CI = 0.13-0.60]) to moderate (κ = 0.57 [95% CI = 0.35-0.79]), whereas intraclass correlation coefficient among all 4 physicians was 0.68 (95% CI = 0.47-0.82). Moderate agreement on AVM diffuseness (n = 80) was found between attending and resident assessments (κ = 0.57 [95% CI = 0.39-0.75]) and between neurosurgeon and interventional neuroradiologist assessments (κ = 0.55 [95% CI = 0.37-0.73]). CONCLUSIONS Agreement of individual physicians on AVM diffuseness varies from fair to substantial. Objective and three-dimensional measures of AVM diffuseness should be developed for consistent clinical application.
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Affiliation(s)
- Maria Braileanu
- Department of Radiology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Wuyang Yang
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Justin M Caplan
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Li-Mei Lin
- Department of Neurosurgery, University of California Irvine Medical Center, Orange, California, USA
| | - Martin G Radvany
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA; Department of Radiology, WellSpan York Hospital, York, Pennsylvania, USA
| | - Rafael J Tamargo
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Judy Huang
- Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
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Lai LF, Chen JX, Zheng K, He XY, Li XF, Zhang X, Wang QJ, Duan CZ, Chen M. Posterior fossa brain arteriovenous malformations. Clin Neuroradiol 2016; 28:17-24. [DOI: 10.1007/s00062-016-0514-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 04/11/2016] [Indexed: 11/28/2022]
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Crimmins M, Gobin YP, Patsalides A, Knopman J. Therapeutic management of cerebral arteriovenous malformations: a review. Expert Rev Neurother 2015; 15:1433-44. [PMID: 26567441 DOI: 10.1586/14737175.2015.1079129] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The therapeutic management of cerebral arteriovenous malformations has undergone significant change over the past 40 years. Embolization, radiosurgery, advanced imaging modalities, neuropsychological testing and advances in surgical technique has both significantly improved our ability to treat patients, as well as confounding the landscape as to what constitutes best medical practice. Variability in natural history provides additional challenges in that it is challenging to determine an accurate estimate of the risk of hemorrhage, morbidity and mortality. It is clear that the complexity of the treatment of these lesions demands a multidisciplinary approach. The need for a team of neurosurgeons, interventional and diagnostic neuroradiologists, neurologists, radiation oncologists and neuropsychologists will improve outcomes and aid in determining best therapy for patients.
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Affiliation(s)
- Michael Crimmins
- a Weill Cornell Medical Center - Neurosurgery , 525 East 68th Street Starr Pavilion, 10065 , NY , USA
| | - Y Pierre Gobin
- a Weill Cornell Medical Center - Neurosurgery , 525 East 68th Street Starr Pavilion, 10065 , NY , USA
| | - Athos Patsalides
- a Weill Cornell Medical Center - Neurosurgery , 525 East 68th Street Starr Pavilion, 10065 , NY , USA
| | - Jared Knopman
- a Weill Cornell Medical Center - Neurosurgery , 525 East 68th Street Starr Pavilion, 10065 , NY , USA
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Stereotactic radiosurgery for cavernous malformations: prejudice from ignorance. Acta Neurochir (Wien) 2015; 157:51-2. [PMID: 25391973 DOI: 10.1007/s00701-014-2269-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 10/29/2014] [Indexed: 10/24/2022]
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Matsunaga S, Shuto T. Long-term outcomes of gamma knife surgery for posterior fossa arteriovenous malformations. Neurol Med Chir (Tokyo) 2014; 54:799-805. [PMID: 24418791 PMCID: PMC4533388 DOI: 10.2176/nmc.oa.2013-0090] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The long-term outcomes of gamma knife surgery (GKS) in patients with posterior fossa arteriovenous malformations (AVMs) were retrospectively analyzed in 82 patients followed up for more than 5 years to evaluate the efficacy and safety. The median AVM volume at GKS was 0.95 cm3. The prescribed dose to the AVM margin was median 18 Gy with 1–18 isocenters. The actual complete AVM obliteration rate was 58.5% at 3 years and 78.0% at 5 years. The significant factors for higher complete obliteration rate were younger patient age and smaller maximum/minimum nidus diameter ratio. Two patients experienced hemorrhage caused by residual AVM rupture at 4 and 49 months. Twenty patients developed peri-nidal edema as an adverse radiation-induced reaction at median 13 months. One patient developed radiation-induced necrosis at 6.8 years. Neurological complication was observed in 12 patients and 6 patients remained with neurological dysfunction permanently. Larger nidus volume and location adjacent to an eloquent area significantly increased the risk of neurological complication. Pittsburgh radiosurgery-based AVM grading scale was significantly correlated with the outcome of neurological symptoms after GKS. GKS achieved acceptable and complete obliteration rate for posterior fossa AVM with relatively low risk of morbidity on neuroimaging and neurological symptoms for the long-term period after treatment. We recommend conformable and selective treatment planning to achieve both obliteration of the AVM nidus and preservation of neurological function.
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