Radiosurgical Techniques and Clinical Outcomes of Gamma Knife Radiosurgery for Brainstem Arteriovenous Malformations

Objective

Brainstem arteriovenous malformation (AVM) is rare and radiosurgical management is complicated by the sensitivity of the adjacent neurological structures. Complete obliteration of the nidus is not always possible. We describe over 20 years of radiosurgical procedures for brainstem AVMs, focusing on clinical outcomes and radiosurgical techniques.

Methods

Between 1992 and 2011, the authors performed gamma knife radiosurgery (GKRS) in 464 cerebral AVMs. Twenty-nine of the 464 patients (6.3%) reviewed had brainstem AVMs. This series included sixteen males and thirteen females with a mean age of 30.7 years (range : 5-71 years). The symptoms that led to diagnoses were as follows : an altered mentality (5 patients, 17.3%), motor weakness (10 patients, 34.5%), cranial nerve symptoms (3 patients, 10.3%), headache (6 patients, 20.7%), dizziness (3 patients, 10.3%), and seizures (2 patients, 6.9%). Two patients had undergone a previous nidus resection, and three patients had undergone a previous embolization. Twenty-four patients underwent only GKRS. With respect to the nidus type and blood flow, the ratio of compact type to diffuse type and high flow to low flow were 17 : 12 and 16 : 13, respectively. In this series, 24 patients (82.8%) had a prior hemorrhage. The mean target volume was 1.7 cm³ (range 0.1-11.3 cm³). The mean maximal and marginal radiation doses were 38.5 Gy (range 28.6-43.6 Gy) and 23.4 Gy (range 18-27 Gy), and the mean isodose profile was 61.3% (range 50-70%).

Results

Twenty-four patients had brainstem AVMs and were followed for more than 3 years. Obliteration of the AVMs was eventually documented in 17 patients (70.8%) over a mean follow-up period of 77.5 months (range 36-216 months). With respect to nidus type and blood flow, the obliteration rate of compact types (75%) was higher than that of diffuse types (66.7%), and the obliteration rate of low flow AVMs (76.9%) was higher than that of high flow AVMs (63.6%) (p<0.05). Two patients (6.9%) with three hemorrhagic events suffered a hemorrhage during the follow-up period. The annual bleeding rate of AVM after GKRS was 1.95% per year. No adverse radiation effects or delayed cystic formations were found.

Conclusion

GKRS has an important clinical role in treatment of brainstem AVMs, which carry excessive surgical risks. Angiographic features and radiosurgical techniques using a lower maximal dose with higher isodose profiles are important for lesion obliteration and the avoidance of complications.     

Gamma Knife Radiosurgery for Ten or More Brain Metastases

Objective

This study was performed to assess the efficacy of GKS in patients with ten or more brain metastases.

Methods

From Aug 2002 to Dec 2007, twenty-six patients (13 men and 13 women) with ten or more cerebral metastatic lesions underwent GKS. The mean age was 55 years (32-80). All patients had Karnofsky performance status (KPS) score of 70 or better. According to recursive partitioning analysis (RPA) classification, 3 patients belonged to class I and 23 to class II. The location of primary tumor was lung (21), breast (3) and unknown (2). The mean number of the lesions per patient was 16.6 (10-37). The mean cumulated volume was 10.9 cc (1.0-42.2). The median marginal dose was 15 Gy (9-23). Overall survival and the prognostic factors for the survival were retrospectively analyzed by using Kaplan Meier method and univariate analysis.

Results

Overall median survival from GKS was 34 weeks (8-199). Local control was possible for 79.5% of the lesions and control of all the lesions was possible in at least 14 patients (53.8%) until 6 months after GKS. New lesions appeared in 7 (26.9%) patients during the same period. At the last follow-up, 18 patients died; 6 (33.3%) from systemic causes, 10 (55.6%) from neurological causes, and 2 (11.1%) from unknown causes. Synchronous onset in non-small cell lung cancer (p=0.007), high KPS score (≥80, p=0.029), and controlled primary disease (p=0.020) were favorable prognostic factors in univariate analysis.

Conclusion

In carefully selected patients, GKS may be a treatment option for ten or more brain metastases.     

伽玛刀治疗原发性三叉神经痛临床随访疗效分析

目的总结分析伽玛刀治疗原发性三叉神经痛（ITN）的效果。方法对132例ITN患者进行了伽玛刀治疗，随访77例，其中早期选择三叉神经根邻近半月节处照射治疗16例，后期选择三叉神经根人脑桥处（脑桥段）照射治疗6例；选用4mm单准直器照射56例，多准直器照射21例；照射中心剂量〈70Gy27例，70-90Gy50例。结果随访3～47个月，平均25．6个月，66例（85．7％）有效，其中完全缓解41例（53．2％），部分缓解25例（32．5％）；无效11例（14．3％）；出现相关并发症（面部麻木）13例（16．9％）。结论 伽玛刀治疗1TN有良好效果，是一种安全、成熟、副作用少的治疗技术。     

Gamma Knife radiosurgery in the management of brainstem metastases

Background

Metastases to the brainstem portend a poor prognosis and present a challenge in clinical management. Surgical resection is rarely a viable option.

Methods

Post-treatment MRI scans of patients with brainstem metastases treated with radiosurgery were used to determine local control and disease progression. Median survival was calculated using Kaplan–Meier analysis. Univariate and multivariate analyses were performed using log-rank test and Cox proportional hazards model, respectively.

Results

Thirty-two consecutive patients with brainstem metastasis underwent Gamma Knife radiosurgery. Median age was 50 years. Median tumor volume was 0.71 cm³ and median tumor margin dose was 13 Gy. Seventeen of 32 patients received WBRT prior to stereotactic radiosurgery. Median survival was 5.2 months. There was a statistically significant difference in survival based on RTOG recursive partition analysis (RPA) class. Median survival of patients categorized as RPA class I was 19.2 months, RPA class II was 8.4 months, and RPA class III was 1.9 months. The overall local tumor control rate was 87.5%. There were no acute complications following stereotactic radiosurgery and no evidence of radiation necrosis noted on post-treatment MRI scans.

Conclusion

Stereotactic radiosurgery is an effective treatment for brainstem metastases and should be considered especially for patients with good performance status.     

Retrospective Analysis on 76 Cases of Cerebral Arteriovenous Malformations Treated by Gamma Knife Radiosurgery

Objective

Outcome of gamma knife radiosurgery (GKS) in the consecutive 100 cases with cerebral arteriovenous malformations (AVMs) was analyzed.

Methods

Data from initial 100 patients treated with GKS in the authors'' institute were reviewed retrospectively. Spetzler-Martin grade at diagnosis were I in 18 patients, II in 27, III in 36, IV in 11, and V in 8. Thirty-five patients had experienced previous bleeding, 27 patients presented with seizure, and 31 patients presented with headache. The mean volume of the lesion was 4.3 cm³ (0.1-29.3 cm³). The median radiation dose delivered to the margin was 20.0 Gy (13-32 Gy). Mean follow-up period was 37.5 months (5-63 months).

Results

Angiographic follow-up was performed in 48 patients at least 2 years after GKS. Sixteen patients were lost in follow up following 2 years from GKS. Twenty-eight of 48 patients (58%) showed complete obliteration and 20 patients (42%) showed partial obliteration. Seven patients presented with post-GKS hemorrhage. Adverse radiation effect (ARE) was observed at follow-up MRI in 25 of 76 patients, and it was symptomatic in 5 patients. Complete obliteration was confirmed in 24 of 31 (77%) patients with volume less than 4 cm³, meanwhile only 4 of 17 (24%) patients with volume of 4 cm³ or more showed complete obliteration. Complete obliteration rate was 67% with 20 Gy or higher marginal dose, 63% with 15-20 Gy, and 17% with less than 15 Gy.

Conclusion

GKS can provide high rates of obliteration with acceptable risk of morbidity in a subgroup of small AVMs. However, overall outcome in whole spectrum of AVMs, in which large proportion of cases have unfavorable characteristics for radiosurgery, is much worse. More effective therapeutic strategy needs to be developed for large AVMs that are difficult to be managed with current available treatment modalities.     

伽玛刀在海绵窦脑膜瘤治疗中的价值

目的探讨伽玛刀在海绵窦脑膜瘤治疗中的效果。方法1997年至2004年间93例海绵窦脑膜瘤患者接受了伽玛刀治疗。其中57例有开颅手术史,36例为初发。治疗前肿瘤容积为1.3～128.6cm^3（平均24.18cm^3）,采用40%～60%（平均48%）的等剂量曲线,边缘剂量为7～18Gy（平均10.9Gy）,中心剂量为16～40Gy（平均22.5Gy）,等中心点为2～21个（平均8.7个）。结果本组93例患者获得36～78个月（平均43.7个月）的影像学随访,其中肿瘤消失12例（12.9%）,肿瘤缩小37例（39.8%）,肿瘤无明显变化26例（28.0%）,肿瘤增大18例（19.3%）,肿瘤总控制率为80.6%。结论对于累及海绵窦区的脑膜瘤,伽玛刀治疗手术风险小,并发症少,长期随访效果较好。     

Preliminary Report of Multisession Gamma Knife Radiosurgery for Benign Perioptic Lesions: Visual Outcome in 22 Patients

Objective

Radiosurgery may be contraindicated for lesions adjacent to the optic pathways because of the substantial risk of visual complication. Multisession radiosurgery has been tried as a compromise between single session radiosurgery and fractionated radiotherapy. The purpose of this study is to evaluate the outcomes of multisession gamma knife radiosurgery (GKRS) in 22 patients with perioptic lesions of benign pathology.

Methods

In all 22 cases, the lesions were within 1 mm of the optic apparatus and were therefore not considered suitable for single session radiosurgery. Radiation was delivered in 3 to 4 fractions with a median cumulated marginal dose of 20 Gy (range, 15-20 Gy).

Results

During a mean follow-up of 29 months (range, 14-44 months), tumor control was achieved in 21 patients. Visual function improved in 7 patients, remained unchanged in 14 patients, and deteriorated in 1 patient with tumor progression. No other complication was observed.

Conclusion

This preliminary result supports the idea that multisession GKRS may be an effective and safe alternative for treatment in perioptic lesions that are unsuitable for single session radiosurgery.     

巨大脑胶质瘤的分次伽玛刀治疗

目的 探讨巨大脑胶质瘤的分次γ刀治疗及其疗效。方法 巨大脑胶质瘤的γ刀治疗分两次或三次完成,每次间隔1d,分次照射的周边剂量为5～10 Gy。治疗效果通过MRI和临床表现综合评估。结果 随访3～33月,28例巨大脑胶质瘤分次γ刀治疗有效率为78.6％,2例病人γ刀术后出现迟发性脑水肿。治疗效果与肿瘤分化程度有关,而与肿瘤大小无关。结论 巨大脑胶质瘤分次γ刀治疗效果显著,但其远期疗效有待进一步的临床和实验观察。     

海绵窦区的肿瘤及伽玛刀治疗

目的 探讨各种海绵窦区肿瘤的诊断特点以及伽玛刀放射外科治疗的作用。方法 本文回顾性地分析我中心1994年至2000年底用Leksell伽玛刀治疗的175例累及海绵窦肿瘤的临床材料，其中90例（51．4％）患者有开颅手术史；总结了各种肿瘤的鉴别诊断及伽玛刀治疗的经验。结果 本组82．3％的病人随诊1－84个月，平均32．5个月。主要良性肿瘤的总有效率控制率达94．0％；3例因肿瘤再生长开颅手术治疗。伽玛刀治疗海绵窦转移瘤的近期疗效显著，患者平均1年后的死因皆非海绵窦病灶所致。结论 伽玛刀可以作为海绵窦区小型良性肿瘤，或手术后残存肿瘤的主要的治疗手段；对已造成神经功能障碍的海绵窦区的转移瘤，伽玛刀也被认为是重要的综合治疗方法之一。     

The Variable Ellipsoid Modeling Technique as a Verification Method for the Treatment Planning System of Gamma Knife Radiosurgery

Objective

The secondary verification of Leksell Gamma Knife treatment planning system (LGP) (which is the primary verification system) is extremely important in order to minimize the risk of treatment errors. Although prior methods have been developed to verify maximum dose and treatment time, none have studied maximum dose coordinates and treatment volume.

Methods

We simulated the skull shape as an ellipsoid with its center at the junction between the mammillary bodies and the brain stem. The radiation depths of the beamlets emitted from 201 collimators were calculated based on the relationship between this ellipsoid and a single beamlet expressed as a straight line. A computer program was coded to execute the algorithm. A database system was adopted to log the doses for 31×31×31 or 29,791 matrix points allowing for future queries to be made of the matrix of interest.

Results

When we compared the parameters in seven patients, all parameters showed good correlation. The number of matrix points with a dose higher than 30% of the maximal dose was within ± 2% of LGP. The 50% dose volume, which is generally the target volume, differs maximally by 4.2%. The difference of the maximal dose ranges from 0.7% to 7%.

Conclusion

Based on the results, the variable ellipsoid modeling technique or variable ellipsoid modeling technique (VEMT) can be a useful and independent tool to verify the important parameters of LGP and make up for LGP.     

累及眶内肿瘤的伽玛刀治疗

目的 总结累及眶内肿瘤的伽玛刀治疗效果.方法 共治疗累及眶内的肿瘤患者35例,随访25例(脑膜瘤16例,脑膜血管外皮细胞瘤3例,神经鞘瘤2例,腺样囊性癌2例,转移癌1例,血管纤维瘤1例),采取1.5T PHILIPS或3.0T GE磁共振2 mm薄层扫描定位,Kula或GammaPlan剂量计划系统.肿瘤平均体积2.91 cm3(0.17～19.50 cm3),平均周边剂量12.4 Gy(8～15 Gy),中心剂量26.7 Gy(16～32 Gy).结果 本组随访期为1-62个月,平均30.4个月,23例控制满意,总体控制率为92%;6例(24%)症状减轻,13例(52%)症状无改变,5例(20%)出现了一过性的新发或原有症状加重;2例肿瘤增大,其中1例因突眼加重而行手术治疗.结论 对于累及眶内的较小病变、或经手术治疗后残留、复发等不宜手术治疗的病例,伽玛刀治疗可作为综合治疗的重要手段.     

Growing Organized Hematomas Following Gamma Knife Radiosurgery for Cerebral Arteriovenous Malformation : Five Cases of Surgical Excision

Organized hematoma is a rare complication that can develop following gamma knife radiosurgery (GKS) for cerebral arteriovenous malformation (AVM). Here, we describe 5 patients with growing organized hematomas that developed from completely obliterated AVMs several years after GKS. The patients were 15, 16, 30, 36, and 38 years old at the time of GKS, respectively, and 3 patients were female. Four AVMs were located in the lobe of the brain, and the remaining AVM were in the thalamus. Between 2-12 years after GKS, patients developed progressive symptoms such intractable headache or hemiparesis and enhancing mass lesions were identified. Follow-up visits revealed the slow expansion of the hematomas and surrounding edema. Steroids were ineffective, and thus surgery was performed. Histology revealed organized hematomas with a capsule, but there was no evidence of residual AVMs or vascular malformation. After surgery, the neurological symptoms of all patients improved and the surrounding edema resolved. However, the hematoma continued to expand and intraventricular hemorrhage developed in 1 patient whose hematoma was only partially removed. GKS for cerebral AVM can be complicated by growing, organized hematomas that develop after complete obliteration. Growing hematomas should be surgically evacuated if they are symptomatic. Radical resection of the hematoma capsule is also strongly recommended.     

伽玛刀治疗脑干部位动静脉畸形

目的回顾性伽玛刀治疗脑干动静脉畸形(brainstemarteriovenous malformation,BAVM)的疗效。方法我院自2003年3月～2009年4月应用国产MASEP头部伽玛刀治疗脑干AVM30例。患者平均年龄为23.9岁(17～38岁)。22(73%)例患者首发症状为血管瘤出血。血管畸形部位:中脑18例、桥脑9例、延髓3例。AVM体积平均为3.5 ml(0.5～7 ml)。采用核磁共振加数字减影血管造影(MRI+DSA)检查及联合定位。边缘计量12～18Gy,平均15.5Gy,45%～50%(平均48.5%)的等剂量曲线包绕脑干AVM病灶。治疗一年后经MRI及DSA复查,连续复查3年,如血管巢缩小不理想者,行复次治疗。结果随访时间12～64个月,平均28个月。使用较低剂量情况下,伽玛刀治疗脑干AVM具有较好的闭塞率;脑干AVM闭塞率与其体积、边缘计量有关。3年后随访:脑干AVM闭塞率为53.3%,年出血率为2.3%。伽玛刀治疗后大多数患者临床症状消失或改善,未出现神经功能障碍。结论伽玛刀是治疗脑干AVM安全、有效、低创的新方法,可以作为脑干AVM的首选治疗方法之一。     

伽玛刀治疗颅内软骨肉瘤四例报道及文献回顾

目的 探讨伽玛刀放射外科治疗颅内软骨肉瘤的临床疗效. 方法 回顾性分析天津医科大学第二医院神经外科伽玛刀中心自2004年11月至2012年1月收治的4例软骨肉瘤患者诊治过程.4例患者均行手术切除并经病理证实,其中男1例,女3例;年龄26～36岁,平均31.3岁.肿瘤体积0.6～25.4 cm3,平均13.8 cm3;边缘剂量15～20 Gy,平均17.3 Gy;中心剂量30～40 Gy,平均35 Gy;靶点数4～19个,平均10个.本组随访时间5～28个月,平均14.5个月. 结果 1例左侧乳突及颈静脉孔区患者及1例鞍区患者治疗后分别随访19个月、9个月,肿瘤未见增大,生存良好;1例右侧眶颅沟通患者随访28个月后复发,后两次行手术治疗,效果不佳,于伽玛刀治疗后56个月死亡;1例左侧鞍旁患者治疗后5个月肿瘤复发,伴脑积水,随后失访.4例均未出现任何与伽玛刀治疗相关的并发症. 结论 伽玛刀治疗定位精确度高,疗效可靠且对周围组织损伤小,可作为术后残留软骨肉瘤辅助治疗方法.     

Mask-based immobilization in Gamma Knife stereotactic radiosurgery

The Gamma Knife Icon (Elekta AB, Stockholm) is a cobalt-based stereotactic radiosurgery (SRS) unit to support the use of a thermoplastic mask in lieu of a rigid frame, using an onboard cone-beam CT (CBCT) and an intrafraction motion management system (IFMM). We retrospectively reviewed 124 patients treated with Gamma Knife SRS from January 2018 to December 2019 at our institution using a mask-based immobilization system. Patient and treatment characteristics were collected and summarized as well as interfraction shifts and treatment-related outcomes. This dataset includes 124 patients with an associated 358 intracranial tumors. Twenty-four patients presented with primary brain tumors, which included 14 meningiomas and 10 other histologies, with 100 patients having brain metastases. Sixty tumors were post-operative, while 298 were intact. The median dose for primary tumors was 25 Gy in 5 fractions. Median doses to metastases were 20 Gy in 1 fraction, 27 Gy in 3 fractions, and 25 Gy in 5 fractions. Median interfraction CBCT shifts were submillimeter. Median patient follow-up was 6.28 months. 91% of patients with metastases maintained local control. Our early clinical experience has demonstrated limited toxicity profiles and high patient tolerance, which suggests that mask-based Gamma Knife SRS provides a safe alternative option for frameless SRS. Patients with large target volumes where fractionation is preferred or with small target volumes in non-eloquent areas can be considered for this approach. Response rates are encouraging, and continued follow-up is necessary to investigate long-term control and survival.     

脑内海绵状血管瘤的伽玛刀治疗(附85例报告)

目的评价脑内海绵状血管瘤伽玛刀(γ-刀)治疗的效果。方法105例脑内海绵状血管瘤进行γ-刀治疗,病灶直径大小0.4￣1.8cm(平均1.2cm)。采用多个等中心照射,周边剂量12￣15Gy,平均13Gy,40%￣60%的等剂量曲线包绕病灶,中心剂量20￣30Gy,平均24Gy。85例获得随访。结果随访期6￣72个月(平均36个月)。5.8%(5/85)再出血;31%(26/85)病灶缩小,69%(59/85)无变化;20%(17/85)病灶周围脑水肿,经治疗后脑水肿明显减轻好转。50%(15/30)癫痫发作频率和程度减轻。41%(35/85)临床症状改善,40%(34/85)症状无明显改善,19%(16/85)症状加重,17.6%(15/85)经治疗后恢复,1例遗留明显肢体活动障碍。结论当海绵状血管瘤位于主要功能区或深部组织,手术风险极大时,可选择γ-刀治疗;控制周边剂量<15Gy,可以获得较好的疗效和较低的并发症。