Venous Stenosis and Hemorrhage After Radiosurgery for Cerebral Arteriovenous Malformations

Risk for Hemorrhage the First 2 Years After Gamma Knife Surgery for Arteriovenous Malformations: An Update

BACKGROUND

Knowledge about the natural course of brain arteriovenous malformations (AVMs) have increased during the past 20 years, as has the number of AVMs treated, especially larger ones. It is thus timely to again analyze the risk for hemorrhage after Gamma Knife Surgery (GKS).

OBJECTIVE

To confirm or contradict conclusions drawn 20 years ago regarding factors that affect the risk for post-GKS hemorrhage.

METHODS

The outcome after GKS was studied in 5037 AVM patients followed for up to 2 years. The relation between post-treatment hemorrhage rate and a number of patient, AVM, and treatment parameters was analyzed. The results were also compared with the results from our earlier study.

RESULTS

The annual post-treatment hemorrhage rate was 2.4% the first 2 years after GKS. Large size, low treatment dose, and old age were independent risk factors for AVM hemorrhage. After having compensated for the factors above, peripheral AVM location and female sex, at least during their child bearing ages, were factors associated with a lower post-GKS hemorrhage rate.

CONCLUSION

Large AVMs (>5 cm 3 ) treated with low doses (≤16 Gy) had higher and small AVMs treated with high doses a lower risk for hemorrhage as compared with untreated AVMs. This was detectable within the first 6 months after GKS. No difference in hemorrhage rate could be detected for the other AVMs. Based on our findings, it is advisable to prescribe >16 Gy to larger AVMs, assuming that the risk for radiation-induced complications can be kept at an acceptable level.

Long-term outcomes of 170 brain arteriovenous malformations treated by frameless image-guided robotic stereotactic radiosurgery: Ramathibodi hospital experience

This study was conducted to report long-term outcomes of the frameless robotic stereotactic radiosurgery (SRS) for brain arteriovenous malformation (AVM) at Ramathibodi Hospital.Retrospective data of patients with brain AVM (bAVM), who underwent CyberKnife SRS (CKSRS) at Ramathibodi Hospital from 2009 to 2014, were examined. Exclusion criteria were insufficient follow-up time (<36 months) or incomplete information. Patients' demographics, clinical presentation, treatment parameters, and results were analyzed. Excellent outcome was defined as AVM obliteration without a new neurological deficit. Risk factors for achieving excellent outcome were assessed.From a total of 277 CKSRS treatments for bAVM during the 6 years, 170 AVMs in 166 patients met the inclusion criteria. One hundred and thirty-nine cases (81.76%) presented with hemorrhages from ruptured bAVMs. Almost two-thirds underwent embolization before radiosurgery. With the median AVM volume of 4.17 mL, three-quarters of the cohort had single-fraction CKSRS, utilizing the median prescribed dose of 15 Gray (Gy). In the multisession group (25.29%), the median prescribed dose and the AVM volume were 27.5 Gy and 22.3 mL, respectively. An overall excellent outcome, at a median follow-up period of 72.45 months, was observed in 99 cases (58.24%). Seven AVMs (4.12%) ruptured after CKSRS but 1 patient suffered a new neurological deficit. Two patients (1.18%) were classified into the poor outcome category but there were no deaths. Negative factors for excellent outcome, by multivariate regression analysis, were the male sex and multisession SRS delivery, but not age, history of AVM rupture, previous embolization, or AVM volume.Despite relatively larger bAVM and utilizing a lower prescribed radiation dose, the excellent outcome was within the reported range from previous literature. This study offers one of the longest follow-ups and the largest cohorts from the frameless image-guided robotic SRS community.

Brain Arteriovenous Malformations: The Role of Imaging in Treatment Planning and Monitoring Response

Brain arteriovenous malformations (AVMs) are characterized by shunting between pial arteries and cortical or deep veins, with the presence of an intervening nidus of tortuous blood vessels. These lesions present a therapeutic challenge, because their natural history entails a risk of intracranial hemorrhage, but treatment may cause significant morbidity. In this article, imaging features of AVMs on MR imaging and catheter angiography are reviewed to stratify the risk of hemorrhage and guide appropriate management. The angioarchitecture of AVMs may evolve over time, spontaneously or in response to treatment, necessitating ongoing imaging surveillance.

Haemorrhage rates of ruptured and unruptured brain arteriovenous malformation after radiosurgery: a nationwide population-based cohort study

OBJECTIVES

The present nationwide population-based cohort study aims to assess the effectiveness of gamma knife radiosurgery (GKS) on ruptured and unruptured brain arteriovenous malformations (AVMs) by evaluating the haemorrhage rates.

DESIGN

A nationwide, retrospective cohort study.

SETTING

Taiwan National Health Insurance Research Database (NHIRD).

PARTICIPANTS

An observational study of 1515 patients who were diagnosed with brain AVMs between 1997 and 2013 from the Taiwan NHIRD.

PRIMARY OUTCOME AND SECONDARY OUTCOME MEASURES

We performed a survival analysis using the Kaplan-Meier method. Multivariate Cox proportional hazards regression models were used to explore the relationship between treatment modalities (GKS vs non-GKS) and haemorrhage, adjusted for age and sex.

RESULTS

The GKS and non-GKS groups included 317 and 1198 patients, respectively. Patients in the GKS group (mean±SD, 33.08±15.48 years of age) tended to be younger than those in the non-GKS group (37.40±17.62) (p<0.001). The 15-year follow-up revealed that the rate of bleeding risk was lower in the GKS group than in the non-GKRS group (adjusted HR (aHR) 0.61; 95% CI 0.40 to 0.92). The bleeding risk of ruptured AVMs was significantly lower in GKS group than in the non-GKS group (aHR 0.34; 95% CI 0.19 to 0.62). On the other hand, the bleeding risk of unruptured AVMs was higher in the GKS group than in the non-GKS group (aHR 1.95; 95% CI 1.04 to 3.65). In the unruptured AVM group, the incidence of bleeding was significantly higher among patients in the GKS group that were of >40 years of age (aHR 3.21; 95% CI 1.12 to 9.14).

CONCLUSIONS

GKS is safe and it reduces the risk of haemorrhage in patients with ruptured AVMs. The administration of GKS to patients with unruptured AVMs who are above the age of 40 years old male might increase the risk of haemorrhage.

Cerebellar Arteriovenous Malformation Rupture Despite Apparent Angiographic Obliteration

BACKGROUND

Arteriovenous malformations (AVMs) can occur in all regions of the brain and spinal cord, with clinical consequences and risks varying by location. Delayed AVM rupture despite digital subtraction angiography-confirmed obliteration post-radiation is exceedingly rare.

CASE DESCRIPTION

To our knowledge, we present the first documented case of delayed hemorrhage associated with a cerebellar AVM 5 years after linear accelerator-based radiation in a man aged 31 years despite apparent angiographic obliteration.

CONCLUSIONS

Intracranial hemorrhage after radiosurgery in digital subtraction angiography-confirmed obliterated AVMs is rare, with limited understanding of risk factors, appropriate preventative management, and mechanisms of occurrence. This case serves to demonstrate the need for greater awareness of this rare complication, as well as the need for appropriate surveillance and management strategies.