Thrombosis and hemorrhage in the acute period following Gamma Knife surgery for arteriovenous malformation

Parietal Arteriovenous Malformation Mimicking Carotid-cavernous Fistula in Context of Sinus Thrombosis: Bidirectional or Unidirectional Relationship? Literature Review

Cortically located arteriovenous malformations (AVMs) constitute majority of brain AVMs. A common drainage is through respective cortical veins into superior sagittal or transverse sinuses. Through a case report and literature review, we discuss three issues: first, the anomalous drainage of a cortical AVM into an anterior orbital venous drainage system; second, the impact of this drainage on the clinical picture; and third, importantly, the bidirectional versus unidirectional relationship of AVM and old venous sinus thrombosis.

Brain Edema after Repeat Gamma Knife Radiosurgery for a Large Arteriovenous Malformation: A Case Report

Brain edema due to venous thrombosis following stereotactic radiosurgery for a cerebral arteriovenous malformation (AVM) has rarely been reported. We report a patient with a large AVM in the eloquent area, and brain edema developed in this area after repeat Gamma knife stereotactic radiosurgery (GKRS). An 18-year-old female presented with a 4-year-history of persistent headache. Magnetic resonance imaging and transfemoral carotid angiogram revealed a high-flow large AVM in the left parieto-occipital area. Brain edema developed and aggravated patient's symptoms after time-staged GKRS. The cause of edema was thought to be the failure of the surrounding venous channels to drain the venous flow from the normal brain and the drainage was hampered by the persistent shunt flow from the AVM, which was due to the thrombosis of one huge draining vein of the AVM. The microsurgical resection of the AVM nidus eliminated shunt flow and completely normalized the brain edema. Microsurgical resection of the AVM nidus completely normalized the brain edema due to thrombosis of a draining vein of an AVM develops after SRS.

Retrospective analysis of imaging techniques for treatment planning and monitoring of obliteration for gamma knife treatment of cerebral arteriovenous malformation

BACKGROUND

It has been well established that Gamma Knife radiosurgery (GKS) is an effective treatment for brain arteriovenous malformations (AVMs).

OBJECTIVE

To evaluate complete obliteration rates for magnetic resonance imaging (MRI)-based GKS treatment planning performed with and without angiography and to conduct a preliminary assessment of the utility of using pulsed arterial spin labeling (PASL) magnetic resonance (MR) perfusion imaging to confirm complete obliteration.

METHODS

Forty-six patients were identified who had undergone GKS without embolization with a minimum follow-up of 2 years. One group was planned with integrated stereotactic angiography and MR (spoiled gradient recalled) images obtained on the day of GKS. A second technique avoided the risk of arteriography by using only axial MR images. Beginning in 2007, PASL MR perfusion imaging was routinely performed as a portion of the follow-up MRI to assess the restoration of normal blood flow of the nidus and surrounding area.

RESULTS

The overall obliteration rate for the angiography/MRI group was 88.0% (29 of 33). Patients in the MRI-only group had an obliteration rate of 61.5% (8 of 13), with P=.092 with the Fisher exact test, which is not statistically significant. A Kaplan-Meier analysis was also not statistically significant (log rank test, P=.474). Four of 9 patients with incomplete obliteration on angiography also had shown residual abnormal blood flow on PASL imaging.

CONCLUSION

This retrospective analysis shows that treatment planning technique used in GKS does not play a role in the eventual obliteration of treated AVMs. PASL may have potential in the evaluation of AVM obliteration.

Repeated linac-based radiosurgery in high-grade cerebral arteriovenous-malformations (AVM) Spetzler-Martin grade III to IV previously treated with radiosurgery

BACKGROUND

Aim was to access outcome and toxicity of repeated linac-based radiosurgery in incompletely obliterated cerebral AVM.

PATIENTS AND METHODS

Between 1998 and 2008, 11 patients were treated with repeated radiosurgery. The median dose to the 80%-isodose was 15 Gy (range, 12-18 Gy). During initial radiosurgery the median dose was 18 Gy (range, 9-22 Gy).

RESULTS

The median time interval between initial radiosurgery and re-treatment was 9 years (range, 4-16 years). The median follow-up was 26 months (range, 2-115 months). Treatment response was seen in 8 patients (89%). Complete (partial) obliteration was achieved in 5 (3) patients (56%, 33%, respectively).The median time to complete obliteration was 26 months (range, 5-45 months). Pre-existing neurological symptoms improved in 2 patients (18%), were stable in 7 patients (64%) and worsened in 2 patients (18%). Prevalence of intracranial hemorrhage was 9% (1/11). Post-re-treatment intracranial hemorrhage rate was 2.7% (1/38 years at risk). During follow-up, no secondary malignancies or toxicity>grade III were observed.

CONCLUSION

Repeated linac-based radiosurgery in incompletely obliterated cerebral AVM is an effective treatment option with a high rate of treatment response and an acceptable risk for side effects. Marginal doses above 15 Gy might further improve the rate of complete obliterations.

Early rerupture of cerebral arteriovenous malformations: beware the progressive hemispheric swelling

While early rerupture of cerebral arteriovenous malformations (AVMs) may not be as rare as previously thought, its determinants and risk factors remain unknown. Impairment of the venous drainage of AVMs is a well known risk factor for rupture and has been linked with the development of perinidal cerebral edema. We propose that a significant proportion of early AVM reruptures are the result of post-hemorrhagic venous drainage impairment, which may manifest as refractory perihematomal edema. To support this hypothesis, an illustrative case of early AVM rerupture occurring 3 weeks following intracranial hemorrhage and heralded by progressive perinidal and perihematomal edema is presented. This finding should be viewed as a marker for unstable lesions with a high risk of imminent rerupture and should thus prompt a rapid definitive treatment for the AVM.